Lactate Dehydrogenase (LDI)

CPT Code: 



Serum and Plasma 


1 mL 

Minimum Volume: 

0.3 mL 


Sterile body fluid container




Phlebotomies to obtain samples for lactate dehydrogenase activity concentration should be carefully done to avoid hemolysis since the abundant lactate dehydrogenase in red blood cells can contaminate such samples.

Hemolyzed samples should not be used with the LDI method

For serum, complete clot formation should take place before centrifugation.

Serum or plasma should be physically separated from cells as soon as possible with a maximum limit of two hours from the time of collection.

For plasma, make sure separated specimen is free of platelet contamination.  Platelets contain high activity concentration of lactate dehydrogenase.

Storage Instructions:

Maintain specimen at room temperature.

Reference Range:  Expected Values (Dimension RXL) 

Male:  85-227 U/L 
Female:  81-234 U/L 


Temperatures  Period 
Room Temperature  3 Days 
  Do not refrigerate or Freeze



LDH is an enzyme found in red blood cells and in many different human tissues, including heart, kidney, liver, and muscle. Trauma to any of these organs or muscles can result in tissue damage, releasing LDH into the blood. 

Clinical Significance: 

High LDI amounts may occur in association with ischemic necrosis, meningitis, leukemia, metastatic cancer of the CNS, and lymphoma. Lactate dehydrogenase is also elevated in proportion to severity of CNS hemorrhage.

LDH1 and LDH2 are decreased in lavage fluid in pulmonary alveolar proteinosis.

Causes for Rejection: 

Improper labeling 

Interfering Substances: 

Hemoglobin (hemolysate) at 50 mg/dL increases LDI results by 13.7% at a lactate dehydrogenase activity of 300 U/L and 500 U/L.
• Note: Lactate dehydrogenase released from red blood cells especially intravascularly may vary by disease state.  Therefore bias from hemolysis in any individual sample may vary from patient to patient.

Dopamine at 65 mg/dL increases LDI results by 113% at a lactate dehydrogenase
activity of 300 U/L.

Samples from patients with unexpectedly high levels of lactate dehydrogenase should be investigated for prescence of immunoglobulin-complexed enzyme as a cause for such results.