FSH

Where it comes from

Made in

Gonadotroph cells of the anterior pituitary

Sent out by

Slow GnRH pulses favour it; activin raises it, inhibin and oestrogen hold it down; highest in the early follicular phase

Acts on

• Ovarian granulosa cells
• Testicular Sertoli cells

What it does

• Recruits a cohort of follicles each cycle and makes them produce oestrogen; the one most sensitive to it becomes dominant as FSH falls
• Supports sperm production through the Sertoli cells
• Rises steeply at menopause, the laboratory sign of it

In medicine

• Recombinant FSH (follitropin alfa and beta, and the weekly corifollitropin alfa) and urinary menotropins drive the multiple follicles of IVF and induce ovulation ⁴
• Measured for ovarian reserve, menopause, male infertility and pituitary disease
• Mutations of FSH or its receptor cause infertility; an overactive receptor causes ovarian hyperstimulation in pregnancy

Beyond the body’s own use

• Recombinant and urinary gonadotrophins were compared across 42 trials and 9,606 couples with no difference in live birth or hyperstimulation, so the choice turns on cost and convenience ¹
• Corifollitropin alfa, a single injection covering the first week of stimulation, was approved in Europe on non-inferiority to daily follitropin beta rather than on any advantage in births ⁴
• Blocking FSH with an antibody turned white fat beige and reduced body fat in mice, which raised the idea of one treatment for the fat and bone changes of menopause ²
• The bone half of that was shown earlier with an antibody against the FSH beta subunit, also in mice; no anti-FSH antibody has entered a human trial ³