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LDH is an enzyme that helps your cells make energy. A high level may point to tissue damage, and a low level is rare and usually not a health problem.[1]
On this page you can read what LDH is, what the guidelines say about a level that is too low or too high, what affects your level and which values are best to look at alongside it.
Also known as: LD test, lactate dehydrogenase, lactic acid dehydrogenase. At the lab: LDH.
LDH stands for lactate dehydrogenase. It is an enzyme: a protein that speeds up certain chemical reactions in your body. LDH helps your cells make energy.[1]
LDH is found in almost all of your tissues. The largest amounts are in your muscles, your liver, your kidneys and your red blood cells. It is normal to have some LDH in your blood.[1]
The lab usually measures LDH in your blood. Sometimes LDH is measured in other body fluids, such as the fluid around your brain and spinal cord, in your abdomen or in your chest.[1]
When tissue containing LDH is damaged, the cells release the enzyme into your blood. That is why the test is mainly used to check whether tissue has been damaged somewhere.[1]
A doctor can use LDH when looking into blood conditions, such as anaemia. The test can also help with conditions of the liver, the lungs, the kidneys, the heart, the pancreas, or the brain and spinal cord.[1]
The test also helps to monitor conditions that can slowly get worse. And it shows how a value changes over the course of care.[1]
LDH alone does not show what is damaging the tissue or where. That is why the test is usually done together with other tests. If your level is high, your doctor may order an LDH isoenzyme test, which measures five forms of LDH.[1]
Labplusarts, the lab BioProfile works with, uses a reference range of 0 to 247 u/l for LDH. The lab calls a level between those limits normal.[2]
| Value | What the lab says | Who it is for |
|---|---|---|
| 0 to 247 u/l[2] | Normal according to the lab | Results from this lab |
Source: Labplusarts, the laboratory BioProfile works with; applies to this lab's LDH test.[2]
A level that is too low is rare and is usually not seen as a health problem. A lot of vitamin C or vitamin E can give a low level. A low level can also point to a rare inherited condition in which your body makes too little LDH.[1]
A higher level than normal may point to tissue damage, usually from a condition or from an injury caused from outside the body. But a high level does not always mean there is something that needs care. Hard exercise, some medicines such as aspirin, and a sample in which a lot of red blood cells broke open can also raise the level. Your doctor may order more tests.[1]
BioProfile is working on its own zones for each value, from risk to optimal. A doctor reviews those zones before they appear in your result.
Heavy exercise can raise your LDH level.[1]
Some medicines, including aspirin, can raise your level.[1]
Large amounts of vitamin C or vitamin E can give a low level.[1]
If a lot of red blood cells break open while your blood is being taken or tested, your level may come out higher. You do not need to prepare in any special way for the blood test.[1]
LDH is included in BioProfile 87, 121 and 150.[3]
The BioProfile editorial team wrote this page on 10 October 2026 from the sources below, which we read on 10 October 2026. Every number on this page appears in one of those sources, with that source's number next to it. An expert has yet to check this page; after that check, the expert's name and the date of the check will appear at the top. This page offers explanation, not a diagnosis. Discuss a value outside the range with your GP.
