Pitfalls in the determination of common analytes in the critically ill

In the critically ill, the pre-analytical aspects of blood gas analysis sti ll require attention from the clinician. Sampling and transport remain crit ical factors. Use of drugs may create analytical interferences for common a nalytes like glucose and protein. Icterus may falsely reduce creatinine and albumin values. Changes in the serum or plasma matrix (reduction of protei n, increased covolume of solutes,...) may furthermore cause important effec ts on the distribution of electrolytes. Enzyme activity measurements may be erroneous due to lack of essential oligoelements or reducing substances. I mmunoassays may suffer from interferences caused by auto-antibodies. In cas e of hemolysis, a careful interpretation of test results is mandatory.