Hormone levels can fluctuate throughout your cycle, day, and even hour. Testing at the wrong time can give misleading results.
Menstrual Cycle Timing
Days 1-5 (Early Follicular)
Best for baseline hormones:
- FSH
- LH
- Estradiol
- Testosterone
- DHEA-S
- AMH (any time)
Days 19-21 (Luteal Phase)
Best for:
- Progesterone (can peak mid-luteal)
- Estrogen/progesterone ratio
Any Day
- Thyroid hormones
- Vitamin D, B12, iron
- Metabolic markers
Time of Day
Morning (before 9am)
- Cortisol (can peak in early morning)
- Testosterone (can be highest in morning)
- Fasting glucose and insulin
Any Time
- Most other hormones
- Vitamins and nutrients
Special Circumstances
Perimenopause
Hormones can fluctuate unpredictably. Test early follicular phase if still cycling, or any time if periods are irregular.
On Birth Control
Hormonal contraceptives can suppress natural hormone production. Testing may not reflect your true levels.
Postmenopause
Hormones can be tested any time.
References
- Practice Committee of the American Society for Reproductive Medicine. (2015). Diagnostic evaluation of the infertile female: a committee opinion. Fertility and Sterility, 103(6), e44-e50. PMID 25936238
- Harlow, S. D., et al. (2012). Executive summary of the Stages of Reproductive Aging Workshop + 10: addressing the unfinished agenda of staging reproductive aging. Journal of Clinical Endocrinology & Metabolism, 97(4), 1159-1168. PMID 22344196
- Rosner, W., et al. (2007). Position statement: utility, limitations, and pitfalls in measuring testosterone. Journal of Clinical Endocrinology & Metabolism, 92(2), 405-413. PMID 17090633
