Diabetes modifies effect of high-phosphate diet on fibroblast growth factor-23 in chronic kidney disease

J Clin Endocrinol Metab. 2013 Dec;98(12):E1901-8. doi: 10.1210/jc.2013-2418. Epub 2013 Oct 3.

Abstract

Context: The pathophysiology of calcium-phosphate disturbances in diabetic (DM) kidney disease differs from that in non-DM chronic kidney disease (CKD).

Objective: We compared the effect of a 6-day high-phosphate diet on serum fibroblast growth factor-23 (FGF-23) and other parameters of calcium-phosphate metabolism in DM and non-DM CKD patients.

Design and setting: This was a prospective interventional study in a research center setting. PARTICIPANTS, INTERVENTION, AND MEASURES: Twenty-six nondialysis patients with stages 3-5 CKD and albuminuria less than 300 mg/g creatinine were recruited from February 2011 to November 2012 (15 DM, 11 non-DM). All patients received a high-phosphate diet (1800 mg/d) for 6 days. At baseline, day 3, and day 7 serum FGF-23, PTH, Ca, P, 25-hydroxyvitamin D, 1,25 dihydroxyvitamin D, monocyte chemoattractant protein-1, and calcium and phosphate urine excretion were measured.

Results: In DM CKD patients, serum calcium was lower on days 3 and 7 vs baseline (P < .01, respectively), and in non-DM patients, it was unchanged. Serum phosphorus increased significantly only in non-DM patients on days 3 and 7 vs baseline (P < 0.01, respectively). Serum PTH was higher in the DM group on day 7 vs baseline (P = .04). Plasma 25-hydroxyvitamin D, 1,25 dihydroxyvitamin D, and serum monocyte chemoattractant protein-1 were unchanged in both groups. Serum FGF-23 increased in DM patients, from baseline to day 3 (58.1 ± 52.7 and 91.6 ± 71.1 pg/mL, P = .001) but later tended to decrease. In non-DM patients, there was a steady increase of FGF-23 between baseline and day 7 (75 ± 84.3 to 176 ± 197 pg/mL, P = .04). Urine phosphate excretion was significantly higher on day 7 in DM patients only (P < .05).

Conclusions: PTH seems to play the major role in the regulation of phosphate excretion in DM CKD. The role of FGF-23 in phosphate disposal in DM CKD remains debatable.

Publication types

  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Biomarkers / blood
  • Biomarkers / urine
  • Calcium / blood
  • Calcium / urine
  • Diabetes Mellitus, Type 2 / complications*
  • Diabetic Nephropathies / blood*
  • Diabetic Nephropathies / physiopathology
  • Diabetic Nephropathies / urine
  • Diet / adverse effects*
  • Down-Regulation
  • Female
  • Fibroblast Growth Factors / blood*
  • Humans
  • Kidney / physiopathology*
  • Male
  • Middle Aged
  • Parathyroid Hormone / blood
  • Parathyroid Hormone / metabolism
  • Phosphates / adverse effects*
  • Phosphates / urine
  • Phosphorus / adverse effects
  • Phosphorus / blood
  • Renal Insufficiency, Chronic / blood
  • Renal Insufficiency, Chronic / complications*
  • Renal Insufficiency, Chronic / physiopathology
  • Renal Insufficiency, Chronic / urine
  • Severity of Illness Index
  • Time Factors
  • Up-Regulation

Substances

  • Biomarkers
  • PTH protein, human
  • Parathyroid Hormone
  • Phosphates
  • Phosphorus
  • Fibroblast Growth Factors
  • fibroblast growth factor 23
  • Calcium