Chemistry, toxicology & urinalysis

Organ specific

Cardiac

lactate dehydrogenase



Last author update: 1 December 2010
Last staff update: 27 June 2020

Copyright: 2002-2024, PathologyOutlines.com, Inc.

PubMed Search: Lactate dehydrogenase [title]

Larry Bernstein, M.D.
Page views in 2023: 618
Page views in 2024 to date: 107
Cite this page: Bernstein L. lactate dehydrogenase. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/chemistrycardiaclactatedehydrogenase.html. Accessed March 29th, 2024.
Definition / general
  • LDH measures the amount of serum lactate dehydrogenase (LDH), which is released into the circulation after tissue damage
  • Causes of tissue damage include acute myocardial infarction (AMI), hepatitis and acute renal failure
  • LDH is elevated on the second day after AMI, and remains elevated for up to 4 days
  • LD1 is usually measured
Pathophysiology
  • LDH is an enzyme (EC 1.1.1.27) ubiquitous in tissue (Wikipedia - Lactate dehydrogenase)
  • It has five isoenzymes, each with a different composition of M-type and H-type subunits in a tetrameric structure
  • The M-type isoenzyme is predominant in liver and skeletal muscle
  • The H-type isoenzyme is predominant in heart and renal cortex
  • LDH catalyzes the conversion of pyruvate to lactate in the glycolytic pathway
Diagrams / tables

Images hosted on other servers:
Missing Image Missing Image

Pyruvate to Lactate conversion

Laboratory
Methodology
  • The measurement of the enzyme uses the reduction of the coenzyme NAD to NADH with increasing optical density and oxidation of lactic acid to pyruvate
  • Alternatively, one can follow the reverse reaction of pyruvate to lactate and NADH to NAD at 340 nm

Indications
  • Patients presenting 12+ hours after the onset of chest pain
    • High levels are suggestive of acute myocardial infarction
  • Staging (S classification) patients with nonseminomatous testicular cancer
  • Evaluating patients with metastatic cancer
  • Assessing nature of pleural / pericardial fluids: ratio of fluid LDH to upper limit of normal serum LDH of more than 0.6 suggests an inflammatory process (exudate)

Limitations
  • Elevated in hemolyzed specimens, since enzyme is present in erythrocytes

Reference ranges
  • A typical range is 105 - 333 IU/L
  • Must interpret values in context of patient clinical findings
Back to top
Image 01 Image 02