Resistin is present in human breast milk and it correlates with maternal hormonal status and serum level of C-reactive protein

Background: The main objectives of our study were to determine whether resistin was present in human breast milk and to assess resistin status in breast milk and serum in breastfeeding women for up to 180 days post-partum. Methods: Blood and breast milk samples were collected from 160 breastfeeding women enrolled on 1-3, 4-14, 15-30, 31-90 or 91-180 post-partum days. Blood samples were collected from 48 breast-fed infants at 8-24 days after birth. Milk and serum resistin levels were measured by ELISA. Results: Serum and breast milk resistin concentrations were highest (5800 +/- 1100 and 1710 +/- 68 pg/mL, respectively) at 1-3 post-partum days and decreased to 1645 +/- 210 and 1130 +/- 115 pg/mL, 1600 +/- 105 and 710 +/- 25 pg/mL, 1980 +/- 155 and 595 +/- 20 pg/mL and to 2060 +/- 300 and 670 +/- 18 pg/mL at 4-14, 15-30, 31-90 and 91-180 post-partum days, respectively. Serum resistin concentrations were correlated with those of milk (r=0.822, p < 0.001). Both milk and serum resistin concentrations were correlated positively with maternal serum estradiol, progesterone, prolactin, thyroxine, triiodothyronine, cortisol, leptin and C-reactive protein concentrations. Serum resistin concentration in breast-fed infants (4915 +/- 340 pg/mL) was higher than that observed in their consumed breast milk (1745 +/- 70 pg/mL, p < 0.001) or in serum of their breastfeeding mothers (3760 +/- 360 pg/mL, p < 0.05). Conclusions: Resistin is present in human breast milk and its concentration in breast milk decreases with time during lactation. Its concentrations in breast milk and serum are correlated with circulating levels of various reproductive and metabolic hormones and with those of the general inflammatory marker, C-reactive protein.