What are thyroid tests and why are they important. How do thyroid tests work and what do the results mean. When should you get thyroid tests and what can they reveal about your health. What are the different types of thyroid tests available and how are they performed.

The Importance of Thyroid Health and Testing

The thyroid gland plays a crucial role in regulating various bodily functions. Located in the front of the neck, this small, butterfly-shaped organ produces hormones that influence nearly every aspect of our physiology. From controlling metabolism and heart rate to affecting mood and digestion, the thyroid’s impact on our overall health is profound.

Given its significance, monitoring thyroid function through specialized tests is essential for maintaining optimal health. These tests serve as valuable diagnostic tools, helping healthcare providers identify and manage thyroid disorders such as hyperthyroidism and hypothyroidism.

Types of Thyroid Blood Tests

Blood tests are the primary method for assessing thyroid function. They provide crucial information about hormone levels and can indicate potential thyroid abnormalities. Here are the main types of thyroid blood tests:

TSH (Thyroid-Stimulating Hormone) Test

The TSH test is typically the first line of investigation when evaluating thyroid function. It measures the level of thyroid-stimulating hormone in the blood, which is produced by the pituitary gland to regulate thyroid hormone production. Abnormal TSH levels can indicate an overactive or underactive thyroid.

T3 and T4 Tests

These tests measure the levels of triiodothyronine (T3) and thyroxine (T4), the two main thyroid hormones. T3 and T4 tests can provide a more comprehensive picture of thyroid function, especially when combined with TSH results.

Thyroid Antibodies Test

This test detects the presence of specific antibodies in the blood that may indicate an autoimmune thyroid disorder. It can be particularly useful in diagnosing conditions such as Hashimoto’s thyroiditis or Graves’ disease.

Imaging Tests for Thyroid Evaluation

In addition to blood tests, imaging studies can provide valuable information about the thyroid gland’s structure and function. These tests include:

• CT scans: Provide detailed cross-sectional images of the thyroid and surrounding tissues
• Ultrasound: Offers a non-invasive way to visualize the thyroid’s size, shape, and texture
• Nuclear medicine tests: Use small amounts of radioactive material to assess thyroid function and structure

Thyroid Scan

A thyroid scan creates a detailed picture of the gland, revealing its size, shape, and position. This test can be particularly helpful in identifying thyroid nodules and determining the cause of hyperthyroidism.

Radioactive Iodine Uptake Test

Also known as a thyroid uptake test, this procedure measures how much radioactive iodine the thyroid absorbs. It provides insights into the gland’s function and can aid in diagnosing hyperthyroidism.

Understanding Thyroid Test Results

Interpreting thyroid test results requires careful consideration of various factors. Normal ranges can vary depending on the specific test, laboratory, and individual patient characteristics. Here’s a general overview of what different test results might indicate:

TSH Levels

Elevated TSH levels often suggest an underactive thyroid (hypothyroidism), while low TSH levels may indicate an overactive thyroid (hyperthyroidism). However, these results should always be interpreted in conjunction with T3 and T4 levels for a comprehensive assessment.

T3 and T4 Levels

High T3 and T4 levels typically point to hyperthyroidism, while low levels suggest hypothyroidism. The relationship between these hormones and TSH helps doctors determine the underlying cause of thyroid dysfunction.

Thyroid Antibodies

The presence of thyroid antibodies may indicate an autoimmune thyroid disorder. However, not all individuals with antibodies will develop thyroid disease, and further evaluation is often necessary.

When to Consider Thyroid Testing

Thyroid testing may be recommended in various situations. Some common reasons to undergo thyroid evaluation include:

• Symptoms suggestive of thyroid dysfunction (e.g., unexplained weight changes, fatigue, mood swings)
• Family history of thyroid disorders
• Presence of a goiter or thyroid nodules
• Pregnancy or planning to conceive
• Regular monitoring for individuals with known thyroid conditions

Is thyroid testing necessary for everyone? While routine screening is not recommended for all adults, certain high-risk groups may benefit from regular thyroid function assessment. These include older adults, individuals with autoimmune disorders, and those with a history of thyroid problems.

The Role of Calcitonin in Thyroid Health

Calcitonin is another hormone produced by the thyroid gland, specifically by cells called C-cells. While not as commonly measured as TSH, T3, or T4, calcitonin levels can provide valuable information in certain situations.

Calcitonin Test

A calcitonin test measures the amount of this hormone in the blood. It is primarily used to:

• Diagnose and monitor medullary thyroid cancer
• Assess the effectiveness of treatment for medullary thyroid cancer
• Screen individuals with a family history of multiple endocrine neoplasia type 2 (MEN2)

How is the calcitonin test performed? The test involves a simple blood draw, similar to other thyroid blood tests. Results are typically available within a few days, and interpretation should be done by a healthcare professional familiar with thyroid disorders.

