Thyroid Tests

A thyroid blood test is a laboratory blood test used to assess thyroid function and help identify hypothyroidism, hyperthyroidism, autoimmune thyroid disease, and other disorders. TSH is usually measured first, followed when necessary by free T4 (FT4), free T3 (FT3), and thyroid antibodies.

The test is performed using a venous blood sample. Fasting is generally not required for individual thyroid hormone tests, although certain medications and supplements, especially biotin, may affect the results.

What does a thyroid examination show?

The thyroid gland produces the hormones T4 and T3, which are involved in regulating metabolism, heart function, body temperature, weight, the nervous system, and many other physiological processes.

Thyroid testing with laboratory blood tests helps determine whether the gland is functioning normally, producing too little or too much hormone, and whether there are signs of autoimmune changes.

Main thyroid hormone tests

TSH - thyroid-stimulating hormone

TSH is produced by the pituitary gland and regulates thyroid function. It is usually the first laboratory marker assessed when evaluating the thyroid.

A high TSH level is commonly associated with reduced thyroid function, or hypothyroidism, while a low TSH level may indicate increased thyroid activity, or hyperthyroidism.

T4 and free T4 - FT4

T4 is the main hormone produced by the thyroid gland. In laboratory testing, its free fraction, FT4, is often measured because it represents the amount of biologically available hormone in the blood.

FT4 is particularly important when TSH is outside the reference range or when a pituitary disorder is suspected.

T3 and free T3 - FT3

T3 is a more active hormone than T4. Measuring it is particularly useful when hyperthyroidism is suspected.
If TSH is low, international guidelines recommend measuring FT4 and FT3 to clarify the type of hormonal abnormality.

Anti-TPO

Anti-TPO is a test for antibodies against thyroid peroxidase. Elevated levels may be seen in autoimmune thyroiditis, including Hashimoto’s thyroiditis.

This test is particularly useful when TSH is elevated and it is necessary to determine whether the thyroid dysfunction has an autoimmune cause.

Anti-Tg

Anti-Tg measures antibodies against thyroglobulin. It may also be used in the assessment of autoimmune thyroid disease, although it generally does not replace TSH, FT4, or Anti-TPO testing.

TRAb

TRAb measures antibodies against the TSH receptor. It is used particularly to confirm Graves’ disease, an autoimmune form of hyperthyroidism.

Therefore, a thyroid hormone panel may include different tests, and it is not always necessary to perform all of them at the same time.

When are thyroid tests indicated?

Thyroid tests may be ordered when there are signs suggesting reduced or increased thyroid function.

Testing may be needed in cases of:

• unexplained weight gain or weight loss,
• persistent fatigue or weakness,
• palpitations or changes in heart rhythm,
• marked intolerance to cold or heat,
• hand tremor,
• sleep disturbances or significant anxiety,
• dry skin or hair loss,
• an enlarged thyroid gland or a neck nodule,
• menstrual cycle disturbances,
• evaluation for infertility,
• monitoring treatment of an already diagnosed thyroid disorder.

TSH testing is also performed when there is a clinical suspicion of thyroid disease. International guidelines also recommend assessing thyroid function in certain autoimmune diseases and in newly diagnosed atrial fibrillation.

Contraindications

There are virtually no specific contraindications to a routine thyroid hormone blood test, as only a small amount of venous blood is required.

How to prepare for a thyroid blood test

In most cases, no complicated preparation is required. Blood is drawn from a vein in the arm and sent for laboratory analysis.

Fasting is generally not required if only TSH, FT4, FT3, or thyroid antibodies are being tested. If glucose, lipid levels, or other tests are planned on the same day, they may have separate preparation requirements.

Before testing, it is important to inform the healthcare provider about all medications and dietary supplements being taken. Prescribed medications should not be stopped without medical advice.

It is particularly important to mention biotin, or vitamin B7, because it can interfere with certain thyroid laboratory results and produce falsely altered values. The American Thyroid Association recommends avoiding biotin for at least 2 days before thyroid blood testing.

If the patient takes levothyroxine or another thyroid medication, it is advisable to keep the timing between the medication dose and blood collection consistent for repeated tests, so that results can be compared more accurately.

Thyroid tests at Nairi Medical Center

Nairi Medical Center has its own laboratory diagnostic service, where clinical, biochemical, immunological, hormonal, and serological tests are performed. The laboratory uses automated analyzers, and a LIMS laboratory information system is integrated into its workflow.

When necessary, thyroid laboratory results can be evaluated together with an endocrinology consultation and instrumental examinations performed at the same center.

To find out the cost of a thyroid test or thyroid blood test price, you can call 89 00.

What additional thyroid examinations are available?

Blood tests assess thyroid function but do not provide complete information about the structure of the gland. For this reason, additional examinations may be necessary in some cases.

Thyroid ultrasound

Thyroid ultrasound is available at Nairi Medical Center.

Ultrasound can be used to assess:

• the size and structure of the thyroid gland,
• the presence of nodules,
• cysts,
• inflammatory changes,
• other structural abnormalities.

It may be recommended in cases of thyroid enlargement, a suspected nodule, or abnormal thyroid hormone blood test results.

Fine-needle aspiration biopsy of the thyroid

If a thyroid nodule detected on ultrasound requires further assessment, a fine-needle aspiration biopsy may be performed.

At Nairi Medical Center, the procedure is performed using a thin needle under ultrasound guidance. The collected cells are sent for cytological examination to determine the nature of the nodule.

Other examinations

Within the Endocrinology Service at Nairi Medical Center, additional imaging studies of the endocrine glands are also available, including scintigraphy, CT, and MRI when clinically indicated.

To book an appointment, call 89 00 or visit Nairi Medical Center at 21 Paronyan Street.