TSH Blood Test: Normal Levels & Range

Thyroid-stimulating hormone (TSH) is considered to be the “master controller” of your thyroid. TSH stimulates your thyroid gland to produce the hormones thyroxine (T4) and triiodothyronine (T3), which control how fast your metabolism runs. Read on to find out how TSH works, why doctors order the TSH blood test, and whether your levels are within the normal range.

What is TSH (Thyroid-Stimulating Hormone)?

The “Master Controller” of Your Thyroid

Thyroid-stimulating hormone (TSH), also known as thyrotropin or thyrotrophin, is made by the pituitary gland. The pituitary secretes TSH into the bloodstream, through which it travels to the thyroid gland. The main purpose of TSH is to stimulate the thyroid gland to produce the main thyroid hormones: T4 (thyroxine) and T3 (triiodothyronine) [1, 2].

Since the thyroid needs TSH’s cue to produce hormones, TSH is often viewed as the “master controller” of thyroid function.

The thyroid gland is located at the base of your neck, below the Adam’s apple. It absorbs iodine from the blood to make T4 and T3 hormones [3].

The thyroid is important for your overall health because thyroid hormones play major roles in almost every part of the body, including the brain, heart, and liver. They control your metabolism, heart health, mood, and so much more [3].

TSH from the pituitary stimulates the thyroid gland to produce T4 and T3, which control how fast your metabolism runs.

Thyroid activity is controlled by the hypothalamus, which produces thyrotropin-releasing hormone (TRH) to tell the pituitary gland to make TSH, thereby causing the thyroid to produce more T4 and T3 when levels are low. If T4 and T3 levels are high, the hypothalamus reduces TRH production and thus, less TSH is made. This process helps keep T4 and T3 in balance [4].

So even though TSH works as the thyroid’s main switch, T4 and T3 can fine-tune it with the help of the hypothalamus. They do this to prevent their own levels from getting too high (or too low), which maintains balanced thyroid function.

High enough levels of T4 and T3 can decrease TSH.

How TSH Works

Thyroid-stimulating hormone increases T3 and T4 levels in several different ways.

First of all, TSH stimulates the production of T4 and T3 by binding to TSH receptors (TSH-R) on the thyroid gland. There it helps the thyroid make more proteins that absorb iodine from the bloodstream. The thyroid then uses iodine to make more T4 and T3 [5, 6].

Iodine can exist in different forms, and it can only be used to make T4 or T3 if it’s in the active form (oxidized). For this reason, TSH further boosts T4 and T3 production by increasing the protein that converts iodine into its active form (thyroid peroxidase) [7, 8].

Thyroid-stimulating hormone also stimulates the release of thyroid hormones into the bloodstream. When T4 and T3 are made, they are stored by binding with another protein (thyroglobulin), which keeps them from entering the bloodstream. TSH helps break down this protein (by increasing proteases), which allows T4 and T3 to be released [7, 9].

TSH helps the thyroid absorb more iodine to make thyroid hormones and then release them into the bloodstream.

TSH Blood Test

Why Doctors Order It

The TSH blood test measures the amount of thyroid-stimulating hormone (TSH) in the blood.

TSH is often the first test doctors use to determine whether you have too little (hypothyroidism) or, conversely, too much thyroid hormones (hyperthyroidism).

Because TSH controls T4 and T3 hormone levels, getting your TSH levels measured with a blood test can be helpful for determining how well your thyroid is functioning [10, 11].

High TSH levels can indicate an underactive thyroid, while low TSH levels can indicate an overactive thyroid. This is because when you have an underactive thyroid the thyroid hormones T4 and T3 are low, and so the pituitary gland responds by increasing TSH to stimulate T4 and T3 production. The opposite happens in the case of an overactive thyroid.

The timing of the TSH test can make a difference in the results because your TSH levels change naturally throughout the day (following a circadian rhythm). Studies show that TSH levels are highest at night and lowest during the afternoon [12, 13, 14, 15].

Your TSH levels also depend on the timing of your meals. Testing levels within 2 hours of a meal instead of in a fasted state can give lower TSH values [16].

However, looking at TSH levels alone can result in a misdiagnosis. If needed, doctors will order a thyroid panel that includes T4 (free T4) and T3 (free or total T3) levels for a more complete and accurate picture [17].

Doctors usually order the TSH blood test as part of a thyroid panel to determine how well your thyroid is working. High TSH levels point to an underactive thyroid, while low TSH levels signal an overactive thyroid.

Normal Levels & Range

TSH is usually measured in uIU/mL (micro-international units per milliliter), which is equivalent to mIU/L (mili-international units per liter). The normal range is 0.4-4.5 mIU/ml, though low-normal and high-normal levels may be suboptimal [18, 19, 20].

The normal range may slightly vary from lab to lab.

If you already have a thyroid disorder, your doctor may target a narrower TSH range.

By Age

TSH normally increases with age. That’s why some scientists think normal ranges should be different for different age groups.

While high levels of TSH are generally undesirable in children and adults, the opposite might be the case for the elderly. Some studies suggest that slightly higher TSH levels may be considered normal or even protective in older people, whereas lower TSH levels can cause problems [21, 22].

In fact, a number of studies have found that slightly higher TSH levels may be beneficial for living longer.

In a study of over 2k adults aged 70-79, those with slightly elevated TSH levels had less difficulty walking, were able to walk faster, and were in better shape than those with “normal” TSH levels. Plus, in a study of 558 adults from ages 85 to 89, higher TSH levels were associated with the lowest overall risk of dying [23, 24].

Higher TSH levels have been linked to longevity and better health in older people.

Learn More

This post is part of a three-part series about TSH.

Takeaway

TSH is a hormone produced by the pituitary that stimulates your thyroid to produce T4 and T3 hormones. Your doctor may order a TSH blood test to assess your thyroid health, often as part of a thyroid panel. Normal TSH levels are around 0.4-4.5 mIU/ml. If your TSH levels are high, you may have an underactive thyroid. On the other hand, low TSH levels can signal an overactive thyroid. TSH levels also normally increase with age and studies suggest that slightly higher TSH levels may be beneficial in older people.

