Clinical Types of Lactic Acidosis

 

Testing may be performed on arterial or venous blood samples, which have different reference ranges.

 

Suspect lactic acidosis when the anion gap is > 18 mmol/L in the absence of another explanation.

Metabolic Features	Lactate to Pyruvate Ratio	Pathogenesis	Type
increased lactic acid but without acidosis	normal		Type I
increased lactic acid with acidosis	increased	hypoxia-related (decreased oxygen delivery)	Type IIA
increased lactic acid with acidosis	increased	metabolic (drugs or toxin, concurrent disease, inborn error metabolism)	Type IIB

 

Criteria for Type II (Sacks, 1999):

(1) increased lactate concentration (> 5 mmol/L)

(2) pH < 7.25

 

Causes of Type I:

(1) muscular exercise

(2) hyperventilation

(3) glucagon administration

(4) glycogen storage disease

(5) severe anemia

(6) insulin administration

(7) Reye's syndrome

 

Causes of Type IIA:

(1) acute hemorrhage

(2) acute heart failure

(3) circulatory shock

(4) severe hypoxemia

(5) extracorporeal circulation

(6) cardiac arrest

 

Causes of Type IIB - drugs or toxins:

(1) ethanol

(2) phenformin

(3) fructose or sorbitol infusion

(4) recovery from diabetic ketoacidosis

 

Causes of Type IIB - inborn errors of metabolism

(1) glycogen storage disease type I

(2) defects in pyruvate metabolism

 

Causes of Type IIB - concurrent disease:

(1) mild uremia

(2) infection (pyelonephritis, subacute bacterial endocarditis, poliomyelitis)

(3) cirrhosis

(4) third trimester of pregnancy

(5) severe vascular disease

(6) leukemia or neoplastic disease

(7) anemia

(8) thiamine deficiency

(9) metabolic myopathy

 

Limitations:

• Lactate levels may be increased by improper collection, handling and testing.