Endocrine tests

The triad of endocrine abnormalities consists of:

• elevated luteinizing hormone with normal follicle stimulating hormone
  
  
• elevated free testosterone:
  • a combination of increased testosterone production and reduced sex hormone binding globulin
    
    
• insulin resistance with compensatory hyperinsulinaemia

Blood should be taken during the first week after menstruation.

Characteristically serum concentration of testosterone is above 2.5nmol/l and serum LH above 10 IU/l (1). A serum testosterone level of above 4.8 nmol/l requires exclusion of other causes of androgen hypersecretion such as an androgen-secreting adrenal or ovarian tumour, Cushing's syndrome or non-classical congenital adrenal hyperplasia (1).

Suggested differential diagnoses and screening tests (2)

• pregnancy - pregnancy test
• hypothyroidism - TSH
• hyperprolactinemia - PRL
• Cushing's syndrome - 24-hour urine free cortisol
• late-onset CAH (congenital adrenal hyperplasia) - 17-hydroxyprogesterone
• ovarian tumor - total testosterone
• hyperthecosis - total testosterone
• adrenal tumor - dehydroepiandrosterone sulfate (DHEAS)

Reference:

• (1) Balen AH et al (1995). Polycystic ovary syndrome: the spectrum of the disorder in 1741 patients. Hum Reprod, 10, 2107-11.
• (2) Sheehan MT. Polycystic ovarian syndrome: diagnosis and management. Clin Med Res. 2004 Feb;2(1):13-27.