THE ROLE OF MAGNESIUM IN THE PATHOGENESIS OF BONE-DISEASE IN CHILDHOOD CHOLESTATIC LIVER-DISEASE - A PRELIMINARY-REPORT

Background: Magnesium deficiency may contribute to the metabolic bone disease that complicates chronic cholestatic liver disease. We hypothe sized that magnesium deficiency alters vitamin D metabolism by decreas ing parathyroid hormone (PTH) response, resulting in decreased serum o steocalcin and decreased bone accretion. Methods: Nine subjects, age 3 -22 years, with cholestatic liver disease were evaluated with the magn esium retention test. The response of PTH, 1,25(OH)(2) vitamin D, and osteocalcin to provocative stimuli and dual x-ray absorptiometry measu rement of bone mineral density (BMD) of the lumbar spine were assessed . Thereafter, subjects were treated with oral magnesium supplements. R esults: All nine subjects were magnesium depleted. Repletion with magn esium was successful in seven subjects, and required 4 to 31 (median 1 4) months with doses of 6 to 34 (median 11) mg/kg/day. Baseline serum PTH was significantly reduced in the cholestatic subjects compared to 15 age-matched controls. Comparison of baseline to repleted provocativ e testing was performed in six Mg-repleted subjects. Osteocalcin respo nse increased significantly (p = 0.048) with repletion, while PTH resp onse increased (p = 0.061). Lumbar spine BMD increased modestly with r epletion (p = 0.093). Conclusions: This preliminary report suggests th at magnesium depletion is extremely common in children with chronic ch olestasis. We speculate that magnesium supplementation may be warrante d to forestall the progression of metabolic bone disease in chronic ch olestasis. (C) 1997 Lippincott-Raven Publishers.