Thyroid Antibodies and Autoimmune Thyroid Disorders

Thyroid antibodies are proteins produced by the immune system that can target thyroid tissue. Their presence can indicate an autoimmune thyroid disorder, where the body’s immune system mistakenly attacks the thyroid gland.

Types of Thyroid Antibodies

Several types of thyroid antibodies can be detected through blood tests:

• Thyroid peroxidase antibodies (TPOAb)
• Thyroglobulin antibodies (TgAb)
• Thyroid-stimulating hormone receptor antibodies (TRAb)

What do positive thyroid antibody results mean? The presence of thyroid antibodies doesn’t always indicate active thyroid disease. However, it may suggest an increased risk of developing thyroid dysfunction in the future. Regular monitoring and follow-up with a healthcare provider are often recommended for individuals with positive antibody results.

Advanced Thyroid Function Tests

In some cases, standard thyroid tests may not provide a complete picture of thyroid function. Advanced tests can offer additional insights into thyroid health and help diagnose complex cases.

Free T3 and Free T4 Tests

These tests measure the unbound (free) forms of T3 and T4 hormones, which are considered more biologically active. Free hormone tests can be particularly useful when total T3 and T4 levels are affected by changes in protein binding.

Reverse T3 (rT3) Test

Reverse T3 is an inactive form of T3. Elevated rT3 levels may indicate problems with thyroid hormone conversion or utilization, which can occur in certain medical conditions or during periods of stress.

Thyroid-Binding Globulin (TBG) Test

TBG is the main protein responsible for transporting thyroid hormones in the blood. Measuring TBG levels can help explain discrepancies between total and free thyroid hormone levels.

When are advanced thyroid tests necessary? Advanced tests are typically reserved for complex cases or when standard tests yield inconclusive results. They may be ordered by endocrinologists or thyroid specialists to gain a more comprehensive understanding of thyroid function.

Thyroid Testing in Special Populations

Certain groups may require special considerations when it comes to thyroid testing and interpretation of results. These populations include:

Pregnant Women

Thyroid function changes during pregnancy, and proper thyroid hormone levels are crucial for fetal development. Pregnant women may need more frequent thyroid testing and different reference ranges for interpreting results.

Newborns

Newborn screening for congenital hypothyroidism is standard practice in many countries. Early detection and treatment of thyroid disorders in infants can prevent serious developmental issues.

Older Adults

Thyroid function can change with age, and symptoms of thyroid disorders may be subtle or attributed to other conditions. Regular thyroid screening may be beneficial for older adults, especially those with risk factors for thyroid dysfunction.

How do thyroid testing protocols differ for these special populations? Healthcare providers may use adjusted reference ranges, more frequent testing intervals, or additional tests to ensure accurate assessment of thyroid function in these groups.

The Future of Thyroid Testing

As our understanding of thyroid physiology continues to evolve, so do the methods for assessing thyroid function. Emerging technologies and research are paving the way for more accurate and comprehensive thyroid testing.

Genetic Testing

Advances in genetic testing may help identify individuals at risk for thyroid disorders before symptoms appear. This could lead to earlier interventions and personalized treatment strategies.

Artificial Intelligence in Thyroid Imaging

AI-powered analysis of thyroid ultrasound and other imaging studies shows promise in improving the accuracy of nodule detection and classification.

Point-of-Care Testing

The development of rapid, portable thyroid testing devices could make thyroid assessment more accessible, especially in remote or resource-limited settings.

What impact will these advancements have on thyroid care? As new technologies become available, they may lead to earlier detection of thyroid disorders, more precise treatment plans, and improved outcomes for patients with thyroid conditions.

In conclusion, thyroid testing plays a crucial role in maintaining overall health and well-being. From basic blood tests to advanced imaging studies, these diagnostic tools provide valuable insights into thyroid function and help guide treatment decisions. As research continues to expand our understanding of thyroid physiology, we can expect even more sophisticated and personalized approaches to thyroid assessment in the future.

Thyroid Tests: MedlinePlus

Also called: Thyroid panel

Your thyroid is a small, butterfly-shaped gland in the front of your neck. It makes hormones that control the way the body uses energy. These hormones affect nearly every organ in your body and control many of your body’s most important functions. For example, they affect your breathing, heart rate, weight, digestion, and moods.

Thyroid tests check how well your thyroid is working. They are also used to diagnose and help find the cause of thyroid diseases such as hyperthyroidism and hypothyroidism. Thyroid tests include blood tests and imaging tests.

