LH

Where it comes from

Made in

Gonadotroph cells of the anterior pituitary, which make FSH too

Sent out by

Fast GnRH pulses favour it; a surge at mid-cycle when oestrogen flips from inhibiting to stimulating; steady pulses in men

Acts on

• Ovarian theca cells and the dominant follicle
• Corpus luteum
• Testicular Leydig cells

What it does

• Its mid-cycle surge ruptures the follicle and releases the egg, then turns the follicle into the corpus luteum
• Drives testosterone from the Leydig cells
• Rises after menopause and in testicular failure when the feedback is gone

In medicine

• Home ovulation tests detect the urinary LH surge
• Lutropin alfa, recombinant LH, is added to FSH in fertility treatment for women who lack it; hCG is usually used in its place to trigger ovulation ³
• Measured with FSH to sort out amenorrhoea, delayed puberty and hypogonadism: high in gonadal failure, low in pituitary or hypothalamic causes

Beyond the body’s own use

• Adding recombinant LH to FSH in IVF was reviewed across 14 trials and 2,612 women without a clear gain in pregnancy or live birth; the one group that may benefit is poor responders ¹
• Kisspeptin, which sits upstream of GnRH, has been tried as a gentler trigger than hCG: in 60 women at high risk of ovarian hyperstimulation, kisspeptin-54 matured eggs in 95 per cent and none developed moderate or worse hyperstimulation ²
• Luteinizing hormone and chorionic gonadotropin are banned in sport in male athletes, because they raise testosterone from the testis; they are not prohibited for women ⁴
• A urinary test shows the surge and not the egg: a follicle can luteinise without rupturing, so a positive strip is evidence that LH rose and not proof that ovulation followed