Tsh results high: TSH (Thyroid-stimulating hormone) Test: MedlinePlus Medical Test

30.07.202311.06.2023 by alexxlab

Содержание

Low to high ranges, symptoms, and what they mean

The thyroid-stimulating hormone (TSH) test measures the amount of TSH in the blood. TSH levels convey how well a person’s thyroid is functioning.

Doctors can use TSH test results to diagnose thyroid disorders, such as hypothyroidism and hyperthyroidism.

The pituitary gland produces TSH, which is a hormone that stimulates the thyroid gland.

The thyroid is a butterfly-shaped gland in the throat. It produces hormones that help regulate many bodily functions, such as metabolism, heart rate, and body temperature.

This article describes the TSH test and results. We also discuss what high and low TSH levels indicate and available treatments.

Share on PinterestMNT-infographic_guide infographic by Diego Sabogal 1401179-TSH-levels-original

The normal range depends on a person’s age and whether they are pregnant.

The ranges tend to increase as a person gets older. Research has not shown a consistent difference in TSH levels between males and females.

However, according to the American Thyroid Association, doctors generally consider levels are within a normal range between 0.4–4.0 milliunits per liter (mU/l).

The following table provides estimates of TSH levels that are normal, low (indicating hyperthyroidism), and high (indicating hypothyroidism):

Hyperthyroidism	Normal	Mild hypothyroidism	Hypothyroidism
0–0.4	0.4–4	4–10	10

Many labs use these reference values.

However, there is some debate about these ranges. The author of a 2016 review suggests that normal levels are more likely to fall between 0.5–2.5 milli-international units (mIU) per milliliter.

Females are more likely to experience thyroid dysfunction than males. The Office on Women’s Health reports that 1 in 8 females experience thyroid problems at some point. This includes hyperthyroidism and hypothyroidism. The risk of thyroid problems increases during pregnancy and around menopause.

Research does not show a consistent difference in TSH levels between males and females. However, some evidence suggests that TSH levels are generally higher in females. For example, studies in 2020 investigating Chinese and French populations suggest that TSH levels are higher in females, but other factors, such as age, are more likely to affect TSH levels.

In some people, thyroid conditions are linked with sexual dysfunction. This may affect more males than females. According to a 2019 study, 59–63% of males with hypothyroidism also experience sexual dysfunction, compared with 22–46% of females who have hypothyroidism.

Blood TSH levels tend to increase as people get older, with evidence noting that hypothyroidism is the most common thyroid condition in people over 60 and steadily increases with age.

Research involving older adults suggests that roughly 7–14% of people may have TSH levels above the upper limit of reference ranges.

Pregnancy hormones naturally increase the levels of certain thyroid hormones in the blood. This is essential for the development of the fetal brain and nervous system.

At the same time, the levels of TSH in the blood decrease. As a result, doctors use lower reference ranges during pregnancy. The lower TSH range is decreased by around 0.4 mU/l, and the upper limit reduced by approximately 0.5 mU/l.

Levels of TSH in the blood increase gradually during the second and third trimesters, but they remain lower than normal levels in women who are not pregnant.

Doctors carefully monitor TSH levels throughout pregnancy. Having unusually high or low levels can affect the risk of miscarriage and cause pregnancy-related complications, such as:

preeclampsia
premature birth
low birth weight
congestive heart failure

TSH levels are highest at birth and gradually decrease as a child gets older. As such, TSH levels can vary among children. After the newborn phase, health experts may define mild hypothyroidism in children as TSH levels ranging between 4.5–10 mU/l.

The following table shows TSH levels for children by age, according to an older study using data from 512 healthy children:

Age	Reference ranges (mU/l)
Day of birth	3.84–11.75
1 month	1.18–3.57
1 year	1.17–3.55
5 years	1.15–3.47
12 years	1.09–3.31
18 years	1.05–3.16

High TSH levels indicate hypothyroidism. People develop hypothyroidism when their thyroid produces low levels of hormones.

When someone’s thyroid gland does not produce enough hormones, the pituitary gland produces more TSH to compensate.

