EDTA contamination in laboratory specimens-effect of an awareness campaign

Abstract

Objective: To measure the effects of awareness campaign on the frequency of EDTA contamination.

Study design: A cohort study.

Place and duration of study: The study was carried out in Combined Military Hospital, Peshawar, from October to December 2008.

Methodology: A cohort of 200 doctors, nurses and paramedical staff involved in sample collection for laboratory investigations were selected for this three phased study. In all samples with plasma potassium level > 6.0 mmol/L, plasma Ca++ was measured for one month before, during and after a campaign of correct filling order of sample tubes for two weeks. Renal function test and LDH were also measured to rule out chronic renal failure and in-vitro haemolysis, respectively. Fisher's exact test was used for comparison of frequency of hyperhalemia.

Results: There was a significant decrease (75%, p < 0.01) in the cases of spurious hyperkalaemia and hypocalcaemia.

Conclusion: EDTA contamination is a common and important source of pre-analytical error which can be prevented to some extent by education of medical and nursing staff.