LH to FSH Ratio

The LH to FSH ratio compares the levels of luteinizing hormone to follicle-stimulating hormone in the blood, with an elevated ratio of 2:1 or higher (and sometimes 3:1) being a classic hormonal pattern seen in many women with PCOS. This abnormal ratio reflects the characteristic hormonal imbalance in PCOS where LH is overproduced (driving androgen excess) while FSH is suppressed (preventing normal follicle maturation and ovulation). While the LH:FSH ratio is not formally required for PCOS diagnosis under the Rotterdam Criteria, it remains a useful clinical indicator that helps explain the hormonal mechanism behind each woman's symptoms and can guide treatment decisions.