Oral calcium carbonate affects calcium but not phosphorus balance in stage 3-4 chronic kidney disease

Kidney Int. 2013 May;83(5):959-66. doi: 10.1038/ki.2012.403. Epub 2012 Dec 19.


Patients with chronic kidney disease (CKD) are given calcium carbonate to bind dietary phosphorus, reduce phosphorus retention, and prevent negative calcium balance; however, data are limited on calcium and phosphorus balance during CKD to support this. Here, we studied eight patients with stage 3 or 4 CKD (mean estimated glomerular filtration rate 36 ml/min) who received a controlled diet with or without a calcium carbonate supplement (1500 mg/day calcium) during two 3-week balance periods in a randomized placebo-controlled cross-over design. All feces and urine were collected during weeks 2 and 3 of each balance period and fasting blood, and urine was collected at baseline and at the end of each week. Calcium kinetics were determined using oral and intravenous (45)calcium. Patients were found to be in neutral calcium and phosphorus balance while on the placebo. Calcium carbonate supplementation produced positive calcium balance, did not affect phosphorus balance, and produced only a modest reduction in urine phosphorus excretion compared with placebo. Calcium kinetics demonstrated positive net bone balance but less than overall calcium balance, suggesting soft-tissue deposition. Fasting blood and urine biochemistries of calcium and phosphate homeostasis were unaffected by calcium carbonate. Thus, the positive calcium balance produced by calcium carbonate treatment within 3 weeks cautions against its use as a phosphate binder in patients with stage 3 or 4 CKD, if these findings can be extrapolated to long-term therapy.

Trial registration: ClinicalTrials.gov NCT01161407.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Aged
  • Analysis of Variance
  • Biomarkers / blood
  • Biomarkers / urine
  • Calcium / blood*
  • Calcium / urine
  • Calcium Carbonate / administration & dosage*
  • Calcium Carbonate / adverse effects
  • Chelating Agents / administration & dosage*
  • Chelating Agents / adverse effects
  • Cross-Over Studies
  • Feces / chemistry
  • Female
  • Glomerular Filtration Rate
  • Humans
  • Indiana
  • Kidney / drug effects*
  • Kidney / metabolism
  • Kidney / physiopathology
  • Kinetics
  • Least-Squares Analysis
  • Male
  • Middle Aged
  • Phosphorus / blood*
  • Phosphorus / urine
  • Renal Insufficiency, Chronic / blood
  • Renal Insufficiency, Chronic / diagnosis
  • Renal Insufficiency, Chronic / drug therapy*
  • Renal Insufficiency, Chronic / physiopathology
  • Renal Insufficiency, Chronic / urine
  • Severity of Illness Index
  • Treatment Outcome


  • Biomarkers
  • Chelating Agents
  • Phosphorus
  • Calcium Carbonate
  • Calcium

Associated data

  • ClinicalTrials.gov/NCT01161407