Management of low bone mass in patients with inflammatory bowel disease

Abstract

Prevention of osteoporosis requires first that those at increased risk be identified. Risk factors for osteoporosis include age, gonadal hormone deficiency, chronic illness such as inflammatory bowel disease (IBD) and rheumatoid arthritis, drugs such as glucocorticoids, low body mass index, and smoking. Since patients with IBD generally have two or more risk factors they must be considered at increased risk to develop osteoporosis. They therefore should, as part of the initial medical work-up, have bone mineral density (BMD) measured. If the BMD is decreased they should be treated.

The strategies for prevention and treatment are the same and are based on the assumption, supported by considerable evidence, that decreasing BMD is due primarily to a relative increase in bone resorption. The ultimate objective of therapy is to prevent fracture. This objective is best accomplished by eliminating risk factors and using drugs to inhibit bone resorption. Elimination of risk factors includes optimizing nutritional status, especially calcium and vitamin D intake, ensuring normal gonadal function, encouraging weight-bearing physical activity, eliminating smoking and excess alcohol consumption, and where possible eliminating or diminishing total consumption of drugs such as glucocorticoids and agents such as psychoactive drugs and antihypertensives, which tend to increase the risk of falling. All patients should have a baseline BMD measurement of lumbar spine and hip and these measurements should be repeated as risk changes, e.g. introduction of glucocorticoid therapy, weight loss or other evidence of failing nutrition, and fracture. If BMD is decreased antiresorptive drugs should be introduced. Those approved for use in Canada include oestrogen, bisphosphonates, calcitonin, and selective oestrogen receptor modulators (SERMs). In postmenopausal women the treatment of choice, according to most published guidelines is hormone replacement therapy (HRT), with one of the bisphosphonates as a second choice. In premenopausal women and men the antiresorptive agent of choice is a bisphosphonate. Response to therapy should be monitored with bone density measurements. Evidence of treatment failure includes decreasing BMD, and occurrence of a ‘fragility’fracture. If this occurs combination therapy, e.g. HRT+bisphosphonate, may be considered.

Bisphosphonates are very poorly and unpredictably absorbed from the normal gastrointestinal tract. The rate of absorption of these drugs from the intestine of IBD patients is unknown. It may therefore be desirable or necessary to use intravenous bisphosphonate therapy in IBD patients.

The efficacy and safety of drugs which increase BMD (fluoride) and/or normal bone formation (intermittent parathyroid hormone) have yet to be demonstrated.