Thyroid function tests – blood test for thyroid problems

On this page

What is being tested?

Thyroid function tests are used to check for a number of thyroid problems. The tests measure the amount of different hormones including thyroid stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3). Other tests on the thyroid include various antibodies related to thyroid tissue.

TSH is produced by the pituitary gland in the brain. TSH is carried in the blood to the thyroid gland, which sits at the front of the neck. From there, TSH influences how much T4 and T3 are released into the blood.

TSH, T3 and T4 levels can all be tested in the blood. Your doctor will probably test TSH first, then T3 and T4 if TSH is abnormal. Tests can also be used to measure antibodies to diagnose autoimmune thyroid disease.

Why would I need these tests?

The thyroid gland’s hormones help control some of your body’s metabolic processes, such as heart rate, blood pressure, body temperature and weight. Too much or too little of these hormones can make you ill.

You might need thyroid tests if:

• you have symptoms of hyperthyroidism (overactive thyroid) or hypothyroidism (underactive thyroid)
• you are taking some form of thyroid hormone replacement treatment
• you are female and being investigated for infertility

Very rarely, babies are born without a working thyroid gland. For this reason, all Australian newborns are screened for hypothyroidism with a TSH test using a drop of blood taken from a heel prick.

How to prepare for this test

No preparation is usually needed for this test. In many cases, it can be done at any time of the day without fasting, but do check with your doctor ahead of time. Also let your doctor know if you are taking any medications before the test.

Understanding your results

A high TSH result might mean:

• hypothyroidism
• that you are receiving too little thyroid hormone medication to treat hypothyroidism
• there might be a problem with your pituitary gland

A low TSH result might mean:

• hyperthyroidism
• you are taking too much thyroid hormone medication to treat hypothyroidism

Your doctor will be aware of your circumstances and can discuss what the results mean for you.

More information

About thyroid function testing

Lab Tests Online has more information about TSH, T4 and T3 tests.

About blood testing

Visit our ‘Guide to blood testing’ to learn more about blood tests in general with information such as:

• what to consider before having the test
• what happens during a blood test
• results accuracy
• blood tests cost

What is the role of third-generation thyroid-stimulating hormone (TSH) assays in the diagnosis of hypothyroidism, and how might biotin interfere with screening?

Sleepy, Stressed, or Sick? – The Atlantic

When I first suspected I was suffering from hypothyroidism, I did what any anxious, Internet-connected person would do and Googled “dysfunctional thyroid symptoms,” and, in another tab, “hypothyroid thinning hair??” for good measure.

What came up sounded like someone describing me for an intimately detailed police sketch:

• increased fatigue
• heightened sensitivity to cold
• unexplained weight gain
• dry skin
• muscle weakness
• a pale, puffy face (“Finally, a medical explanation for this,” I thought.)

This, combined with the fact that a close family member had recently been diagnosed with a thyroid disorder, sent me scurrying to the nearest endocrinologist’s office. They took a blood test, and two weeks later the results came back. Sure enough, the doctor said solemnly, I had hypothyroidism, which meant my thyroid was under-active. She would be starting me on thyroid medication. She couldn’t know for sure, but I might have to take drugs for the rest of my life.

I took the news well. This was, after all, exactly what I was hoping for—a pill that would act like kind of a Photoshop for real life, making me skinnier, more energetic, less puffy, and more moisturized practically overnight.

Just to be sure, though, I asked to see my blood test results. The document said I tested positive for Hashimoto’s thyroiditis, a condition in which the immune system attacks the thyroid. (Somehow knowing I have a disease named after someone made it seem worse.)

At the same time, the blood test showed I had normal levels of the thyroid hormones T3 and T4, which play a critical role in regulating metabolism.

The doctor said my levels of TSH, the thyroid stimulating hormone that tells the thyroid to make T3 and T4, were too high, however. A high TSH is the marker that most endocrinologists use to diagnose hypothyroidism. It means the pituitary gland is telling the thyroid, “Go, go! Work harder!” And the thyroid is saying, “Chilll man, I’m sooo sleepy.” Conversely, too little TSH means hyperthyroidism, or an over-active thyroid.

I studied my blood-work printout. My TSH levels were 3.5, which was, according to the lab, within the normal range of 0.35 to 5.5.

“This says the TSH is normal,” I said.

My doctor begged to differ.

“If you were pregnant or trying to get pregnant, we’d medicate you at 3.5,” she said.

“But I’m not trying to get pregnant,” I said.

“Well, a family doctor might not treat you for a 3.5, but an endocrinologist would. And that’s what we’re recommending,” she said firmly. I was to call her, she added, if the meds gave me tremors or if my hair started falling out.

I stammered, saying I didn’t really understand. I wasn’t sure I wanted to take a pill for the rest of my life to fix something that wasn’t technically broken. I mean, what if the side effects were worse than being slightly tired and puffy all the time?

“I don’t know if I’m ready for this!” I blurted, then realized I sounded like some sort of medicine-fearing anti-vaxer.

“Well, you don’t have to take it,” she said. “But it’s perfectly safe.”

She finally convinced me to take the prescription with me and think about whether I wanted to actually start on the drug.

“You know, you’re low on Vitamin D, too,” she added as I walked out the door. “You should really take a supplement. And don’t worry, it’s all natural.”

* * *

Elsewhere Artist Collaborative/Flickr

Little did I know that I had stumbled into one of the hottest controversies in endocrinology, one that touches on one of the most common diseases in the U.S. Twelve percent of Americans will develop some sort of thyroid disorder within their lifetimes, and levothyroxine, the drug used to treat hypothyroidism, is by some measures the second-most-frequently prescribed drug in the country. For some reason, thyroid disorders are exponentially more common in women than men. Hashimoto’s is hypothyroidism’s most common cause.

