Longitudinal study of bone metabolism after ethanol withdrawal in alcoholic patients.

The pathogenesis of osteopenia in chronic alcoholism remains unclear, and many ethanol-related abnormalities have been advocated to explain bone loss. A direct inhibitory effect of ethanol on osteoblast function was suggested by in vivo and in vitro studies. We measured biochemical markers of bone turnover in 12 alcoholic men before and during a 2 week period of alcohol withdrawal, and we compared the results with those obtained in 15 nonalcoholic men. Our alcoholic patients presented with (1) decreased serum concentrations of bone gla protein (BGP), suggesting decreased bone formation; (2) increased urinary excretion of hydroxyproline, suggesting increased bone resorption; (3) increased renal threshold of phosphate excretion without modification of serum PTH concentration, suggesting a direct effect of ethanol on the renal handling of phosphate. The rapid increase in serum BGP concentrations following ethanol withdrawal suggests that low serum BGP concentrations in alcoholics may result from a direct toxic effect of ethanol on osteoblast function and/or numbers.