PCOS responsive to metformin therapy despite very low BMI
R Thomas1, D Woods1, E Michael2 & R Quinton1
A 19-year old ethnic Pakistani presented with severe, longstanding hirsutes without virilisation. Menarche had occurred at age 14, following which she had experienced 4-6 periods a year. She had always been “underweight by UK/WHO criteria and, given a BMI of 16.5 kg.m−2, there were concerns about hypothalamic oligomenorrhoea.
Fasting glucose 5.5 mmol/L & Insulin 15.8 mU/L (NR 1.6–10.9); LH 36.9 & FSH 4.7 U/L, E2 208 pmol/L, 17OHP 5 nmol/L (<14.8). Androgens at baseline (BL) and after 1 mg overnight dexamethasone (DST) given in Table 1. 9 am cortisol with DST<25 nmol/L; no evidence for CAH or Cushings on 2×24 hr urine steroid profiles. Trans-abdominal ultrasound: normal adult uterus with bilateral PCO morphology.
Treatment & Progress
Despite very low BMI, clinical and biochemical features were of PCOS with hyperinsulinaemia. Her diet already appeared reasonably healthy, so she was prescribed metformin (MF) 250 mg od, building up gradually to 1 g tds. On review 4 months later menstrual cyclicity was fully restored, hirsutes had improved, and androgen levels were significantly reduced (Table 1), though BMI had fallen slightly to 16.0 kg.m−2.
The IMA has long proposed lower BMI cut-offs for “healthy, “overweight and “obesity for ethnic Indian-subcontinentals and “slim PCOS with insulin resistance is described, with some evidence for therapeutic benefit of MF. Nevertheless, such a striking PCOS phenotype and response to MF has hitherto never been described in association with such a low BMI.