Low serum magnesium concentration in Paget's disease of bone (osteitis deformans)

Approximately 25% of patients presenting with Paget's disease of bone have a low serum magnesium concentration (below 0.74 mmol/L). Metabolic balance studies of 12 normomagnesaemic and seven hypomagnesaemic subjects show that the latter have a significantly more positive balance and a significantly higher net absorption of magnesium than have the former. The urinary output of the two groups did not differ significantly. The serum magnesium and alkaline phosphatase (log) concentrations were significantly negatively correlated, as were the serum magnesium and the daily urinary hydroxyproline (log) output. Low serum magnesium concentrations are thus associated with highly active Paget's disease; they do not arise from increased urinary loss nor from a lowered net absorption of magnesium, but probably from increased uptake by bone. The balance data show that to avoid a negative magnesium balance, the magnesium intake in Paget's disease should be at least 8.0 mmol/day.