FAQ Category: Drugs That Affect Thyroid Function Tests

Not at the same time. Calcium, iron, and antacids reduce absorption. Separate by at least 4 hours.

Usually every 6–8 weeks after any dose change. Once stable, once or twice per year is enough

Glucocorticoids and dopamine agonists may reduce TSH secretion without clinical hypothyroidism

Yes, some drugs interfere with assay methods or hormone-binding proteins, leading to false positives or negatives in TFTs, even when thyroid function is normal.

Yes. Immune checkpoint inhibitors often trigger thyroiditis, leading to fluctuating TSH and hormone levels. Endocrinology follow-up is usually needed during cancer therapy.