Symptoms of hypothyroidism may include:

fatigue
weight gain
swelling of the face and neck
increased sensitivity to cold temperatures
dry skin
thinning hair
a slow heart rate
irregular or heavy menstrual periods
fertility problems
depression
constipation

Low TSH levels indicate hyperthyroidism. This is also known as an overactive thyroid.

If a person’s thyroid gland is secreting levels of hormones that are too high, the pituitary gland produces less TSH.

Symptoms of hyperthyroidism can include:

irregular or rapid heartbeat
muscle weakness
nervousness or irritability
difficulty sleeping
frequent bowel movements or diarrhea
weight loss
mood changes

The TSH test involves a healthcare professional drawing blood from a vein in the inner arm. They then send the blood sample for laboratory testing.

Usually, people do not need to prepare for a TSH test. However, if the doctor is checking the blood for more than one issue, a person may need to fast or prepare in another way. The doctor will provide this information beforehand.

A TSH test is often the best way to monitor thyroid function. However, if a person has abnormally high or low TSH levels, the doctor may need to perform at least one other diagnostic test to identify the underlying cause. These tests look at levels of specific thyroid hormones and antibodies.

In addition to age, sex, and pregnancy, many other factors can also affect TSH levels. Evidence suggests that genetic, environmental, or intrinsic factors can alter TSH levels. Some of these factors may include:

other conditions occurring at the same time
medications
supplements
ethnicity
diet and iodine status
time of day and time of year
autoantibodies and heterophilic antibodies
smoking
pollutants

Doctors can treat hypothyroidism with medications, such as levothyroxine, that replace the missing thyroid hormones.

A person should take this medication once a day or as prescribed. The doctor will monitor how well the treatment is working by running additional blood tests every few months.

According to the Food and Drug Administration (FDA), people should take levothyroxine once a day: in the morning and on an empty stomach, at least half an hour before eating.

The FDA also recommends that a person informs their doctor if they eat soybean flour, walnuts, dietary fiber, or cottonseed meal — these foods can affect how the body processes levothyroxine. Drinking grapefruit juice may also delay the absorption of levothyroxine.

Hyperthyroidism treatments focus on reducing thyroid hormone levels to prevent long-term health complications.

A person may need to take beta-blockers and antithyroid medications.

Another effective treatment is radioiodine therapy. This involves taking a capsule or liquid that contains radioactive iodine-131, which destroys cells that produce thyroid hormones. However, people who take radioiodine therapy may develop hypothyroidism in the future.

Surgical removal of the thyroid gland can treat severe hyperthyroidism. Doctors often reserve this for individuals who cannot take first-line medications and severe cases of hyperthyroidism.

A TSH test measures the amount of the hormone in the blood. Doctors can use the results to diagnose thyroid conditions, such as hypothyroidism and hyperthyroidism.

Normal TSH ranges can vary widely, depending on a person’s age, sex, and weight. Reference TSH ranges remain controversial, but for most people, the normal range falls between 0.4 and 4.0 mU/l.

Having an overactive or underactive thyroid can cause health issues that interfere with a person’s daily life. During pregnancy, unusually high or low TSH levels can lead to complications.

A doctor can provide more information about the TSH test and interpreting the results.

Low to high ranges, symptoms, and what they mean

The thyroid-stimulating hormone (TSH) test measures the amount of TSH in the blood. TSH levels convey how well a person’s thyroid is functioning.

Doctors can use TSH test results to diagnose thyroid disorders, such as hypothyroidism and hyperthyroidism.

The pituitary gland produces TSH, which is a hormone that stimulates the thyroid gland.

The thyroid is a butterfly-shaped gland in the throat. It produces hormones that help regulate many bodily functions, such as metabolism, heart rate, and body temperature.

This article describes the TSH test and results. We also discuss what high and low TSH levels indicate and available treatments.

Share on PinterestMNT-infographic_guide infographic by Diego Sabogal 1401179-TSH-levels-original

The normal range depends on a person’s age and whether they are pregnant.

The ranges tend to increase as a person gets older. Research has not shown a consistent difference in TSH levels between males and females.

However, according to the American Thyroid Association, doctors generally consider levels are within a normal range between 0.4–4.0 milliunits per liter (mU/l).

