TFT calculator – Thyroid Function Tests

Thyroid Function Tests (TFT) Calculator

Created by Team y2calculate

Content written by Sajid Khan (MBBS, FCPS, 

Coding and design by Marcelino (Ms computer science)

Reviewed by Junaid khan (Ph.D. Nutrition)

Fact checked 🔍✓

Published: November 11, 2023 → Last Updated: February 3, 2024

What are Thyroid Tests?

A thyroid function test is a medical assessment that measures the levels of thyroid hormones (T3 and T4) and thyroid-stimulating hormone (TSH) in the blood to evaluate the functioning of the thyroid gland. These tests help diagnose and monitor thyroid disorders, including hypothyroidism and hyperthyroidism.

Common thyroid tests include:

  1. TSH (Thyroid Stimulating Hormone) Test:

    • TSH is produced by the pituitary gland and stimulates the thyroid to release thyroid hormones (T3 and T4). Elevated TSH levels may indicate an underactive thyroid (hypothyroidism), while low levels may suggest an overactive thyroid (hyperthyroidism).
  2. Free T3 and Free T4 Tests:

    • These tests measure the levels of the active thyroid hormones, triiodothyronine (T3) and thyroxine (T4), in the bloodstream. Abnormal levels can indicate thyroid dysfunction.
  3. Thyroid Antibody Tests:

    • Tests like TPO (thyroid peroxidase) antibodies and thyroglobulin antibodies are conducted to detect autoimmune thyroid diseases, such as Hashimoto’s thyroiditis and Graves’ disease.
  4. Radioactive Iodine Uptake (RAIU) Test:

    • This test measures how much iodine the thyroid takes up from the bloodstream. It is often used to assess thyroid function and detect hyperthyroidism.
  5. Thyroid Scan:

    • A nuclear medicine scan that provides images of the thyroid. It helps identify the size, shape, and position of the thyroid gland and any abnormalities.
  6. Fine Needle Aspiration (FNA) Biopsy:

    • In cases of suspicious thyroid nodules, a small sample of tissue is taken using a thin needle to check for cancer or other abnormalities.

Thyroid tests are crucial for diagnosing thyroid disorders, such as hypothyroidism, hyperthyroidism, goiter, or thyroid cancer. The choice of tests depends on the specific symptoms, medical history, and the doctor’s clinical judgment. If you have concerns about your thyroid health, it’s important to consult with a healthcare professional for proper evaluation and guidance.

How the calculator interpret the test ?


  • The calculator then interprets the results based on commonly used reference ranges for these thyroid hormones:
    • TSH should typically fall between 0.4 and 4.0 mIU/L.
    • T3 levels are generally considered normal between 0.8 and 2.0 ng/dL.
    • T4 levels typically range from 4.5 to 12.0 mcg/dL.

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