Thyroid Function Test

What are thyroid hormones?

Thyroid hormones¹ are essential for the smooth functioning of various body processes. They regulate growth, metabolism, heart rate, breathing, and muscle development. They also influence menstruation, ovulation, and fertility. Hence, thyroid function tests (T3, T4, TSH) are included in the comprehensive women's hormone test panel.

Thyroid hormones require three glands to sync: the thyroid, pituitary, and hypothalamus. Here is a quick look at the group of hormones involved in thyroid function:

Hormone	Function
Thyroxine or tetraiodothyronine (T4)	The inactive or less active form of thyroid hormone, precursor to T3
Triiodothyronine (T3)	The active form of thyroid hormone, formed by conversion of T4
Thyroid-stimulating hormone (TSH)	A pituitary hormone that regulates T4 and T3 production
Thyrotropin-releasing hormone (TRH)	A hypothalamic hormone that regulates TSH production

Who needs a thyroid function test?

You may need a thyroid function test if you have symptoms of any of the two thyroid-related conditions: hypothyroidism and hyperthyroidism. In hypothyroidism, the thyroid gland does not produce enough thyroid hormones, while in hyperthyroidism, it produces excessive amounts of thyroid hormones.

Symptoms of hypothyroidism include:

• Neurological and psychological: Depression, poor concentration and memory

• Metabolic: Reduced appetite, weight gain, constipation, cold intolerance, fatigue, hair loss, skin dryness, joint stiffness, muscle cramps

• Cardiovascular: Slow heart rate, high blood pressure

• Body changes: Puffy face and eyes, hoarse voice

• Reproductive and hormonal: Heavy periods, absence of periods, fertility problems, abnormal nipple discharge, reduced sex drive

• Visible physical signs: Goiter (abnormal swelling of the thyroid gland located in the front of the neck)

Symptoms of hyperthyroidism include:

• Metabolic/ General: Increased appetite, weight loss, heat intolerance, excessive sweating, fatigue, nail separation

• Cardiovascular: Palpitations, high blood pressure, irregular heart beat, chest pain

• Musculoskeletal: Tremors, weak and brittle bones

• Neurological and psychological: Restlessness, anxiety, depression, emotional instability, insomnia, overactive reflexes

• Eyes: Bulging eyes

• Visible physical signs: Goiter (abnormal swelling of the thyroid gland located in the front of the neck)

What is the normal thyroid hormones range?

A thyroid function test typically measures TSH, T4, and T3 levels. The normal ranges of these hormones in women of the reproductive age group are discussed below.

Hormone	Normal range
TSH	0.52 to 4.16 μIU/mL2
T4	5.23 to 12.31 mcg/dL2
T3	100 to 200 ng/dL3

Note: Additional testing (thyroid antibodies test) may be necessary to determine if you have Graves' disease (cause of hyperthyroidism) or Hashimoto thyroiditis (cause of hypothyroidism).

What do the thyroid test results mean?

Abnormal TSH, T4, and T3 levels may either mean hypothyroidism or hyperthyroidism. Here’s how to distinguish between the two conditions:

Thyroid condition	TSH	T4/T3
Hypothyroidism	High	Low
Hyperthyroidism	Low	High

How much does a thyroid blood test cost?

In India, the price of a thyroid profile test (TSH, T4, T3) ranges between ₹350 and ₹1089.

Note: The price of the test may vary depending on your location and the lab you choose.

References

1. Shahid MA, Ashraf MA, Sharma S. Physiology, Thyroid Hormone.

2. Ganie MA, Chowdhury S, Suri V, Joshi B, Bhattacharya PK, Agrawal S, Malhotra N, Sahay R, Jabbar PK, Nair A, Rozati R. Normative range of various serum hormonal parameters among Indian women of reproductive age: ICMR-PCOS task force study outcome. The Lancet Regional Health-Southeast Asia. 2023 Aug 1;15.

3. Rana S, Soni B, Darney DP, Jeyan JM. Experimental Investigation of Effects of T3 Hormones on Human Body and their Analysis. International Journal of Science and Research(IJSR), https://www ijsr net/get_abstract php. 2022 Jun;11(6):785-9.