The following table provides estimates of TSH levels that are normal, low (indicating hyperthyroidism), and high (indicating hypothyroidism):

Hyperthyroidism	Normal	Mild hypothyroidism	Hypothyroidism
0–0. 4	0.4–4	4–10	10

Many labs use these reference values.

However, there is some debate about these ranges. The author of a 2016 review suggests that normal levels are more likely to fall between 0.5–2.5 milli-international units (mIU) per milliliter.

Blood TSH levels tend to increase as people get older, with evidence noting that hypothyroidism is the most common thyroid condition in people over 60 and steadily increases with age.

Research involving older adults suggests that roughly 7–14% of people may have TSH levels above the upper limit of reference ranges.

Pregnancy hormones naturally increase the levels of certain thyroid hormones in the blood. This is essential for the development of the fetal brain and nervous system.

Levels of TSH in the blood increase gradually during the second and third trimesters, but they remain lower than normal levels in women who are not pregnant.

Doctors carefully monitor TSH levels throughout pregnancy. Having unusually high or low levels can affect the risk of miscarriage and cause pregnancy-related complications, such as:

preeclampsia
premature birth
low birth weight
congestive heart failure

The following table shows TSH levels for children by age, according to an older study using data from 512 healthy children:

Age	Reference ranges (mU/l)
Day of birth	3.84–11.75
1 month	1.18–3.57
1 year	1.17–3.55
5 years	1.15–3.47
12 years	1. 09–3.31
18 years	1.05–3.16

High TSH levels indicate hypothyroidism. People develop hypothyroidism when their thyroid produces low levels of hormones.

When someone’s thyroid gland does not produce enough hormones, the pituitary gland produces more TSH to compensate.

Symptoms of hypothyroidism may include:

fatigue
weight gain
swelling of the face and neck
increased sensitivity to cold temperatures
dry skin
thinning hair
a slow heart rate
irregular or heavy menstrual periods
fertility problems
depression
constipation

Low TSH levels indicate hyperthyroidism. This is also known as an overactive thyroid.

If a person’s thyroid gland is secreting levels of hormones that are too high, the pituitary gland produces less TSH.

Symptoms of hyperthyroidism can include:

irregular or rapid heartbeat
muscle weakness
nervousness or irritability
difficulty sleeping
frequent bowel movements or diarrhea
weight loss
mood changes

The TSH test involves a healthcare professional drawing blood from a vein in the inner arm. They then send the blood sample for laboratory testing.

other conditions occurring at the same time
medications
supplements
ethnicity
diet and iodine status
time of day and time of year
autoantibodies and heterophilic antibodies
smoking
pollutants

Doctors can treat hypothyroidism with medications, such as levothyroxine, that replace the missing thyroid hormones.

A person should take this medication once a day or as prescribed. The doctor will monitor how well the treatment is working by running additional blood tests every few months.

According to the Food and Drug Administration (FDA), people should take levothyroxine once a day: in the morning and on an empty stomach, at least half an hour before eating.

Hyperthyroidism treatments focus on reducing thyroid hormone levels to prevent long-term health complications.

A person may need to take beta-blockers and antithyroid medications.

Surgical removal of the thyroid gland can treat severe hyperthyroidism. Doctors often reserve this for individuals who cannot take first-line medications and severe cases of hyperthyroidism.

A TSH test measures the amount of the hormone in the blood. Doctors can use the results to diagnose thyroid conditions, such as hypothyroidism and hyperthyroidism.

Normal TSH ranges can vary widely, depending on a person’s age, sex, and weight. Reference TSH ranges remain controversial, but for most people, the normal range falls between 0.4 and 4.0 mU/l.

Having an overactive or underactive thyroid can cause health issues that interfere with a person’s daily life. During pregnancy, unusually high or low TSH levels can lead to complications.

A doctor can provide more information about the TSH test and interpreting the results.

