Fibroblast growth factor 23 is increased in calcium nephrolithiasis with hypophosphatemia and renal phosphate leak.

Abstract

CONTEXT:

Nephrolithiasis affects about 10% of the population in industrialized countries, with calcium salts composing more than 80% of renal stones. A significant percentage of patients with calcium nephrolithiasis and normal parathyroid function show hypophosphatemia and reduced renal phosphate reabsorption (i.e. a renal phosphate leak).

OBJECTIVES:

The objective of the study was to compare serum levels of fibroblast growth factor 23 (FGF23), a regulator of phosphate homeostasis, in 110 recurrent stone formers with or without renal phosphate leak, six patients affected by X-linked hypophosphatemic rickets, five patients affected by oncogenic osteomalacia, and 60 unrelated healthy controls.

DESIGN:

This was a prospective interventional study.

METHODS:

Renal phosphate leak was identified based on the occurrence of idiopathic hypophosphatemia [serum phosphate concentration < 2.50 mg/dl (<0.80 mmol/liter)] and reduced renal threshold phosphate concentration [<2.2 mg/liter (<0.70 mmol/liter)].

RESULTS:

In 22 stone formers with renal phosphate leak, serum FGF23 concentration was significantly higher as compared with 88 stone formers without renal phosphate leak and with controls [83.3 (65.6-101.1) vs. 32.1 (26.8-37.4) and 24.5 (19.8-29.1) reference units (RU)/ml, respectively]. Stone formers with renal phosphate leak showed lower FGF23, compared with patients with oncogenic osteomalacia and X-linked hypophosphatemic rickets [572.3 (235.9-908.7) RU/ml]. Among stone formers and controls, serum FGF23 concentration displayed a strong inverse association with serum phosphate (r = -0.784, P = 0.009) and the rate of tubular phosphate reabsorption (r = -0.791, P = 0.008).

CONCLUSIONS:

In our study population, renal phosphate leak affected 20% of stone formers and was strongly associated with increased serum FGF23 concentration.

• Authors: Domenico Rendina, Giuseppe Mossetti, Gianpaolo De Filippo, Michele Cioffi, Pasquale Strazzullo
• Journal: The Journal of clinical endocrinology and metabolism (J Clin Endocrinol Metab) Vol. 91 Issue 3 Pg. 959-63 (Mar 2006) ISSN: 0021-972X [Print] United States
• PMID: 16352682 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Biomarkers
• FGF23 protein, human
• Phosphates
• Fibroblast Growth Factors
• Fibroblast Growth Factor-23
• Calcitriol
• Calcifediol
• Calcium

Topics

• Adult
• Biomarkers (blood)
• Body Mass Index
• Calcifediol (blood, urine)
• Calcitriol (blood, urine)
• Calcium (blood, urine)
• Female
• Fibroblast Growth Factor-23
• Fibroblast Growth Factors (blood)
• Humans
• Hypophosphatemia (blood, urine)
• Kidney Calculi (blood, urine)
• Male
• Phosphates (blood, urine)
• Prospective Studies
• Reference Values