URINARY GROWTH-HORMONE MEASUREMENTS AS A MARKER OF RENAL TUBULAR FUNCTION IN DIABETES-MELLITUS

Urinary growth hormone (UGH) excretion was assessed in 44 adult subjec ts (10 control, 21 insulin dependent diabetics (Group I), 13 diabetics in poor glycaemic control (Group II)). UGH was markedly elevated in t he diabetic population. The UGH excretion in (1) control subjects rang ed from undetectable levels to 0.7 muU/h, mean 0.4, (2) Group I 73-422 muU/h, mean 250 and (3) Group II 10-5,283 muU/h, mean 705. There was a significant correlation between UGH excretion and albumin excretion rate (AER) (r = 0.38, P < 0.05) in the subjects studied although only 50% of patients had an AER of > 20 mug/min. A stronger correlation was observed between beta2-microglobulin and UGH excretion (r = 0. 7, P < 0.0 1). There was no significant change in the 6-h serum GH levels fo llowing treatment in the patients in Group II. However a 23-79% declin e in UGH excretion was observed following improvement of glycaemic con trol, although UGH levels failed to revert to normal. We conclude that the major factor responsible for increased UGH excretion in DM appear s to be reduced tubular reabsorption of the hormone. This test may the refore prove useful as an additional marker for screening for diabetic nephropathy and may help in the understanding of the contribution of renal tubular abnormalities to the nephropathic process.