Acute correction of metabolic acidosis increases serum procollagen type I carboxyterminal propeptide in patients with chronic renal failure

Background and Purpose: Previous in vitro study has shown that an acidic medium increases osteoclastic and inhibits osteoblastic activity. The present study sought to determine the role of alkali therapy in osteoblast function in patients with chronic renal failure by assessing the serum concentration of procollagen type I carboxyterminal propeptide (PICP), a marker of bone formation, before and after bicarbonate infusion. Patients and Methods: Eighteen patients with chronic renal failure (creatinine clearance 12 ± 6.6 mL/min) associated with mild to moderate metabolic acidosis were enrolled in this study. None had undergone dialysis. Metabolic acidosis was corrected by continuous bicarbonate infusion while plasma ionized calcium was clamped at the preinfusion level by calcium gluconate infusion throughout the procedure. Results: After bicarbonate infusion, there were significant increases in plasma pH (7.31 ± 0.04 to 7.40 ± 0.03, p <0.001), bicarbonate concentration (18.46 ± 2.49 to 23.66 ± 2.72, p <0.001), serum total calcium concentration (2.01 ± 0.24 to 2.12 ± 0.24 mmol/L, p <0.001), and PICP concentration (137.3 ± 56.25 to 159.6 ± 57.30 μg/L, p <0.05), whereas serum parathyroid hormone concentrations assessed by radioimmunoassay decreased significantly (153.7 ± 88.6 to 111.5 ± 78.7, p <0.001). Serum ionized calcium concentrations showed no significant difference before and after bicarbonate infusion. Conclusion: These results suggest that acute correction of metabolic acidosis improves osteoblast function and appear to underline the importance of maintaining normal acid-base homeostasis in chronic renal failure.