[Growth and renal function]

Some genetic conditions, as cystinosis, familial hypophosphataemic rickets, type-I vitamin D-resistant rickets and renal tubular acidosis have an impact on growth and growth failure is one of the major problem in children with chronic renal failure (CRF). In early childhood, anorexia and malnutrition, electrolyte disturbances and metabolic acidosis are the main contributing factors for reduced growth, whereas renal osteodystrophy, anemia and hormonal disturbances are responsible for growth impairment later and during puberty. During infancy, loss of growth potential can be prevented by adequate nutrition. Later in life, catch-up growth cannot be induced by nutritional intervention or dialysis and renal transplantation allows catch-up growth in only a small percentage of patients. There is evidence for a state of resistance to growth hormone (GH) and insulin-like growth factor-I (IGF-I) in CRF. GH secretion is normal, but GH half-life is prolonged and the binding activity of the GH-binding protein is reduced, which points to a low receptor expression. IGF-I production may be diminished and the serum concentration of IGF-binding proteins (IGFBP-1 and 3) is increased. The imbalance between normal IGF-I and excessive IGFBP serum levels results in decreased IGF bioactivity that plays a pathogenic role in the growth failure. This insensitivity seems to be overcome by supraphysiological doses of recombinant human GH (rhGH). Many clinical studies have confirmed that rhGH increases growth velocity in children with CRF with and without dialysis and after renal transplant, without significant side-effects. The improvement of growth is more marked in prepubertal patients and during the first year of rhGH treatment. Long-term rhGH treatment in children with CRF improves the growth potential of children, achieving target adult height. The Authors discuss the recent studies employing rhGH in renal diseases and attempt to give some guide lines to rhGH treatment in these illnesses.