Effects of intravenous calcitriol on lipid profiles and glucose tolerance in uraemic patients with secondary hyperparathyroidism

Secondary hyperparathyroidism in chronic renal failure may contribute to abnormalities of lipid metabolism and glucose tolerance. Amelioration of secondary hyperparathyroidism has been reported to mitigate the hyperlipidaemia and improve glucose tolerance experimentally. The effect of the partial suppression of hyperparathyroidism by intravenous calcitriol on lipid levels and glucose tolerance was studied in 15 haemodialysis patients with secondary hyperparathyroidism. All received intravenous calcitriol 1 μg at the end of haemodialysis thrice weekly for eight weeks. Oral glucose tolerance test and plasma lipid profiles including triglyceride, total cholesterol, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), apoprotein A-I and apoprotein B were determined simultaneously before and after eight weeks of therapy. Before calcitriol treatment, uraemic patients with secondary hyperparathyroidism displayed a significant higher triglyceride and a significant lower HDL-C and apoprotein A-I as well as marked glucose intolerance with an increment of the area below the glucose curve when compared with healthy control subjects. After eight weeks of calcitriol treatment, there was a significant decrement in serum intact parathyroid hormone (476.45 ± 48.33 versus 191.37 ± 30.17 ng/l, P <0.001) and plasma triglyceride (2.24 ± 0.34 versus 1.80 ± 0.29 mmol/l, P <0.05) as well as a significant increment of plasma apoprotein A-I (38.13 ± 2.14 versus 44.19 ± 2.18 μmol/l, P <0.05), whereas there was no significant change in serum total cholesterol, LDL-C, HDL-C, and apoprotein B. These patients also became more glucose tolerant with a significant decrease of the area below the glucose curve and a significant rise in the area under the insulin curve after glucose load. Furthermore, the insulinogenic index increased significantly. It was concluded that in addition to 1,25-dihydroxyvitamin D₃ deficiency, secondary hyperparathyroidism may participate in the abnormal lipid metabolism, glucose tolerance and insulin secretion seen in dialysis patients and these abnormalities could be, at least in part, improved by intravenous calcitriol treatment.