Unit Converter
Glutamate dehydrogenase (GLDH)
(Mitochondrial Liver-Enzyme Marker – Highly Specific for Hepatocellular Injury & Mitochondrial Damage)
Synonyms
- GLDH
- GLuDH
- Glutamate dehydrogenase
- α-ketoglutarate dehydrogenase (older term)
- Mitochondrial liver enzyme
- Oxidative deamination enzyme
Units of Measurement
GLDH activity may be reported in:
- nkat/L
- µkat/L
- nmol/(s·L)
- µmol/(s·L)
- U/L
- IU/L
- µmol/(min·L)
- µmol/(h·L)
- µmol/(h·mL)
Unit Conversions (IFCC Enzyme Standards)
1 U/L = 1 IU/L
1 U/L = 16.67 nkat/L
1 nkat/L = 0.06 U/L
1 µmol/(min·L) = 60 U/L
1 µmol/(h·L) = 1 U/L
1 µmol/(h·mL) = 1000 U/L
(All conversions follow SI enzyme-activity recommendations.)
Description
Glutamate dehydrogenase (GLDH) is a mitochondrial enzyme located primarily in:
- Liver (hepatocytes) → highest concentration
- Kidney
- Brain
- Pancreas
Its presence in the blood is a highly specific marker of hepatocellular mitochondrial injury.
Because GLDH resides inside mitochondria, it is released only when severe liver cell injury occurs, making it a valuable marker in:
- Acute liver failure
- Drug-induced liver injury
- Hypoxic hepatitis
- Alcoholic hepatitis
- NAFLD/NASH with necrosis
Physiological Role
GLDH catalyzes:
- Oxidative deamination of glutamate → α-ketoglutarate + NH₄⁺
- Key enzyme in amino acid metabolism
- Links nitrogen and carbohydrate metabolism
It is highly abundant in zone 3 (centrilobular) hepatocytes, where most toxic injury occurs.
Clinical Significance
↑ GLDH (Elevated Levels)
Indicates mitochondrial hepatocellular injury.
More specific than ALT/AST.
1. Acute Liver Failure
Markedly elevated GLDH occurs in:
- Hypoxic hepatitis (shock liver)
- Severe ischemia
- Viral hepatitis A, B, E
- Drug-induced liver injury (acetaminophen, anti-TB drugs)
2. Alcoholic Hepatitis
Due to mitochondrial toxicity of ethanol.
3. NAFLD / NASH
GLDH rises earlier than ALT in necroinflammation.
4. Wilson Disease
Hepatocellular necrosis → high GLDH.
5. Sepsis & Multi-organ Failure
Due to hypoxic/ischemic liver damage.
6. Toxin Exposure
- Amanita mushroom poisoning
- Carbon tetrachloride
- Hepatotoxic chemicals
7. Post–Cardiac Arrest or Shock States
Severe hypoxia → hepatocyte death → GLDH rise.
Normal or Low GLDH
- Seen in mild liver disease
- Normal in isolated cholestasis (ALP/GGT rise instead)
- Helps differentiate hepatocellular vs cholestatic injury
Reference Intervals
(Tietz 8E + Mayo + ARUP + IFCC)
Values vary by method.
Adults (Typical Range)
- < 7 U/L
(or < 116 nkat/L)
Children
Similar or slightly lower depending on age.
Marked Elevation
- >50 U/L → severe hepatocellular injury
- >100 U/L → acute liver failure likely
Diagnostic Uses
1. Assess Hepatocellular Necrosis
GLDH is specific for mitochondrial damage, unlike ALT/AST.
2. Differentiating Hepatic vs Non-Hepatic Injury
- ALT/AST may rise in muscle disease
- GLDH is liver-specific
3. Alcoholic & Toxic Hepatitis
- Mitochondrial toxins → GLDH elevation
- More reliable than AST/ALT ratio
4. Hypoxic Liver Injury
- GLDH strongly increases in ischemic hepatitis
5. Drug-Induced Liver Injury Monitoring
Useful for hepatotoxic medications:
- Anti-TB drugs
- Acetaminophen
- Chemotherapy agents
6. NAFLD/NASH Severity Assessment
- Higher GLDH → more necroinflammation
Analytical Notes
- Serum sample
- Hemolysis insignificant (mitochondrial enzyme)
- Highly stable enzyme
- More specific than ALT/AST for hepatic injury
- IFCC-compliant kinetic assays recommended
Clinical Pearls
- GLDH rises only when mitochondria are damaged → a sign of deep hepatocyte injury.
- ALT and AST may remain mild while GLDH shows severe damage.
- Very high GLDH strongly suggests acute liver failure or toxin-induced injury.
- Normal GLDH with high ALP/GGT → likely cholestatic disease.
- GLDH is not influenced by muscle injury, unlike AST.
Interesting Fact
Because GLDH is located in zone 3 hepatocytes (most oxygen-sensitive area), it is one of the best markers of hypoxic hepatitis.
References
- Tietz Clinical Chemistry & Molecular Diagnostics, 8th Edition - Liver Enzymes.
- AASLD/EASL Guidelines on Drug-Induced Liver Injury.
- Mayo Clinic Laboratories - GLDH.
- ARUP Consult - Liver Injury Markers.
- IFCC Enzyme Standardization.
- MedlinePlus / NIH - Liver Function Tests.