Interference due to haemolysis in routine photometric analysis--a survey

To assess the affect of haemolysis on routine photometric methods used by participants in the Irish External Quality Assessment Scheme for Clinical Biochemistry (IEQAS) a sample was distributed with a supplied diluent containing haemoglobin. A sample of the same batch had previously been circulated as a normal distribution. Many analytes/methods were affected by the haemolysis. The range of values reported for each analyte was as follows. Albumin 34-48 g/L (baseline 37 g/L). Calcium 2.16-2.68 mmol/L (baseline 2.34 mmol/L). Urate 90-470 mumol/L (baseline 195 mumol/L). Creatinine 55-161 mumol/L (baseline 140 mumol/L). Glucose 4.1-5.6 mmol/L (baseline 4.8 mmol/L). Bilirubin 14-60 mumol/L (baseline 36 mumol/L). Urea 3.4-7.3 mmol/L (baseline 3.8 mmol/L). Iron 17.9-55.0 mumol/L (baseline 26.8 mumol/L). Inorganic phosphorus 0.22-2.41 mmol/L (baseline 1.59 mmol/L). Cholesterol 3.0-5.9 mmol/L (baseline 4.1 mmol/L). In some situations the use of an appropriate blank may solve the problem, but it must be remembered that interference caused by haemoglobin may be more complex than merely spectral.