Somatostatinergic tone in children on chronic haemodialysis and after renal transplantation

The role of somatostatinergic tone (SST) in growth hormone (GH) neuroregulation in children with chronic renal failure (CRF) and short stature (mean height standard deviation score -3.47) was investigated. Ten children (9 males, 1 female), mean age 13.4 years (range 8-17 years), five with renal transplants (TP) and five on chronic haemodialysis (HD), underwent three separate investigations: (1) measurement of spontaneous GH secretion; (2) measurement of GH after infusion of GH releasing hormone (GHRH); (3) measurement of GH following treatment with pyridostigmine bromide (PD) and subsequent infusion of GHRH. All patients showed normal or exaggerated spontaneous nocturnal GH secretion (mean concentration values ranging between 3.8 and 19.07 ng/ml). In four of ten patients GHRH was not able to cause an increase in GH levels (mean peak GH 7.35±2.05 ng/ml) while PD pretreatment reinstated the GH response to GHRH (mean peak GH 55.25±17.23 ng/ml) in these children. In the other patients in whom GHRH-induced GH release was normal or exaggerated (mean peak GH 42.0±13.8 ng/ml), PD did not potentiate the GH response to GHRH (mean peak GH 54.83±7.88 ng/ml). These different types of responses were observed both in TP and HD patients. Our data indicate that: (1) PD potentiates the response to GHRH only when GHRH alone is not able to cause GH release, suggesting that SST is already reduced in patients with a normal or exaggerated GH response to GHRH; (2) in CRF patients the SST can be either reduced or increased, at least during the daytime.