The importance of FSH and LH


FSH = Follicle stimulating hormone

LH = Luteinizing hormone

Are they normally monitored to measure a man’s fertility? Are they reliable in this regard? Can they be used as biomarkers for anything else?

In: Biology

I remember reading about these in my anatomy class and the descriptions were pretty vague but the overall importance seemed to be to help the body communicate between the reproductive system and the brain through feedback loops. Sorry I don’t have the material available.

The hormone system keeps the body in equilibrium through slow changes that take into account many different inputs and exert their effects through the physical presence of the hormones.

Hopefully someone who knows more shows up lol

One could argue that FSH and LH dictate the propagation of our species.

Okay, dramatics aside, yes, they are very important. Both are made in the pituitary gland. Both enter the bloodstream to exert their effects on sex organs (testes or ovaries). But, for men and women, that’s where the similarities end.

For women, the hormone FSH stimulates the production of the egg, and LH stimulates estrogen production in the ovaries.

For men, FSH stimulates the production of sperm, and LH stimulates testosterone production in the testes.

Without getting into nitty-gritty feedback loops (e.g. how they shut each other off), these hormones literally control what allows humans to reproduce (i.e. the sperm and egg) as well as what makes men ‘men’ and women ‘women’ (i.e. the testosterone and estrogen). Typically, however, they are not the first thing monitored to evaluate a man’s fertility. A detailed semen analysis is done first, including quantity and quality of the semen, before secondary causes are investigated (e.g. pituitary problems, low testosterone production, etc.).

They also typically aren’t used as “biomarkers,” in the pure sense of the word. Rarely, one can have what’s called a gonadotropin-secreting pituitary tumor (“gonado” – meaning pertaining to gonads, i.e. ovaries and testes, and “tropin” – referring to the hormones that ACT on these organs, i.e. FSH and LH, and cause the release of other hormones, i.e. estrogen and testosterone). This would cause FSH and LH levels to be very elevated on a blood test, but this needs to be distinguished from normal processes which cause elevated FSH and LH (e.g. pregnancy, puberty, menses).