Are transaminases (enzymes) part of a chemistry panel in medical diagnostics?

Transaminases Are Part of Chemistry Panels in Medical Diagnostics

Yes, transaminases (specifically ALT and AST) are standard components of chemistry panels in medical diagnostics. 1 These enzymes are routinely included in liver chemistry tests and are essential markers for detecting hepatocellular injury.

What Are Transaminases?

Transaminases are enzymes that catalyze the transfer of amino groups between amino acids. The two most clinically relevant transaminases are:

• Alanine Aminotransferase (ALT): Primarily concentrated in the liver, making it more specific for liver injury
• Aspartate Aminotransferase (AST): Found in the liver but also present in heart, skeletal muscle, kidneys, brain, and red blood cells

Transaminases in Standard Laboratory Panels

Transaminases are included in:

1. Routine liver chemistry panels: ALT and AST are fundamental components of standard liver function tests 1
2. Comprehensive metabolic panels: These typically include transaminases alongside other metabolic markers
3. Hepatocellular injury assessment: Elevated transaminases indicate potential liver cell damage 1

Clinical Significance of Transaminases

• Normal ranges:

  • ALT: 29-33 IU/L in men, 19-25 IU/L in women 1
  • Elevations classified as mild (<5× upper limit), moderate (5-10× upper limit), or severe (>10× upper limit) 1

• Diagnostic value:

  • Elevated transaminases are often the first indication of liver disease 1
  • Up to 80% of patients with NASH (Non-alcoholic Steatohepatitis) may be identified through elevated transaminases 1
  • Transaminase patterns help distinguish between different types of liver injury 2

Important Considerations When Interpreting Transaminases

1. Not true measures of liver function: Despite being called "liver function tests," transaminases indicate hepatocellular injury rather than actual liver function 1

2. AST/ALT ratio significance:

   • Ratio <1: Typical in early NAFLD (Non-alcoholic Fatty Liver Disease) 1
   • Ratio >1: May indicate advanced fibrosis or cirrhosis 2
   • Ratio >2: Strongly suggests alcoholic liver disease 2

3. Normal transaminases don't exclude liver disease:

   • Up to 50% of patients with NAFLD have normal liver enzymes 1
   • Significant liver disease, including cirrhosis, can exist with normal transaminases 2

Common Pitfalls in Transaminase Interpretation

1. Overreliance on transaminases alone: They should be interpreted alongside other clinical and laboratory findings 2

2. Non-hepatic causes of elevation: Transaminases can be elevated due to muscle disorders, thyroid disorders, celiac disease, and hemolysis 2

3. Transient elevations: More than 30% of elevated transaminases may spontaneously normalize during follow-up 2

4. Pharmacology-related elevations: Some medications can cause transaminase elevations without true liver injury 2

Transaminases remain valuable "oldies but goldies" 3 in clinical practice, serving as sensitive markers of potential liver injury and playing a crucial role in the initial evaluation of suspected liver disease.