Low bone mineral density in cystic fibrosis patients.

The goals of this practice-based, observational study were to describe the prevalence of low bone mineral density in patients at the Edmonton Cystic Fibrosis Centre, and to determine if body mass index and previous systemic corticosteroid use of over one month's duration were predictors of low bone mineral density. One hundred and thirteen pediatric and adult patients were studied. Bone mineral density of the lumbar spine region was measured using dual-energy X-ray absorptiometry. A total of 42.5% of patients had a bone mineral density Z-score of less than -1 standard deviation. Low bone mineral density was apparent at nine to 12 years of age, and was most evident in the 20- to 34-year-old group. All but one patient under age 20 with a Z-score of less than -2.5 also had a body mass index below the fifth percentile. A low Z-score was also associated with previous systemic corticosteroid use of over one month's duration (relative risk 1.81, p=0.003). We conclude that low bone mineral density is common in cystic fibrosis patients. Low body mass index percentiles may be used to identify children and adolescents at risk of low bone mineral density. These patients may benefit from aggressive nutrition therapy. Systemic corticosteroid use should be assessed carefully, as it is a risk factor for low bone mineral density.