Luteinising hormone: triggers ovulation and supports sex-hormone production.
What it is
LH in IU/L. Surges mid-cycle in women; supports Leydig cell testosterone production in men.
Luteinising hormone (LH) is a pituitary gonadotrophin. In women it surges to trigger ovulation; in men it stimulates Leydig cells to produce testosterone. Reported in IU/L. Sample timing relative to the menstrual cycle is essential for meaningful female results.
Why it matters
LH:FSH patterns are sometimes discussed in PCOS assessment but are not diagnostic alone. Interpret with cycle timing, symptoms, and other androgens/ultrasound as appropriate.
This guide is educational only and cannot diagnose you. Discuss results, especially anything outside your laboratory’s reference interval, or that does not match how you feel, with a GP or other appropriately qualified clinician.
LH:FSH ratios are sometimes discussed in PCOS pathways but do not diagnose PCOS alone. Low LH with absent periods in sport often reflects hypothalamic suppression from low energy availability. High LH appears after menopause or in some primary gonadal failure states.
This guide is educational only and cannot diagnose you. Discuss results, especially anything outside your laboratory’s reference interval, or that does not match how you feel, with a GP or other appropriately qualified clinician.
How it affects the body
LH pulses drive ovulation and gonadal steroidogenesis via pituitary–gonadal signalling.
LH pulses translate brain signals into gonadal steroid production. Without adequate LH drive, oestradiol/progesterone or testosterone fall, affecting bone, muscle, libido, and reproductive tissues.
For athletes
Low LH with amenorrhoea in sport often points toward hypothalamic suppression from low energy availability: medical and dietetic care, not more hard sessions.
Amenorrhoeic or oligomenorrhoeic athletes need a sports-aware endocrine and nutrition review: more mileage is not the treatment. Male athletes with low libido and low testosterone also need LH (and FSH) to locate the problem along the axis.
For fertility planning when you want AMH with key reproductive and thyroid markers in one private panel. AMH does not predict natural conception chances.
