pseudometabolic acidosis

pseudometabolic acidosis

A lab artifact seen when vacuum blood collection tubes–eg, Vacutainer are underfilled with blood, resulting in falsely ↓ bicarbonate value, falsely ↑ anion gap.
Pseudometabolic acidosis  
Amount of blood in 10 ml tube  1 ml  3 ml  10 ml
Bicarbonate mmol/L, unvented tube  21.7  19.4 16.3
Bicarbonate mmol/L, vented tube  23.3  20.3 17.3
Anion gap mmol/L 16.7 17.5 19.2