Birmingham epidermolysis severity score and vitamin D status are associated with low BMD in children with epidermolysis bullosa

Summary: Bone status impairment represents a complication of generalized forms of epidermolysis bullosa (EB); however, the prevalence and the main determinants of this event in localized forms remain poorly defined. Birmingham epidermolysis bullosa severity (BEBS) score and 25-hydroxyvitamin D levels are strongly associated with low bone mass, suggesting that vitamin D may play a potential beneficial role in bone health. Further longitudinal studies are needed in order to confirm this hypothesis. Introduction: Bone status impairment represents a complication of generalized forms of EB; thus, we aimed to estimate the prevalence of low bone mass, to examine mineralization differences in various EB subtypes and to identify the most important determinants of bone impairment in children with either generalized or localized EB. Methods: An observational study of 20 children (11 males; mean age\ua0\ub1\ua0standard deviation, 11.7\ua0\ub1\ua03.9\ua0years) with EB was performed. Clinical history, physical examination, laboratory studies, X-ray of the left hand and wrist for bone age, and dual energy X-ray absorptiometry scans of the lumbar spine were obtained. Areal bone mineral density (aBMD Z-scores) and bone mineral apparent density were related to the BEBS score. Results: Areal BMD Z-score (mean 121.82\ua0\ub1\ua02.33, range, 127.6-1.7) was reduced (< 122 SD) in 8 patients (40%), whereas aBMD Z-score adjusted for bone age was low in 7 patients (35%). BEBS score and 25-hydroxyvitamin D serum levels were the most important elements associated with aBMD (P\ua0=\ua00.0001 and P\ua0=\ua00.016, respectively). A significant correlation between the aBMD Z-score and area of skin damage, insulin-like growth factor-1, C-reactive protein, and sodium serum levels was also found. Conclusions: Low aBMD can be considered a systemic complication of EB, primarily associated with BEBS score and 25-hydroxyvitamin D levels. Therefore, longitudinal evaluation of bone status is ongoing in these patients to define whether vitamin D supplementation would prevent, or at least reduce, bone status impairment