Active and total ghrelin concentrations increase in breast milk during lactation

Aim: To assess ghrelin status in breast milk and maternal serum for up to 180 days during lactation and to determine relationships between the concentrations of ghrelin in mother's milk and in serum of breastfed infants. Methods: Blood and breast milk samples were collected from 159 breastfeeding women enrolled either in the first 3 days, or in days 4-14, 15-30, 31-90 and 91-180 postpartum. Blood samples were also collected from 49 breastfed infants at 4-30 days of age. Milk and serum active and total ghrelin concentrations were measured by radioimmunoassay. Results: Active and total ghrelin concentrations in breast milk were lowest (450 +/- 25 and 880 +/- 80 pg/mL, respectively) at 0-3 days, whereas they increased progressively during 180 days of lactation period to 801 +/- 43 and 3250 +/- 380 pg/mL at 91-180 days postpartum. Milk total ghrelin concentrations correlated with serum concentrations of active (r = 0.503; p < 0.001) and total ghrelin (r = 0.331; p < 0.05) in breastfed infants at 4-30 days of age. In breastfeeding women, serum total ghrelin concentrations increased whereas serum active ghrelin concentrations decreased significantly during the next 4-180 days. Conclusion: Active and total ghrelin concentrations in breast milk increase with time during lactation and show significant relations with serum ghrelin concentrations in breastfed infants.