Blood Test

LDH (Lactate Dehydrogenase) Test

Name: LDH Blood Test: Normal Range & High Levels | HealthReview
Creator: Suman Konda
Published: 2026-07-05

LDH is an enzyme found in almost every cell in the body. When cells are damaged or destroyed, LDH is released into the blood. High LDH is a non-specific marker of tissue damage used in multiple conditions.

Written and clinically reviewed by Suman Konda, PharmD, Clinical Pharmacist · Based on peer-reviewed sources · Editorial policy · Not medical advice

Last reviewed and updated: 01 August 2026 · How we check our content

What is LDH?

Lactate dehydrogenase (LDH or LD) is an enzyme involved in converting lactate to pyruvate during energy metabolism. It is present in nearly all body tissues: heart, liver, kidney, muscle, lung and red blood cells. When cells are damaged, LDH leaks into the blood. Because it is non-specific (not tied to one organ), LDH is used as a general marker of tissue injury and cell turnover. LDH isoenzymes (LDH1-5) can sometimes identify which organ is involved.

LDH normal range

Group	Normal Range (U/L)
Adults	140 – 280 U/L (varies slightly by lab)
Children	Higher than adults (normally elevated)

Causes of high LDH

Cause	How high LDH rises	Notes
Haemolysis (red cell breakdown)	Very high	LDH1 dominant; check haptoglobin
Liver disease	Moderately high	LDH5 dominant; use with LFT
Heart attack (MI)	High (historic use)	Troponin now preferred
Pulmonary embolism	Mild-moderate	Non-specific
Lymphoma / leukaemia	Very high	Very high LDH = aggressive tumour
Anaemia (megaloblastic)	High	B12/folate deficiency with ineffective erythropoiesis
Muscle injury / rhabdomyolysis	Very high	CK also very high
Kidney infarction	High	LDH5
COVID-19 / severe infections	Elevated	Marker of tissue damage severity

LDH in cancer staging and monitoring

LDH is widely used in oncology as a prognostic marker. In testicular cancer, lymphoma, melanoma and lung cancer, a very high LDH correlates with higher tumour burden and poorer prognosis. It is included in staging systems for non-Hodgkin lymphoma (IPI score) and melanoma. Falling LDH during cancer treatment is a good sign; rising LDH during remission may indicate relapse.

Questions to ask your doctor

Why is my LDH elevated?
Do I need LDH isoenzyme testing to identify which organ is affected?
Is this related to my anaemia, liver, or another cause?
If being monitored for cancer, what LDH trend is expected?

Frequently Asked Questions

What does a high LDH level mean?

LDH is released when cells are damaged, so it rises in many conditions: tissue injury, haemolysis, infection, and some cancers. It's a sensitive but non-specific marker, interpreted alongside other tests.

Why is LDH sometimes checked in lymphoma?

LDH can reflect disease activity and is used as part of staging and monitoring in some lymphomas and other cancers, though it's never diagnostic on its own.

Can exercise raise LDH?

Yes. Strenuous exercise and even a difficult blood draw (causing red cell breakdown) can raise LDH, which is why mild elevations are often repeated and interpreted cautiously.

References

The clinical information on this page is drawn from peer-reviewed sources indexed by the US National Library of Medicine. Links go to the source so you can read it yourself.

Overview on Ordering and Evaluation of Laboratory Tests. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK570615