Abstract 131

Background : Human milk fortifiers (HMF) are frequently used to improve nutritional supplies and to ensure optimal growth in VLBW infants. Aim of the study : To evaluate the influence of various HMF supplementation on osmolality of human milk (HM). Methods : Osmolality of 39 samples of HM was determined at baseline, after supplementation and at 24 hours at 4°C and at room temperature. Amylase levels were also determined (Clin Chem 1988;34 :2005-9) in 18 set of samples before and 24 hours after the supplementation. Statistics: Data are expressed as M±SD ; paired t test was performed for statistical significance. Results : At baseline osmolality of HM and HMF were 284±11 and 58±19 osm/kg.H2O respectively. Ten minutes after HMF supplementation (369±26 osm/kg.H2O) osmolality was higher than the sum of the individual values (342±21 osm/kg.H2O) p<0.0001. After 24 hours at 4°C (404±41 osm/kg.H2O) and at room temperature (416±43 osm/kg.H2O), osmolality were significantly increased (p<0.001). The raise in osmolality was positively related to the dextrines supplementation (r=0.83; p<0.0001). Amylase activity in HM was similar before (1737±474 U/l) and 24 hours after addition of HMF (1644±460 U/l). Conclusions : Our data suggest that amylase activity of HMF induces hydrolysis of the dextrines content of HMF leading to glucose production and to a progressive increase of osmolality. The high osmolality of fortified HM (>400 osm/kg.H2O) needs to be considered in nutritional programs and in clinical practice of VLBW infants.