How to prepare for TSH Check

Preparing for a TSH (thyroid-stimulating hormone) test is straightforward, but several factors can affect accuracy. TSH follows a circadian rhythm, peaking in the early morning (around 8–10 AM), so blood draw is typically scheduled then. Fasting is not strictly required, but some labs recommend it to avoid lipemic interference. Crucially, high-dose biotin (vitamin B7) – common in hair, skin, and nail supplements – can falsely lower TSH results; it should be discontinued at least 3–5 days before testing. Certain medications (e.g., thyroid hormones, corticosteroids, dopamine) also alter TSH levels. The test alone is a screening tool; a full thyroid panel includes free T3, free T4, and antibodies. Evidence for these recommendations is based on clinical practice and laboratory guidelines, not strong randomized trials. Note: The provided context does not address TSH preparation specifically – this answer relies on general medical knowledge.