Secondary hyperparathyroidism in diabetic and nondiabetic patients on long-term continuous ambulatory peritoneal dialysis (CAPD).
Serum values of calcium, phosphate, alkaline phosphatases and parathyroid hormone (PTH) are reported for 24 diabetic and 26 nondiabetic patients treated with continuous ambulatory peritoneal dialysis (CAPD) for a total of 779 months, without the use of vitamin D or calcium supplements. Radiographic data are reported for 25 patients followed on CAPD for at least 12 months. Serum calcium was well maintained and control of hyperphosphataemia acceptable, but phosphate-binding therapy had to be continued in the majority of patients. Diabetic patients had lower serum phosphate levels and higher serum calcium than nondiabetic patients during the first year of CAPD. In nondiabetic patients the institution of CAPD was followed by a fall in PTH, possibly largely reflecting transperitoneal PTH elimination. No patient achieved normalization of serum PTH on CAPD. Although no symptomatic bone disease was observed, radiographic evidence of progressive hyperparathyroid bone disease developed in 3 of the 25 examined patients, all nondiabetic. In summary, long-term CAPD with a dialysate calcium concentration of 1.75 mmol/l seems to be compatible with normocalcaemia and a steady-state situation with regard to secondary hyperparathyroidism in the majority of patients. Despite transperitoneal elimination, serum PTH remains elevated, and definite progression of hyperparathyroidism is observed in some patients, however, probably making a case for vitamin D therapy and/or intraperitoneal or peroral calcium supplementation in these patients.