SM-Clinic endocrinologist spoke about thyroid hormones

Thyroid diseases are often associated with hormonal imbalance. Let’s find out why thyroid hormones are needed and what problems can arise if their amount is underestimated
or too high

ALENA PARETSKAYA

Pathophysiologist,

immunologist, WHO expert

ZUKHRA PAVLOVA

Candidate of Medical Sciences, Endocrinologist, Senior Researcher at the Faculty of the Fundamental Clinic of Moscow State University, Scientific Director of the Systemic Medicine Clinic

ELENA ZHUCHKOVA

Endocrinologist “SM-Clinic”

Thyroid diseases are quite complex, their symptoms are variable and very individual. This means that thyroid problems will look different for each person, sometimes for a long time the patient does not have any complaints.

In any case, it is important to have a general idea of how the thyroid gland works, why and what hormones it produces. This will help a person to detect the problem in time, take tests and ask the right questions to the doctor. Also, this data may give clues to some of the mysterious symptoms that a person may experience in everyday life.

Key thyroid hormones are produced by the thyroid gland, an endocrine organ located in the lower front of the neck. Thyroid hormones enter the bloodstream and are carried to all body tissues. They help us use energy from incoming food, store and produce heat, stimulate the brain, heart, muscles and other organs.

Thyroid hormone production is controlled by another endocrine organ, the pituitary gland, which is located in the brain. The pituitary gland secretes thyroid-stimulating hormone (TSH) into the blood to stimulate the peripherals. The amount of TSH that the pituitary gland sends into the bloodstream depends on the amount of peripheral thyroid hormones in the body. If the pituitary gland reads a low level of thyroid hormones, then it produces more of them. As soon as their level in the bloodstream rises above normal, the pituitary gland stops producing TSH. Thus, the pituitary gland senses and controls the synthesis of thyroid hormones.

Which thyroid hormones should be tested

Hormone tests can show levels of total (protein-bound) and free hormones.

– Thyroid stimulating hormone (TSH) is the most significant hormone, says Zukhra Pavlova, an endocrinologist. – It is synthesized in the brain and stimulates the thyroid gland, as well as the synthesis of the hormone thyroxine. Most often, doctors look at the amount of TSH, because this is the most indicative hormone – it reflects the lack of synthesis of thyroid hormones.

Most of the hormones in the blood bind to proteins – they help deliver them to organs and tissues. And only a small part of them is “free” to penetrate into tissues, directly exerting biological effects.

– The second priority is T4 free hormone, not associated with a carrier protein, – continues Dr. Pavlova. – When we want to determine the hormonal state, endocrine and thyroid disorders, we look at TSH and T4. If TSH is high, and T4 is still normal, then the disease begins to develop, but it is still without pronounced clinical manifestations.

T4 is the main form of thyroid hormone circulating in the blood (about 95% on average). To exert its effect, T4 is converted to T3 by removing an iodine atom. This occurs mainly in the liver and in certain tissues where T3 acts, such as the brain. T3 usually makes up about 5% of the thyroid hormones circulating in the blood.

“Doctors evaluate several factors in diseases,” says Zukhra Pavlova, an endocrinologist. – If there is a suspicion of an autoimmune thyroid disease, for example, an ultrasound doctor wrote in an ultrasound report that the patient has diffuse changes in the thyroid gland like thyroiditis, the doctor may prescribe tests for antibodies to the thyroid gland. If diffuse toxic goiter is suspected, tests for antibodies to thyroid-stimulating hormone receptors will be ordered. These tests will help to make the correct diagnosis and choose the appropriate treatment.

TSH test

The best way to initially check the activity of the thyroid gland is to measure the level of TSH. Changes in TSH can serve as a kind of early monitoring system. It often changes in advance, even before the moment when the actual level of thyroid hormones reaches low or too high levels.

High TSH is an indicator that the thyroid gland does not secrete enough T3 together with T4, which is possible with primary hypothyroidism. If TSH is low, this may indicate that the thyroid gland is too active, producing an excess of hormones, which is typical for hyperthyroidism.

Sometimes low TSH results from an abnormality in the pituitary gland that prevents it from producing enough hormone to stimulate the thyroid gland (central hypothyroidism).

