Thyroid Profile: T3, T4, and TSH Explained Simply

Thyroid tests are among the most commonly prescribed blood tests, yet many patients struggle to understand their results. Let's break down what T3, T4, and TSH actually mean.

The Thyroid Hormones

TSH (Thyroid Stimulating Hormone)

• Produced by the pituitary gland
• Normal range: 0.4–4.0 mIU/L
• High TSH = Underactive thyroid (hypothyroidism)
• Low TSH = Overactive thyroid (hyperthyroidism)

T4 (Thyroxine)

• Main hormone produced by the thyroid
• Normal Free T4: 0.8–1.8 ng/dL
• Low T4 with high TSH confirms hypothyroidism

T3 (Triiodothyronine)

• The active form of thyroid hormone
• Normal: 80–200 ng/dL
• Usually tested when hyperthyroidism is suspected

Common Thyroid Conditions

• Hypothyroidism: Fatigue, weight gain, cold intolerance, depression
• Hyperthyroidism: Weight loss, anxiety, rapid heartbeat, sweating
• Hashimoto's Disease: Autoimmune hypothyroidism
• Graves' Disease: Autoimmune hyperthyroidism

Who Should Get Tested?

• Women (especially over 30)
• People with family history of thyroid disease
• Anyone with unexplained weight changes or fatigue
• Pregnant women (thyroid affects fetal development)

Thyroid testing is included in our ADC Essential Panel onwards. Book your thyroid test at Aarvak Diagnostics today.