---
title: "What day of your cycle should you get hormone blood tests?"
type: prep
url: "https://www.test-well.com/prep/menstrual-cycle"
factor: Menstrual cycle day
aliases:
  - cycle day 3 blood test
  - day 21 progesterone
  - hormone test timing period
reviewed_at: 2026-09-06
review_status: reviewed
date_published: 2026-09-05
---

# What day of your cycle should you get hormone blood tests?

> It depends on the hormone. FSH, LH and estradiol are usually drawn on cycle days 2–5 (day 1 = first day of full flow); progesterone about 7 days after ovulation (day 21 of a 28-day cycle); AMH, TSH, prolactin, testosterone and DHEA-S can be drawn any day. Note the cycle day on every hormone result — it changes the interpretation.


## Which results does it affect?

| Marker | Direction | How long the effect lasts | What to do | Source |
| --- | --- | --- | --- | --- |
| FSH | raises or lowers | Varies across the cycle; baseline is days 2–5 | Draw on cycle days 2–5 | [Testing.com (AACC) — FSH / LH](https://www.testing.com/tests/follicle-stimulating-hormone-fsh/) |
| LH | raises or lowers | Surges mid-cycle (ovulation) | Draw on cycle days 2–5 for baseline | [Testing.com (AACC) — FSH / LH](https://www.testing.com/tests/follicle-stimulating-hormone-fsh/) |
| Estradiol | raises or lowers | Lowest early follicular; peaks before ovulation | Draw on cycle days 2–5 unless told otherwise | [Testing.com (AACC) — FSH / LH](https://www.testing.com/tests/follicle-stimulating-hormone-fsh/) |
| Progesterone | raises | Rises after ovulation, peaks ~day 21 | Draw ~7 days after ovulation to confirm it | [Testing.com (AACC) — FSH / LH](https://www.testing.com/tests/follicle-stimulating-hormone-fsh/) |
| Ferritin, iron, hemoglobin | can lower | During and just after heavy periods | Test mid-cycle for a stable iron picture | [NIH Office of Dietary Supplements — Iron fact sheet](https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/) |
| AMH, TSH, prolactin, testosterone, DHEA-S | interferes | Little cycle variation | Any day; prolactin fasting and rested | [Testing.com (AACC) — FSH / LH](https://www.testing.com/tests/follicle-stimulating-hormone-fsh/) |

## Why cycle day matters

Estradiol can differ several-fold between day 3 and the day before ovulation, and LH spikes briefly at ovulation. A 'high' estradiol or LH drawn mid-cycle may be completely normal for that day. Baseline values — the ones fertility and menopause assessments rely on — are day 2–5 numbers. Progesterone only tells you whether ovulation happened if it's drawn in the second half of the cycle.

If your cycles are irregular or absent, draw any day and tell your clinician; the interpretation adjusts. Hormonal contraception suppresses the natural pattern, so results on the pill reflect the medication, not your cycle.

## Common questions

### How do I count cycle days?

Day 1 is the first day of full menstrual flow (not spotting). Day 3 is two days later.

### Can I test hormones while on birth control?

You can, but FSH, LH and estradiol will reflect the pill's suppression rather than your ovaries. Ask your clinician whether a washout is appropriate before drawing them.

## Related

- [Do you need to fast before a blood test — and which tests does eating affect?](https://www.test-well.com/prep/fasting)
- [Does biotin affect blood test results?](https://www.test-well.com/prep/biotin)
- [How does alcohol affect blood test results?](https://www.test-well.com/prep/alcohol)
- [Should you exercise before a blood test?](https://www.test-well.com/prep/exercise)
- [All preparation guides](https://www.test-well.com/prep)
- [Lab visit guide](https://www.test-well.com/at-the-lab)

## Sources

- [Testing.com (AACC) — FSH / LH](https://www.testing.com/tests/follicle-stimulating-hormone-fsh/)
- [NIH Office of Dietary Supplements — Iron fact sheet](https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/)

---

Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-09-06. Review policy: https://www.test-well.com/editorial-policy

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