T4 tests

The total T4 test measures plasma bound and free thyroxine (T4). Free T4 is not associated with protein molecules, it can freely penetrate into the tissues of the body and act on them. It is important to know that drugs and various pathological conditions affect the overall level of T4. Estrogen, oral contraceptive pills, pregnancy, liver disease, or a viral infection (such as hepatitis C) are some of the common causes of an increase in thyroid hormone-binding proteins, leading to a high total T4 level. Testosterone, androgens and anabolic steroids are common causes of a decrease in thyroid hormone binding proteins resulting in a decrease in total T4.

Sometimes, for example in pregnant women, there may be normal thyroid function, but the level of total T4 is outside the normal range. Blood tests that measure the free T4 index can more accurately reflect how the thyroid gland is functioning under these circumstances.

T3 tests

The T3 test measures the level of triiodothyronine (T3) in the blood. The total T3 test shows the bound and free fractions of triiodothyronine. Patients with hyperthyroidism usually have elevated total T3 levels. T3 tests can be used to confirm the diagnosis of hyperthyroidism and determine its severity.

In some thyroid disorders, T3:T4 proportions change and may provide diagnostic information. A significant increase in T3 relative to T4 is characteristic of Graves’ disease. Medications such as steroids and amiodarone, as well as severe illness, can reduce the amount of the hormone that the body converts from T4 to T3 (active form), leading to a lower proportion of T3.

T3 levels are the last to fall in hypothyroidism and are therefore not commonly used in diagnosing patient problems.

Functions of thyroid hormones

These hormones are essential for maintaining a healthy weight, energy levels, core temperature, skin, hair, nails, and many other functions.

Thyroid hormone norm

The normal value of indicators is determined by measuring the hormone in a large population of healthy people and finding the normal (average) range of values.

Normal TSH values are 0. 5 to 5.0 mIU/L.
Normal free T4 values are 0.7 to 1.9 ng/dl.
The normal level of total T4 is from 5.0 to 12.0 mcg / dl.
The normal level of total T3 is 80 – 220 ng / dl.

Which diseases are associated with thyroid hormones

Thyrotoxicosis. This condition often results from an overactive thyroid gland or hyperthyroidism and is associated with an increased amount of T3 in the bloodstream.

Signs of thyrotoxicosis include weight loss, increased appetite, increased heart rate, irregular menstruation, fatigue, irritability, and thinning hair.

Hyperthyroidism. This is a condition in which the level of thyroid hormones is elevated. It occurs in conditions such as Graves’ disease, inflammation of the thyroid, or a benign tumor. Hyperthyroidism can also show up after taking T3 supplements.

Hypothyroidism. It occurs when the thyroid gland does not produce enough thyroid hormone. This may be due to autoimmune diseases such as Hashimoto’s thyroiditis or certain medications. Hypothyroidism can also occur when the pituitary gland is dysfunctional, such as pituitary tumors or inflammation. Hypothyroidism tends to run in the family and is more common in adults as well as women.

Symptoms may include fatigue, mental depression, feeling cold, weight gain, dry skin, constipation and menstrual irregularities.

Where to get tested for thyroid hormones

Tests for the level of thyroid hormones are performed by both municipal laboratories and private centers. Analyzes can be either free, under the MHI policy, or paid, or under the VHI policy.

A doctor of any specialty can order a test for thyroid hormones. The specialist will determine the indications for a consultation with an endocrinologist, or he will independently prescribe examinations, and if any deviations are found, he will refer him to an endocrinologist.

Standards for the level of thysotropic hormone in the blood: the current state of the problem | Samsonova

One of the most controversial issues in modern thyroidology is the issue of TSH blood levels [4, 10]. The interest in this problem is understandable, since it is well known that the determination of the concentration of TSH in the blood is considered today as a reference test in the laboratory assessment of the functional state of the thyroid gland, which allows timely detection of any violation of its function, including at the stage of asymptomatic hyper- and hypothyroxinemia. Thus, an increase in the content of TSH in the blood is the earliest laboratory sign of not only obvious, but also threatened thyroid pathology, especially thyroid insufficiency. In this regard, it is quite obvious that the verification of thyroid insufficiency largely depends on the standard upper limit of the TSH level in the blood. Currently, it is generally accepted that the concentration of TSH in the blood more than 4-5 mU / l indicates a decrease in thyroid function.

