The term hypogonadism usually means permanent rather than transient or reversible defects, and usually implies deficiency of reproductive hormones, with or without fertility defects. The term is less commonly used for infertility without hormone deficiency. There are many possible types of hypogonadism and several ways to categorize them. Hypogonadism is also categorized by endocrinologists by the level of the reproductive system that is defective. Physicians measure gonadotropins (LH and FSH) to distinguish primary from secondary hypogonadism. In primary hypogonadism the LH and/or FSH are usually elevated, meaning the problem is in the testicles (hyper-gonatropic hypogonadism); whereas in secondary hypogonadism, both are normal or low, suggesting the problem is in the brain (hypo-gonatropic hypogonadism). Affected system
Hypogonadism resulting from defects of the gonads is referred to as hypergonadotropic hypogonadism or primary hypogonadism. Examples include Klinefelter syndrome and Turner syndrome. Mumps is known to cause testicular failure, and in recent years has been immunized against in the US. A varicocele can reduce hormonal production as well. Hypogonadism resulting from hypothalamic or pituitary defects is termed hypogonadotropic hypogonadism (HH), secondary hypogonadism, or central hypogonadism (referring to the central nervous system).Examples of hypothalamic defects include Kallmann syndrome. Examples of pituitary defects include hypopituitarism and pituitary hypoplasia. An example of a hypogonadism resulting from the lack of hormone response is androgen insensitivity syndrome, where there are inadequate receptors to bind the testosterone, resulting in varying clinical phenotypes of sexual characteristics despite XY chromosomes.
Transgender hormone therapy
Finasteride is sometimes used in hormone replacement therapy for transgender women due to its antiandrogenic effects, in combination with a form of estrogen. However, little clinical research of finasteride use for this purpose has been conducted and evidence of safety or efficacy is limited. Moreover, caution has been recommended when prescribing finasteride to transgender women, as finasteride may be associated with side effects such as depression, anxiety, and suicidal ideation, symptoms that are particularly prevalent in the transgender population and in others at high risk already. Adverse effects
A 2010 Cochrane review of finasteride for BPH found that, in men with a weighted mean age of 62.4, adverse effects are "rare; nevertheless, men taking finasteride are at increased risk for impotence, erectile dysfunction, decreased libido, and ejaculation disorder, versus placebo." As of 2016 fresh evidence suggested such effects, along with disturbed neurosteroid production, may persist after finasteride use is stopped.Finasteride is contraindicated in pregnancy. The Food and Drug Administration advises that donation of blood or plasma be deferred for at least one month after taking the last dose of finasteride.The FDA has added a warning to 5α-reductase inhibitors concerning an increased risk of high-grade prostate cancer, as the treatment of BPH lowers PSA (prostate-specific antigen), which could mask the development of prostate cancer.