Patterns of bone mineral acquisition in children with epidermolysis bullosa: a longitudinal study

Abstract

Reduced bone mass and fractures are known complications of generalized forms of epidermolysis bullosa (EB). However, the aetiology - inadequate bone acquisition, premature bone loss, or a combination - is unclear. To determine patterns of bone mineral acquisition in children with EB and to identify clinical and laboratory correlates of change in areal bone mineral density (aBMD). Seventeen subjects ≥ 6 years of age with generalized EB were studied at two visits at least 12 months apart with clinical and laboratory evaluations and dual energy X-ray absorptiometry scans of the lumbar spine. Wilcoxon signed-rank tests were used to determine if changes from baseline to follow-up were significant. Wilcoxon rank-sum tests were used to compare subjects with gains in aBMD Z-score with those who experienced no change or decreases to determine if baseline laboratory or clinical characteristics differed between the two groups. Subjects gained height and weight at follow-up, but there was no significant improvement in mean Z-scores for height, weight or body mass index. Laboratory values did not change significantly. Mean bone mineral content and aBMD of the lumbar spine increased significantly at follow-up, but mean aBMD Z-scores remained static. No differences in clinical characteristics or laboratory values were seen between subjects with increased aBMD Z-scores vs. those whose scores decreased or did not change. Low bone mass in children with generalized EB is due primarily to inadequate gains in aBMD. Interventions to improve overall health and to help build bone mass in this patient population are warranted.