Is Lactic Acid an Indicator of Anemia? ♦ 1392

Abstract

Anemia is diagnosed by the decrease in the circulating hemoglobin concentration. It is frequently observed in NICU patients, specially in low birth weight infants (LBW) who may suffer the consequence of decreased tissue oxygenation. The decision for transfusion is made based on relatively unspecific parameters such as tachycardia, tachypnea, absence of weight gain or apnea. However, the degree of tissue hypoxia cannot be established with the sole measurement of hematocrit (HC), often used in clinical practice. A mismatch between oxygen requirement and oxygen delivery may lead to anaerobic glucose metabolism with an increase in lactic acid (LA) levels. Lactacidemia could therefore be an indicator of the need for transfusion. Normal values in adults range from 0.64 to 2.4 mmol/l. Although normal levels have not been established in healthy newborns, data on the rise of LA in talasemias and iron deficiency anemia in adults, and in severe hemorrhage in animals, and their fall after transfusion have been reported. The present study was designed to determine a) LA levels in LBW infants before and after transfusion of packed red blood cells and correlation with HC and b) if LA levels can be used as indicators of the need for transfusion. Ten LBW (< 2000gr) infants, stable, feeding and in room air (no IMV), in whom a transfusion was indicated for the correction of anemia were included. Arterial blood samples of 0.2 ml were drawn pre and postransfusion and LA levels (enzymatic assay) were compared(paired t-Test). Pre transfusion LA levels and HC values were correlated. Mean pre and post-transfusion values for LA were 3.10 mmol/l (1.2-9.2) and 1.75 mmol/l (0.65-4.85) respectively (p = 0.009). Correlation coefficient between pretransfusion LA and HC was 0.65. These data show a significant difference between pre and post-transfusional LA and a poor correlation of HC and LA. Although values after transfusions were significantly different from pretransfusional levels, values overlapped. We conclude that LA levels in this group of patients may not be an accurate indicator of the need for transfusions. Further work is needed to determine if there is an individual LA level for each patient that might help establish the need for transfusion.