FSH Test

Description

The FSH Test from BiomarkersLabs.com measures Follicle Stimulating Hormone — a pituitary gonadotropin that plays a central regulatory role in female reproductive function. FSH is secreted by the anterior pituitary in response to GnRH stimulation and acts directly on the ovarian granulosa cells to drive follicular development and oestrogen production during the follicular phase of the menstrual cycle. FSH secretion is subject to negative feedback from oestradiol and inhibin B — both produced by growing follicles — so that as the dominant follicle matures, rising oestradiol suppresses FSH to allow monoovulatory selection.

In clinical practice, serum FSH is most informative when measured on Day 2–3 of the menstrual cycle, where it serves as a proxy for ovarian reserve. Elevated early-follicular FSH indicates reduced inhibin B feedback from a diminished follicular pool and is one of the earliest detectable markers of declining ovarian reserve. In post-menopausal women, FSH rises markedly and persistently — typically above 30–40 IU/L — as the hypothalamic-pituitary axis attempts to drive a depleted ovary. In primary amenorrhoea or premature ovarian insufficiency, elevated FSH confirms gonadal failure. In hypothalamic or pituitary causes of amenorrhoea, FSH is low or inappropriately normal. Results are CLIA-certified (USA) and IVDR-compliant (EU/UK), delivered to the licensed practitioner portal within 1–3 business days.

What does the FSH Test measure?

FSH (Follicle Stimulating Hormone) — pituitary gonadotropin responsible for driving follicular development and oestrogen production in the ovary. Day 2–3 serum FSH is the standard clinical reference point for ovarian reserve assessment. Elevated FSH in the early follicular phase indicates diminished ovarian reserve. Markedly elevated FSH with low oestradiol confirms menopause or premature ovarian insufficiency. Low or inappropriately normal FSH in the context of amenorrhoea suggests a hypothalamic or pituitary cause. FSH is always most informative when interpreted alongside oestradiol and, where relevant, AMH and LH.

Clinical indications

Ovarian reserve and fertility assessment — Day 2–3 FSH is a standard first-line ovarian reserve marker in women undergoing fertility evaluation. Elevated FSH indicates a diminished follicular pool and reduced IVF response probability.

Menopausal status confirmation — persistently elevated FSH (typically >30–40 IU/L) alongside low oestradiol and amenorrhoea for 12 or more months confirms post-menopausal status. Useful in women with atypical presentations or after surgical interventions.

Primary amenorrhoea investigation — elevated FSH in a patient with absent menses and no prior menstrual history suggests primary ovarian insufficiency or Turner syndrome; low FSH points to a hypothalamic or pituitary aetiology.

Pituitary gonadotropin function — FSH forms part of pituitary function assessment where gonadotropin deficiency (hypogonadotropic hypogonadism) is suspected, including in eating disorders, hypothalamic amenorrhoea, and hyperprolactinaemia.

IVF pre-treatment baseline — Day 3 FSH is a mandatory component of pre-IVF ovarian reserve assessment, used alongside oestradiol and AMH to guide stimulation protocol selection and predict response.

Sample type and collection

Blood (serum). No fasting required. Venepuncture at an approved collection site. Day 2–3 of the menstrual cycle is the standard recommended timing for ovarian reserve and fertility assessment. Post-menopausal women may be tested on any day.

Turnaround time

1–3 business days from specimen receipt.

Availability

USA · EU · UK · Canada

Compliance

CLIA Certified · IVDR Compliant · CE Marked · HIPAA Compliant · GDPR Compliant · PIPEDA Compliant

How to order

Register free at BiomarkersLabs.com. Licensed practitioners only. Pay per test — no subscription required. Results are delivered directly and securely to your practitioner portal and are never released directly to patients.