LDH test

LDH (lactate dehydrogenase) is an enzyme found in almost every cell in the body, and this blood test measures how much of it is circulating. Higher-than-usual levels suggest cell damage or turnover somewhere in the body, though LDH alone doesn't point to a specific cause.

It's often used alongside other tests when investigating tissue damage, anaemia, liver or muscle conditions, or as part of monitoring for certain cancers and their response to treatment. It's rarely ordered on its own because it's a general marker rather than a specific diagnostic tool.

Usually no special preparation is needed, though your clinician may ask you to avoid strenuous exercise beforehand, as this can temporarily raise LDH. Always mention any recent injuries, infections, or medications when booking, as these can affect results.

It's a simple blood draw from a vein in your arm, typically taking only a few minutes. There's no sedation or special equipment involved, and most people can return to normal activities straight away.

You may feel a brief pinch or scratch as the needle goes in, similar to any standard blood test, followed by mild pressure while a small dressing is applied. Any discomfort is usually gone within minutes.

Results are often available within a few days for private testing, sometimes sooner depending on the laboratory. Your clinician will discuss the findings with you rather than leaving you to interpret a number alone.

Raised LDH can reflect anything from recent exercise or minor infection to liver disease, blood disorders, or, less commonly, more serious conditions, so it needs to be read alongside your symptoms and other test results. If your level is outside the expected range, your doctor will usually suggest further, more targeted tests rather than jumping to conclusions.

LDH can be requested on the NHS, but access often depends on symptoms and can involve a wait for a routine appointment and results review. Private testing is typically available within days, with your results reviewed by a doctor; cost varies by provider.

The laboratory measurement itself is well established and reliable, but LDH is a non-specific marker, meaning many different conditions can raise it. This is why it's almost always interpreted together with your history and other test results rather than in isolation.

You can book directly online or by phone, often with appointments available within a day or two. A specialist will review your results with you and advise on any follow-up that might be useful.