Hormone Testing: A Timing and Preparation Guide
A hormone test is only as good as its timing. Here is how to get it right the first time.
Time of day
Testosterone peaks between 7 and 10 a.m., especially in younger men. Cortisol peaks around 7–8 a.m. and falls through the day. Prolactin and TSH also have diurnal variation and are best drawn in the morning.
Cycle day for cycling women
Estradiol, LH, and FSH: cycle days 2–5 (early follicular). Progesterone: 7 days before expected menses (mid-luteal, roughly day 21 in a 28-day cycle). Always write the cycle day on the requisition.
Interfering supplements and medications
Stop biotin (over 5 mg/day) for 48–72 hours — it distorts many immunoassays. Skip intense exercise for 24–48 hours. Note recent steroid use, opioids (suppress LH/testosterone), and contraceptives (change SHBG and estradiol readings).
Plan your draw with our team
Ready to discuss hormone therapy? Book an initial hormone therapy consultation or a perimenopause / menopause appointment, or contact us via our booking page.
Frequently asked questions
Do I need to fast?+
Fasting is preferred for consistency; required for lipids if drawn at the same time.
Can I test on birth control?+
Yes but interpretation is limited; some panels require a 6–8 week pause.