GGT Levels in Cats: What Elevated Values Mean
GGT (Gamma-Glutamyl Transferase) is a liver enzyme that specifically indicates bile duct disease. Normal range: 0-6 IU/L. Elevated GGT suggests cholangitis, bile duct obstruction, or pancreatitis.
If your cat's bloodwork shows elevated GGT, it's a more specific indicator of bile duct problems than ALT or ALP. Understanding GGT helps pinpoint whether liver disease involves bile flow issues (cholestatic disease) or primarily liver cell damage.
What Is GGT?
GGT (Gamma-Glutamyl Transferase) is an enzyme found in cells lining the bile ducts, liver, pancreas, and kidneys. In cats, elevated GGT almost always indicates problems with the hepatobiliary system—the liver and bile duct network.
Why GGT Matters:
- Bile Duct-Specific: More specific for cholestatic disease than ALT or ALP
- Differentiates Disease Types: Helps distinguish bile duct vs liver cell problems
- Confirms True Cholestasis: High GGT + high ALP confirms bile flow issues (not steroid effects)
- Pancreatitis Indicator: Often elevated in cats with pancreatitis
Normal GGT Ranges for Cats
- 0-6 IU/L: Normal (reference range may vary by lab)
- 7-10 IU/L: Borderline (monitor and recheck)
- 11-20 IU/L: Mild elevation (investigate cause)
- 21-50 IU/L: Moderate elevation (likely cholestatic disease)
- 50+ IU/L: Severe elevation (significant bile duct pathology)
Important: GGT should always be interpreted alongside ALT, ALP, and bilirubin for the complete picture.
GGT vs Other Liver Enzymes
ALT (Alanine Aminotransferase)
• Indicates liver cell damage
• High in hepatic lipidosis, toxins, infections
• Most common elevated liver enzyme in cats
ALP (Alkaline Phosphatase)
• Indicates cholestasis (bile flow blockage)
• Can be elevated by steroids (less specific)
• Naturally lower in cats than dogs
GGT (Gamma-Glutamyl Transferase)
• Indicates bile duct disease specifically
• Not affected by steroids (more specific than ALP)
• Elevated in cholangitis, bile duct obstruction, pancreatitis
What Causes Elevated GGT in Cats?
1. Cholangitis (Bile Duct Inflammation)
The most common cause of elevated GGT in cats. Bacterial infection or immune-mediated inflammation of bile ducts.
Symptoms: Jaundice, vomiting, lethargy, fever, abdominal pain
2. Pancreatitis
GGT often rises alongside lipase in cats with pancreatitis due to proximity of pancreas to bile ducts.
Symptoms: Vomiting, decreased appetite, abdominal tenderness, lethargy
3. Hepatic Lipidosis (Fatty Liver Disease)
While ALT is usually higher, GGT can be moderately elevated if bile flow is impaired.
Symptoms: Severe jaundice, anorexia, rapid weight loss
4. Bile Duct Obstruction
Physical blockage from stones, tumors, or strictures causing bile backup.
Symptoms: Severe jaundice, pale stool, dark urine
5. Liver Tumors (Less Common)
Primary or metastatic tumors involving bile ducts.
Symptoms: Weight loss, jaundice, enlarged liver on palpation
Not sure if your cat's GGT indicates cholangitis or pancreatitis?
Upload your cat's bloodwork to VetLens for instant analysis of GGT alongside ALT, ALP, lipase, and clinical context.
Analyze Bloodwork NowInterpreting GGT With Other Enzymes
High GGT + High ALP + High Bilirubin
→ Cholestatic disease confirmed (bile duct obstruction or cholangitis)
High GGT + High ALT + Normal ALP
→ Hepatic lipidosis or cholangitis affecting liver cells and bile ducts
High GGT + High Lipase + Vomiting
→ Pancreatitis with secondary bile duct involvement
High ALT + Normal GGT
→ Liver cell damage without bile duct issues (toxins, infection, lipidosis early stage)
High ALP + Normal GGT
→ Possibly steroid-induced ALP (GGT confirms if cholestasis is real)
What to Do If Your Cat's GGT Is Elevated
Step 1: Additional Testing
- • Ultrasound: Visualize bile ducts, liver structure, gallbladder
- • Bile acids test: Assess liver function
- • Bilirubin levels: Measure bile accumulation
- • fPLI (feline pancreatic lipase): Rule out pancreatitis
- • Fine needle aspiration (FNA): If mass or severe disease suspected
Step 2: Diagnosis & Treatment
For Cholangitis:
- • Antibiotics (amoxicillin-clavulanate, metronidazole)
- • Ursodiol (bile acid supplement to improve flow)
- • Anti-nausea medications
- • Nutritional support (feeding tube if needed)
For Pancreatitis:
- • IV fluids for hydration
- • Pain management
- • Anti-nausea medications
- • Low-fat diet once eating resumes
Prognosis: Can GGT Go Back to Normal?
Yes, in many cases GGT can normalize with treatment:
- Bacterial cholangitis: Often responds well to antibiotics; GGT may normalize in 4-8 weeks
- Pancreatitis: GGT typically decreases as pancreatic inflammation resolves
- Hepatic lipidosis: With aggressive nutritional support, GGT can return to normal over months
- Chronic cholangitis: May require long-term management; GGT may never fully normalize but can stabilize
Key Point:
Unlike chronic kidney disease, many bile duct conditions are treatable. Early diagnosis and appropriate treatment often lead to full recovery, especially with bacterial cholangitis.
When to Worry About GGT
Seek immediate veterinary care if:
- • Your cat is jaundiced (yellow gums, skin, eyes)
- • GGT is above 50 IU/L
- • Your cat is vomiting repeatedly or not eating
- • Fever is present (above 103°F)
- • Abdominal pain or lethargy is severe
Get Your Cat's GGT Results Explained
Upload your cat's bloodwork into VetLens and get:
- ✓ GGT interpretation with cholestatic disease assessment
- ✓ Comparison with ALT, ALP, and bilirubin
- ✓ Differential diagnosis (cholangitis vs pancreatitis vs lipidosis)
- ✓ Treatment questions to discuss with your vet
Frequently Asked Questions
What is a normal GGT level for cats?
Normal GGT levels in cats typically range from 0-6 IU/L, though reference ranges may vary slightly by laboratory. Values above 10 IU/L are generally considered elevated and warrant further investigation.
What causes elevated GGT in cats?
High GGT in cats typically indicates bile duct disease, cholangitis (bile duct inflammation), pancreatitis, bile duct obstruction, hepatic lipidosis, or certain medications. Unlike ALT and ALP, GGT is more specific for cholestatic (bile flow) problems.
Is GGT more important than ALT in cats?
Both are important but measure different things. ALT indicates liver cell damage, while GGT indicates bile duct problems. GGT is particularly valuable when elevated alongside ALP, as it confirms true cholestatic disease rather than steroid-induced ALP elevation.
Can GGT be normal if my cat has liver disease?
Yes. GGT specifically indicates bile duct involvement. A cat can have liver cell damage (high ALT) without bile duct issues (normal GGT). Conversely, high GGT with normal ALT suggests primary bile duct disease without significant hepatocyte damage.