About Luteinizing Hormone
LH (Luteinizing Hormone) triggers ovulation in women and stimulates testosterone production in men. An LH surge mid-cycle is the signal that ovulation is imminent — the principle behind at-home ovulation predictor kits. Elevated basal LH in women with a high LH-to-FSH ratio is a key diagnostic feature of polycystic ovary syndrome (PCOS); in men, elevated LH alongside low testosterone confirms that the problem lies with the testes rather than the pituitary.