Many people—possibly up to 2 million—who have a thyroid disorder haven’t been diagnosed. Some might lack access to or money for doctors, but for many, it’s just that the symptoms of hypothyroidism are so vague. Who doesn’t feel tired, fat, and depressed sometimes?

“The symptoms of hypothyroidism are diverse and they mimic the symptoms of everyday life,” said Scott Isaacs, the medical director at the Atlanta Endocrine Associates in Georgia. “They could be the thyroid, but they could be something else.”

It’s the TSH levels that are the source of all the squabble among doctors. Most doctors agree that any TSH above 10, especially when combined with an abnormal T3 or T4 reading, should be treated. Many labs, like mine, consider a TSH reading above five or so to be abnormal.

However, some studies have found that only 5 percent of people have a TSH above 2. 5 (though others say it’s more like 15 percent). That is to say, being above 2.5 is statistically abnormal. And abnormalities are, by and large, how medicine decides what a disease is.

People like me, whose level falls between 2.5 and 4.5, have a higher risk of developing full-blown hypothyroidism over time. That suggests, to some doctors, that the upper TSH limit should actually be lower—like four, or maybe even 2.5, as my endocrinologist said. The problem is, a 10th of Americans have a TSH level between 2.5 and 4.5, by some estimates. It’s an awfully big step to suggest that an additional 30 million-some people belong on a medication for a condition they might never have heard of.

In 2004, a group of thyroid experts came together to figure out whether they should tweak the TSH range that should be considered normal. They concluded, essentially, that there’s no compelling evidence to treat people whose TSH is below 10.

This prompted widespread consternation among patients and some doctors. Hypothyroidism feels crappy; some patients with readings of six or seven might be begging to be put on medication.

“If our job as doctors is to make people feel better, I see no reason not to do it.”

“What’s normal for me may not be normal for you,” said one prominent thyroid activist, Mary Shomon, to the New York Times in the wake of the 2004 findings. “We’re patients, not lab values.”

Last month, researchers from Oregon Health and Science University performed another meta-analysis. In 10 years, they wondered, have any new thyroid studies come out and shown that there’s a benefit to treating people with so-called “subclinical” hypothyroidism?

Their findings, published last month in the Annals of Internal Medicine, confirmed the 2004 panel’s conclusion. If a person has a TSH reading between four and 10, the authors found, there’s no evidence that taking medication improves their quality of life or cognitive functioning. These individuals didn’t lose weight when they were medicated. The authors said the data on whether it might actually be harmful to take medications for this kind of mild hypothyroidism is too poor to come to any kind of conclusion.

There’s also no real downside to letting subclinical hypothyroidism go untreated. Some experts point to studies showing a higher prevalence of thyroid cancer among people with normal-yet-high TSH levels, but others say the connection is weak.

To Martin Surks, the program director of the endocrinology department at the Albert Einstein College of Medicine and chair of the 2004 panel, the two meta-analyses are a clear signal that endocrinologists shouldn’t be too eager to scribble levothyroxine prescriptions for patients without true hypothyroidism. He wouldn’t suggest treating a patient with Hashimoto’s, normal T4 and T3, and a slightly elevated TSH, for example. With numbers like those, a person only has a small chance of developing real hypothyroidism, he said.

Once a person goes on levothyroxine, he added, they usually take it for the rest of their lives. There’s a chance it could work too well—lower the TSH by too much and make the person jittery, anxious, or worse. “Such a situation is definitely associated with adverse health outcomes such as atrial fibrillation, osteoporosis, heart failure, and mortality,” Surks wrote in an email.

Plus, Isaacs told me, TSH levels might not be as iron-clad as some think. They can vary widely over the course of a few months, or even within a single day. “A lot of people who are three, they come back and they’re one the next time,” he said.

David Cooper, a professor in the division of endocrinology at the Johns Hopkins University School of Medicine, largely agreed, but he said some individual patients who don’t meet the clinical limit might still see improvements in their health with thyroid medication. Levothyroxine is just a hormone, after all—as far as pharmaceuticals go, that’s fairly harmless.

“Just because it doesn’t help 1,000 people on average, doesn’t mean that it won’t help an individual person,” he said. If a person is tired and cold all the time, and their TSH is four, why not treat them? “Many physicians would say to a patient, ‘We’ll give you a therapeutic trial and see how they feel in six months.’ If they feel better, great. If they don’t, then we’ll take them off the medication. It’s not a foreign substance, it’s the same stuff your own body makes.”

Cooper said he doesn’t have a TSH cutoff when deciding whether to treat patients. “Even if it’s between 2.5 and four, there might be somebody I would treat who has symptoms of hypothyroidism, and someone I wouldn’t, if they feel well,” he said. “If our job as doctors is to make people feel better, I see no reason not to do it.”

* * *

It’s amazing how even the slightest brush with hormonal drama can send a hardened skeptic wandering deep into pseudoscience land.

“I feel like all the stressors and toxins in my life are just inflaming it, you know?” I found myself saying to my boyfriend three or four times per evening. “All the crap that I’ve been eating because I’ve been too busy to cook. That’s not good for the thyroid.”

The thyroid is so mysterious. The clean-eating crowd likes to think you can help it along through intricate dietary strategies, as though all the quinoa and chia seeds will form a gentle poultice at the base of the neck and nurse the ailing gland back to health. The reason Gwyneth Paltrow eats so healthily, allegedly, is that she suffers from thyroid issues and “liver congestion.” Every other yoga class I attend involves some pose “that’s good for the thyroid.”

Others act like the thyroid is like a bald tire you have to be careful driving on: A few years ago Oprah claimed she “literally blew out my thyroid” by working too much. (In reality, you can’t really prevent hypothyroidism by eating or doing certain things. Like most things in life, luck and genes largely determine its fate).

“This whole topic of the thyroid is the biggest Internet-type thing that endocrinologists have to deal with,” Isaacs told me. “There’s a huge disconnect between what’s out there on blogs and the research.”

Cooper said sometimes the pressure to treat subclinical hypothyroidism comes from “angry patients who feel doctors don’t listen to them.”

