TSH blood test: how to prepare

How to take a TSH test

• Blood is drawn from a vein in the standard way; women can take the test on any day of the cycle.
• Have your blood taken in the morning, between 8:00 and 11:00.
• Take the test at the same time and in the same laboratory: different labs may use different equipment, reagents, methods and reference scales.
• If your thyroid function is impaired, check your TSH level twice a year — in spring and autumn.

How to prepare

• Take the test on an empty stomach: after sleep and 8–12 hours of fasting. You may drink only plain still water (up to 200 ml).
• For 1–2 days before the test, avoid spicy, fatty and fried food and alcohol.
• The day before the test, avoid physical and emotional strain.
• Do not smoke for at least an hour before the test.
• Do not take the test right after an X-ray, physiotherapy or instrumental examinations.
• On the morning of the test, skip your thyroid medication (Euthyrox, L-thyroxine) and take it after the blood draw.

Normal TSH levels

Reference ranges may vary between laboratories. The target TSH level (including when planning a pregnancy) is set by your doctor individually.