Reasoning GP · Algorithm · 1-page summary
Female hormone abnormalities
For: adolescents and adults with an abnormal or requested FSH/LH, oestradiol, prolactin, testosterone or progesterone. Not for: pregnancy (test first); absent puberty → paediatric endocrinology (block 2).
Core rule: pregnancy test first, then choose hormones by phenotype — no universal panel. POI needs HRT, not reassurance, and rapid virilisation or a markedly raised testosterone needs urgent specialist assessment, not a PCOS label.
0Stop — call 999 now
- Pituitary apoplexy: sudden severe headache + visual loss, diplopia, altered consciousness or vomiting → 999 No outpatient MRI.
- Adrenal crisis: any of shock, vomiting, abdominal pain, confusion, hypoglycaemia or deterioration, especially with known or possible adrenal insufficiency → 999
- Haemodynamic instability, severe hypoglycaemia, acute neurological/visual symptoms → 999
- While waiting: adrenal crisis → hydrocortisone 100 mg IV/IM now, IV 0.9% saline per protocol; no waiting for bloods.
1Triage — read the pattern with the clinical picture
| Pattern | Meaning → next step |
|---|---|
| FSH ↑, under 40 | Possible POI → repeat FSH in 4–6 weeks |
| Aged 45 or over | Menopause is clinical; no FSH (40–45: consider) |
| FSH/LH low/normal, E2 ↓ | Hypothalamic or pituitary → prolactin, TSH |
| Prolactin ↑ | Mild → repeat rested ± macroprolactin; drugs, TSH |
| Testosterone ↑ | Mild → PCOS (exclusion); >4 nmol/L → endocrinology; about ≥5 → confirm and investigate promptly (SfE 2025); about ≥6–7 → block 2 |
2Screen — serious causes
- Rapid virilisation (deep voice, clitoromegaly, muscle change) or testosterone about 6–7 nmol/L or higher → Urgent endocrinology/gynaecology; no repeat-test delay if virilised.
- Ascites or unexplained pelvic/abdominal mass → Suspected cancer referral. Persistent bloating/satiety/pelvic pain → NG12 CA-125 (40+)/ultrasound.
- Unexplained postmenopausal bleeding ≥55, not HRT → Suspected cancer; <55 consider.
- Haematocolpos or suspected torsion → Same-day gynaecology.
- Very high/rising prolactin, field loss, suspected Cushing's → Urgent endocrinology.
- Primary amenorrhoea, no secondary sexual characteristics → Urgent karyotype, paediatric endocrinology.
3Assess
☐ Pregnancy test ☐ Cycle, contraception, medicines ☐ BMI, exercise, eating disorder ☐ Hirsutism, clitoromegaly, Cushing features, galactorrhoea ☐ Visual fields if high prolactin ☐ Progesterone only for fertility, ~7 days before the period
Not routinely: LH:FSH ratio, AMH for POI, CA-125 screening, IGF-1, fixed day-21 progesterone.
4Classify — only if blocks 0–2 are negative
- PCOS — adults 2 of: ovulatory dysfunction, hyperandrogenism, polycystic ovaries/AMH (adolescents: first two). Exclusion diagnosis.
- POI — under 40, symptoms + raised FSH on two samples 4–6 weeks apart.
- Functional hypothalamic — low FSH/LH and oestradiol; energy deficit, exercise, stress.
- Hyperprolactinaemia — drugs, hypothyroidism, stress; pituitary if very high or rising.
- Menopause — 45+: clinical; 12 months with no periods, off hormonal contraception.
- Uncertain — pelvic ultrasound; refer.
5Treat today — only these
- POI: offer HRT or combined hormonal contraceptive (CHC) unless contraindicated, until at least average menopause age; progestogen if uterus. HRT is not contraception.
- PCOS: lifestyle, no weight stigma; CHC first line if not seeking pregnancy (VTE-risk check). Prolonged amenorrhoea → endometrial protection (CHC, LNG-IUS or intermittent progestogen).
- Menopause HRT: consider transdermal if VTE risk (incl. BMI >30). Review 3 months, then yearly — not by FSH.
- Hypothalamic: restore energy intake, reduce excess exercise; sex steroids = specialist. Doses: NICE/SPC, BNF, local formulary.
6Refer routinely — and monitor
- POI → reproductive medicine (fertility, DXA); Urgent if complex.
- PCOS with heavy or persistent bleeding, ovarian pathology → gynaecology.
- Anovulatory infertility → fertility service, not GP letrozole.
- PCOS: glycaemia every 1–3 years by risk. POI: repeat DXA by result, not yearly.
7Never reassure by
- A PCOS label when virilisation is rapid or testosterone markedly raised.
- "Polycystic ovaries" on a scan alone, or the LH:FSH ratio.
- A single FSH — or leaving confirmed POI without HRT.
- A low day-21 progesterone in a long or irregular cycle.
- A normal testosterone when hyperandrogenism is clinically obvious.
- FSH/LH as ovarian tumour markers, or CA-125 in isolation.
8Safety-net — say it, then document it
999 “Call 999 for a sudden severe headache with loss of or double vision, or if very unwell with vomiting, faintness or confusion.” Same-day “Sudden severe pelvic pain — get seen today.” Urgent “Your voice deepening or body hair changing fast, or any bleeding after the menopause — contact us promptly.”
Remote or OOH: any block 0 feature → 999, not a booked appointment. POI: HRT is not contraception. Follow-up: review booked.
✓Safe to leave primary care only if — all five, documented
No block 0–2 trigger applies
Pregnancy excluded; tests chosen by phenotype and correctly timed
Abnormal result confirmed (FSH twice; prolactin rested)
POI/PCOS plan: HRT/CHC or endometrial protection; contraception discussed
Safety-net given; review date booked
Summary of the full Reasoning GP female hormone abnormalities algorithm, which holds HRT, hirsutism, fertility, bone-health and monitoring detail. Sources: NICE NG23, NG243, NG12 (updated April 2026), TA1143; International PCOS Guideline 2023; ESHRE POI 2024; Society for Endocrinology; MHRA (co-cyprindiol, fezolinetant); local formulary. Clinical reference — follow local pathways and check doses: NICE/SPC, BNF.