A high lactate dehydrogenase (LDH) result does not identify one disease. LDH is present in many tissues, and a raised level can reflect several different processes. It can also rise because red blood cells broke down in the sample after it was collected. The useful next step is to check the laboratory comment, your symptoms and the rest of the results together.
For someone opening a private health-check report between meetings or after a trip, a red flag without an explanation is unsettling. A focused review should turn that flag into a proportionate plan: what needs attention now, whether the sample needs repeating, and which additional tests would actually answer the clinical question.
What does LDH measure?
LDH is an enzyme found in cells throughout the body, including blood cells, liver and muscle. When cells are damaged or their turnover increases, more LDH may appear in the blood. Because so many tissues contain it, LDH cannot reliably locate the source by itself.
The size of the rise matters, but there is no single number that diagnoses cancer, a blood disorder or a liver condition in every person. Laboratories use different methods and reference intervals. Bring the actual value, units and range rather than a screenshot showing only the word high.
Why does a haemolysed sample matter?
Red blood cells contain much more LDH than serum. If they break down during collection, transport or handling, the measured result may not represent what is happening in your body. Mayo Clinic Laboratories identifies LDH as particularly sensitive to this type of sample problem.
A report may say haemolysed, unsuitable or repeat required. That comment deserves attention before a long list of investigations is arranged. Your clinician may discuss a fresh sample with the laboratory. However, haemolysis within the body is a separate clinical problem, so the comment must be interpreted rather than used to dismiss symptoms.
Which other results help explain it?
A GP may review the full blood count, liver tests, kidney function and previous LDH results. If the history suggests increased red-cell breakdown, other tests may include bilirubin, reticulocytes and haptoglobin. These are selected for a reason, not added automatically to every panel.
The consultation should cover recent illness, injury, strenuous activity, medicines and established conditions. A stable small rise in a person who feels well is a different situation from a rapidly changing result with anaemia, jaundice or significant symptoms. A narrative laboratory review recommends starting with the clinical picture and targeted first-line investigations rather than treating LDH as a general screening answer.
Does high LDH mean cancer?
No. Some cancers can raise LDH, but so can many non-cancer conditions and sample problems. The result is neither a stand-alone cancer test nor a reliable way to rule cancer out. Searching an isolated LDH value often produces alarming possibilities without showing how likely they are in your circumstances.
Persistent unexplained abnormalities may need further assessment or referral. The decision should rest on your history, examination, trend and accompanying findings. Ordering repeated broad cancer panels without that context can create more uncertainty rather than a clear answer.
When should I seek urgent care?
Do not wait for a routine results appointment if you have severe chest pain, severe breathlessness, collapse or stroke-like symptoms: call 999. Rapidly worsening illness, marked jaundice or significant new weakness needs prompt clinical advice. Follow any urgent instruction already given by the laboratory or treating team.
LDH is not the modern test used to diagnose a heart attack. Mayo's laboratory guidance notes that troponin has replaced it for that purpose. Equally, an LDH result should not be used at home to decide whether chest pain or breathlessness is safe.
Arrange a focused results review
What should a good private review include?
Bring the complete report, previous results, your medicine and supplement list, and the reason the test was requested. Note any recent infection, unusual exertion or difficult blood draw. If you had a broad executive screening panel, ask which abnormal results change management and which need only confirmation.
The value is a joined-up explanation and a written next step, not the largest possible repeat panel. Ask who will review a repeat result, what change would trigger further investigation and how you will receive the outcome. A reassuring conversation is most useful when responsibility for follow-through is clear.
Can I lower LDH with a supplement?
There is no universal supplement treatment for a high LDH result. Management depends on the cause, if a cause is found. Do not stop prescribed medicines or start an intensive supplement programme based on this number alone. Discuss potential medicine effects with the prescribing clinician.
Arrange a results review in London
The Online GP can help you discuss an unexplained result and plan the appropriate next assessment. Share your report through the team's agreed secure route when requested; the initial enquiry can simply say that you would like a review of raised LDH.
Ask the team about a GP appointment
Evidence and further reading
Mayo Clinic Laboratories: LDH interpretation and sample cautions
Journal of Laboratory and Precision Medicine: investigating LDH abnormalities
Reviewed for publication: 3 November 2026. General information, not a diagnosis or a substitute for individual medical advice. Appointment route, suitability and complete fees are confirmed for your enquiry.