Home Biomarkers FSH

FSH

Fertility profile Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Fertility profile

Overview

Follicle-stimulating hormone (FSH) is a pituitary gonadotropin that regulates ovarian follicle growth and estrogen production in women and stimulates spermatogenesis in men. The blood test measures circulating FSH to assess pituitary–gonadal axis function. It is used when investigating infertility, irregular or absent periods, early/late puberty, sexual dysfunction, or suspected menopause/primary gonadal failure. Normal FSH values vary by sex, age and in women by menstrual-cycle phase; levels are typically low in premenopausal women during the luteal phase and physiologically high after menopause. Acute illness, medications and body habitus can also alter levels.

People also test for

Test Preparation

In females, the preferred sampling time is day 2 or 3 of the menstrual cycle for LH & FSH

Why Do I Need This Test

Profile: Included in a Fertility profile (reproductive hormone panel).
When to test: infertility, oligomenorrhea/amenorrhea, suspected menopause, delayed/precocious puberty, low libido or reduced sperm count.
Diagnoses/monitoring: ovarian reserve/diminished ovarian reserve, primary ovarian or testicular failure, hypogonadotropic hypogonadism, menopausal status.
Causes of abnormal levels: pituitary/hypothalamic disorders, gonadal failure, PCOS (relative changes), medications, extreme exercise or weight loss, smoking.
Family history: early menopause, chromosomal/genetic conditions (e.g., Turner syndrome) may prompt testing.

Run our symptom checker to see if this test is right for you

Symptom Checker

Understanding Test Results

Elevated FSH in women: values >25 mIU/mL are typical of menopause or primary ovarian insufficiency/ovarian failure.
Intermediate elevations (≈10–25 mIU/mL) may indicate diminished ovarian reserve and reduced fertility potential.
In men, FSH above the upper limit (>12.4 mIU/mL) suggests primary testicular failure (impaired spermatogenesis).
Low FSH: values below the reference for age/sex (e.g., <1.5–2 mIU/mL in adults) suggest hypogonadotropic hypogonadism due to pituitary or hypothalamic dysfunction, or suppression from exogenous sex steroids (combined oral contraceptives, high-dose androgens/GnRH analogues), pregnancy, extreme stress or weight loss.
Pattern interpretation: in women, a low or normal FSH with high LH or an elevated LH:FSH ratio can be seen in PCOS; very high FSH with low estradiol supports primary gonadal failure.
Results should be interpreted with cycle timing, clinical picture and other hormones (LH, estradiol, prolactin, AMH) for accurate diagnosis.

Normal Range

Women Follicular: 3.5–12.5 mIU/mL; Mid‑cycle (ovulatory peak): 4.7–21.5 mIU/mL; Luteal: 1.7–7.7 mIU/mL; Postmenopausal: 25.8–134.8 mIU/mL; Men (adult): 1.5–12.4 mIU/mL

FAQs

Q: What does the FSH hormone do?

A: Follicle-stimulating hormone (FSH), released by the anterior pituitary, promotes ovarian follicle growth and estrogen production in women, helping regulate the menstrual cycle and enabling ovulation alongside LH. In men, FSH acts on Sertoli cells to stimulate spermatogenesis. Its secretion is controlled by GnRH from the hypothalamus and modulated by feedback from sex steroids and inhibin.

Q: What are normal FSH levels by age?

A: Typical FSH values (mIU/mL) by life stage: Children: usually <3 Reproductive-age women: follicular 3–10, midcycle 4.7–21.5, luteal 1.5–5 Perimenopause: variable, rising Postmenopausal women: 25.8–134.8 Adult men: ≈1.5–12.4 Ranges vary by lab; discuss borderline or unexpected results with your clinician they may repeat tests or check estradiol and AMH.

Q: What are the symptoms of low FSH?

A: Low FSH may cause irregular or absent periods, infertility, reduced libido and vaginal dryness in women, and decreased sperm production, small testes and infertility in men. Low sex hormones from low FSH can lead to fatigue, low bone density and hot flashes. If due to pituitary disease, headaches and visual changes may also occur.

Q: How to improve FSH levels?

A: To improve FSH levels, address underlying causes: consult an endocrinologist or fertility specialist; correct thyroid or high prolactin, restore a healthy weight, avoid extreme exercise, stop smoking, limit alcohol, manage stress, and ensure adequate vitamin D and balanced nutrition. For fertility-related low FSH, specialists may prescribe ovulation-inducing medications (clomiphene, gonadotropins) or other targeted treatments.

Q: When does FSH start to rise?

A: FSH rises in two contexts: during each menstrual cycle and across the reproductive lifespan. During the cycle, FSH increases in the early follicular phase to recruit follicles. Over the lifespan, as ovarian reserve declines FSH begins to rise in perimenopause—often in the late 30s to mid‑40s—and rises more markedly in the years just before and after menopause (average menopause ~51).

Q: Does high FSH mean poor egg quality?

A: High FSH often signals diminished ovarian reserve and a lower number of remaining eggs, and is associated with poorer response to stimulation. However, it doesn't directly measure egg quality—age is the main determinant of egg quality—and some women with raised FSH still conceive. A full fertility assessment (AMH, antral follicle count, and clinical review) gives better insight and guides treatment options.