Evaluation of three different specimen types (serum, plasma lithium heparin and serum gel separator) for analysis of certain analytes: clinical significance of differences in results and efficiency in use.

Background: There is a lack of consensus regarding the most appropriate specimen type for analysis of many biochemistry analytes. The aim of this study was to compare renal and lipid analyte profiles and phenytoin values in plain serum (S), serum gel (G) and plasma (lithium heparin, P) tubes and to investigate the stability of these analytes after prolonged contact with cells or gel at room temperature (RT, 20 degrees C) and as aliquoted and stored at 4 degrees C.

Methods: Primary specimens were centrifuged once, maintained at RT and analysed within 2 h (T(0)) and after 24 h (T(24)) and 48 h (T(48)).