Biochemical Evidence of Metabolic Bone Disease in Women Following Roux-Y Gastric Bypass for Morbid Obesity

Twenty-six female patients were recalled for examination 10 years after a Roux-Y gastric bypass (RGB) procedure for morbid obesity, to determine whether there was biochemical and/or bone densitometry evidence of metabolic bone disease. These patients were compared with seven control patients who had achieved weight loss by dietary restriction. The serum calcium (4.3 ± 0.03 vs 4.6 ± 0.06 mEq/l; p = 0.002) was decreased in the RGB group. Both the serum alkaline phosphatase level (121.0 ± 7.6 vs 87.3 ± 8.3 U/l; p = 0.018) and the serum osteocalcin (12.6 ± 1.2 vs 9.5 ± 1.9 mug/ml; p = 0.078) level increased in the RGB group. The 1,25(OH) vitamin D level (50.5 ± 2.5 vs 40.5 ± 4.9 pg/ml; p = 0.152) was similar for both groups; the 25(OH) vitamin D level (24.3 ± 1.6 vs 35.9 ± 3.4 ng/ml; p = 0.008) was decreased in the RGB group as compared with the control group. Bone mineral density was elevated in three of the lumbar measurement sites, and marginally decreased (0.90 ± 0.02 g/cm₂ vs 1.03 ± 0.06 g/cm₂; p = 0.067) in the femoral neck of the RGB group compared with the controls. This biochemical pattern suggests the development of metabolic bone disease following the RGB.