Introduction
When you have a blood test and notice the word LDH on your report, it's reasonable to be curious about what it represents, particularly if your levels are higher or lower than normal. LDH is an abbreviation for Lactate Dehydrogenase, and it's a significant enzyme found in numerous tissues all around your body — including your heart, liver, kidneys, muscle, lungs, and red blood cells.
LDH test is usually employed to identify tissue damage, track disease progression, or identify certain medical conditions. Knowing about the LDH test normal range and your results can make you more aware about your health.
LDH blood test measures how much lactate dehydrogenase is in your blood. LDH enters the blood when cells are broken down or destroyed. So, high levels of LDH typically indicate that some kind of tissue damage has been done.
The test is frequently ordered when doctors wish to:
So what is a normal LDH level?
A normal range for LDH can differ slightly between laboratories. But generally, most laboratories use the following as a normal range:
140 to 280 units per liter (U/L)
For other labs, the normal range will be between 100 and 190 U/L or even 105 and 333 U/L based on the method they use to test.
Because levels of LDH naturally differ between people and even slightly according to age or sex, be sure to compare your test result with the reference range on your own test report. And values in children and infants are usually higher than in grown-ups.
LDH is not specific to any single organ or disease but rather serves as a general indicator of cell damage within the body. This is why LDH tests tend to be used in conjunction with other blood tests and clinical data to determine what's happening.
When there is an elevation of LDH, it typically indicates that tissues or organs have been inflamed or damaged. If LDH is abnormally low, and this is not common, it may not be of much clinical value unless accompanied by other signs.
LDH can also be divided into five isoenzymes (LDH-1 to LDH-5) to identify what area of the body is involved:
Your LDH test results will be reported as either:
If your LDH is within the normal range, it indicates there's no clear tissue damage, hemolysis (red blood cell destruction), or inflammation at the time of testing. Normal LDH, however, doesn't necessarily eliminate disease — certain diseases won't reveal elevated LDH levels immediately.
That's why physicians consider LDH levels in combination with symptoms, physical exams, and other blood or imaging studies.
If your LDH level is elevated, it generally indicates some form of cell or tissue injury. Frequent causes are:
Physicians can recommend LDH isoenzyme tests if they prefer to limit the source of increased LDH. For instance, if LDH-1 is increased, it can be indicative of heart or red blood cell disorders, while raised LDH-5 can imply liver or muscle injury.
Decreased LDH is uncommon and not typically concerning. Still, in very specific situations, it might have something to do with:
Low LDH levels most commonly do not have clinical importance unless part of other abnormal results.
There are a few factors that may interfere with your LDH test results. These include:
Always tell your doctor about your current medical conditions, recent surgery, and any medications that you are currently taking to enable them to interpret your test correctly.
The LDH blood test is a straightforward test. A healthcare provider will take a small sample of blood, typically from a vein in your arm. The sample is then analyzed in a lab.
You usually don't have to fast or prepare in any way unless other tests are ordered at the same time by your doctor.
Results are normally ready within a day or two, depending on the lab.
If your test indicates elevated LDH levels, your physician will probably:
Treatment will depend on the cause. For example:
So, instead of only concentrating on the number of LDH, your physician considers the larger picture.
LDH is not included in routine health check-ups unless your physician has reason to believe there is tissue damage or is tracking a particular condition. In patients with established conditions such as cancer or chronic liver disease, LDH will be measured more often to monitor disease activity or response to therapy.