Lactate Dehydrogenase (LDH)
LDH is an enzyme found in many body tissues. Elevated levels can indicate tissue damage from various causes including heart attack, liver disease, haemolytic anaemia, or certain cancers.
- DHA-licensed lab
- Includes Doctor Consultation
- Physician-reviewed
- Same Day Collection
24 hours
Turnaround
Blood
Sample
What the Lactate Dehydrogenase (LDH) test tells you
Lactate dehydrogenase is an enzyme that sits inside almost every cell in the body, where it converts pyruvate to lactate and back again as cells generate energy. Because it works inside cells rather than in the bloodstream, only a small amount is normally found in blood. When cells are injured and their membranes break down, LDH spills into the circulation. That is the whole basis of the test: it is a general signal that cells somewhere have been damaged or are turning over rapidly.
Different tissues contain slightly different forms of the enzyme, with particular isoenzymes predominating in the heart and red cells, in the liver and skeletal muscle, and in the lungs. Laboratories rarely separate these forms today, so the total value is what is reported and it is interpreted alongside the clinical picture and more specific tests. Its usefulness comes from being read in context: with reticulocytes, bilirubin and haptoglobin it supports the assessment of red cell breakdown; with liver enzymes it fits a pattern of liver injury; with muscle enzymes it fits muscle damage.
Today LDH is used mainly for monitoring rather than diagnosis. It helps follow haemolytic conditions, contributes to prognosis and treatment monitoring in lymphoma and germ-cell tumours, and adds a measure of severity in some acute illnesses. It has largely been retired from the assessment of heart attacks, where troponin is far more specific. LDH is also notorious for artefactual elevation, because red cells are packed with the enzyme: a difficult blood draw or a delay before the sample is separated releases LDH into the specimen and raises the reported value without anything having happened in the body.
Used as a general marker of tissue damage, monitoring treatment response in lymphoma, evaluating haemolytic anaemia, and assessing liver injury.
- General tissue-damage signal
A raised value tells your doctor that cells somewhere are being damaged or replaced rapidly, which directs where to look next.
- Monitoring red cell breakdown
In haemolytic conditions LDH rises as red cells rupture, and it is followed alongside reticulocytes and bilirubin to track activity.
- Following lymphoma and related tumours
It reflects tumour bulk and cell turnover, so it is used for prognosis and to monitor response during treatment.
- Adding severity context
In several acute illnesses a markedly raised LDH indicates more extensive tissue involvement and helps gauge how unwell someone is.
Reasons your doctor may request the Lactate Dehydrogenase (LDH) test
Your doctor may order this test for any of the reasons below. Some are routine checks, others follow specific symptoms or an earlier result.
Anaemia, liver & muscle
- Suspected haemolytic anaemia or unexplained anaemia with jaundice.
- Investigation of abnormal liver enzymes or unexplained muscle symptoms.
- Investigating an unexplained raised value found on a previous panel.
Cancer staging & follow-up
- Staging and monitoring of lymphoma or germ-cell tumours.
- Follow-up of known tissue injury to see whether it is resolving.
Severity in acute illness
- Assessment of severity in an acute illness alongside other markers.
LDH, reported in U/L, sits inside almost every cell and leaks into the blood when cells are injured or are turning over quickly. A result in the Normal band is reassuring in context, though a small area of injury may not release enough enzyme to move the total. A High result signals that cells somewhere have been damaged, but it localises nothing on its own. Red cell breakdown, liver injury, muscle damage from trauma, seizures or intense exercise, infarction of tissue, severe infection and some cancers all raise it. Sample handling matters as much as biology here: red cells are packed with the enzyme, so a difficult draw or a delay before the sample is separated lifts the reported value without anything having happened in the body. Values below the usual range carry no established significance. Your doctor reads it with more specific tests and your clinical picture.
Medically reviewed by Dr Nirupama Sabhapathy
Ranges are a guide: your physician interprets your result alongside your symptoms and history.
What a higher result can point to
- Breakdown of red cells, whether inside the body or within the sample tube after collection.
- Liver disease, including hepatitis, congestion and drug-induced injury.
- Muscle injury from trauma, intense exercise, seizures or inflammatory muscle disease.
- Lymphoma, leukaemia, germ-cell tumours and other extensive malignancy.
- Infarction of tissue, such as heart, lung, kidney or bowel.
- Severe infection, pancreatitis, or anaemia caused by vitamin B12 or folate deficiency.
These are possibilities, not diagnoses. A single value outside the reference range is interpreted alongside your symptoms, history and other tests: your doctor decides what it means for you.
