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

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