LDH Levels Explained: Normal Range, Causes of High and Low LDH

Understanding LDH levels is crucial for interpreting various health conditions. LDH, or lactate dehydrogenase, is an enzyme found in nearly every cell of your body. It plays a vital role in energy production, but its levels in the blood can provide critical insights into tissue health and possible diseases.

What is LDH?

Lactate dehydrogenase (LDH) is an enzyme that plays a role in cellular energy production. Specifically, it helps convert sugar into energy, something your cells require to function. Because LDH is present in most body tissues—including the heart, liver, lungs, muscles, kidneys, and even red blood cells—we can learn a lot by analysing its levels in the blood.

When tissues are damaged or cells die, LDH is released into the bloodstream. This makes LDH a general marker for tissue damage or organ injury, though it is not specific to one condition. Health professionals often use LDH levels, alongside other tests, to help diagnose and monitor diseases.

Understanding Normal LDH Levels

LDH levels are measured through a blood test or sometimes a fluid test (for example, in the case of pleural or cerebrospinal fluids). The normal range for LDH can vary depending on the individual, their age, and the lab performing the test. These levels typically fall within these ranges for adults:

Normal LDH Range (Serum or Plasma)

140 to 280 units per liter (U/L)

It’s important to remember that "normal" levels can vary between labs based on their methods of analysis, so always consult your healthcare provider about your specific results.

Causes of High LDH Levels

High LDH levels often signal tissue damage or an underlying health issue. Below are some of the most common conditions and factors that can elevate LDH levels.

1. Tissue or Cell Damage

LDH is commonly elevated in response to damage to tissues or cells. Injuries, infections, and diseases that destroy cells cause LDH to leak into the blood.

Examples include:

Heart Attack – Following a heart attack, damaged cardiac cells release LDH into the bloodstream.
Liver Disease – Conditions like hepatitis or cirrhosis can increase LDH levels due to liver cell damage.
Muscle Injuries – Strains, tears, or conditions like rhabdomyolysis may increase LDH.

2. Cancer

Elevated LDH may signal certain cancers, including lymphoma, leukemia, or metastatic cancers. High LDH can indicate advanced stages of cancer or active tumor growth, as cancerous cells die and release LDH.

3. Hemolysis (Destruction of Red Blood Cells)

Conditions that break down red blood cells, such as hemolytic anemia, can elevate LDH levels.

4. Severe Infection

Systemic infections, such as sepsis or meningitis, can damage tissues and elevate LDH as the body battles the infection.

5. Lung or Respiratory Issues

LDH levels can also increase due to damage from conditions like pneumonia, pulmonary embolisms, or chronic obstructive pulmonary disease (COPD).

6. Other Causes

Other potential causes include pancreatitis, kidney disease, and autoimmune disorders like lupus. Certain medications can also affect LDH levels, so it’s important to include your medication history when interpreting results.

Causes of Low LDH Levels

While less common, LDH levels can also fall below the normal range. Low LDH levels are usually not considered a significant health issue on their own but may provide additional insights when combined with other tests.

Potential Causes of Low LDH Levels:

Excess Vitamin C Intake: Large doses of vitamin C supplementation can sometimes lower LDH levels.
Advanced Cancer Treatment: Chemotherapy drugs may suppress LDH production in rare cases.
Inherited Conditions: A rare genetic mutation known as LDH deficiency can result in consistently low levels.

Low LDH levels rarely signal a clinical concern. However, unusual results should always be assessed in the broader context of your overall health.

Why Your Doctor Might Order an LDH Test

Medical professionals use LDH levels when they suspect tissue damage, organ injury, or other underlying conditions. Here are some common situations where an LDH test might be used:

Monitoring Progress: Following recovery from tissue damage, healthcare providers use LDH levels to ensure healing is progressing as expected.
Diagnosing a Condition: LDH levels might form part of a diagnostic workup when unexplained symptoms are present, such as fatigue, swelling, or pain.
Assessing Chronic Diseases: Conditions like liver or kidney disease are often monitored using LDH as one metric of organ function.
Fluid Analysis: If a doctor is analyzing specific fluids (e.g., cerebrospinal fluid or pleural fluid), LDH testing can help determine the cause of abnormalities, including infections or malignancies.

What to Do if Your LDH Levels Are Abnormal

An abnormal LDH level is typically a sign that further investigation is needed. Here are some steps you might take if your LDH levels fall outside the normal range:

1. Consult Your Healthcare Provider

Your doctor will interpret your LDH results in the context of other tests and your symptoms. Never self-diagnose based on LDH levels alone.

2. Follow-Up Testing

Additional testing might be recommended to pinpoint the cause of abnormal LDH levels. This may include imaging, more specific bloodwork, or other diagnostic tools.

3. Lifestyle Adjustments

Sometimes, abnormal LDH levels can be tied to lifestyle factors such as alcohol consumption, high physical stress, or medication side effects. Simple lifestyle changes may help bring levels back to normal.

4. Treatment of Underlying Conditions

If an underlying condition is detected, addressing it directly typically normalizes LDH levels. For instance, treating anemia, managing infections, or controlling chronic diseases will generally stabilize LDH levels.

Conclusion

Understanding LDH levels is an essential piece of the diagnostic puzzle. While an LDH test cannot independently diagnose a condition, it offers valuable clues about your overall tissue health and organ function.

If your LDH levels are abnormal, don’t panic. Work with your healthcare provider to determine the underlying cause and create a plan moving forward. With appropriate testing, contextual insights, and proper care, LDH levels can aid in achieving better health outcomes.