What this test cannot tell you
- LDH is present in almost every tissue, so it is highly sensitive but very non-specific: a raised value localises nothing on its own.
- Red cells are rich in the enzyme, so haemolysis during a difficult draw or a delay before the sample is separated falsely raises the result.
- An unremarkable LDH does not exclude significant disease, since localised damage may not release enough enzyme to move the total.
- Total LDH cannot identify which tissue is involved, and isoenzyme separation is rarely performed in routine practice.
Risks of the blood draw
- Mild bruising or brief soreness where the needle went in.
- Occasional lightheadedness, which settles after a few minutes of rest.
- Bleeding or infection at the site, which is rare with sterile single-use equipment.
- 1LDH is found inside nearly all cells and leaks into blood when they are damaged.
- 2It is a sensitive but non-specific marker, so it is always read with the clinical picture and more targeted tests.
- 3Sample handling matters: a difficult draw or delayed processing can raise the result artificially.
- 4It has been replaced by troponin for assessing heart attacks and is now used mainly for monitoring.
- 5Low values carry no established clinical significance, so only raised results are acted upon.
Lactate Dehydrogenase (LDH) also comes in these focused packages, which pair it with the tests usually read alongside it.
- BiochemistryAspartate Aminotransferase (AST/SGOT)
AST is an enzyme found in the liver, heart, and muscles. Elevated levels may signal liver disease, heart problems, or muscle injury. It is often…
15View - HaematologyComplete Blood Count (CBC)
The CBC is the most commonly ordered blood test. It measures red blood cells, white blood cells, haemoglobin, haematocrit, and platelets to assess…
35View - HaematologyReticulocyte Count
Reticulocytes are immature red blood cells freshly released from bone marrow. This count reflects how actively your bone marrow is producing red…
25View - BiochemistryBilirubin, Indirect (Unconjugated)
Indirect bilirubin is the unconjugated form that has not yet been processed by the liver. Elevated levels often indicate excessive red blood cell…
15View
Frequently Asked Questions
Everything you need to know about the Lactate Dehydrogenase (LDH) test. Can't find what you're looking for?
Talk to our team→Our laboratory reports 140 to 280 U/L as normal for LDH, and 281 to 600 U/L as high, a non-specific marker of tissue stress. A normal result is reassuring in context, although a small area of injury may not release enough enzyme to move the total. A high result needs more specific tests to show where it comes from.
A high LDH signals that cells somewhere in the body have been damaged or are turning over quickly, but it does not say where. Red cell breakdown, liver injury, muscle damage from trauma, seizures or intense exercise, tissue infarction, severe infection, pancreatitis and some cancers all raise it. Your doctor uses more targeted tests and your symptoms to find the source.
LDH rises when cells are turning over quickly, so in lymphoma and some other cancers it reflects how active the disease is. It is used mainly to monitor treatment response: a falling value over successive tests supports a response. It does not diagnose lymphoma, and a raised LDH on its own is far more often due to other causes.
Red cells are packed with LDH, so when they break down inside the body the level in the blood rises. In someone with anaemia, a raised LDH can support red cell destruction as the cause, and it is also raised in anaemia from vitamin B12 or folate deficiency. Your doctor reads it with the blood count and other markers of red cell breakdown.
No. Values below the usual range carry no established clinical significance, so only raised results are acted upon. A low LDH does not need further investigation on its own, and your doctor will focus instead on any other results or symptoms that prompted the test.
The two most common explanations in a well person are recent vigorous exercise and a technical problem with the sample, where red cells break during collection and release the enzyme. Your doctor will usually repeat it before investigating further.
No. It is one of the least specific tests in common use, and infection, exercise, liver problems, muscle injury and red cell breakdown all raise it. It is a prompt to look further in the light of your symptoms, not a finding that stands alone.
Red blood cells contain far more LDH than plasma does, so if some rupture during or after the draw, the enzyme leaks into the sample. The reported value then describes the specimen rather than you, which is why a repeat is sometimes requested.
Troponin is released almost exclusively by heart muscle and rises early and reliably, so it answers the question far more precisely. LDH rises with damage to many tissues and could never localise the injury on its own.
No fasting is required for LDH, though it is often taken with other blood work that does, so follow the instruction you are given. Avoid strenuous exercise, contact sport or unaccustomed heavy lifting in the day or two before the sample, since muscle activity releases LDH.
The LDH test is AED 20, including a physician-reviewed report, with results usually within 24 hours. Home collection anywhere in Dubai is free when your order reaches AED 300 or includes a package; below that, a AED 100 home collection fee applies (AED 50 for a lab walk-in).