Lactic Acid

Test ID: 

703010

CPT code:

83605

Clinical Use:

Hypoperfusion is the most common cause of lactic acidosis and hyperlactacidemia may be the only marker of tissue hypoperfusion.1 Suspect lactic acidosis when unexplained anion gap metabolic acidosis is encountered, especially if azotemia or ketoacidosis are not present. Evaluate metabolic acidosis, regional or diffuse tissue hypoperfusion, hypoxia, shock,2 congestive heart failure, dehydration, complicated postoperative state, ketoacidosis or nonketotic acidosis in diabetes mellitus, patients with infections, inflammatory states, postictal state, certain myopathies, acute leukemia and other neoplasia, enzyme defects, glycogen storage disease (type I), thiamine deficiency, and hepatic failure. A spontaneous form of lactic acidosis occurs. It is a prognostic index in particular clinical settings, especially in critically ill patients in shock.3 A relationship to renal disease also exists. With skin rash, seizures, alopecia, ataxia, keratoconjunctivitis, and lactic acidosis in children, consider defective biotin metabolism.4 Phenformin, ethanol, methanol, and salicylate poisoning and ethylene glycol may cause lactic acidosis. Acetaminophen toxicity causes lactic acidosis, sometimes with hypoglycemia. Cyanide, isoniazid, and propylene glycol are among the causes of lactic acidosis.1 Lactic acidosis may be due to inborn errors of metabolism.

Specimen Type:

Plasma

Requested Volume: 

1 mL

Minimum Volume: 

0.5 mL

Container Type: 

Gray-top (sodium fluoride/potassium oxalate or sodium fluoride/sodium heparin) tube

Patient Preparation: 

Patient should not be on any intravenous infusion that would affect the acid-base balance. Patient should be in a fasting and resting state (should not exercise).

Collection:

Keep gray-top tube on ice. Draw blood in gray-top tube. Mix well by gentle inversion at least six times. Return to ice bath to cool. Avoid hand-clenching and, if possible, avoid use of a tourniquet. A tourniquet with patient clenching and unclenching hand will lead to high potassium and lactic acid buildup from the hand muscles, and pH will decrease. It is best to avoid a tourniquet for electrolytes and lactic acid or to release it after blood begins to flow into the tube. If the tourniquet is released before blood is drawn, wait about a minute before drawing. Within 15 minutes of draw, separate the plasma from blood by centrifugation for 10 minutes. Immediately transfer the plasma portion of the sample to a labeled plastic transport tube. Avoid excessive forces that contribute to hemolysis.

Storage Instructions:

Room temperature

Stability Requirements:

Rejection Criteria

Specimen not separated from cells within 15 minutes of draw; marked hemolysis; slight or moderate turbidity; perchloric acid supernatant; serum specimen