Metabolic bone disease in home total parenteral nutrition

Home total parenteral nutrition (HTPN) is in its infancy but has proved to be lifesaving for patients unable to manage on enteral nutrition alone. However, this mode of nutrition therapy is not without problems. Aside from mechanical and other metabolic complications, a peculiar metabolic bone disease has been reported to occur in some HTPN recipients. The disease, characterized by abnormalities in calcium and phosphorus homeostasis, often results in osteomalacia, bone pain, and fractures. Reports of approximately 50 cases of metabolic bone disease have been published by centers in the United States and Canada. Factors that have been implicated as possible causes include infusion of excess vitamin D, aluminum, calcium, protein, or glucose; cyclic vs. continuous TPN administration; and the patient's previous nutritional state. Although removal of vitamin D or aluminum from the TPN solution and discontinuation of TPN altogether have been associated with improvement in symptoms, histology, and laboratory values, no single factor has been identified as the cause of this troubling phenomenon.