Metabolic bone disease in a patient on long-term total parenteral nutrition: a case report with review of literature.

A 38-yr-old woman with Crohn's disease and short bowel on home total parenteral nutrition was studied. Metabolic bone assessments were done prospectively. Daily total parenteral nutrition included 500 IU vitamin D2, 6 to 8 mmol calcium, 10 to 15 mmol phosphorus, 12 to 16 mmol magnesium, and trace elements including zinc, cooper, and chromium. After 6 months, while asymptomatic, chemistries and x-rays were normal. Calcium bone index was 0.79. The bone biopsy showed mild hyperkinetic picture. At 26 months, she had a spontaneous rib fracture and bone pains in the hands and lower back. Chemistries were normal except that calcium bone index was 0.75. Bone biopsy showed mild osteomalacia. Vitamin D2 was withdrawn for 2 months and then restarted at 1000 IU/wk. She improved symptomatically for 4 months, but then developed rib fractures, and the bone pains recurred. After 48 months, chemistries were normal, except that the calcium bone index was 0.57 and bone biopsy showed regression of osteomalacia toward normal. Vitamin D2 was now withdrawn for 6 months, resulting in loss of bone pain. Vitamin D2 may produce a metabolic bone disease, requiring prolonged withdrawal for improvement.