High prevalence of hyperparathyroidism among peritoneal dialysis patients: A review of 176 patients

Objectives: Parathyroid dysfunction continues to produce significant morbidity in dialysis patients. Since the introduction of low calcium dialysate for peritoneal dialysis (PD), no large studies have been done to determine the prevalence of parathyroid dysfunction in these patients. This study was done to assess the prevalence of parathyroid disease in the PD population and to determine the risk factors associated with this dysfunction. Design: We analyzed data on 176 patients who received PD at a single center between August 1998 and February 1999. Clinical data, laboratory variables related to parathyroid function, and data pertaining to dialysis treatment and weekly drug dosing were obtained for each patient on two different occasions, approximately 3 months apart. Variables predictive of the development of parathyroid dysfunction were calculated by univariate and multivariate logistic regression analysis. Results: Two-thirds of the patients surveyed had an abnormal intact parathyroid hormone (iPTH) level: 47% had an iPTH level more than three times normal, the mean was 54.6 +/- 35.4 pmol/L; 23% had an iPTH value below the upper limit of normal, here the mean was 3.6 +/- 1.8 pmol/L. Diabetic patients had lower iPTH levels (22.2 +/- 28.4 pmol/L) than nondiabetics (33.9 +/- 34.8 pmol/L) (p = 0.02). On multivariate regression analysis, we found that age, duration of dialysis, Kt/V, serum bicarbonate, and serum ionized calcium levels did not significantly affect parathyroid function. Hyperphosphatemia was the only factor that was associated with the development of secondary hyperparathyroidism in this study population (p = 0.029). Conclusion: There is a high prevalence of hyperparathyroidism in the current PD population. Phosphate control is suboptimal and hyperphosphatemia is an independent risk factor for the development of hyperparathyroidism.