Effect of acute citrate load on markers of bone metabolism in healthy volunteers.

BACKGROUND AND OBJECTIVES

This study aims to investigate the possible effects of acute citrate administration on bone metabolism in healthy men.

MATERIALS AND METHODS

A placebo-controlled, crossover trial was conducted on 10 male volunteers. The volunteers received either a standardized infusion of citrate at 1.5 mg/kg body weight/min or the equal volume of placebo, separated by a washout period of 14 days. Serial blood and urine samples were collected and analysed for bone biochemical markers and electrolytes.

RESULTS

Infusion of citrate resulted in increased serum levels of the bone formation marker osteocalcin (OC) and bone resorption marker C-telopeptide of type 1 collagen (CTX). Increases in CTX and OC were positively correlated to the surge in the serum concentration of intact parathyroid hormone (iPTH) but only OC showed correlation to changes in ionized calcium. Citrate infusion showed no effect on serum concentrations of bone alkaline phosphatase, osteoprotegerin, and bone tartrate-resistant acid phosphatase 5b, or the expression of receptor activator of nuclear factor kappa B ligand. Variations in OC and CTX were short-term as both bone markers gradually declined within 90 min following citrate exposure.

CONCLUSION

Acute citrate load resulted in profound alterations of the bone markers OC and CTX. The short-term increase of CTX suggests a temporary shift to a higher bone turnover rate, although the clinical consequence of the observed changes in bone markers remains open.