Male hypogonadism is the result of deficiency of the male sex hormone testosterone. It leads to loss of sex drive and function, delayed puberty, osteoporosis, and there can also be associated failure of the testes to produce sperm.
Alternative names for male hypogonadism
Testosterone deficiency syndrome; testosterone deficiency; primary hypogonadism; secondary hypogonadism; hypergonadotrophic hypogonadism; hypogonadotropic hypogonadism
What is male hypogonadism?
Male hypogonadism describes a state of low levels of the male hormone testosterone in men. Testosterone is produced in the testes and is important for the formation of male characteristics such as deepening of the voice, development of facial and pubic hair, and growth of the penis and testes during puberty. Gonadotrophin-releasing hormone, made in the hypothalamus, stimulates the pituitary gland to produce luteinizing hormone and follicle stimulating hormone (gonadotrophins), which then act on the testes causing them to produce testosterone. Low levels of testosterone can occur due to disease of the testes or from conditions affecting the hypothalamus or pituitary gland. Men can be affected at any age and present with different symptoms depending on the timing of the disease in relation to the start of puberty.
What causes male hypogonadism?
Male hypogonadism can be divided into two groups. Classical hypogonadism is where the low levels of testosterone are caused by an underlying specific medical condition, for example Klinefelter’s syndrome, Kallmann’s syndrome or a pituitary tumor. Late-onset hypogonadism is where the decline in testosterone levels is linked to general aging and/or age-related diseases, particularly obesity. It is estimated that late-onset hypogonadism only affects a small number of men over the age of 40.
There are two types of classical male hypogonadism – primary and secondary. Primary hypogonadism occurs when the low level of testosterone is due to conditions affecting the testes. Primary hypogonadism is also referred to as hypergonadotrophic hypogonadism, whereby the pituitary produces too much luteinizing hormone and follicle stimulating hormone (gonadotrophins) to try and stimulate the testes to produce more testosterone. However, as the testes are impaired or missing, they are not able to respond to the increased levels of gonadotrophins and little or no testosterone is produced.