When he said that, I immediately thought of Dana Trentini, otherwise known as “Hypothyroid Mom.” She’s a woman who feels that her hypothyroidism went under-treated for years by careless doctors, and now she advocates for better testing and treatment for people with thyroid issues. She’s immensely popular: Her blog gets 1.6 million monthly pageviews. She has a quarter-million followers on Facebook—more than The New Republic magazine.

I was initially wary because her blog promotes some dubious herbal remedies and treatments like oil pulling. But when I talked to her for this story, she came off as well-read and rational. More importantly, when it comes to her own case, she’s right.

Trentini was already taking medication for hypothyroidism when she got pregnant in 2009. When her doctor checked her TSH level, it would range from 5.6 and 8.6, she said—lower than the official hypothyroidism ceiling of 10. Her doctor told her the levels were normal, she says, and he kept her on the same dose of medication. Yet she felt terrible, tormented by crashing fatigue and cracking skin.

Twelve weeks into her pregnancy, Trentini miscarried.

What her doctor hadn’t picked up on, for whatever reason, is that pregnant women should have a lower TSH than other people—they are the ones the 2.5 limit is intended for. The experience left Trentini wracked with guilt and rage.

“I could feel that I was very ill, but I was the kind of person who believed doctor knows best,” she said. “I should have gotten a second or third opinion. I should have done something, but I didn’t. The blog began because I was angry with myself.”

Trentini went to see an alternative-medicine-oriented M.D., and she now takes a medication derived from pig thyroid and says she “feels fabulous. ” She said she’s heard from hundreds of women who have had multiple miscarriages, preterm births, stillbirths, and other problems they believe were caused by under-treated hypothyroidism.

Trentini thinks her doctor and others are reluctant to aggressively treat hypothyroidism because of a “lack of interest” in following the proper guidelines. Doctors I spoke with said, on the contrary, they are interested, but there are few good studies on subclinical hypothyroidism because so little research funding goes toward non-life-threatening diseases. Others say they’re just being cautious. Unless a patient is pregnant, “observation and retesting without prescribing medications is not ‘ignoring the problem,’” Isaacs said.

But there’s also a tendency, it seems, for hypothyroidism to be the disease some patients want to be diagnosed with. It’s a much more satisfying explanation for fatigue, weight gain, mental fog, and depression than are the countless mental illnesses that cause many of the same symptoms. People seek solvable problems; hypothyroidism is, at least, that.

“It’s always easier to prescribe a pill for someone versus saying, ‘you need to see a psychiatrist or have a sleep study,'” Isaacs said. If you can fix a problem with one pill, he said, “that’s the Holy Grail.”

Timing Your Thyroid Medications To Get Accurate Lab Results

posted: Apr. 19, 2018.

When To Take Thyroid Medications To Get Accurate Lab Results

I’ve been getting a lot of messages lately from people who began to feel hypothyroid after having their thyroid medications reduced based on a faulty lab interpretation. 

One lady began to lose her hair in clumps, and another became nearly bed-ridden! 

What all of these people had in common was that they were feeling great on a regimen of T4 and T3 medications, then found to have a low TSH (suggestive of hyperthyroidism or overdosing) on a monitoring test, which prompted their doctor to reduce their medications. Severe hyperthyroidism can be a life-threatening situation, and doctors worry about even slight hyperthyroidism due to its effects on the heart and bones.

Thyroid hormones are goldilocks hormones, meaning the dose has to be “just right” for us to feel optimal. Doses that are too high or too low can result in symptoms. 

Whenever I see a low TSH number in someone who is taking thyroid medications, my first question is always: “Did you take your thyroid medications before you had your thyroid labs drawn?” 

Depending on the type and timing of medication, a person’s TSH number may be inaccurate. 

How to get accurate thyroid lab results when taking medications.

When first initiating treatment with thyroid medications for hypothyroidism, guidelines generally recommend testing thyroid function about 4-6 weeks after the start of the treatment, to determine if the dose of medication is correct. It may be prudent to run these tests sooner, and more often, if the person was severely hypothyroid, hyperthyroid or experiencing symptoms of either.  

In addition to looking out for symptoms of hypothyroidism or hyperthyroidism, I also recommend lab testing to monitor. There are three main thyroid tests I recommend to measure your response to medications:

• TSH– This is a pituitary hormone that responds to low/high amounts of circulating thyroid hormone. In advanced cases of Hashimoto’s and primary hypothyroidism, this lab test will be elevated. In the case of Graves’ disease the TSH will be low. People with Hashimoto’s and central hypothyroidism may have a normal reading on this test. 

Slightly different rules apply to the timing of the lab draw based on the type of thyroid medication you are taking…

T4-Only Medications like Synthroid, Levoxyl, Tirosint and Levothyroxine:

T4 has a five to nine day long half-life, which means that once you have become stable on it, it will take as many as 9 days for 50% of the dose to clear the body. T4 has a slow and steady release and won’t produce many peaks or valleys that can make a person feel like they are on a thyroid rollercoaster.  

Whether you take T4 right before your lab tests, or haven’t taken it for up to 48 hours, your TSH value should be the same. Thus, you will get an accurate representation of your TSH value whether or not you take your T4 medication before a lab test.

Same goes for free T3 levels when you take a T4 medication. The free T3 level will also be relatively constant. Levels of free T4, however, will show a peak 2 hours after your T4 medication is given. 

So let’s say you take your medication at 8am, and have your blood test at 10am- your thyroid labs may show that your T4 is falsely elevated, and this may result in your doctor lowering your medication, when in reality, your T4 levels may be within range for the rest of the day.

In most cases, taking a T4 medication the morning before your lab test will not be an issue, as most doctors adjust the dosages according to the TSH, which stays stable after T4 dosing. However, to get a reading of your T4 levels that is reflective of most of the day, you would want to postpone your medication until after the lab test.

