In normal subjects, the gastric ionisation of calcium and phosphate seems to be a prerequisite for their intestinal absorption. We investigated the behavior of the plasma calcium and phosphate profile in 30 patients on regular dialysis treatment in the 6 h following a meal containing 1 g of calcium and 2 g of phosphate. Moreover, to assess the role of gastric acidity, the study was repeated after 3 days on omeprazole administration, to nearly abolish gastric acid secretion. Both total plasma calcium and ionized calcium peaked after the meal (at 30 and 120 min, respectively) only in basal study, while no peak was observed after the administration of omeprazole. Surprisingly, both in basal and in the omeprazole study the levels of plasma phosphate did not increase after the test meal. In conclusion, as in normal subjects, the gastric ionization of dietary calcium promotes the intestinal absorption of calcium in uremic patients on dialysis treatment, while the acute gastric acid inhibition by omeprazole reduced the intestinal calcium transport. In contrast, with the ‘trade off’ hypothesis we did not observe any postprandial phosphate peak after the dietary load, and, in contrast with normal subjects, omeprazole administration did not influence the phosphate profile.

Keywords:
Calcium and phosphate absorption, Gastric acid secretion, Parathyroid hormone, Dialysis patients
1.
Llach F: Secondary hyperparathyroidism in renal failure: The trade-off hypothesis revisited. Am J Kidney Dis 1995;25:663–679.
2.
Tessitore N, Venturi A, Adami S, Roncari C, Rugiu C, Corgnati A, Bonucci E, Maschio G: Relationship between serum vitamin D metabolites and dietary intake of phosphate in patients with early renal failure. Min Electrolyte Metab 1987;13:38–44.
3.
Lopez Hilker S, Dusso AS, Rapp NS, Martin KJ, Slatoplsky E: Phosphorus restriction reverses hyperparathyroidism in uremia independent of changes in calcium and calcitriol. Am J Physiol 1990;259:F432–F437.
4.
Aparicio M, Combe C, Lafage MH, de Precigout U, Potaux L, Bouchet JL: In advanced renal failure dietary phosphorus restriction reverses hyperparathyroidism independent of changes in the levels of calcitriol. Nephron 1993;63:122–123.
5.
Fine A, Cox D, Fontaine B: Elevation of serum phosphate affects parathyroid hormone levels in only 50% of hemodialysis patients, which is unrelated to changes in serum calcium. J Am Soc Nephrol 1993;3:1947–1953.
6.
Slatopolsky E, Finch J, Dends M, Ritter C, Zhong M, Dusso A, Mac Donald P: Phosphorus restriction prevents parathyroid gland growth. High phosphorus directly stimulates PTH secretion in vitro. J Clin Invest 1996;11:2534–2540.
7.
Slatopolsky E, Bricker NS: The role of phosphorus restriction in the prevention of secondary hyperparathyroidism in renal disease. Kidney Int 1973;4:141–145.
8.
Schiller LR, Santa Ana CA, Sheikh MS, Emmett M, Fordtran JS: Effect of the time of administration of calcium acetate on phosphorus binding. N Engl J Med 1989;320:1110–1113.
9.
Walling MW: Intestinal calcium and phosphate transport: Differential response of Vitamin D metabolites. Am J Physiol 1977;233:E488–494.
10.
Portale AA, Curtis-Morris R Jr: Pathogenesis of secondary hyperparathyroidism in chronic renal insufficiency. Min Electrolyte Metab 1991;17:211–220.
11.
Graziani G, Como G, Badalamenti S, Finazzi S, Malesci A, Gallieni M, Brancaccio D, Ponticelli C: Effect of gastric acid secretion on intestinal phosphate and calcium absorption in normal subjects. Nephrol Dial Transplant 1995;10:1376–1380.
12.
Loghman-Adham M: Renal and intestinal Pi transport adaptation to low phosphorus diet in uremic rats. J Am Soc Nephrol 1993;3:1930–1937.
13.
Hardy P, Sechet A, Hottelard C, Oprisiu R, Abighanem O, Said S, Rosombolona M, Brazier M, Morinière P, Achard JM, Pruna A, Fournier A: Inhibition of gastric secretion by omeprazole and efficiency of calcium carbonate on the control of hyperphosphatemia on patients on chronic hemodialysis. Artif Organs 1998;22:569–573.
14.
Burget DH, Chiverton SG, Hunt RH: Is there an optimal degree of acid suppression for healing of duodenal ulcer? Gastroenterology 1990;99:345–351.
15.
Ramirez JA, Emmett M, White MG, Fathi N, Santa Ana CA, Morawski SG, Fordtran JS: The absorption of dietary phosphorus and calcium in hemodialysis patients. Kidney Int 1986;30:753–759.
16.
Bover J, Rodriguez M, Trinidad P, Jara A, Martinez ME, Machado L, Llach F, Felsenfeld AJ: Factors involved in the development of secondary hyperparathyroidism during graded renal failure in the rat. Kidney Int 1994;45:953–961.
17.
Drueke TB: The pathogenesis of parathyroid gland hyperplasia in chronic renal failure. Kidney Int 1995;48:259–272.
18.
De Soi CA, Umans JG: Phosphate kinetics during high-flux hemodialysis. J Am Soc Nephrol 1993;4:1214–1218.
19.
Nowicki M, Fliser D, Fode P, Ritz E: Changes in plasma phosphate levels influences insulin sensitivity under euglycaemic conditions. J Endocrinol Metab 1996;81:156–159.
20.
Fliser D, Franek E, Fode P, Stefanski A, Schmitt CP, Lyons M, Ritz E: Subacute infusion of physiological doses of parathyroid hormone raises blood pressure in humans. Nephrol Dial Transplant 1997;12:933–938.
21.
Kilav R, Silver J, Naveh-Many T: Parathyroid hormone gene expression in hypophosphatemic rats. J Clin Invest 1995;96:327–333.
22.
Miyamoto KI, Tatsumi S, Morita K, Takeda E: Does the parathyroid ‘see’ phosphate? Nephrol Dial Transplant 1998;13:2727–2729.
© 2002 S. Karger AG, Basel
2002
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.