Somatomedin activity in sera from twelve insulin-dependent diabetics was measured by the chick embryo cartilage assay system. All patients required insulin for control of hyperglycemia, and had been continuously treated with exogenous insulin for 3 to 25 years. Mean fasting somatomedin activity was elevated in this group of diabetics, and activity did not correlate with the simultaneous blood glucose concentrations. No significant differences were demonstrable between levels in diabetics with and without retinopathy or in patients with and without proteinuria.

Hypercupremia has been described in patients undergoing chronic dialysis. To further characterize dialysis-associated hypercupremia, we studied plasma copper (PCu) and ceruloplasmin (Cp) in patients on hemodialysis (n = 20) and peritoneal dialysis (n = 25), in uremic patients (n = 10) not yet on dialysis, and in normal age-matched control subjects (n = 20). PCu was significantly elevated in all three patients groups (mean +/- SD) (20.6 +/- 4.1, 19.8 +/- 4.6, 19.8 +/- 4.9 mumol/L, respectively) vs control subjects (16.5 +/- 2.7 mumol/L). However, Cp levels were not significantly different among the four study groups (330 +/- 60, 320 +/- 70, 370 +/- 100, and 360 +/- 90 mg/L, respectively). Calculated nonceruloplasmin copper was significantly higher in all uremic groups. The measurement of chelatable Cu confirmed the presence of significantly higher extractable Cu in hemodialysis (2.7 +/- 0.6 mumol/L) and peritoneal dialysis patients (2.4 +/- 0.5 mumol/L) than control subjects (1.5 +/- 0.3 mumol/L). Cu is elevated in uremia regardless of dialysis status and this elevation is not accounted for by an increase in plasma ceruloplasmin.