The aim: of this study was to assess concentrations of sclerostin and biochemical markers of bone metabolism in children with cow's milk allergy.
Material and methods: The study included 45 children (age range 2-6 years) with diagnosed cow`s milk allergy, who were on a dairy-free diet and under systematic medical and dietary control at the Institute of Mother and Child in Warsaw. The control group consisted of 40 healthy children (2-6 years), who did not have any symptoms of cow`s milk allergy nor any diseases influencing bone metabolism. Their diets included milk and dairy products. Dietary intake of macro- and micronutrients was assessed based on 3-day records using the Dietetyk2® nutritional program. In the serum samples, we measured concentrations of calcium, phosphate and total alkaline phosphatase by standard methods, 25-hydroxyvitamin D3 by chemiluminescence method and bone metabolism markers by immunoenzymatic methods. The Statistica (version 10.0) computer software was used for statistical analysis.
Results: The nutritional status of studied children based on BMI value was normal. In all patients, the average daily value of dietary energy and percentage of energy from protein, fat and carbohydrates were consistent with the recommended values. The intake of calcium in the diets of all children was deficient, however, the intake of vitamin D was consistent with recommendations in the children with allergy, while in the healthy children it was below the recommended values. Mean serum concentrations of calcium, phosphate, alkaline phosphatase, 25-hydroxyvitamin D3, osteocalcin and C-terminal telopeptide of type I collagen were similar in both studied groups. We observed significantly lower sclerostin levels in children with cow`s milk allergy (0.295±0.116 ng/ml) than in the healthy children (0.353±0.126 ng/ml) (p<0.05). The ratio of cytokines RANKL/OPG (receptor activator of nuclear factor κB ligand/osteoprotegerin) was significantly higher in children with allergy compared with their healthy counterparts (p<0.05).
Conclusions: Basic laboratory parameters related to bone turnover in children with cow`s milk allergy, who were under medical and nutritional care, were normal. Reduced levels of sclerostin and increased ratio of cytokines RANKL/OPG may suggest disturbances in the balance between bone formation and bone resorption in these patients. Further research is needed on bone metabolism in children with food allergy, who due to the use an elimination diet may be at risk of developing abnormalities in the skeletal system.