Acute effect of oral phosphate loading on serum fibroblast growth factor 23 levels in healthy men

• Published in: Kidney international Vol. 70; no. 12; pp. 2141 - 2147
• Main Authors: Nishida, Y., Taketani, Y., Yamanaka-Okumura, H., Imamura, F., Taniguchi, A., Sato, T., Shuto, E., Nashiki, K., Arai, H., Yamamoto, H., Takeda, E.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.12.2006; Nature Publishing; Elsevier Limited
• Subjects: Administration, Oral; Adult; Biological and medical sciences; Calcium - blood; Cross-Over Studies; fibroblast growth factor 23; Fibroblast Growth Factors - blood; Homeostasis - drug effects; Homeostasis - physiology; Humans; Male; Medical sciences; Nephrology. Urinary tract diseases; parathyroid hormone; Parathyroid Hormone - blood; Phosphates - administration & dosage; Phosphates - blood; Phosphates - pharmacokinetics; Phosphates - urine; phosphorus metabolism; postprandial change; Vitamin D - analogs & derivatives; Vitamin D - blood; parathyroid hormone; postprandial change; phosphorus metabolism; fibroblast growth factor 23; Human; Phosphates; Nephrology; Healthy subject; Fibroblast growth factor 23; Postprandial; Acute; Oral administration; Male; Phosphorus; Metabolism; Urology; Parathormone; Parathyroid hormone; Adult; Serum factor
• ISSN: 0085-2538; 1523-1755; 1523-1755
• DOI: 10.1038/sj.ki.5002000

Serum fibroblast growth factor 23 (FGF23) is a novel phosphaturic factor and important for the regulation of inorganic phosphate (Pi) homeostasis. In this study, we examined an acute effect of oral Pi loading on serum FGF23 levels to clarify the role in rapid adjustment of serum Pi level. We performed a randomized, double-blind, crossover study in eight healthy male volunteers. The subjects were alternately served one of three test meals containing different Pi amounts (400mg (P400), 800mg (P800), and 1200mg (P1200)) as lunch at noon. The postprandial changes in serum levels of Pi, Ca, 1,25-dihydroxyvitamin D, intact-parathyroid hormone (iPTH), intact-FGF23 (iFGF23), and urinary excretion of Pi and Ca until 8h after Pi loading were estimated. Serum Pi levels and urinary Pi excretion significantly increased within 1h after P400 and P800 intake. Serum iPTH levels at 1–2 and 4–6h after P1200 intake was significantly higher than those of P400 intake. Serum iFGF23 levels slightly decreased up to 8h after P400 intake and up to 6h after P800 intake, but not changed in P1200 intake. Significant increase of iFGF23 was observed at 8h after P1200 intake compared with both P400 and P800 intake. Additionally, negative association was detected between iFGF23 and serum Pi, whereas positive association was observed between iPTH and serum Pi during the short period. We conclude that oral Pi loading cannot rapidly increase serum FGF23 level. FGF23 may be not associated with rapid adaptation of Pi homeostasis.