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.¹

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

Last reviewed and updated: 26 September 2026 · How we check our content

Quick answer

LDH is an enzyme in nearly every cell; normal is roughly 140-280 U/L. High LDH is a non-specific marker of tissue damage: haemolysis, liver disease, muscle injury and some cancers can all raise it. In cancer care it is a prognostic marker, where falling LDH during treatment is reassuring. LDH isoenzymes can sometimes identify the organ involved.

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.² 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)

Key points

LDH is an enzyme in nearly every cell; when cells are damaged, LDH leaks into the blood, making it a non-specific marker of tissue injury.
Rough normal range is 140-280 U/L; children run higher than adults.
Raised LDH has many causes: haemolysis, liver disease, muscle injury, B12 or folate deficiency, severe infections and cancer.
In oncology it is a prognostic marker: very high LDH suggests greater tumour burden; falling LDH during treatment is reassuring, while rising LDH in remission may signal relapse.
LDH isoenzymes (LDH1-5) can sometimes identify which organ is involved.
Because it is so non-specific, LDH is always interpreted with the clinical context and other tests.

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.³ 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?

LDH vs troponin vs CK vs ALT at a glance: the compiled comparison

LDH lives in almost every tissue — which is both its use and its problem. Here is how it compares with more specific markers:

Feature	LDH	Troponin	CK	ALT
Main source	Nearly every tissue	Heart muscle	Muscle (heart + skeletal)	Liver cells
Specificity	Very low — a general damage flag	High for heart	Moderate	High for liver
Raised by exercise?	Yes	No (at rest)	Yes, markedly	Mildly
Raised by haemolysis?	Yes — red cells are full of it	No	No	No
Typical cost*	&rupee;300–&rupee;600	Priced per test; LDH is often cheapest inside a panel

*Approximate bands; prices vary by city and lab. LDH is reported in U/L.

LDH myths vs facts

LDH's non-specificity makes it a magnet for over-interpretation. Here is what the evidence actually says:

MYTH A high LDH is a cancer screening test.

Fact: It isn't — LDH rises in many cancers, but also in haemolysis, muscle injury, liver disease, infections and after exercise. It is used to monitor some known cancers (like lymphoma), not to screen healthy people.

MYTH Any raised LDH means something is seriously wrong.

Fact: Slight rises are common and often trivial — a difficult blood draw (haemolysis), recent exercise, even a delayed sample. The size of the rise and the context decide, not the flag alone.

MYTH You don't need to avoid exercise before LDH.

Fact: Strenuous exercise does raise LDH — avoiding hard workouts for a day or two before the draw avoids a confusing result. Mention recent exertion if the value surprises.

MYTH LDH pinpoints which organ is affected.

Fact: It can't — that is its defining limitation. Localising needs the specific markers (troponin, ALT, CK) and the clinical picture; LDH alone only says tissue damage happened somewhere.

What matters most with your LDH result

How high, and with what? A slight rise alone is usually noise; a large rise, or one with anaemia (haemolysis?) or muscle pain, is a signal. The company the number keeps decides.
Rule out the draw itself. A difficult venepuncture haemolyses red cells and floods the sample with LDH — if the draw was hard, say so; repeat testing may be all that's needed.
Declare the exercise. Recent strenuous workouts raise LDH for a day or two. The test should reflect your baseline, not your leg day.
It's a monitor, not a screen. LDH earns its keep following known conditions (lymphoma is the classic) — as a standalone screening test in healthy people it mostly generates worry. Discuss the full picture with your doctor.

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.

How much does the LDH test cost in India?

There is no single fixed price — it varies by city, lab, and whether the test is ordered alone or as part of a panel. NABL-accredited labs usually publish their rates online, so it is worth comparing a couple near you. Whatever you pay, the reference range printed on your own report is what counts — discuss the result with your doctor.

What is the full form of LDH?

LDH stands for lactate dehydrogenase.

What does a slightly high LDH mean?

Very often, nothing on its own. A mildly raised LDH with no symptoms and otherwise normal results is commonly due to the sample itself (red cells breaking during the draw) or recent strenuous exercise. Doctors look at the pattern with other tests before deciding whether it needs a repeat.

Can a difficult blood draw raise my LDH?

Yes — this is one of the classic causes of a falsely high LDH. When red blood cells break during a prolonged or difficult collection, their LDH spills into the sample. If your LDH is unexpectedly high, a clean repeat draw is often all it takes to settle the question.

Should I avoid exercise before an LDH test?

Heavy exercise in the 24–48 hours before the test can raise LDH from muscle turnover. You do not need to change your routine for weeks, but mention a hard workout at the time of the draw so it is factored into interpretation.

Is LDH a cancer screening test?

