Serum Lactate Dehydrogenase Levels Test

Serum Lactate Dehydrogenase (LDH) Activity

LDH is an intracellular enzyme present in nearly all body tissues, with its elevation indicating cell damage or death. It exists in five different isoenzymes (LDH1-LDH5), each predominant in different tissues.

Key Points:

Marker of tissue damage and cell death
Five distinct isoenzymes with tissue specificity
Important prognostic marker in various conditions
Useful for disease monitoring and treatment response
Critical in oncology and tissue injury assessment

Clinical Utility and Applications

Primary Indications:

Oncologic conditions
- Lymphomas
- Leukemias
- Neuroblastoma
- Wilms tumor
Tissue injury assessment
- Myocardial injury
- Liver disease
- Muscle disorders
- Hemolysis

Monitoring Applications:

Treatment response in malignancies
Disease progression
Prognostic assessment
Therapy effectiveness
Recovery monitoring

Sample Collection and Processing

Collection Requirements:

Serum separator tube (SST)
Minimum volume: 0.5 mL
Avoid hemolysis
Process within 4 hours
Patient should be resting

Pre-analytical Factors:

Physical activity affects levels
Diurnal variation present
Age-dependent variations
Hemolysis interference
Storage temperature critical

Sample Stability:

Room temperature: 4 hours
Refrigerated (2-8°C): 48 hours
Frozen (-20°C): 6 weeks

Age-Specific Reference Values

Pediatric Reference Ranges:

Newborns (0-3 days): 290-2000 U/L

Infants (4-30 days): 240-900 U/L

Children (1-12 months): 180-430 U/L

Children (1-9 years): 150-380 U/L

Children (10-18 years): 120-330 U/L

Isoenzyme Distribution:

LDH-1: Heart and red blood cells
LDH-2: Reticuloendothelial system
LDH-3: Lungs
LDH-4: Kidneys and pancreas
LDH-5: Liver and skeletal muscle

Result Interpretation and Clinical Correlation

Elevation Patterns:

Mild elevation (1-2x normal)
- Viral infections
- Mild tissue injury
- Exercise
Moderate elevation (2-4x normal)
- Myocarditis
- Pneumonia
- Hepatitis
Severe elevation (>4x normal)
- Malignancies
- Severe tissue damage
- Shock

Monitoring Guidelines:

Serial measurements more valuable
Consider trend patterns
Correlate with other markers
Account for age-specific ranges

Disease-Specific Associations

Oncologic Conditions:

Lymphomas
- Prognostic indicator
- Treatment response marker
- Disease progression monitor
Solid Tumors
- Neuroblastoma staging
- Wilms tumor monitoring
- Germ cell tumors

Non-Oncologic Conditions:

Cardiac Disorders
- Myocarditis
- Cardiomyopathy
Liver Disease
- Viral hepatitis
- Drug-induced injury
Muscle Disorders
- Muscular dystrophy
- Myositis
- Rhabdomyolysis