LDH Test Normal Range: What Your Results Mean

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.

What is the LDH Test?

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:

• Determine the reason for unexplained pain or inflammation
• Follow ongoing conditions such as cancer, liver disease, or hemolytic anemia
• Assess for heart or lung injury
• Monitor treatment performance in some diseases

LDH Normal Value in Blood

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.

Why Do LDH Levels Matter?

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:

1. LDH-1: Primarily located in the heart and red blood cells
2. LDH-2: In white blood cells
3. LDH-3: In the lungs
4. LDH-4: In the kidneys, pancreas
5. LDH-5: In the liver and muscles

LDH Test Interpretation: What Do Results Mean?

Your LDH test results will be reported as either:

• Normal LDH levels
• High LDH levels
• Low LDH levels

Here's what each could mean.

1. Normal LDH Levels

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.

2. Elevated LDH Levels

If your LDH level is elevated, it generally indicates some form of cell or tissue injury. Frequent causes are:

• Heart Attack (Myocardial Infarction): Abnormal heart muscle cells spill LDH into the blood.
• Liver Disease: Such conditions as hepatitis, liver failure, or cirrhosis can elevate LDH.
• Hemolytic Anemia: Red cell breakdown rapidly raises LDH.
• Muscle Injury or Disease: Any injury or muscular disease can raise LDH.
• Specific Infections: Bacterial or viral infections can lead to inflammation and damage.
• Lung Diseases: LDH can increase in pneumonia, lung cancer, or pulmonary embolism.
• Cancer: LDH usually increases in solid tumors, leukemia, and lymphomas.
• Pancreatitis and Kidney Disorders: These too can increase LDH.
• Sepsis: Life-threatening body-wide infections can increase LDH to a great extent.

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.

3. Decreased LDH Levels

Decreased LDH is uncommon and not typically concerning. Still, in very specific situations, it might have something to do with:

• Genetic enzyme deficiency (extremely rare)
• Dietary excessive intake of Vitamin C
• Laboratory error or sample degradation

Low LDH levels most commonly do not have clinical importance unless part of other abnormal results.

What can Affect LDH Test Results?

There are a few factors that may interfere with your LDH test results. These include:

• Hemolysis during sample collection: If red blood cells are ruptured during blood collection, it will artifactually elevate LDH.
• Strenuous exercise: Severe exercise can transiently increase LDH levels due to muscle stress.
• Medications: Certain medications such as aspirin, narcotics, anesthetics, and alcohol may influence LDH results.
• Recent injury or surgery: Healing tissue can release LDH, even if you are doing well.

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. 

How Is the LDH Test Performed?

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.

What If My LDH Levels Are Elevated?

If your test indicates elevated LDH levels, your physician will probably:

• Consult your symptoms and medical history
• Examine other blood test values including liver enzymes, CBC, creatinine, and inflammatory markers
• Probably perform imaging tests such as ultrasound, CT scan, or MRI
• Prescribe LDH isoenzyme testing if tissue damage source is unknown

Treatment will depend on the cause. For example:

• Infections can be treated with antivirals or antibiotics.
• Liver issues can require lifestyle modifications or drugs.
• Cancer LDH changes are utilized to track disease development or the reaction to treatment.

So, instead of only concentrating on the number of LDH, your physician considers the larger picture. 

How Often Should LDH Be Tested?

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.

Key Takeaways on LDH Test and Normal Range

• LDH (Lactate Dehydrogenase) is an enzyme that is released in injured tissues.
• The typical LDH value in most adults is around 140 to 280 U/L but can vary a little from laboratory to laboratory.
• Elevated LDH levels are most often a sign of tissue damage, inflammation, or illness such as anemia, liver disease, cancer, or infection.
• Low LDH levels are rare and rarely significant.
• LDH testing is employed in combination with other tests to diagnose or track different diseases.
• Always have a doctor interpret it — LDH levels are only one part of the diagnostic puzzle.