hormone-guides

When to Test Your Hormones: Timing by Cycle Day

Hormone test results depend on when in your menstrual cycle blood is drawn. This guide covers the correct timing for Day 3 panels, mid-luteal progesterone, LH, and other cycle-dependent tests.

Hormone testing is one of the most timing sensitive diagnostic tools in medicine. A result that is perfectly normal on one cycle day may be flagged as abnormal on another — not because your hormones changed, but because the reference range did. This guide covers when to test each hormone and why the timing matters. This article is for educational purposes and is not medical advice. Consult a healthcare provider for diagnosis or treatment. The Day 3 Baseline Panel When: Days 2–4 of the menstrual cycle (Day 1 = first day of full menstrual flow, not spotting). What is tested: FSH (follicle stimulating hormone). At baseline, FSH reflects how hard the pituitary is working to stimulate follicle development. A higher baseline FSH suggests the ovaries need more stimulation to respond — a marker of diminished ovarian reserve. Typical Day 3 range: 3–10 mIU/mL. Levels above 10 mIU/mL warrant discussion, though clinical significance depends on context. LH (luteinizing hormone). Baseline LH is compared to FSH. A normal early follicular LH:FSH ratio is approximately 1:1. In PCOS, this ratio is often elevated (2:1 or higher), reflecting disrupted pituitary signaling. Estradiol. Baseline estradiol