Combination Medication:

If you’re taking a combination medication that contains T3, like Armour, Nature-Throid, WP thyroid, compounded T4/T3 or the medication Cytomel (liothyronine), the timing of your tests really does matter, and may make a huge difference in getting you on an appropriate medication dose. This is because T3 has a half-life of only 18 hours to 3 days, depending on the person. In some, that’s less than a day for it to start rapidly declining in your body.

When scientists monitored the levels of TSH, free T3, and free T4 in people with hypothyroidism who were taking combination thyroid medications over a 24 hour period, they found that TSH levels may be falsely suppressed for 5 hours after taking a T3 containing medication. Right after taking a T3 containing medication, the TSH level begins to drop and stays suppressed for 5 hours. The TSH level then begins to increase again 5 hours after the dose, and continues to rise until 13 hours after the last dose, after which point it stays stable.

Free T3 levels are also affected, increasing after the dose is given and hitting a peak at 4 hours after dose.

This means that if you were to take your thyroid medication within 5 hours of getting your thyroid function tests done, your lab results may show that you are overdosed, even when you may be accurately dosed, or they may show your labs to be within normal limits, when you may actually be under-dosed.

Thus, it is usually best to postpone your combination medication until after you get your lab test done. I recommend getting your thyroid function tests done first thing in the morning, bringing your medications with you, and taking them right after you have your thyroid function tests to ensure that you get accurate test results. 

 **Please note, the half-life of the medications may vary per person, so some people may have a falsely suppressed TSH, even at the euthyroid state when taking T3 containing medications. 

This is when T3 and T4 testing will come in handy, as well as of course, looking out for symptoms of hypo- or hyperthyroidism. 

Reference

1. Saravanan P, Siddique H, Simmons DJ et al. Twenty-four hour hormone profiles of TSH, Free T3 and free T4 in hypothyroid patients on combined T3/T4 therapy. Exp Clin Endocrinol Diabetes 2007; 115(4): 261–267. 

Blood Test: Thyroid Stimulating Hormone (TSH)

Article Translations: (Spanish)

What It Is

A thyroid stimulating hormone (TSH) test is a common blood test used to evaluate how well the thyroid gland is working. The thyroid gland is located at the lower front of the neck. TSH is produced by the pituitary, a pea-sized gland located at the base of the brain.

When the thyroid gland isn’t producing enough thyroid hormone (a condition called hypothyroidism), the pituitary gland produces more TSH in an attempt to stimulate the thyroid and increase its production of thyroid hormones. If the pituitary gland isn’t functioning properly, it may produce too little TSH, and this can result in hypothyroidism as well.

If the thyroid gland is producing too much thyroid hormone (a condition called hyperthyroidism), the pituitary gland produces less TSH in an attempt to decrease the thyroid’s production of thyroid hormones.

Symptoms of hypothyroidism in children include tiredness or fatigue, dry skin, constipation, slow growth, and delayed pubertal development. Hyperthyroidism can cause unexpected weight loss, a rapid or irregular heartbeat, sweating, nervousness, and irritability.

In both hypothyroidism and hyperthyroidism, the child may develop a goiter — a lump in the neck due to enlargement of the thyroid gland. Both conditions are treatable.

Why It’s Done

TSH testing is used to:

• diagnose and monitor the treatment of a thyroid disorder
• help evaluate pituitary gland function

Your doctor may order a TSH test if your child has symptoms of hyperthyroidism or hypothyroidism, or shows signs of an enlarged thyroid gland. The TSH test also may be ordered at regular intervals to monitor the effectiveness of treatment if your child is being treated for a thyroid disorder.

TSH tests are routinely ordered for newborns in many states as part of the screening program to enable the prompt diagnosis and treatment of infants with congenital (present at birth) hypothyroidism.

Preparation

Your child doesn’t have to fast or limit activity before the test. However, some medications may affect test results. Check with your doctor to see if you should discontinue any medications until after the test. Extreme stress and acute or chronic illness also can affect TSH test results.

On the day of the test, it may help to have your child wear a T-shirt or short-sleeved shirt to allow easier access for the technician who will be drawing the blood.

Procedure

A health professional will usually draw the blood from a vein. For an infant, the blood may be obtained by puncturing the heel with a small needle (lancet). If the blood is being drawn from a vein, the skin surface is cleaned with antiseptic and an elastic band (tourniquet) is placed around the upper arm to apply pressure and cause the veins to swell with blood. A needle is inserted into a vein (usually in the arm inside of the elbow or on the back of the hand) and blood is withdrawn and collected in a vial or syringe.

After the procedure, the elastic band is removed. Once the blood has been collected, the needle is removed and the area is covered with cotton or a bandage to stop the bleeding. Collecting the blood for the test will only take a few minutes.

What to Expect

Collecting a blood sample is only temporarily uncomfortable and feels like a quick pinprick. Afterward, there may be some mild bruising, which should go away in a day or so.

Getting the Results

The blood sample will be processed by a machine. The results are commonly available within a day or two.

Whether your child’s results are high or low, an abnormal TSH usually indicates an excess or deficiency in the amount of thyroid hormone available to his or her body. It does not, however, indicate what the specific problem is. To determine the cause, your doctor will usually do additional testing, such as measurement of the blood levels of the hormones produced by the thyroid gland itself.

Risks

The TSH test is considered a safe procedure. However, as with many medical tests, some problems can happen with having blood drawn. These include:

• fainting or feeling lightheaded
• hematoma (blood accumulating under the skin causing a lump or bruise)
• pain associated with multiple punctures to locate a vein

Helping Your Child

Having a blood test is relatively painless. Still, many children are afraid of needles. Explaining the test in terms your child can understand might help ease some of the fear.

Allow your child to ask the technician any questions he or she might have. Tell your child to try to relax and stay still during the procedure, as tensing muscles and moving can make it harder and more painful to draw blood. It also may help if your child looks away when the needle is being inserted into the skin.

If You Have Questions

If you have questions about the TSH test procedure, speak with your doctor. You can also talk to the technician before the procedure.

