Bone histomorphometry and vitamin D status after biliopancreatic bypass for obesity.

Bone histomorphometry and vitamin D status were investigated in 41 patients studied 1-5 yr after partial or total biliopancreatic bypass. Metabolic bone disease, characterized by defective mineralization, decreased bone formation rate, and increased surface extent of resorption, was present in 30 patients (73%). Nine patients (22%) were hypocalcemic, but serum 25-hydroxyvitamin D concentrations were normal in all 41 patients. We conclude that metabolic bone disease is common after biliopancreatic bypass and usually occurs in the absence of simple vitamin D deficiency. The pathogenesis of the bone disease is unclear.