Lactate Dehydrogenase (LD) Isoenzymes
Also known as: Lactic Acid Dehydrogenase Isoenzymes, LD Isoenzymes, LDH Isoenzymes
Use
Lactate dehydrogenase (LD) is an enzyme that is found in almost all of the body's cells, but only a small amount of it is usually detectable in the blood. LD is released from the cells into the bloodstream when cells are damaged or destroyed. Because of this, the LD test can be used as a general marker of injury to cells.
Special Instructions
Cardiac enzymes and isoenzymes should be interpreted sequentially; typically, a series involves one test at admission and two additional tests at six- to eight-hour intervals. Specimens should be collected and handled promptly, with serum separated from cells within 45 minutes of collection.
Limitations
The timing of testing is critical for diagnosing acute myocardial infarction (MI). In some cases, the expected 'flip' of LD1:LD2 may not occur; instead, there may be simply an increase in LD1. Some individuals, even without MI, may show high LD1:LD2 ratios. Other limitations include the presence of macroenzymes and abnormalities in isoenzyme patterns due to various conditions such as liver disease and neoplastic processes, which may affect the interpretation of results.
Methodology
Other
Biomarkers
LOINC Codes
- 42929-0
- 14804-9
- 2536-1
- 2539-5
- 2542-9
- 2545-2
- 2548-6
Result Turnaround Time
3-6 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
2 mL
Minimum Volume
1 mL
Container
Red-top tube or gel-barrier tube
Collection Instructions
Separate serum from cells within 45 minutes of collection.
Storage Instructions
Maintain specimen at room temperature. Do not freeze. Do not refrigerate for more than three days.
Causes for Rejection
Hemolysis; prolonged contact of serum with red cells; frozen specimen; specimen refrigerated more than three days after collection at time of testing
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 3 days |
| Frozen | Unstable |