Human and cow milk contains several factors active in the regulation of bone metabolism and mineralization of the growing skeleton. Children with cow milk allergy (CMA) are under a potential risk of eating insufficient quantity of calcium in the diet [1]. We aimed to analyze the markers of bone mineralization and metabolism through an observational study. Our studied group consisted of 25 CMA children (aged 8±4.2 months) and 65 healthy controls (4± 2.8 months). CMA was confirmed by standardized open oral food challenge [2]. Enrolled children were fed with extensively hydrolyzed or amino acid formulas. The duration of milk-free diet was 4±0.26 months. Vitamin D was administered to all the children from second week of life (666 I.U of cholecalciferol per day). The markers of bone metabolisms and turnover were analyzed from the serum and urine. The study was approved by the Ethical Committee.

In the control group of healthy children, all the examined parameters were within physiological ranges. Conversely, cow milk-allergic children showed lower serum and urine concentration of calcium (serum: 2.06±0.06 vs. 2.26±0.03 mmol/L, P=0.008; urine: 0.36±0.30 vs. 1.51±0.68 mmol/kg/day, P=0.008). Alkaline phosphatase (ALP) and its bone isoform (BALP), the two markers of increased bone turnover, were significantly increased in children with CMA (ALP: 9.07±0.59 mkat/L vs. 4.04±0.42 mkat/L, P=0.008; BALP: 87.67±3.88% of total serum ALP vs. 61.80±11.73% of total serum ALP, P<0.001). Serum osteocalcin and urine hydroxyproline did not differ between the two groups.

We found enhanced bone turnover in cow milk allergic children compared to healthy infants during the first year of life. Patients with cow milk allergy are at potential risk for osteopenia because their milk-free diet usually contains low calcium contents [3]. Appropriate substitution of essential minerals into the diet of cow-milk allergic children could result in complete resolution of the clinical symptoms of osteopenia and rickets [4].

Acknowledgement: This work was supported by project "Center of Experimental And Clinical Respirology I" co-financed from EU sources - European Regional Development Fund.

1. Jensen VB, Jorgensen IM, Rasmussen KB, Molgaard C, Prahl P. Bone mieral status in children with cow milk allergy. Pediatr Allergy Immunol. 2004;15:562-5.

2. Saarinen KM, Juntunen-Backman K, Jarvenpaa AL, Kuitunen P, Lope L, Renlund M, et al. Supplementary feeding in maternity hospital and the risk of cow´s milk allergy: A prospective study of 6209 infants. J Allergy Clin Immunol. 1999;104:457-61.

3. Tuokkola J, Kaila M, Kronberg-Kippila C, Sinkko HK, Klaukka T, Pietinen P, et al. Cow´s milk allergy in children: adherence to a therapeutic elimination diet and reintroduction of milk into the diet. Eur J Clin Nutr. 2010;64:1080-5.