Blood tests for your thyroid include:

• TSH. It measures thyroid-stimulating hormone. This is usually the first test your healthcare provider will order.
• T3 and T4.They measure the level of the different thyroid hormones in your blood.
• Thyroid antibodies test. It measures certain thyroid antibodies (markers in the blood). This test may help diagnose autoimmune thyroid disorders.

Imaging tests include:

• CT scans
• Ultrasound
• Nuclear medicine tests, including:
  • Thyroid scan. It uses small amounts of radioactive material to create a picture of the thyroid, showing its size, shape, and position. It can help find the cause of hyperthyroidism and check for thyroid nodules (lumps in the thyroid).
  • Radioactive iodine uptake test, or thyroid uptake test. It checks how well your thyroid is working and can help find the cause of hyperthyroidism.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases

• Calcitonin Test

  (National Library of Medicine)

  Also in Spanish

• Thyroid Antibodies

  (National Library of Medicine)

  Also in Spanish

• Thyroid Function Tests

  (American Thyroid Association)

  Also in Spanish

• Thyroid Scan and Uptake

  (American College of Radiology; Radiological Society of North America)

  Also in Spanish

• Thyroid Tests

  (Nemours Foundation)

• Thyroid Tests

  (National Institute of Diabetes and Digestive and Kidney Diseases)

  Also in Spanish

• Thyroxine (T4) Test

  (National Library of Medicine)

  Also in Spanish

• Triiodothyronine (T3) Tests

  (National Library of Medicine)

  Also in Spanish

• TSH (Thyroid-stimulating hormone) test

  (National Library of Medicine)

  Also in Spanish

• Ultrasound – Thyroid

  (American College of Radiology; Radiological Society of North America)

  Also in Spanish

• ClinicalTrials. gov: Thyroid Function Tests

  (National Institutes of Health)

• Article: Circulating free T3 associates longitudinally with cardio-metabolic risk factors in euthyroid. ..

• Article: Assessment of thyroid function tests in patients with chronic obstructive pulmonary…

• Article: The impact of covid-19 on thyroid function tests in pregnancy.

• Thyroid Tests — see more articles

Sensitive thyroid-stimulating hormone assays: clinical applications and limitations

Review

. 1988 Sep;14(9):26-33.

E T De Los Santos 
¹
, E L Mazzaferri

Affiliations

Affiliation

• ¹ Division of Endocrinology and Metabolism, Ohio State University, Columbus 43210.

• PMID:

  3064960

Review

E T De Los Santos et al.

Compr Ther.

1988 Sep.

. 1988 Sep;14(9):26-33.

Authors

E T De Los Santos 
¹
, E L Mazzaferri

Affiliation

• ¹ Division of Endocrinology and Metabolism, Ohio State University, Columbus 43210.

• PMID:

  3064960

Abstract

Sensitive TSH assays have important applications in various conditions, including the diagnosis of hypothyroidism and hyperthyroidism, monitoring thyroid hormone therapy and treated thyrotoxic patients, and evaluating thyroid dysfunction in nonthyroidal illnesses and pregnancy. Interpretation of the TSH value should be made with a clear understanding of its limitations. TSH may be inappropriately secreted by pituitary tumors and by pituitary dysfunction due to thyroxine resistance. At present, it is uncertain whether clinically euthyroid patients with autonomously functioning thyroid nodules, or with multinodular goiters, or patients taking thyroid hormone who have suppressed TSH values, are actually euthyroid at a cellular level. Other factors that affect TSH levels are the biologic variation in its secretion, the presence of heterophilic antibodies in a patient’s serum, and various drugs. But perhaps the most important factor affecting the TSH assay is severe nonthyroidal illness in hospitalized patients. The new ultrasensitive TSH assay does not yet replace other thyroid function tests, but it is clearly emerging as an important means of screening patients for thyroid dysfunction, especially ambulatory patients without other serious illnesses. It can usually separate patients with thyroid dysfunction from euthyroid individuals. Good clinical assessment is always necessary, and other thyroid function tests are often needed. The sensitivity of these new TSH assays in the diagnosis of thyrotoxicosis and hypothyroidism is excellent; the specificity is not as good. Nonetheless, at present this test can be used in the initial diagnosis of thyroid dysfunction as outlined in Figure 2.(ABSTRACT TRUNCATED AT 250 WORDS)

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Publication types

MeSH terms

Substances

Blood thyroid stimulating hormone (TSH) test

Brief description:
Thyroid-stimulating hormone (TSH) is the main regulator of thyroid function, synthesized by the pituitary gland. Its main function is to maintain a constant concentration of thyroid hormones. When their blood levels decrease, the hypothalamus releases a hormone that stimulates the secretion of TSH by the pituitary gland.

