General & BloodNo Fasting RequiredTurnaround: 4–8 hours (same day)

Lactate Dehydrogenase (LDH — Tissue Breakdown & Hemolysis Marker)

Also known as: Serum LDH, Lactic Dehydrogenase, LDH Total, Cell Turnover Marker, Hemolysis Marker

Parameters Measured in the Report

A breakdown of individual biomarkers and biological reference intervals typically found in your report:

Biomarker	Standard Range	Unit	What It Means
Total Serum LDH (Lactate Dehydrogenase)	Adults: 140–280 (Severe Hemolysis / Lymphoma: > 500–2,000+)	U/L	Intracellular glycolytic enzyme; surges in states of rapid cellular turnover, membrane lysis, and malignant proliferation.

* Note: Reference ranges may vary slightly between testing instruments and reagent kits. Always refer to the reference interval printed on your specific pathology report.

Clinical Focus

Total catalytic activity of intracellular glycolytic enzyme that catalyzes the interconversion of pyruvate and lactate.

Sample & Specimen

Venous blood (Serum tube without hemolysis)

Fasting Protocol

No fasting required. Sample must not be hemolyzed (red cells contain 100x more LDH than serum).

Turnaround Time

4–8 hours (same day)

What Is This Test?

Lactate Dehydrogenase (LDH) is a ubiquitous intracellular enzyme present in the cytoplasm of virtually all viable cells in the human body, with particularly high concentrations in red blood cells, skeletal muscle, liver, kidneys, lungs, and lymph tissue. LDH catalyzes the final step of anaerobic glycolysis: the reversible conversion of pyruvate to lactate with the regeneration of NAD+. Because LDH is universally present inside cells, it is not specific to any single organ. Rather, it serves as a sensitive **barometer of cellular injury and tissue destruction**. When cells are damaged, rupture, or proliferate with rapid cancerous turnover, massive quantities of LDH spill out into the bloodstream, making it a cornerstone marker in hematology, oncology, and pulmonary medicine.

Why Did Your Doctor Order This Test?

Physicians routinely prescribe the LDH (Lactate Dehydrogenase) in the following clinical scenarios:

Diagnostic evaluation of suspected Hemolytic Anemia: unprovoked drops in hemoglobin accompanied by high LDH, low haptoglobin, and high indirect bilirubin

Baseline staging, prognosis, and therapeutic monitoring in Hodgkin and Non-Hodgkin Lymphomas and Multiple Myeloma

Mandatory serum tumor marker for staging and risk stratification in Testicular Germ Cell Tumors (alongside AFP and beta-hCG)

Diagnostic evaluation of acute Pneumocystis jirovecii Pneumonia (PCP) in immunocompromised or HIV patients

Assessing tissue damage in severe pulmonary embolism, acute myocardial infarction, or extensive tissue trauma

How to Prepare Before Your Test

Fasting Requirement: No fasting required. Sample must not be hemolyzed (red cells contain 100x more LDH than serum).

No fasting or special preparation required.
The blood sample must NOT be hemolyzed; because red blood cells contain 100 to 150 times more LDH than plasma, mechanical hemolysis during blood draw falsely elevates LDH readings.

Understanding Your Results

What higher or lower readings generally mean in clinical practice:

If Values Are Higher Than Normal

Markedly elevated LDH (>500–2,000+ U/L) indicates extensive cellular death or rapid turnover. Classic causes include Hemolytic Anemia (rupture of red cells), active Non-Hodgkin Lymphoma, metastatic cancer, severe sepsis, or acute lung injury. In lymphoma and germ cell tumors, falling LDH confirms successful chemotherapy response.

If Values Are Lower Than Normal

Low LDH is uncommon and has no clinical or pathological consequence.

Frequently Asked Questions

Why does my lab report say "Sample Hemolyzed — LDH Not Reported"?

Red blood cells are packed with 100 times more LDH than the liquid portion of your blood. If a fragile red blood cell breaks inside the needle during blood draw (hemolysis), LDH spills into the tube and gives a falsely astronomical reading. The lab cancels the test and requests a gentle redraw.

Why do oncologists test LDH in lymphoma patients?

Lymphoma cancer cells divide and die at a furious pace, shedding huge amounts of LDH into the blood. Baseline LDH tells oncologists how aggressive the tumor is (higher LDH = more aggressive), and falling levels prove the chemotherapy is working.

Related Laboratory Tests

Tests frequently prescribed together or used as follow-up investigations:

Complete Blood Count (CBC / Hemogram)

Counts and evaluates red blood cells, white blood cells, hemoglobin, hematocrit, and platelets.

Liver Function Test (LFT / Hepatic Panel)

Bilirubin fractions, transaminases (ALT/SGPT, AST/SGOT), Alkaline Phosphatase (ALP), and proteins (Albumin, Globulin).

Inflammatory Markers (ESR & C-Reactive Protein / hs-CRP)

Rate of red blood cell settling (ESR) and hepatic acute-phase reactant protein concentration (CRP / hs-CRP).

Medical & Diagnostic Disclaimer

This guide is published for educational and patient informational purposes only. It is not a substitute for professional medical evaluation, diagnosis, or clinical advice.

A laboratory result that falls slightly outside standard statistical reference intervals does not automatically indicate disease; conversely, a normal result does not guarantee the absence of medical conditions. Only your attending physician can interpret lab findings in the context of your medical history, physical exam, and symptoms.