Anaemia is a feature almost invariably complicating chronic renal failure. Its pathophysiology is multifactorial but the most important cause is erythropoietin (Epo) deficiency. However, either no relation or even a weakly positive relation generally exists between serum immunoreactive (i) Epo and haematocrit values in uraemic anaemia, whereas in anaemias of non-renal origin the correlation is most often strongly negative. Recent evidence indicates that growth hormone also stimulates erythropoiesis. Moreover, late erythroid progenitor cells (CFU-E) require insulin and/or insulin-like growth factor I (IGF-I) for development in vitro. IGF-I has been shown to have a synergistic action with Epo. We have measured serum iEpo and IGF-I levels in 17 haemodialysis patients with severe hyperparathyroid-ism (mean ± sem serum iPTH, 988 ± 88 pg/ml). Mean age and duration of dialysis treatment were 46.1 ± 3.4 and 8.8 ± 1.0 years respectively. Mean haematocrit and haemoglobin values wer 28.1 ± 1.7% and 9.39 ± 0.54 g/dl respectively. Mean serum iEpo and IGF-I levels were 20.3 ± 4.7 mU/ml and 320 ± 20 ng/ml respectively (normal values for serum iEpo and IGF-I, 17.9 ± 6 mU/ml and 91 ± 23 ng/ml respectively). We found that serum IGF-I concentrations were well correlated with haematocrit values (r = 0.68, n = 15, P<0.004) whereas serum iEpo values were not (r = 0.41, n = 12, P = 0.18). IGF-I could therefore be an important factor regulating erythropoiesis in uraemic patients, at least when associated with severe hyperparathyroidis
