ESPE Abstracts

Background: Down syndrome (DS) is the most common genetic (chromosomal) mental retardation syndrome. In these patients, several environmental and hormonal factors contribute to low bone mineral density (BMD), among these factors, vitamin D may play a significant role in the health of patients with DS. However, poor studies have evaluated 25-hydroxy cholecalciferol (25(OH)D) levels in DS.

Objective and hypotheses: The purpose of this study was to assess serum 25(OH)D and to identify risk factors for vitamin D deficiency in this syndrome.

Methods: We have longitudinally evaluated 31 DS children and adolescents (17 males, 14 females, aged 4.5–18.9 years). In all subjects we analysed serum calcium and phosphate, serum parathyroid hormone (PTH), 25(OH)D concentrations, dietary intakes of calcium and 25(OH)D, and we quantified outdoor exposure. After 8.5±2.3 months of 400 UI 25(OH)D supplementation, we re-evaluated these patients. The results were compared to a control group included 99 healthy age- and sex-matched subjects (51 males, 48 females, range 4.8–19.8 years).

Results: DS subjects showed very reduced 25(OH)D levels than controls (P<0.0001), in particular DS with obesity (P<0.05), and history of autoimmune diseases (P<0.005). Moreover, PTH levels were significantly higher than controls (P<0.0001). After 25(OH)D supplementation, 25(OH)D levels was significantly ameliorated (P<0.05), even if significantly reduced than controls (P<0.0001), in particular in DS with obesity (P<0.05), and with autoimmune diseases (P<0.001).

Conclusions: Our results indicate that hypovitaminosis D is very frequent in DS, assessing the importance of vitamin D prophylaxis in these subjects, in particular in DS with obesity and autoimmune diseases. The reduced 25(OH)D levels seem to be also related to reduced outdoor activity levels. Accordingly, DS patients with obesity and autoimmune diseases may require higher 25(OH)D supplementation.