What is the purpose of checking lactate levels?
It is an indicator of tissue hypoperfusion and hypoxia. The greater the levels, the more severe the current condition is. It also indicates the development of lactic acidosis which needs aggressive treatment.
Lactate level is checked because in septic shock (> 4 mM) and severe sepsis (> 2 mM) is associated with hyperlactaemia. The high anion gap in hyperlactaemia produces dysfuntion on cellular and organ level.