Objective
To investigate the cause of osteomalacia following biliopancreatic diversion (BPD) surgery for obesity.
Design
A retrospective, case-comparison study.
Setting
A tertiary care center.
Patients
A case group of 12 subjects (including 9 women; mean age±SEM, 48.5±3.0 years; mean preoperative body mass index ±SEM, 43.7 ± 2.3 kg/m2; and mean weight loss±SEM, 75± 14 kg) who have undergone BPD (referred to as BPD group hereafter) and a comparison group of 10 subjects (including 9 women; mean age±SEM,49.6±3.3 years; mean preoperative body mass index ±SEM, 44.0 ± 2.5 kg/m2; and mean weight loss±SEM, 55±15 kg) following vertical banded gastroplasty (VBG) (referred to as VBG group hereafter).
Main Outcome Measures
Serum and urine markers for bone metabolism.
Results
Compared with the VBG group, the BPD group had significantly lower concentrations of the following components: serum calcium (2.14±0.05 mmol/L vs 2.37±0.05 mmol/L [8.6±0.2 mg/dL vs 9.5±0.2 mg/ dL]), serum 25-hydroxyvitamin D (24±6 nmol/L vs 64±6 nmol/L), urine calcium excretion (1.7±0.7 mmol/d vs 4.5±0.7 mmol/d [68±28 mg/d vs 180±28 mg/d]), and serum carotene (0.40±0.15 mmol/L vs 1.29±0.16 mmol/ L). The BPD group had significantly higher concentrations of the following components: serum parathyroid hormone (13.6±2.1 pmol/L vs 5.2±2.3 pmol/L), serum alkaline phosphatase (139±8 U/L vs 86 ± 9 U/L), and urinary hydroxyproline/creatinine (52±5 µmol/mmol vs 19±5 µmol/mmol).
Conclusion
These data suggest that following BPD, secondary hyperparathyroidism attributed to hypocalcemia results from malabsorption of vitamin D. However, we cannot exclude the possibility of concurrent calcium malabsorption with vitamin D malabsorption.
Arch Surg. 1996;113:1048-1052
