Thyroid Profile (T3, T4, TSH)
What Is This Test?
The Thyroid Profile (T3, T4, TSH) is a comprehensive blood test used to evaluate the functioning of the thyroid gland. It measures three important thyroid hormones:
- TSH (Thyroid Stimulating Hormone): Produced by the pituitary gland, it regulates thyroid hormone production.
- T3 (Triiodothyronine): The active thyroid hormone that regulates metabolism, energy production, heart rate, and body temperature.
- T4 (Thyroxine): The primary hormone produced by the thyroid gland, which is converted into T3 in body tissues.
This test helps diagnose hypothyroidism (underactive thyroid), hyperthyroidism (overactive thyroid), thyroid inflammation, and other thyroid disorders. It is also commonly used to monitor patients receiving thyroid medication.
Why this test is performed?
Why is this Test Performed?
Doctors may recommend the Thyroid Profile to:
- Diagnose hypothyroidism
- Diagnose hyperthyroidism
- Evaluate thyroid gland function
- Monitor thyroid hormone replacement therapy
- Monitor treatment for hyperthyroidism
- Investigate unexplained weight changes
- Evaluate infertility and menstrual irregularities
- Assess thyroid disorders during pregnancy
- Evaluate thyroid nodules or goiter
- Screen individuals at high risk of thyroid disease
Test Preparation
No fasting is usually required.
Drink water normally before the test.
Inform your healthcare provider about:
- Thyroid medications
- Iodine-containing supplements
- Biotin (Vitamin B7) supplements
- Hormonal medications
High-dose biotin supplements may interfere with thyroid test results. Your doctor may recommend stopping them 24–72 hours before testing if medically appropriate.
If you take thyroid hormone replacement (such as levothyroxine), many healthcare providers recommend collecting the blood sample before your daily dose for consistency.
Medical disclaimer
This article is for general information and education only. It is not medical advice, does not create a doctor–patient relationship, and is not a substitute for consultation with a qualified doctor who has assessed your individual situation. Never delay seeking medical advice because of something you have read here.
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