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Thyroid Function Tests (TFTs) | Memorial Sloan Kettering Cancer Center

This information explains thyroid function tests (TFTs). 

Thyroid function tests are blood tests that let your doctor see if you have the right amount of thyroid hormone in your blood.

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Thyroid Stimulating Hormone (TSH)

Thyroid stimulating hormone (TSH) is made and released by a gland in your brain. This hormone stimulates your thyroid to work.

TSH levels

The level of TSH in your blood shows if your thyroid is too active or not active enough. If you don’t have a thyroid, your TSH level tells your doctor if you’re getting the right dose of thyroid hormone replacement medication.

The normal TSH range differs slightly from one lab to another. At Memorial Sloan Kettering (MSK), the normal range is 0.55 milli-international units per liter (mIU/L) to 4.78 mIU/L. Depending on the type of thyroid cancer you have, your doctor may want your TSH to be below the normal range. Talk to your doctor about your TSH levels.

You can write down your TSH goal below.

Your TSH goal is: _______________________

• If your TSH level is low, you’re in a state of hyperthyroidism. This means your thyroid function is too active.
• If your TSH level is high, you’re in a state of hypothyroidism. This means your thyroid function isn’t active enough.

In people without thyroid cancer, the goal is to keep their TSH level within the normal range.

In some people with thyroid cancer, the goal is to keep their TSH level below the normal range for the first couple of years after being diagnosed. This may lower the risk of the cancer coming back. Your doctor will tell you what level is right for you.

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Free Thyroxine (FT4)

Free Thyroxine (FT4) is another blood test that measures your thyroid function. It tells us how much “free” or available thyroid hormone you have in your blood. At MSK, the normal range for FT4 is 0.9 nanograms per deciliter (ng/dL) to 1.8 ng/dL.

• In people without thyroid cancer, the goal is to keep their FT4 level within the normal range.
• In people with thyroid cancer, the FT4 level may be near the upper limits of the normal range.

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Thyroglobulin

Thyroglobulin is a protein in the blood that your thyroid cells make. We measure your thyroglobulin level to help us monitor your cancer after treatment. If your thyroglobulin level rises, it could mean that you need more tests and follow-up care to be sure your cancer hasn’t returned.

If you have medullary thyroid cancer, other tests are also used to monitor your cancer. Your doctor or nurse will give you more information.

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Thyroid stimulating hormone (TSH)

Thyroid stimulating hormone (TSH) is the main regulator of thyroid function, synthesized by the pituitary gland, a small gland located on the lower surface of the brain. Its main function is to maintain a constant concentration of thyroid hormones – thyroid hormones that regulate the processes of energy production in the body. When their levels in the blood decrease, the hypothalamus releases a hormone that stimulates the secretion of TSH by the pituitary gland.

Russian synonyms

Thyroid stimulating hormone, thyrotropin, TTU.

Synonyms English

Thyroid-stimulating Hormone (THS), Thyrotropin.

Research method

Immunochemiluminescence analysis.

Detection range: 0.005 – 1000 μIU / ml.

Units

μIU / ml (micro-international unit per milliliter).

What biomaterial can be used for research?

Venous blood.

How to properly prepare for the study?

• Do not eat for 2-3 hours before the test (you can drink clean non-carbonated water).
• Avoid taking steroid and thyroid hormones 48 hours before the study (in consultation with your doctor).
• Eliminate physical and emotional stress 24 hours before the study.
• Do not smoke within 3 hours prior to examination.

General information about the study

Thyroid stimulating hormone (TSH) is produced by the pituitary gland, a small gland located on the lower surface of the brain behind the sinus cavity. It regulates the production of thyroid hormones (thyroxine and triiodothyronine) according to a “feedback system” that maintains a stable concentration of these hormones in the blood. With a decrease in the concentration of thyroid hormones, the secretion of thyroid-stimulating hormone increases and their production is stimulated by the thyroid gland, and vice versa – with an increase in the concentration of thyroxine and triiodothyronine, the secretion of thyroid-stimulating hormone decreases.Thyroid hormones are the main regulators of energy expenditure in the body, and maintaining their concentration at the required level is extremely important for the normal functioning of almost all organs and systems.

Dysfunction of the pituitary gland can cause an increase or decrease in the level of thyroid-stimulating hormone. With an increase in its concentration, thyroid hormones are released into the blood in abnormal quantities, causing hyperthyroidism. With a decrease in the concentration of thyroid-stimulating hormone, the production of thyroid hormones also decreases and symptoms of hypothyroidism develop.

The reasons for the violation of the production of thyroid-stimulating hormone can be diseases of the hypothalamus, which begins to produce increased or decreased amounts of thyroliberin – a regulator of TSH secretion by the pituitary gland. Diseases of the thyroid gland, accompanied by a violation of the secretion of thyroid hormones, can indirectly (through a feedback mechanism) affect the secretion of thyroid-stimulating hormone, causing a decrease or increase in its concentration in the blood. Thus, the study of TSH is one of the most important tests for hormones.

What is the research used for?

• To determine the state of the thyroid gland, indirectly assess the production of thyroid hormones.
• To control the therapy of thyroid diseases.
• For the diagnosis of thyroid dysfunction in newborns.
• For the diagnosis of female infertility and monitoring of its treatment.

When is the study scheduled?

1. With an enlarged thyroid gland, as well as with symptoms of hyper- and hypothyroidism.
   • Symptoms of hyperthyroidism:
     • heart palpitations,
     • increased anxiety,
     • weight loss,
     • insomnia,
     • hand shake,
     • weakness, fatigue,
     • diarrhea,
     • intolerance to bright light,
     • decrease in visual acuity,
     • puffiness around the eyes, their dryness, hyperemia, bulging.
   • Symptoms of hypothyroidism:
     • dry skin,
     • constipation,
     • cold intolerance,
     • edema,
     • hair loss,
     • weakness, increased fatigue,
     • violation of the menstrual cycle in women.

• At regular intervals, a test may be ordered to monitor the effectiveness of thyroid therapy. TSH levels are often assessed in newborns at risk for thyroid disease.

