The somatotropic axis in puberty.

Sex steroids markedly affect GH pulsatility by altering GH pulse amplitude without affecting GH pulse frequency. The type of sex steroid (testosterone or estrogen) appears to determine the timing of the pubertal growth spurt although both steroids appear to influence the amount of GH released from the pituitary. GH levels also affect gonadal secretion of sex steroids. The effects of the two are synergistic, but there is a real therapeutic dilemma of what to increase and when in children who are deficient in either GH or gonadotrophin secretion. Augmented GH pulsatility, particularly during the day, may alter markedly the interpretation of standard endocrine tests. Finally, the insulin resistance arising from an increased circulating concentration of GH may have important implications for the management of insulin-dependent diabetes during puberty.