The diagnosis of micropenis was made in 25 boys aged 1 month to 16 years. This abnormality was associated with hypothalamic-pituitary deficiency in 12 boys (hypogonadotrophic hypogonadism, hypopituitary growth failure, Prader-Willi syndrome), with testicular disorders in 5 boys (anorchia, testicular dysgenesis). In the other 8 the micropenis was an isolated finding but the testicular response to HCG and the LH response to LHRH was significantly reduced (p less than 0.005). The results suggest there may be isolated gonadotrophia deficiency. The variety of conditions that are responsible for micropenis suggest that testosterone deficiency is an important causative factor. HGH may also be important as the penis may be small in HGH deficiency and growth occurs with treatment
