Leptin determination in colostrum and early human milk from mothers of preterm and term infants

Background: Leptin is involved in the regulation of food intake and energy expenditure and is therefore important for growth and brain development. Analytical methods used for leptin measurement in human milk differ widely in the literature and yield varying results. Aims: To compare different preparation methods for the analysis of leptin in human milk and to investigate the leptin levels in colostrum and mature human milk from mothers of preterm or term infants. Methods: Mothers delivering a preterm (n=37) or a term infant (n=40) were recruited for a prospective study and were ask to collect breast milk on the 3rd and 28th day of lactation. Leptin, protein and fat concentrations were analysed. Clinical data of mother and child were recorded prospectively. Results: Skim milk was most appropriate for leptin analysis. Human milk leptin concentrations did not differ between preterm and term human milk. In term milk, leptin concentration on day 28 was lower than on day 3 (p<0.05). Milk leptin levels on the 3rd and 28th day were positively correlated with mothers' body mass index, but not with fat content in milk. Conclusion: Skim milk was the most stabile preparation for leptin analysis. Preterm and term human milk contain leptin in equal concentrations. Human milk leptin depends on mothers' body mass index. (C) 2011 Published by Elsevier Ireland Ltd.