Blog
About

0
views
0
recommends
+1 Recommend
1 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found

      The Negative Ca 2+ Balance Is Involved in the Stimulation of PTH Secretion

      Read this article at

      ScienceOpenPublisherPubMed
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          The low calcium (Ca<sup>2+</sup>) dialysate have been developed to diminish the risk of hypercalcemia with the administration of active vitamin D and Ca<sup>2+</sup> carbonate as phosphate binder. Today, increasing numbers of hemodialysis (HD) patients have been on the low Ca<sup>2+</sup> dialysate (Ca<sup>2+</sup> = 2.5 mEq/l). However, the clinical consequences of a negative calcium net-balance which may be induced by the use of low Ca dialysate are not well evaluated. In the present study, we explored the effects of low Ca<sup>2+</sup> dialysate on the calcium balance and the PTH secretion. Eighty one chronic HD patients (male/female: 47/34; mean age: 60.2 ± 1.5 years; mean HD periods: 11.1 ± 0.8 years) who had been dialyzed with 3.0 mEq/l Ca<sup>2+</sup> dialysate were studied. All patients were transferred to the low Ca dialysate, which actually brought about a negative net-balance in Ca (mean: –94.5 mg) and an increase in serum intact PTH levels (mean: +23.7%: p = 0.03) during a single HD session. However, no changes in serum ionized Ca<sup>2+</sup> were found in spite of negative Ca<sup>2+</sup> balance. One month after change to the low Ca<sup>2+</sup> dialysate (total 12 sessions in each case), serum intact PTH levels increased significantly (186.7 ± 19.5 vs. 216.2 ± 21.9 pg/ml: p = 0.01) in spite of the fact that no changes were found in serum ionized Ca<sup>2+</sup>, Pi and Mg. This result indicates that the negative Ca<sup>2+</sup> balance during low-Ca<sup>2+</sup> hemodialysis-stimulated PTH secretion, which offset the decrease of serum Ca<sup>2+</sup>; a trade-off phenomenon between negative Ca balance and PTH. This suggests that low Ca<sup>2+</sup> dialysate may exaggerate the progression of secondary hyperparathyroidism.

          Related collections

          Most cited references 1

          • Record: found
          • Abstract: found
          • Article: found

          Vitamin D Receptor Gene Polymorphism Detected by Digestion with Apa I Influences the Parathyroid Response to Extracellular Calcium in Japanese Chronic Dialysis Patients

          Background: To play its physiological role, 1,25(OH) 2 D 3 must bind to a specific vitamin D receptor (VDR) in the nucleus. We have previously reported that VDR gene polymorphism influences the parathyroid function in patients with end-stage renal disease (ESRD). In the present study, we have investigated the relationship between the parathyroid responsiveness and VDR gene polymorphism, as detected by the Apa I restriction enzyme, by changing the concentration of Ca 2+ in the dialysate. Methods: 58 Japanese ESRD patients undergoing renal replacement therapy in our institution were evaluated. Genomic DNA was extracted from peripheral leukocytes and digested at the intron between exon 8 and exon 9 of the VDR gene using Apa I enzyme. Then alleles were classified into genotype A (undigested allele) and genotype a (digested allele). Extracellular ionized calcium ([Ca 2+ ] e ), serum phosphate, and intact parathyroid hormone (PTH) were measured before and after each hemodialysis (HD) session with dialysates having different concentrations of Ca 2+ (1.5 or 1.25 mmol/l). The significance of differences in statistical analyses was defined within confidence limits of 5.0%. Results: The AA, Aa, and aa genotypes were observed in 7/58 patients (12.1%), 23/58 patients (39.6%), and 28/58 patients (48.3%), respectively. The PTH reduction after HD with the 1.5-mmol/l Ca dialysate did not differ significantly between group AA+Aa and group aa. On the other hand, the PTH increase was significantly higher in group aa than in group AA+Aa after HD with the 1.25-mmol/l Ca dialysate (p = 0.0107), despite a similar PTH level before HD. Similarly, the percent increase of PTH after HD with the 1.25-mmol/l Ca dialysate was significantly higher (p = 0.0112) in group aa (50.2 ± 9.4%) than in group AA+Aa (19.7 ± 7.2%). There were no significant differences between the two groups in [Ca 2+ ] e nor in serum phosphorus (Pi) before and after HD with either dialysate. Group AA+Aa and group aa did not show statistically significant differences in age, female/male ratio, ratio of diabetic nephropathy, or dialysis period. Conclusions: The study results showed that the patients in group aa were more sensitive to changes in [Ca 2+ ] e than those in group AA+Aa. Moreover, they suggested that the VDR gene polymorphism may affect parathyroid responsiveness to changes in [Ca 2+ ] e , which in turn may influence onset and progression of hyperparathyroidism in ESRD patients.
            Bookmark

            Author and article information

            Journal
            NEF
            Nephron
            10.1159/issn.1660-8151
            Nephron
            S. Karger AG
            1660-8151
            2235-3186
            2002
            September 2002
            14 August 2002
            : 92
            : 1
            : 86-90
            Affiliations
            aDivision of Nephrology and Hypertension, Jikei University School of Medicine, Tokyo, bDivision of Nephrology and Dialysis Center, Kobe University School of Medicine, Kobe, Japan
            Article
            64484 Nephron 2002;92:86–90
            10.1159/000064484
            12187089
            © 2002 S. Karger AG, Basel

            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.

            Page count
            Tables: 2, References: 23, Pages: 5
            Product
            Self URI (application/pdf): https://www.karger.com/Article/Pdf/64484
            Categories
            Original Paper

            Comments

            Comment on this article