D-Lactic acidosis : Studies in neonatal diarrhea and effects of processing and storage on lactate concentrations in blood
D-lactate is a significant contributor to acidosis in diarrheic calves. To ensure an accurate measure of D- and L- lactate, this study investigated storage dependent changes in D- and L-lactate concentrations in plasma and serum over time with or without prolonged contact with blood cells. Further studies investigated if D-lactic acidosis occurs in children with diarrhea and if a fecal threshold exists in the gastrointestinal tract at which D-lactate enters the systemic circulation in diarrheic calves. To determine the stability of D- and L-lactate, blood was obtained from eleven healthy calves. D- and L-lactate concentrations in all samples separated following collection (serum, plasma, spiked, untreated) were stable up to 48 hours. L-Lactate concentrations increased significantly (P < 0.05) by 74.4%, 39.4%, and 40.2% in untreated and spiked serum and spiked plasma respectively at 48 hours when stored in contact with blood cells. D-Lactate concentrations in untreated serum stored in contact with blood cells increased significantly, by 82.3%, at 48 hours. For accurate measurements of D- and L-lactate, serum or plasma should separated from blood cells as soon as possible but can thereafter be stored at 4°C for up to 48 hours. To determine whether D-lactic acidosis occurs in children with acute diarrhea, blood samples were obtained from nine children with acute diarrhea, ten months to three years of age. No cases of D-lactic acidosis (> 3 mmol/L) were found, however, D-lactate concentrations ( = 0.15) were found to be higher when compared to healthy children. To determine if a fecal D-lactate threshold exists at which D-lactate enters the blood in diarrheic calves, blood and fecal samples were obtained from 27 calves. The linear regression between fecal D-lactate and serum D-lactate was statistically significant however the range of D-lactate concentrations obtained in this study was not large enough to confirm the fecal threshold at levels previously reported. Collectively, these studies contribute to the knowledge of D-lactate, and D-lactic acidosis, by determining the stability of D- and L-lactate for accurate measurement, revealing elevated D-lactate concentrations in diarrheic children in comparison to healthy children, and further investigation of a potential fecal D-lactate threshold.
D-lactate, L-lactate, acidosis, humans, calves, diarrhea, blood collection, plasma, serum
Master of Science (M.Sc.)