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 Field Name  Data Description
Test Name  LD Isoenzyme Studies
Code  LD Isoenzyme Studies.
CPT Code  83615, 83625
Last Modified  4/24/2018 12:11:00 PM
Test Name  LD Iso.
Synonyms  Lactic Acid Dehydrogenase,LDHISO,LD ,LDH ,ELECTR,LD ISO,LD ISO,ISOENZ,Lactic Acid Dehydrogenase Isoenzymes, LD Isoenzymes, LDH Isoenzymes
Patient Preparation  Cardiac enzymes and isoenzymes are best interpreted as a sequential series. Typically, a series of three: one at admission (or initial event) and two more at six- to eight- hour intervals.
Spec. Requirements  Blood
Tube  Gold or Red
Collection Volume  Gold 3.5 mL or Red 4.0 mL
Storage  Ambient 7 days. Do Not Freeze. Refrigerate 3 days.
Routine TAT  
Days Test Performed  
Performed by BHS  None
See Availability  
Reference Lab  LabCorp of America
Reference Lab Code  0001842 LD Isoenzymes
Clinical Use  Changes of LD isoenzymes periodically measured following onset of chest pain, studying the relationships of the anodic fractions, provide important information for the differential diagnosis of acute infarct of myocardium. The differential diagnosis of certain other diseases is enhancedas well with use of LD isoenzymes. Useful in the differential diagnosis of acute myocardial infarction, megaloblastic anemia (folate deficiency, pernicious anemia), hemolytic anemia, and very occasionally renal infarct. These entities are characterized by LD1 increases, often with LD1:LD2 inversion. The isomorphic pattern (total LD significantly high with no increase in percentage, of any fraction) is seen with neoplasia, cardiorespiratory diseases, hypothyroidism, infectious mononucleosis, and other inflammatory states, uremia, and necrosis. LD5 increases are seen with striated muscle lesions (eg, trauma) and with liver diseases (eg, hepatic congestion, congestive heart failure, hepatitis, cirrhosis, alcoholism).LD5 increase is probably more significant when the LD5:LD4 ratio is increased. Although a modicum of controversy exists regarding the most suitable criteria for LD isoenzymes for the diagnosis of acute myocardial infarction, almost all laboratories recognize abnormality when LD1 equals or is greater than LD2. Alternatives to LD1 greater than LD2 have been proposed.
Reference Range  
Critical Value  
Testing Sample Type  Serum
Min Lab Testing Volume  1.0 mL
Special Handling  Separate serum from cells within 45 minutes of collection.
Lab Notes  Test includes: Total serum LD and relative percentage of isoenzymes (LD1-5)
Methodology  EP - Electrophoresis
Limitations  Timing is important in diagnosis of acute myocardial infarct (MI). In a small percentage of patients with acute myocardial infarction, the expected flip (reversal) of LD1:LD2 does not occur; in such patients, there is often simply an increase in LD1. Causes for rejections: Hemolysis; prolonged contact of serum with red cells; frozen specimen; specimen refrigerated more than three days after collection at time of testing

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