This article is a continuation of the discussion on the standards for the upper limit of normal for the level of TSH in the blood, open on the pages of both foreign and domestic journals.

The reason for discussion was the latest recommendation of the US National Academy of Clinical Biochemistry to reduce the upper limit of normal for blood TSH levels from 4 to 2.5 mU/l [8]. The basis for making such decisions was the results of the epidemiological study NHANES-111, which showed that during the examination of 13,344 people receiving adequate iodine prophylaxis, the level of TSH in the blood above 2.5 mU/l was determined in no more than 5% of cases [11] . At the same time, the study did not include those population groups that could potentially have deviations in the functional state of the thyroid gland [11]. Similar results were obtained in the European study SHIP-1 [18]. Thus, as a result of a survey of 1488 adults in Pomerania, no more than 5% had a TSH level in the blood above 2.12 mU/l [18].

It should be noted that not only after the publication of the recommendations of the US National Academy of Clinical Biochemistry, but also long before that, articles began to appear in foreign literature, indicating that adult patients with a TSH level in the blood of 2-4 mU / l, according to a number of clinical signs and laboratory tests differ from the population with TSH levels in the blood below 2 mU/l. So, back in 1992, J. Staub et al. showed that a group of adults with an average TSH content in the blood of 3.0 ± 0.3 mU/l demonstrates a hyperergic TSH response to thyroliberin stimulation, which, as is known, indicates a decrease in the functional reserve of the thyroid gland [16]. According to the data of the Wickham study, in the group of people with a TSH level in the blood above 2 mU/l, overt hypothyroidism is more often diagnosed in the future [17]. Finally, in adults, this level of TSH is associated with an increased risk of hypercholesterolemia [7, 9, 14], endothelial dysfunction [12], and miscarriage [15]. According to our data, such a concentration of TSH in the blood of women of reproductive age is associated with hypoestrogenemia. Thus, every 8th (12.5%) woman of reproductive age, who, when assessing the functional state of the thyroid gland, determined the level of TSH in the blood from 2 to 4 mU / l, had a reduced level of estrogen in the blood (median estradiol in this group of women was 167 pmol/l), while all women with TSH blood levels below 2 mU/l had estradiol levels within the normal range (median estradiol 235.25 pmol/l; /> = 0.01) [5] .

Moreover, in pregnant women (the most vulnerable part of the population in terms of the formation of pathological conditions associated with hypothyroxinemia), the level of TSH in the first trimester of gestation of more than 2 mU/l is currently recognized as an increased risk factor for the development of gestational hypothyroxinemia. So, according to our data, gestational hypothyroxinemia occurs in almost every 2nd pregnant woman with diffuse endemic goiter, who has a TSH level of 2 to 4 mU/l in the first trimester of gestation (/> = 0.05) [2].

Thus, a similar TSH blood level in adults is associated with a known spectrum of pathological conditions, which today are a recognized consequence of chronic hypothyroxinemia.

At the same time, it should be emphasized that all the accumulated knowledge and understanding of the clinical and prognostic significance of the concentration of TSH in the blood more than 2, but less than 4 mU/l was obtained on the basis of a survey of the adult population. The following data allow us to form an opinion on the significance, legitimacy and expediency of isolating this particular range of TSH levels in the blood and in pediatric practice. So, according to the results of a study by D.E. Shilin (2002), children and adolescents (l = 114) with a basal TSH level in the blood above 2 mU/l (average 2. 57 ± 0.06 mU/l) , differ from children and adolescents (l = 475) with a basal TSH level below 2 mU/l (average 1.19± 0.02 mU/l) [6].

In 94.1% of children (p < 0.05) of this group, a hyperergic TSH response to thyroliberin stimulation is observed, which indicates a reduced functional reserve of the thyroid gland [6]. According to the same author, such children and adolescents have significantly (/> = 0.03) higher concentrations of atherogenic lipid fractions, and adolescent girls with a similar level of TSH in the blood show signs of age-related immaturity of the uterus and gonads (p = 0.01) [6]. In addition, such girls are prone to polymenorrhea (menstruation lasts an average of 5.5 ± 0.3 days versus 4.7 ± 0.1 days in the group of girls with TSH levels in the blood below 2 mU/l; p = 0.01) and a lower level of estradiol in the blood (mean estradiol content 162 ± 23 pmol/l versus 239 ± 22 pmol/l in the group of girls with a TSH concentration in the blood of less than 2 mU/l; p = 0. 05) [6].