What do the results mean?

Reference values ​​(TSH norm):

The reasons for the increase in the concentration of thyroid-stimulating hormone:

• hypothyroidism (primary and secondary),
• pituitary tumor (thyrotropinoma, basophilic adenoma),
• Hashimoto’s thyroiditis,
• syndrome of unregulated TSH secretion,
• thyrotropin-secreting lung tumors,
• adrenal insufficiency,
• preeclampsia,
• lead poisoning,
• mental illness.

Reasons for a decrease in the concentration of thyroid-stimulating hormone:

• diffuse toxic goiter,
• TSH-independent thyrotoxicosis,
• thyrotoxic adenoma (Plummer’s disease),
• hyperthyroidism of pregnant women,
• autoimmune thyroiditis with manifestations of thyrotoxicosis,
• mental illness,
• cachexia.

An increase and decrease in the level of thyroid-stimulating hormone indicates violations in the regulation of the thyroid gland, however, it is often impossible to find out the exact cause of them by the level of TSH alone.Usually, for this, the level of thyroxine (T4) and triiodothyronine (T3) is additionally determined.

Take a blood test for TSH (Thyroid Stimulating Hormone)

Full name of the test: Thyroid stimulating hormone (TSH, thyrotropin, Thyroid Stimulating Hormone, TSH)

Research method: Chemiluminescent microfluoric acid analysis 9000

Thyroid stimulating hormone is produced by the pituitary gland and is involved in the regulation of the thyroid gland.The pituitary gland itself is located in the brain and does not act on organs and systems directly, it works through “intermediaries”, which are thyroxine and triiodothyronine. At the same time, the production of TSH is controlled by a hormone produced by the hypothalamus and biogenic amines, which are derivatives of ammonia.

A change in the level of thyroid-stimulating hormone affects the synthesis of active substances reproduced by the thyroid gland, which ultimately leads to the development of a large number of pathologies.

Deviations in the work of the pituitary gland often occur in women, therefore, this type of examination is prescribed for them more often than for the stronger sex. Determination of the level of TSH is usually carried out in conjunction with the determination of the level of thyroid hormones.

What the analysis shows

The analysis is carried out to assess the work of the pituitary gland and thyroid gland. Determination of the level of thyroid-stimulating hormone is necessary, since this active organic substance has the ability to influence many organs and systems.

With the help of an analysis for TSH, a number of pathologies can be suspected:

• threat of termination of pregnancy;
• disruption of the central nervous system;
• adrenal gland pathology;
• thyroiditis;
• pituitary tumor;
• thyroid tumor;
• toxic goiter;
• mental disorders, etc.

It is important to note that a single blood test does not make a diagnosis.The study helps to suspect abnormalities and to prescribe an additional examination to confirm the diagnosis. Therefore, the choice of analysis and its interpretation should be carried out by an endocrinologist.

Indications for analysis

The sampling of material for thyroid-stimulating hormone is carried out if the following deviations are suspected:

• pituitary gland pathology;
• violation of the cycle in women and infertility;
• thyroid pathology;
• in the presence of symptoms of heavy metal poisoning.

Patients with altered TSH levels often have the following symptoms:

• frequent depression;
• body temperature decreases for unknown reasons;
• in the absence of deviations from the myocardium, the heart rhythm is disturbed;
• with a small amount of work performed, the patient is very tired;
• muscle function deteriorates;
• disappearance of sexual desire;
• Hair loss in large numbers, most often resulting in baldness.;
• in men, a change in the level of the hormone leads to a decrease in potency.

As a rule, the study is prescribed by a doctor, based on the data obtained about the patient’s well-being.

Preparation for procedure

Analysis for TSH requires preliminary preparation; without this, data that really reflects the state of the body cannot be obtained.

Before taking blood, the patient will have to comply with the following recommendations:

• Refuse alcoholic beverages, including those with a low alcohol content.
• For a day, you will have to introduce a diet that excludes the use of fatty, spicy fried foods.
• The analysis should be submitted in a calm psycho-emotional state, therefore, even minimal stress will have to be avoided, especially on the day of the examination.
• The last meal on the eve of the study should take place no later than 8 pm.
• Blood must not be donated after ultrasound, computed tomography and fluorography.
• Any non-essential drugs should be discontinued.It is advisable to use these medicines as directed after blood sampling. If this is not possible, then the name of the drug and its dose are indicated on the direction.

If necessary, repeated sampling of material is allowed to clarify the results obtained. An indispensable condition for re-examination: blood should be taken at the same time as the previous sample.

Reasons for false results

Various external and internal factors can change the true values.First of all, the intake of certain drugs affects the volume of hormones.

Erroneous data can be obtained by improper collection and use of blood samples by medical personnel.

Pregnancy may affect the test result.

How is the analysis done

For research, venous blood is used. To determine the level of the hormone, an immunochemical technique is used. This method of examination is used not only to determine the level of TSH.

The convenience of this method lies in the fact that a special component is introduced into the material, which acts as a label. It forms an antigen-antibody compound, making it easy to detect and enumerate.

If an intravenous infusion of drugs was carried out shortly before the study, this hand should not be used to collect material. Doctors recommend taking blood from a vein in the other arm.

Interpretation of the result

It is important to understand that the interpretation of these studies is the prerogative of the attending physician.It is categorically impossible to use the information received for self-diagnosis and
self-treatment. The specialist makes an accurate diagnosis based on both the test data and by collecting information from the patient, using other sources, anamnesis, etc.
d.

Units of measurement in the Independent Laboratory: mU / l.

Alternative units of measurement: μU / ml = honey / L.

Unit conversion: μU / ml = honey / L.

Reference
values ​​

Estimated pregnancy limits:

• first
  trimester: 0.1-2.5 mU / l
• second trimester: 0.2-3.0 mU / l
• third trimester: 0.3-3.0 mU / l

Increasing values:

1.Primary type of hypothyroidism (iodine deficiency, autoimmune type of thyroiditis; hereditary hormone production defects, congenital
pathology of the thyroid organ, the consequences of the surgical removal of a part of the thyroid gland).

