Liver Function Tests in Pediatric Patients
Liver Function Tests in Pediatric Patients
Overview
Liver function tests (LFTs) are a group of blood tests that provide valuable information about the health and function of the liver in pediatric patients. These tests evaluate various enzymes, proteins, and other substances produced or processed by the liver, allowing for the detection and monitoring of liver injury or dysfunction.
Key Points
- Assesses liver's synthetic, excretory, and metabolic functions
- Helpful in diagnosing and managing a wide range of liver disorders
- Useful for monitoring treatment response and disease progression
- Interpretation requires consideration of age-specific reference ranges
- Part of a comprehensive evaluation, not a standalone diagnostic test
Clinical Indications
Common Indications for LFT Evaluation:
- Suspected Liver Disease:
- Jaundice, hepatomegaly, or abnormal liver palpation
- Elevated liver enzymes on routine screening
- Neonatal cholestasis or persistent hyperbilirubinemia
- Chronic liver diseases (e.g., viral hepatitis, cirrhosis)
- Monitoring Known Liver Conditions:
- Ongoing management of chronic liver disease
- Assessment of treatment response or disease progression
- Evaluation of medication-induced liver injury
- Suspected Systemic Conditions:
- Metabolic disorders (e.g., fatty liver disease, Wilson's disease)
- Infiltrative diseases (e.g., malignancies, granulomatous diseases)
- Autoimmune disorders (e.g., autoimmune hepatitis)
Common Liver Function Test Components
Enzymes:
- Alanine Aminotransferase (ALT): Marker of hepatocellular injury
- Aspartate Aminotransferase (AST): Less specific marker of liver injury
- Alkaline Phosphatase (ALP): Indicator of cholestasis or bone disease
- Gamma-Glutamyl Transferase (GGT): Sensitive marker of biliary tract disease
Proteins:
- Total Bilirubin: Measures both conjugated and unconjugated bilirubin
- Albumin: Reflects liver's synthetic function
- Prothrombin Time (PT) / International Normalized Ratio (INR): Assesses clotting factor synthesis
Other Tests:
- Hepatitis Viral Serologies: Identify viral hepatitis infections
- Autoantibody Panel: Helps diagnose autoimmune liver diseases
- Alpha-Fetoprotein: Tumor marker for hepatocellular carcinoma
Result Interpretation
Patterns of Liver Injury:
- Hepatocellular Injury:
- Marked elevation in ALT and AST
- May be accompanied by hyperbilirubinemia
- Suggestive of viral hepatitis, drug-induced liver injury, etc.
- Cholestatic Injury:
- Predominant elevation in ALP and GGT
- May have mild-to-moderate bilirubin increase
- Indicative of biliary obstruction or duct disease
- Mixed Pattern:
- Elevation in both hepatocellular and cholestatic markers
- Seen in conditions like primary biliary cholangitis
Interpretation Considerations:
- Age-appropriate reference ranges for children
- Clinical context and presenting symptoms
- Pattern and degree of enzyme elevation
- Correlation with other diagnostic tests
- Monitoring of trends over time
Limitations & Considerations
Technical Limitations:
- Sample Collection:
- Appropriate venipuncture technique
- Adequate sample volume
- Proper handling and transport
- Analytical Factors:
- Instrument calibration and quality control
- Assay specificity and sensitivity
- Interference from medications or other conditions
Clinical Limitations:
- LFTs alone do not provide a definitive diagnosis
- Interpretation requires consideration of age-specific reference ranges
- Asymptomatic patients may have incidental LFT abnormalities
- LFT changes may not correlate with the severity of liver disease
- Certain conditions may have normal LFT results (e.g., early cirrhosis)
Recommendations:
- LFTs should be interpreted within the clinical context
- Abnormal results warrant further investigation and specialist consultation
- Repeated testing may be necessary to establish patterns and trends
- Liver biopsy or imaging studies may be required for definitive diagnosis
