Unresolved problems concerning optimal therapy of puberty in children with chronic renal diseases

Many children with chronic renal insufficiency (CRI) show growth retardation and severely delayed pubertal development. Successful renal transplantation (RTx) also rarely results in full growth rehabilitation. Pubertal height gain in CRI patients is only 58% and 48% of that observed in late-maturing boys and girls, respectively. Growth retardation in both CRI and RTx patients is not the result of abnormal GH secretion or decreased levels of IGF-I, but rather of elevated levels of IGFBPs inhibiting the bioavailability of the IGFs. In RTx patients prednisone may also inhibit growth directly via inhibition of bone matrix formation. Several studies have convincingly shown that GH therapy at a dose of 4 IU/m2/day results in a sustained improvement of growth in prepubertal and pubertal children with CRI and in growth-retarded prepubertal and pubertal post-transplant patients. The following consensus was reached concerning optimal therapy of puberty in children with chronic renal disease. GH therapy does not lead to an earlier start of puberty. It is safe to give GH to RTx patients if transplant function is stable. GH therapy will not accelerate bone maturation and can improve the final height of children with CRI and after RTx. Increasing the GH dose above 4 IU/m2/day in pubertal RTx patients does not increase height gain or final height and is not advised as it may increase insulin resistance. GH should best be started before the start of the pubertal growth spurt but will still be effective in RTx patients with advanced bone age. GH testing should not be a prerequisite for starting GH therapy. It is important to optimise other therapies during puberty. During GH therapy of RTx patients use minimum daily, not alternate-day, steroid dosing. Further research is still required on the possible long-term effects of GH therapy in children with chronic diseases. Two studies demonstrated improved long-term growth and final height within the target height range, without significant side effects. Renal graft function did not deteriorate more than in matched controls. A GH dose of 4 IU/m2/day proved adequate.