No. LDH is far too non-specific to screen for cancer — it rises with many benign conditions. It does have established roles in monitoring certain cancers during treatment, which is quite different from using it to look for cancer in a healthy person.

Pharmacist's practical notes

Haemolysis is LDH's great impersonator: red cells are packed with the enzyme, so a traumatic blood draw manufactures a high result from nothing. Before any workup, check how the draw went — a repeat clean sample resolves most mysterious mild elevations.

Several medicines can nudge LDH, but the commoner confounders are exercise and sample handling — both pre-analytical, both avoidable. And as a screening test LDH is a poor buy: its value is in monitoring known disease, where trends at the same lab actually mean something.

In India

Indian labs report LDH in U/L. The test typically costs &rupee;300–&rupee;600, though prices vary by city and lab — it is often cheapest when ordered as part of a panel rather than alone.

Where possible, choose a NABL-accredited lab. Sample handling matters more than usual for this enzyme — a clean draw and prompt processing count.

References

Sources cited on this page. PubMed links open the original abstract.

Drent M, Cobben NA, Henderson RF, Wouters EF, van Dieijen-Visser M. Usefulness of lactate dehydrogenase and its isoenzymes as indicators of lung damage or inflammation. Eur Respir J. 1996;9(8):1736–1742. PMID 8866602 · doi:10.1183/09031936.96.09081736
Khan AA, Allemailem KS, Alhumaydhi FA, Gowder SJT, Rahmani AH. The Biochemical and Clinical Perspectives of Lactate Dehydrogenase: An Enzyme of Active Metabolism. Endocr Metab Immune Disord Drug Targets. 2020;20(7):1007–1016. PMID 31886754 · doi:10.2174/1871530320666191230141110
Comandatore A, Franczak M, Smolenski RT, et al. Lactate Dehydrogenase and its clinical significance in pancreatic and thoracic cancers. Semin Cancer Biol. 2022;86(Pt 3):93–104. PMID 36096316 · doi:10.1016/j.semcancer.2022.09.001

Why LDH is elevated in so many conditions

Lactate dehydrogenase (LDH) is an intracellular enzyme found in virtually every tissue in the body, liver, heart, kidney, muscle, lung, and red blood cells. Its near-universal cellular distribution means that any condition causing cell death or damage, from any organ, can elevate serum LDH. This is why LDH is both a highly sensitive marker of tissue damage and a non-specific one: a high LDH raises the question "where is the tissue damage coming from?" rather than answering it.

LDH isoenzymes (LDH-1 through LDH-5) have organ-specific distributions, LDH-1 and LDH-2 are highest in the heart and red blood cells; LDH-5 is predominant in the liver and muscle. Isoenzyme patterns historically differentiated MI from liver damage, but cardiac troponin has replaced LDH for cardiac diagnosis. LDH isoenzyme testing retains a niche role in specific situations (neonatal haemolysis, confirming Duchenne muscular dystrophy origin of elevated LDH).

Clinical applications where LDH has diagnostic value

Haemolysis: When red blood cells rupture, LDH-1 and LDH-2 are released, often with high LDH (10–50× normal in severe haemolysis). LDH is one of the "haemolysis triad": raised LDH + raised bilirubin (from haemoglobin breakdown) + reduced haptoglobin (consumed by free haemoglobin). Together, these confirm intravascular or extravascular haemolysis.
Lymphoma and haematological malignancies: Tumour lysis (spontaneous or from chemotherapy) releases LDH from lymphoma cells. The pretreatment LDH level is an integral component of prognostic scoring systems, the International Prognostic Index (IPI) for diffuse large B-cell lymphoma includes LDH as one of five factors. A very high LDH (above twice normal) in a patient with lymphoma indicates high tumour burden and poor prognosis.
Tumour lysis syndrome (TLS): After chemotherapy for highly proliferative cancers (acute leukaemia, Burkitt lymphoma), massive tumour cell death releases intracellular contents: uric acid, potassium, phosphate, and LDH all rise dramatically. Cairo-Bishop criteria for TLS require LDH above twice the upper limit of normal.
COVID-19 and critical illness: LDH became a widely used severity marker in COVID-19, elevated LDH (above 300 IU/L) was associated with increased risk of mechanical ventilation and mortality. LDH similarly reflects severity in sepsis, ARDS, and other critical illnesses.
Testicular cancer monitoring: LDH is one of three tumour markers (alongside AFP and beta-hCG) used in the staging and monitoring of non-seminomatous germ cell tumours. Elevated LDH with normal AFP and beta-hCG occurs in seminoma.

Medical Disclaimer: This page is for general educational purposes only and does not constitute medical advice. Always consult a qualified doctor for diagnosis and treatment decisions.