Effects of different hematocrit levels on glucose measurements with handheld meters for point-of-care testing

Objectives.-To determine the effects of low, normal, and high hematocrit le vels on glucose meter measurements and to assess the clinical risks of hema tocrit errors. Design.-Changes in glucose measurements between low and high hematocrit lev els were calculated to determine hematocrit effects. The differences betwee n glucose measured with meters and with a plasma glucose method (YSI 2300) also were compared. Setting.-Six handheld glucose meters were assessed in vitro at low (19.1%), normal (38.5%), and high (58.3%) hematocrit levels, and at 6 glucose conce ntrations ranging from 2.06 mmol/L (37.1 mg/dL) to 30.24 mmol/L (544.7 mg/d L). Results.-Most systems, regardless of the reference to which they were calib rated, demonstrated positive bias at lower hematocrit levels and negative b ias at higher hematocrit levels. Low, normal, and high hematocrit levels pr ogressively lowered Precision C and Precision QID glucose measurements. Hem atocrit effects on the other systems were more dependent on the glucose con centration. Overall, Accu-Chek Comfort Curve showed the least sensitivity t o hematocrit changes, except at the lowest glucose concentration. Conclusions.-We strongly recommend that clinical professionals choose gluco se systems carefully and interpret glucose measurements with extreme cautio n when the patient's hematocrit value changes, particularly if there is a s imultaneous change in glucose level.