Diagnostic Evaluation of Obese Women with Amenorrhea

Hormonal Profile Findings

In severe obesity, FSH may be low‑normal (≈ 3.9 UI/L) while LH can be markedly low (≈ 0.5 UI/L), producing an inverted FSH/LH ratio that is atypical for classic PCOS but observed in class III obesity. 1
Estradiol values around 186 pmol/L (≈ 50 pg/mL) lie at the lower end of the normal range, indicating reduced but not absent ovarian function. 1
Total testosterone that is normal or low‑normal helps exclude overt hyperandrogenism. 1
Normal prolactin (≈ 13.7 µg/L) rules out hyperprolactinemia as a cause of amenorrhea. 1
A normal TSH level excludes primary thyroid disease; free T4 should be checked to rule out central hypothyroidism. 2

Class III obesity (BMI ≈ 41 kg/m²) is strongly linked to PCOS and can alter the typical hormonal pattern. 3
Chronic oligomenorrhea since adolescence suggests persistent ovulatory dysfunction compatible with PCOS. 3
A normal pelvic ultrasound does not exclude PCOS because diagnosis relies on meeting at least two of the three Rotterdam criteria; polycystic ovarian morphology may be absent. 3
Measurement of free or bioavailable testosterone is more sensitive than total testosterone for detecting hyperandrogenism in PCOS. 2
DHEA‑S assessment is recommended to exclude an adrenal source of androgen excess. 2
Fasting 8 am 17‑hydroxyprogesterone helps rule out non‑classic congenital adrenal hyperplasia. 2
An anti‑Müllerian hormone (AMH) level that is normal or elevated supports a PCOS diagnosis. 1
An oral glucose tolerance test (75 g) should be performed to screen for diabetes or impaired glucose tolerance in women with PCOS and severe obesity. 3
A fasting lipid profile is advised to identify dyslipidemia associated with PCOS and obesity. 3

Low‑normal LH and FSH together with low‑normal estradiol are compatible with hypothalamic suppression seen in FHA, even in the context of severe obesity. 2
Classic FHA is characterized by estradiol < 50 pg/mL; the patient’s value is at this threshold, supporting this diagnosis. 2
An acute GnRH stimulation test that raises LH and FSH 2–3‑fold indicates preserved pituitary responsiveness, distinguishing FHA from organic hypogonadotropic hypogonadism. 2

Typical hormonal pattern in EOI includes FSH > 25–35 UI/L, LH > 15 UI/L, and estradiol < 50 pg/mL; these are not present in this patient. 1
If EOI is suspected, AMH < 0.5–1 ng/mL would indicate diminished ovarian reserve. 1
Re‑assessment of FSH and LH after one month is recommended when EOI remains a concern. 1

Organic central hypogonadism would show very low or undetectable gonadotropins and an absent response to GnRH stimulation. 2
Absence of neurological symptoms (headache, visual changes) makes a structural pituitary lesion improbable. 2
Pituitary MRI is indicated only if clinical suspicion persists. 2

Women with severe obesity and menstrual irregularities have an elevated risk of cardiovascular disease; therefore, screening for diabetes (OGTT) and dyslipidemia is essential. 3

Hormonal panel: free testosterone, DHEA‑S, 17‑hydroxyprogesterone, AMH, and repeat FSH/LH if needed. [2][1]3
Metabolic assessment: 75 g oral glucose tolerance test, fasting lipid profile, and HOMA‑IR if available. 3
GnRH stimulation test when differentiation between FHA and central hypogonadism is required. 2
Imaging: pelvic ultrasound (recognizing limitations in obesity) and pituitary MRI only if indicated. [3][2]