A practical analytical quality report on the effect of carotenemia on neonatal bilirubin levels

Abstract

The effect of haematocrit and ß-carotene levels on the serum total bilirubin measurement in two analytical methods was studied as an example of the impact of practical analytical quality in medical decision making. The precision characteristics of the two methods were very similar. Based upon the significant difference in the correlation coefficient in a method comparison study before and after 20% trimming of the data, an interference effect study was performed. Haemoglobin (expressed as haematocrit) and ß-carotene were the substances studied to explain the observed differences. The bilirubin test results from the Wako bilirubinometer were easily affected (n = 19; X(S): 13.83±2.43; t = -6.17; P = 0.000) and more elevated than in the Vitros dry chemistry systems (n = 18; X(S): 12.72±2.21; t = -2.48; P = 0.017), due to the presence of ß-carotene (>200 µg/dl).