According to our data, it is adolescent girls with blood levels of TSH above 2 but below 4 mU/l that are most vulnerable in terms of the formation of functional disorders in the reproductive system. So, according to the results of our research, every 2nd (54%) girl with a similar level of TSH in the blood has menstrual dysfunction like opsomenorrhea (while only 28% of girls with a TSH level below 2 mU/l, Р = 0.032) [1].

So, in our opinion, today there are enough arguments in favor of the fact that the level of TSH in the blood from 2 to 4 mU/l in children also reflects the earliest in terms of onset and the mildest in severity thyroid insufficiency.

Obviously, thyroid insufficiency in iodine-deficient regions has its own evolution. In our opinion, the evolution of thyroid insufficiency can be represented as follows: 1) a normal level of free thyroxin and a TSH level of 2 to 4 mU/l, there are no clinical signs of hypothyroidism; 2) normal level of free thyroxine and TSH level above 4-5 mU/l, there are no clinical symptoms of hypothyroidism; 3) a reduced level of free thyroxine and a TSH level above 4-5 mU/l in combination with clinical signs of hypothyroidism. The last two stages of thyroid insufficiency are well known and are classified as subclinical and overt hypothyroidism, respectively.

At the same time, today there is no single generally accepted term that characterizes the level of TSH from 2 to 4 mU/L. This is understandable, since terminology issues are always the most difficult. In the English literature, the level of TSH in the traditionally normal range, but above 2 mU/l, is denoted by the following terms: “high-normal TSH” [14], “very mild thyroid failure” [15], “a lessened thyroid reserve” [15], “mildest form of subclinical hypothyroidism” [16]. We propose to use the term “minimal thyroid insufficiency” to designate the condition, which is reflected in the level of TSH from 2 to 4 mU/l. In our opinion, it is he who most accurately characterizes the earliest in terms of onset and the mildest in severity thyroid insufficiency.

At the same time, at a given level of TSH, the functionality of the thyroid gland should be assessed depending on its size. So, in persons without goiter, a slight increase in the level of TSH (2-4 mU / l) only indicates that, with normal sizes, the thyroid gland is not able to provide adequate production of thyroid hormones. In this group of people, a similar level of TSH reflects the readiness to turn on compensatory mechanisms leading to an increase in the size of the thyroid gland and to the normalization of the level of thyroid hormones. Thus, in persons with normal thyroid gland sizes, this condition cannot yet be classified as a pathology, but should be considered as a borderline condition.

In patients with a long-term goiter, this TSH level indicates that the enlargement of the thyroid gland did not lead to the elimination of hypothyroxinemia and, therefore, the required level of thyroid hormones was not reached. Most likely, in this case, there was a decrease in the compensatory and functional reserves of the thyroid gland due to a mild genetic defect in morpho- or hormonogenesis. Even with mild congenital insufficiency of the thyroid gland in conditions of insufficient iodine intake, the formation of goiter will not lead to the normalization of thyroid status, i. e., to the elimination of hypothyroxinemia and, consequently, the risk of iodine deficiency diseases.

We are deeply convinced that the use of the term “minimal thyroid insufficiency” in the context in which it is presented in the article will not only not mislead readers, but, on the contrary, will help to understand the essence of the problem and present the evolution of thyroid insufficiency in iodine-deficient regions.

It should be noted that another, no less, and perhaps more important issue of this discussion is whether people with a TSH blood level of 2 to 4 mU / l need therapy. Foreign and domestic authors consider the danger of expanding indications for verification of hypothyroidism and treatment of such a patient with levothyroxine preparations as a serious argument against the recognition of new standards for THG in the blood [4, 10].