2. Subclinical type of hypothyroidism.

3. Subacute thyroiditis (convalescence period).

4. Ectopic release of TSH (tumors of the mammary gland, lungs).

5. TSH-secreting pituitary adenoma (in rare cases).

6.Somatic diseases in severe stages (recovery period).

7. Thyroid hormone resistance syndrome.

8. Oncological processes in the thyroid gland.

9. Taking drugs like: beta-blockers (metoprolol, atenolol, propranolol), antipsychotics (phenothiazine derivatives,
aminoglutethimide), X-ray contrast agents, clomiphene, amiodarone, iodine-containing drugs, antiemetics (motilium, metoclopramide), anticonvulsants
(carbamazepine, phenytoin), furosemide, lithium salts.

Derating:

1. Primary type of hyperthyroidism (diffuse goiter (toxic), multinodular (toxic) goiter, adenoma (toxic) thyroid nodules (functioning autonomously).

2. Subclinical type of hyperthyroidism.

3. With an autoimmune type of thyroiditis (transient thyrotoxicosis).

4. Iatrogenic (artificial hyperthyroidism).

5. Hyperthyroidism during pregnancy.

6. Secondary or pituitary type of hypothyroidism.

7. Fasting, diets,
stress.

8. Non-thyroid diseases of severe course.

9. Insufficiency of the hypothalamic-pituitary gland.

10. Tumor processes in
pituitary gland.

11. Itsenko-Cushing’s syndrome.

12. Reception of drugs such as: corticosteroids, thyroxine, dopamine, cytostatics, beta-adrenomimetics (dobutamine, dopexamine), somatostatin, drugs for therapy
hyperprolactinemia (piribedil, metergoline, bromocriptine), nifedipine, triiodothyronine, amiodarone, octreotide, heparin, acetylsalicylic acid preparations.

Tests for hormones for colds

Hormones are substances that are formed in a certain amount in the endocrine glands. Normal hormonal levels are necessary for the proper functioning of all body systems, especially the endocrine and reproductive systems. Determination of the concentration of hormones is prescribed for infertility, suspicion of hypo- or hyperfunction of the thyroid gland.

Many people wonder if it is possible to take tests for hormones for colds .Found that colds do not affect the test results. To obtain reliable data, it is important to meet the following conditions:

• Refuse from sports training and intense physical activity a few days before the visit to the clinic,
• do not drink alcoholic beverages within 48 hours before the procedure,
• no smoking for at least 2 hours before sampling biomaterial,
• to do a blood test on an empty stomach in the morning, in a state of complete calmness – psycho-emotional stress can affect the results of the test.

It will take from 1 to 14 days to obtain and process the results, depending on the concentration of which substance is to be determined. A complex of tests for hormones for colds can be taken while taking medications – antibiotics, anti-inflammatory drugs, immunomodulators. Do not forget to tell the technician which medications you are taking.

Hormonal research at Litekh

The Litech laboratory network offers a wide range of hormone tests.It is convenient to take tests with us – it is enough to pre-register and arrive at the appointed time. Research available on:

• LH and FSH,
• estradiol,
• progesterone,
• prolactin and macroprolactin,
• testosterone,
• thyroxine total and free,
• cortisol,
• insulin,
• serotonin,
• leptin and many other hormones.

It is recommended to take blood tests at:

• hirsutism,
• malfunctions of the menstrual cycle in women and impaired potency in men,
• decreased sex drive,
• miscarriage,
• metabolic syndrome,
• hypoglycemic conditions, etc.

Hormone test results are reliable even with a cold. To fully assess the characteristics of the hormonal background and identify a tendency to certain hereditary diseases, go through a comprehensive examination at Litekh and order a genetic health passport – male or female.

Sign up for research in any convenient way – through the Internet registration or by calling Litekh offices.

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Rules for the preparation and donation of blood for hormones – FSBI “NMITs TPM” of the Ministry of Health of Russia

1. On the eve of blood sampling for ELISA studies (hormones, tumor markers, autoimmune antibodies, etc.) it is necessary to exclude physical activity, stressful situations, physiotherapeutic procedures, taking medications (except in cases of drug treatment as prescribed by a doctor, when the decision to cancel drug treatment is made by the attending physician), taking oral contraceptives, drinking alcohol and fatty foods. Avoid smoking immediately before testing.
2. Standard blood sampling is performed in the morning, on an empty stomach (at least 8-12 hours after the last meal), in a treatment room, in a sitting or lying position, under physiological rest, from the cubital vein in compliance with the rules of asepsis and antiseptics …Patient must be allowed 15 minutes of rest before blood sampling
3. When examining the function of the thyroid gland during the period of treatment with drugs containing thyroid hormones, the study should be carried out 24 hours after the last dose of the drug. 2-3 days before taking blood, it is necessary to exclude the intake of preparations containing iodine.
4. When examining for PSA one week before the analysis, exclude any manipulations with the prostate gland.
5. When testing for ACTH, renin / angiotensin, blood sampling is recommended from 7 to 9 in the morning.The reference values ​​of these hormones are calculated for this particular time. Before taking blood, the patient must be at rest (sitting or lying) for at least 1 hour.
6. When testing for cortisol and aldosterone, blood should be drawn before 10 am.
7. When examining sex hormones for women of reproductive age, it is necessary to indicate in the direction the time and date of blood sampling, the day and phase of the menstrual cycle, during pregnancy, indicate the gestational age.
8. More informative are complex studies (several studies in one sample).
9. All blood tests for hormones for greater reliability and the ability to interpret the results are recommended to be performed not once, but in dynamics. Repeated studies are carried out at the same time of the day in 2-3 weeks. Analysis of the results of studies performed in dynamics is more informative both in diagnostic and prognostic terms.
10. If the study is carried out during the period of drug treatment, it is necessary to indicate in the direction the name of the drug and the time of the last dose.

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