Hypergonadotropic hypogonadism in males – Most common cause is? (AIPG 2010)
1. In women with hypergonadotropic hypogonadism (ie, gonadal failure), the most common cause of hypogonadism is Turner syndrome, which has an incidence of 1 case per 2,500-10,000 live births. In men with hypergonadotropic hypogonadism, the most common cause is Klinefelter syndrome, which has an incidence of 1 case per 500-1000 live births.
2. Hypergonadotropic hypogonadism is more common in males than in females because the incidence of Klinefelter syndrome (the most common cause of primary hypogonadism in males) is higher than the incidence of Turner syndrome (the most common cause of hypogonadism in females). Incidence of hypogonadotropic hypogonadism is equal in males and females.
3. Hypogonadism may occur if the hypothalamic-pituitary-gonadal axis is interrupted at any level.
4. Hypergonadotropic hypogonadism (primary hypogonadism) results if the gonad does not produce the amount of sex steroid sufficient to suppress secretion of LH and FSH at normal levels.
5. Hypogonadotropic hypogonadism may result from failure of the hypothalamic LHRH pulse generator or from inability of the pituitary to respond with secretion of LH and FSH.
6. Hypogonadotropic hypogonadism is most commonly observed as one aspect of multiple pituitary hormone deficiencies resulting from malformations (eg, septooptic dysplasia, other midline defects) or lesions of the pituitary that are acquired postnatally. In 1944, Kallmann and colleagues first described familial isolated gonadotropin deficiency.