In our opinion, the level of TSH in the range from 2 to 4 mU/l only indicates that in the region of iodine deficiency the thyroid gland is able to maintain an ideal euthyroid state only if there is an adequate supply of iodine. It is quite obvious that in the absence of adequate iodine prophylaxis in regions with even moderate and / or mild iodine deficiency (i.e., in most of the territory of Russia), it is this degree of thyroid insufficiency that will continue to occur frequently and determine the formation of medically and socially significant iodine deficiency states. . Hence the conclusion that the vast majority of people living in these conditions and having a similar level of TSH in the blood need only adequate iodine prophylaxis. Adequate iodine prophylaxis in most of them is able to maintain an ideal euthyroid state for many years of life.

The exception is 2 groups of people. First of all, these are pregnant women with TSH levels in the first trimester of gestation above 2 mU/l, i.e., those with a risk factor for the development of gestational hypothyroxinemia [2]. Considering the exceptional role of the normal level of maternal thyroxine for the formation and maturation of the central nervous system of the unborn child and the need for rapid and effective correction of gestational hypothyroxinemia, today no one doubts and objects that pregnant women with a similar level of TSH need treatment with levothyroxine preparations. In addition, it is required to prescribe levothyroxine preparations to persons exposed to other (except for iodine deficiency) strimogenic environmental factors or having more pronounced genetically determined defects in morpho- or hormone genesis of the thyroid gland. It should be emphasized that these are extremely rare cases.

When deciding on the TSH level standards, the modern double standards used to assess the functional state of the thyroid gland in untreated individuals and in patients receiving levothyroxine replacement therapy are somewhat surprising [3, 13]. In this regard, another strong argument in favor of narrowing the normal range for the level of TSH in the blood is that the vast majority of researchers have recognized and do not raise objections TSH levels ranging from 0.5 to 2 mU / l as reflecting the euthyroid state of the thyroid gland. in patients receiving replacement therapy with levothyroxine preparations [3, 13].

So, the above data convince us that today there are more than enough arguments in favor of recognizing the fact that (in both adults and children) the TSH level from 2 to 4 mU / l reflects the earliest in terms of appearance and the mildest thyroid insufficiency, namely minimal thyroid insufficiency.

Narrowing the normal range of TSH levels in the blood from 0.5 to 2-2.5 mU/l and the speedy implementation of these standards in healthcare practice is a necessary condition for optimizing the early diagnosis, prevention, treatment of hypothyroxinemia and, consequently, the elimination of iodine deficiency conditions in Russia.

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2. Ivakhnenko VN Tirsoid, neuropsychiatric and somatic status of children born to mothers with goiter: Abstract of the thesis. dis…. cand. honey. Sciences. Moscow, 2005.

3. E. P. Kasatkina, M. I. Martynova, V. A. Peterkova, et al., Klin. thyroidol. – 2003. – V. 1, No. 1. – S. 26-27.

4. V. V. Fadeev // Klin. thyroidol. – 2004. – V. 2, No. 3. – S. 5-9.

5. Chubarova D.Yu. Reproductive health of women in the region of mild goiter endemia: Abstract of the thesis. dis…. cand. honey. Sciences. – M., 2006.

6. Shilin D. E. //Laboratory. – 2002. – No. 3. – S. 22-26.

7. Bakker S. J. L., Ter Matten J. C, Popp-Sni/ders C. et al. // J. Clin. Endocrinol. Metab. – 2001. – Vol. 86. – P. 1206-1211.

8. Baloch Z, Carayon P., Conte-Devolx B. et al. // thyroid. – 2003. Vol. 13.-P. 3-126.

9. Bindels A. J., Weslendorp R. C, Frolich M. et al. // J. Clin. Endocrinol. – 1999. – Vol. 50.-P. 217-220.

10. Brabant G., Beek-Peccoz P., Jarzab B. et al. // EUR. J. Endocrinol. – 2006. – Vol. 154. – P. 633-637.

11. Hollowell J. C, Siaehling N. W, Flanders W. D. et al. // J. Clin. Endocrinol. Metab. – 2002. – Vol. 87. – P. 489-499

12. Lekakis J, Paramlchael C, Alevizaki M. et al. // thyroid. – 1997. – Vol. 7. – P. 411-414.

13. McDermott M. T., Ridgway C // i. Clin. Endocrinol. Metab. -2001. – Vol. 86.-P. 585-590.

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