Synonyms (rus): Thyroid stimulating hormone, Thyrotropin, TSH
Synonyms (eng): Thyroid Stimulating Hormone, TSH

Units: µIU/mL (microinternational unit per milliliter)

Methods: Immunochemiluminescent assay

Test preparation:
• Do not eat for 2-3 hours before the study, you can drink clean non-carbonated water.
• Eliminate the use of steroid and thyroid hormones within 48 hours before the study (as agreed with the doctor).
• Avoid physical and emotional stress for 24 hours prior to the study.
• Do not smoke for 3 hours prior to the study.

Biomaterial type: Venous blood

Tube type: Vacuum tubes with coagulation activator and gel (Cap color: red with yellow ring)

Completion time: one business day.

Reference values:

4 months – 1 year 0.7 – 8.35 µIU/ml
1 – 6 years 0.7 – 6 µIU/ml
7 – 11 years 0.6 – 4.84 µIU/ml
12 – 20 years 0.51 – 4.3 µIU/ml
> 20 years 0.24 – 4.3 µIU/mL
During pregnancy: 1st trimester 0.33-4.59 µIU/mL
2nd trimester 0.35-4.10 µIU/ml
3rd trimester 0.21-3.15 μIU/ml

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

Causes of 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.

Code: A09.05.065

Take a blood test for TSH (Thyrotropic hormone)

Full name of the test: Thyroid Stimulating Hormone (TSH)

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 directly on organs and systems, 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 occur more often in women, therefore, this type of examination is prescribed to them more often than to the representatives of 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 analysis shows

The analysis is carried out in order to assess the work of the pituitary gland and thyroid gland. Determining 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:

• threatened miscarriage;
• disruption of the central nervous system;
• pathology of the adrenal glands;
• 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 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

Material sampling for thyroid-stimulating hormone is carried out if the following abnormalities are suspected:

• pathology of the pituitary gland;
• cycle disorder in women and infertility;
• pathology of the thyroid gland;
• if symptoms of heavy metal poisoning are present.

Patients with altered TSH levels often experience 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 work worsens;
• loss of sexual desire;
• hair loss in large quantities, most often ending 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

An 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 follow the following recommendations:

• Avoid alcoholic beverages, including those with low alcohol content.
• During the day it will be necessary to introduce a diet that excludes the use of fatty, spicy fried foods.
• The analysis should be taken in a calm psycho-emotional state, so 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 eight o’clock in the evening.
• Blood can not be donated after undergoing ultrasound, computed tomography and fluorography.
• All non-essential drugs should be discontinued. It is desirable to use these medicines for their intended purpose after blood sampling. If this is not possible, then the name of the drug and its dose are indicated on the referral.

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

Causes of 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 when blood samples are incorrectly obtained and used by medical personnel.

Test results may be affected by pregnancy.

How the analysis is done

For research, venous blood is used. An immunochemical method is used to determine the level of the hormone. 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 plays the role of a label. It forms an antigen-antibody compound, which makes it easy to detect and count.

If intravenous infusion of drugs was performed shortly before the study, this arm cannot be used to take the 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 test data is the prerogative of the attending physician. It is strictly forbidden to use the received information for self-diagnosis and
self-treatment. The specialist makes an accurate diagnosis, based both on the test data and by collecting information from the patient, using other sources, anamnesis, etc.
d.

Units of measurement in the Independent laboratory: honey/l.

Alternate units: µU/mL = mU/L.

Unit conversion: µU/mL = mU/L.

Reference
values ​​

9 0190

Age	TSH level, mU/l
4 days – 6 months	0. 73-4.77
6 months – 14 years	0.7-4, 17
14-19 years old	0.47-3.41
> 19 years	0.4 -4.0

Guideline 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

Increased 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 surgical removal of part of the thyroid gland).

2. Subclinical type of hypothyroidism.

3. Thyroiditis of subacute type (recovery period).

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

5. TSH-releasing 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 such as: beta-blockers (metoprolol, atenolol, propranolol), neuroleptics (phenothiazine derivatives,
aminoglutethimide), radiopaque agents, clomiphene, amiodarone, iodine-containing drugs, antiemetics (motilium, metoclopramide), anticonvulsants
(carbamazepine, phenytoin), furosemide, lithium salts.

Decrease in values:

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

2. Subclinical type of hyperthyroidism.

3. When 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. Severe non-thyroid diseases.

9. Hypothalamic-pituitary insufficiency.

10. Tumor processes in
pituitary gland.