PARATHYROID-HORMONE DURING MAINTENANCE DIALYSIS - INFLUENCE OF LOW-CALCIUM DIALYSATE, PLASMA-ALBUMIN AND AGE

Intact PTH measurements between 1989-96 in a 116-patient (63 HD, 53 PD ) dialysis unit were reviewed to evaluate the determinants of PTH. Pro phylactic treatment included calcium carbonate and maximal alphacalcid ol therapy A forward stepwise multiple regression analysis showed that duration of dialysis, phosphate, albumin and chronic glomerulonephrit is were independently positively correlated with PTH, and that ionized calcium, parathy- roidectomy, age, diabetic nephropathy and systemic disease were independently negatively correlated. During the first fiv e years of dialysis PTH rose from 124 ng/L (SD range 33-462) to 160 (6 3-402) in HD patients but fell from 119 ng/L (33-423) to 88 (31-251)* in PD patients despite the less intensive treatment. PTH fell with i ncreasing age (40-50 years 173 ng/L (52-575); > 60 years 100 (31-316) ) and hypoalbuminemia (< 400 mu mol/L 68 ng/L (22-209); > 550 mu mol/ l 138 (41-457)*), PD patients were generally older and increasingly m alnourished; after correcting for these factors, no influence of dialy sis modality on PTH could be seen. Low-calcium dialysate (1.25 mmol/L) was introduced for both dialysis groups in 1994. Consequent to this, aluminium consumption was virtually eliminated and consumption of alph acalcidol increased. PTH fell from 161 to 128 ng/L in HD patients but rose from 119 to 135 ng/L in PD patients. The incidence of parathyroid ectomy fell from 4.3%/year to 1.5%/year. Conclusion: Malnourishment a nd increasing age reduce PTH secretion and are important determinants of hyperparathyroidism during maintenance dialysis, Adynamic bone dise ase is common in PD patients and associated with law PTH levels, and m ay be a consequence of malnourishment and involutional changes. The in troduction of low-calcium dialysate reduced the incidence of parathyro idectomy, Control of hyperparathyroidism improved in HD but not PD pat ients.