Endocrine Abstracts

Introduction: Malnutrition, deficiency of micro- and macronutrients, including calcium and vitamin D are typical for children with dystrophic form of congenital epidermolysis bullosa (DEB). Thereby, there is a slowdown in osteogenesis and in stimulation of osteoclast activity, bone tissue resorption, which leads to increased bone fragility and low-traumatic fractures.

Aim of the study: To evaluate markers of bone tissue metabolism and phosphorus-calcium metabolism in children with DEB before and during therapy with cholecalciferol.

Methods and materials: 71 children with DEB were included (39 girls (55%), 32 boys (45%)), the median age was 8.5 years [3.67; 11.92] and 5.75 years [3.13; 10.46]. All patients were examined before the therapy with cholecalciferol, and 6 months after. Dual X-ray absorptiometry was used to assess bone tissue density. Vitamin D, total calcium, phosphorus, N-terminal propeptide of procollagen type I (P1NP), osteocalcin (OS) and carboxytherminal cross-linked telopeptide of collagen type I (CTX) levels were determined.

Results: A high frequency of insufficiency (20–30 ng/ml) – 22.5%, deficiency (10–20 ng/ml) – 31% and deep deficiency (<10 ng/ml) – 9.9% of vitamin D, as well as hypocalcemia total calcium (< 2.2 mmol/l) – 39.4% was identified. BMD decrease to osteopenia level was identified in 33.8%, osteoporosis – in 19.7% of children. In patients with hypocalcemia (Me total calcium 2.13 mmol/l [2.1; 2.16]), OS and CTX was significantly lower than in patients with normal calcium (Me OS 53.16 ng/ml [32.86; 64.61] vs 73.61 ng/ml [44.43; 111.9], P=0.001; Me CTx 1.22 ng/ml ml [0.93; 1.38] vs 1.49 ng/ml [1.2; 1.83], P=0.015). P1NP levels did not differ in patients with hypocalcemia and normal calcium (P=0.617). In children with hypocalcemia there was a lower BMD (P=0.004). The median daily dose of colecalciferol was 1100 IU in boys [1000; 2250] and 2000 IU [1000; 3000] in girls. After 6 months of the therapy normalization of 25(OH)D level in 62% of children. Statistically decreased levels of P1NP (409.15 ng/ml [156.1; 695] after the treatment vs. 436.65 ng/ml [196.1; 864] before the treatment, P<0.001), phosphorus (1.51 mmol/l [1.3; 1.68] vs 1.58 mmol/l [1.45; 1.67], P=0.012) were detected. As well as BMD decrease severity (Z-score −1.3SD [−2.3; −0.2] vs −1.5 S.D. [−2.2; −0.4], P=0.024), with simultaneous OS growth 70.1 [56.3; 96.04] vs 65.17 [42.86; 85.4], P<0.001.

Conclusion: On cholecalciferol supplementation, we observed bone tissue metabolism markers positive dynamics and BMD increase. Further research in this field with the optimal medicine dose is needed.

Keywords: congenital epidermolysis bullosa, vitamin D, hypocalcemia, osteoporosis.