Optimal correction of acidosis changes progression of dialysis osteodystrophy

To investigate an eventual role of acidosis on hemodialysis osteodystrophy we prospectively studied 21 patients who were dialyzed with different amounts of bicarbonate in the dialysate for 18 months. According to the level of bone formation rate (BFR) on a prestudy bone biopsy, patients were split in two subgroups. Inside these two subgroups patients were randomly allocated to two therapeutics groups: 10 patients (group A) were dialyzed with the conventional amount of bicarbonate (33 +/- 2 mmol/liter) in the dialysate; the rest of the patients (group B, N = 11) had 7 to 15 mmol/liter sodium bicarbonate added to the dialysate to obtain 24 mEq predialysis bicarbonate plasma levels. An effective correction of acidosis was shown in group B by a higher predialysis plasma bicarbonate level (15.6 +/- 1 group A vs. 24.0 +/- 0.6 mEq/liter group B, P less than 0.005), which was reached three months after start of the study. Compared to the prestudy bone biopsy, osteoid and osteoblastic surfaces increased in group A but not in group B on the bone biopsies performed at the end of the study. Parathormone plasma level (iPTH), measured with an antiserum which cross reacts with the 44-68 region of PTH molecule, increased during the study in group A but not in group B. This finding suggested progression of secondary hyperparathyroidism (HPT) only in group A patients. Osteocalcin plasma values increased in both groups during the 18 months of the study. Consequently the two subgroups of patients formed on the basis of BFR level were evaluated separately.(ABSTRACT TRUNCATED AT 250 WORDS)