[The evaluation of selected parameters of calcium and phosphorus metabolism in children with cow's milk allergy].

THE AIM of this study was to evaluate selected parameters of calcium and phosphorus metabolism in children with CMA treated with the following milk substitute formulas: lactose-containing extensively hydrolyzed wheat protein formula, lactose-free extensively hydrolyzed casein protein formula, as well as soy-based formula.

METHODS

The study involved 66 children with CMA aged 2-5 years treated with milk-free diet for at least one year. Group I included 31 children fed with a lactose-containing formula, group II - 35 children treated with lactose-free formula. In all children the mean energy intake and nutritional value of daily food rations were assessed. Serum concentrations of calcium (Ca), phosphorus (P), sodium (Na) and magnesium (Mg) were determined using standard methods. Serum values of 25 hydroxyvitamin D (25-OH D) and parathormone (PTH) were assessed by chemiluminescence, whereas concentrations of biochemical markers of bone formation-bone alkaline phosphatase (BALP), osteocalcin (OC) and bone resorption marker-collagen type I crosslinked C-telopeptide (CTX) were determined by immunoenzymatic methods (ELISA), using specific monoclonal antibodies.

RESULTS

There were no significant differences in the mean dietary supply of calcium, phosphorus, magnesium, sodium, total protein and vitamin C in children from both groups. In the diets of children from group II, the mean content of lactose (0.5±1.0 vs 10.0±6.8 g/d) and 25-OH vitamin D (4.1±2.3 vs 8.5±4.0 ug/d) were significantly lower and dietary fibre content (14.7±3.9 vs 10.4±3.9 g/d) was higher. Calcium and vitamin D dietary supply was lower with respect to nutritional recommendations in all the studied children, whereas the dietary deficiency of vitamin D was higher in children from group II. The mean serum concentrations of evaluated biochemical parameters did not reveal any differences in children from the study groups and were in the normal ranges. There were also no differences in the mean serum concentration of 25-OH vitamin D, ALP, BALP, CTX and PTH in patients from both groups. The mean concentration of OC was significantly higher in group II (71±26.6 ng/ml) than in children from group I (61.1±23.4 ng/ml) <0.01. Positive correlation was found between OC and CTX in both study groups.

CONCLUSIONS

1. In children with CMA basic blood laboratory tests may have limited importance in the evaluation of calcium and phosphorus metabolism. 2. Our results suggest that the disturbances in the balance between bone formation and bone resorption processes may occur in children with CMA treated with lactose-free formulas. 3. In order to assure optimal conditions for achieving adequate bone mass by children with CMA, it is necessary to provide them with regular medical and nutritional care.