Measurement of follicle stimulating hormone in serum. Useful at the time of menstruation for indicating a significantly decreased number of eggs in the ovaries in the few years leading up to menopause (that is, indicative of depletion of eggs or primary ovarian failure); Continuously high in women after menopause, and then excreted in high amounts in the urine (from which, in turn human menopausal gonadotropin is derived).

The natural process in which the older the female fetus, girl or woman gets the fewer are the eggs (as primordial follicles) left in the ovaries; the huge majority of eggs are lost because of atresia, only a tiny fraction by ovulation. Before the eggs are depleted there is a mild or moderate elevation in serum FSH when measured during the menstrual phase (often called a day 3 FSH. When the eggs are more or less depleted there will be primary ovarian failure and, in women who have had periods, the menopause will take place, perhaps prematurely (premature menopause). Infertility, however, usually precedes total egg depletion by up to 10 years. See also mitochondrion and oopause.

Recombinant follicle stimulating hormone made by Organon. Called Puregon in Europe, Australia and Asia. On an equivalent dose basis, produces serum FSH that are somewhat slower to rise than with the use of hMG preparations, but which are ultimately higher: in other words, follicles and serum estradiol levels take a little longer to respond than they do to Humegon, but the number of mature, preovulatory follicles available for egg retrieval is the same or more. I find that 200 U (units) of Puregon per day produces a similar result to 225 U of Humegon or Metrodin. Generically known as follitropin beta.

A protein hormone produced in women by developing follicles as well as by the corpus luteum, and in men by the testis in the presence of spermatogenesis, and acting on the pituitary gland to inhibit the production of follicle stimulating hormone. In women, falling levels occur as the number of developing follicles reduces to low numbers leading up to menopause, thus causing the elevation of serum FSH and shortening of the follicular phase that characterises the premenopause. In men, appreciable levels of serum inhibin B, a subclass of the inhibin family, predicts the presence of at least a small amount of sperm production.

Early experience with superovulation for in vitro fertilisation, particularly at the original US program in Norfolk VA, saw women patients classified into three classes of responders, depending on how many eggs were obtained at egg retrieval. Poorer than usual outcomes could occur with either a low response or a high response (the high responders generally have polycystic ovaries, with a risk of ovarian hyperstimulation syndrome (OHSS). Many maneuvers have been used to try and retrieve more eggs among low responders, such as starting high dose FSH on day 1, the adding of growth hormone, the avoidance of GnRH-agonists etc., all generally without improving the results. Day 3 serum FSH levels can be high in low responders, indicating a depletion of eggs in the ovaries.

A new term for the normal cessation of female fertility up to 10 years before the menopause, being apparent in some women after the age of 33 and most women by 45. Different from the perimenopause, which occurs as egg numbers fall far enough to cause shortening of the menstrual cycle, particularly the follicular phase, and accompanied by elevation of serum FSH when measured during menstruation. If pregnancies are attempted through the oopausal transition, a woman who has had no prior reproductive disturbance will typically experience recurrent miscarriages before developing otherwise unexplained infertility, manifesting in the IVF lab sequentially with unexplained implantation failure of apparently satisfactory embryos, then, in turn, a decreased rate of forming blastocysts, defective cleavage, and then failure of fertilisation. There is no known method of overcoming its effects short of egg donation, except for some hope that the procedure of cytoplasmic transfer might be helpful.

A time of intermittent symptoms of the menopause that first becomes apparent as egg numbers in the ovaries fall far enough to cause shortening of the menstrual cycle, particularly the follicular phase, and accompanied by elevation of serum FSH when measured during menstruation. As it progresses, menstrual cycles can shorten considerably, while becoming interspersed unpredictably by unusually long cycles, sometimes producing cystic follicles and even anovulatory dysfunctional bleeding, as well as episodes of hot flashes. Different from the oopause.

Recombinant follicle stimulating hormone made by Organon. Called Follistim in US. On an equivalent dose basis, produces serum FSH that are somewhat slower to rise than with the use of hMG preparations, but which are ultimately higher: in other words, follicles and serum estradiol levels take a little longer to respond than they do to Humegon, but the number of mature, preovulatory follicles available for egg retrieval is the same or more. Professor Jansen, medical director of SIVF, notes that 200 U (units) of Puregon per day produces a similar result to 225 U of Humegon or Metrodin. Generically known as follitropin beta.

In women, when measured during menstruation, inversely related to the serum FSH (and probably provides no more information than the day 3 FSH level in predicting depletion of eggs); in men with azoospermia, levels predict the likelihood of being able to obtain sperm for ICSI at testicular sperm extraction.