Lactate Dehydrogenase

Lactate dehydrogenase (LDH) – role in the body

LDH is a key enzymeEnzymes are proteins that accelerate chemical reactions in the body. They ensure the occurrence of metabolic processes such as food digestion, energy release, cell formation, and many others. involved in the energy metabolism of cells. It catalyzes the conversion of lactate to pyruvate (and vice versa) during glycolysis.

Main functions of LDH:

1. Providing oxygen-free (anaerobic) glucose metabolism
2. Maintaining energy balance in hypoxic conditions
3. Participation in muscle work (especially during intense exercise)
4. Indicator of cellular damage (LDH is released into the blood when cells are destroyed)

LDH isoenzymes and their localization:

• LDH-1, LDH-2: heart, red blood cells, kidneys
• LDH-3: lungs, lymph nodes, platelets
• LDH-4, LDH-5: Liver, skeletal muscle

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LDH norm in the blood test

Age Group	Normal LDH (U/L)
Adults	125-220
Newborns	220-600
Children under 2 years	115-450
Children 2-12 years	115-300
Adolescents	100-290

Reference values (may vary from laboratory to laboratory):

Note: Athletes may have higher-than-average LDH levels.

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Symptoms of excessive LDH (elevated levels)

An increase in LDH indicates massive cell destruction:

1. In case of heart damage (myocardial infarction):

• Severe retrosternal pain
• Shortness of breath
• Cold sweat

1. For liver diseases:

• Nausea, weakness
• Jaundice
• Heaviness in the right hypochondrium

1. With hemolytic anemia:

• Paleness
• Weakness
• Yellowness

1. In case of lung damage:

• Shortness of breath
• Cough
• Hemoptysis (with PE)

1. For muscle injuries:

• Muscle aches
• Weakness
• Puffiness

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LDH deficiency (reduced level)

It is extremely rare. May be related to:

• Genetic disorders
• Taking vitamin C in large doses
• Uremia (in CRF)

Symptoms:

• Rapid fatigue
• Muscle weakness
• Physical activity intolerance

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Reasons for changing LDH levels

Increase (main reasons):

1. Myocardial infarction (LDH-1)
2. Hemolytic anemia
3. Liver diseases (hepatitis, cirrhosis)
4. Muscle injuries
5. Malignant neoplasms
6. Pulmonary embolism
7. Shock states
8. Megaloblastic anemia

Downgrade:

1. Genetic defects
2. Excess vitamin C
3. Uremia

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Diagnostic value of LDH isoenzymes

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What should I do in case of LDH deviations?

With increased LDH:

1. Determine the isoenzyme composition
2. Perform additional diagnostics:

• ECG, troponins (if a heart attack is suspected)
• Ultrasound of the liver, liver tests
• General blood test (exclude anemia)
• Creatine Kinase (for muscle damage)

With low LDH:
It usually doesn’t require treatment, but it’s worth it:

• Exclude genetic pathologies
• Adjust your vitamin C intake

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Conclusions

• LDH is a marker of cellular damage
• Norm: 125-220 U/l for adults
• An increase indicates a heart attack, anemia, hepatitis, or muscle injury.
• Downgrades are rare and usually not significant
• Determination of isoenzymes helps to clarify the localization of damage