Apparent contradictions exist in the literature regarding the effect of gastric secretion inhibition on phosphatemia. In healthy adults, omeprazole has been reported to prevent the increase of plasma phosphate or of phosphaturia observed after an acute phosphate load suggesting an inhibition of phosphate absorption. In patients on chronic hemodialysis their hyperphosphatemia is associated to gastric hypersecretion but the inhibition of this latter by ranitidine in patients taking CaCO3 has been reported to increase their plasma phosphate. Because of this contradiction, we have made an open cross-over study in 16 stable and compliant patients in chronic hemodialysis taking a mean daily dose of 9.4 +/- 4 g of CaCO3 and compared their predialysis plasma concentration of phosphate, calcium, protides, bicarbonates, intact PTH, urea and creatine for two successive periods of two months without or with 20 mg of omeprazole. Plasma phosphate did not increased significantly with omeprazole (from 1.80 +/- 0.38 to 1.89 +/- 0.42 mmol/l) whereas plasma corrected calcium significantly decreased from 2.41 +/- 0.18 to 2.36 +/- 0.16 mmol/l (p = 0.04) and plasma bicarbonate decreased significantly from 26.7 +/- 3.5 to 25.7 +/- 3.1 mmol/l (p < 0.05). No significant change was observed in plasma creatine and urea suggesting stability of dialysis efficiency and of protein and therefore phosphate intake.
Conclusion: These data do not support that CaCO3 efficiency as phosphate binder is decreased with inhibition of the gastric secretion by omeprazole.