Metabolic bone disease and parenteral nutrition.

Metabolic bone disease (MBD) is abnormal bone metabolism and includes the common disorders of osteoporosis and osteomalacia, which can develop in patients receiving long-term parenteral nutrition (PN). Patients who require long-term PN have significant gastrointestinal failure and malabsorption, which is generally caused by severe inflammatory bowel disease, intestinal ischemia, or malignancy. The exact cause of MBD in long-term PN patients is unknown, but its origin is thought to be multifactorial, with factors including underlying disease, effect of medications used to treat this disease (eg, corticosteroids), and various components of the PN solution. Caring for patients on long-term PN requires routine assessment and monitoring for MBD. Appropriate adjustments of the PN solution can help reduce the risk for developing PN-associated MBD and in some instances improve bone mineral density. Recent developments in pharmacologic treatment for osteoporosis show promise for patients with MBD receiving PN.