Cat Liver Enzymes Explained (ALT, ALP, AST, GGT)
If your cat's bloodwork shows elevated liver enzymes, you may see values like ALT, ALP, AST, and GGT. Here's what these markers mean, why they matter, and what steps to take next.
What Are Liver Enzymes?
The liver is your cat's metabolic powerhouse, supporting digestion, detoxification, and protein production. When liver cells are stressed or damaged, enzymes leak into the bloodstream.
- ALT (Alanine Aminotransferase): Found primarily in the liver; rises with liver cell injury or inflammation.
- ALP (Alkaline Phosphatase): Found in liver, bile ducts, and bone; elevations suggest bile duct disease or certain liver conditions.
- AST (Aspartate Aminotransferase): Found in liver, muscle, and red blood cells; rises with liver damage or muscle injury.
- GGT (Gamma-Glutamyl Transferase): Found in bile ducts; elevations often indicate bile duct or gallbladder disease.
Why Liver Enzymes Matter in Cats
Elevated liver enzymes signal that the liver or nearby organs are under stress. They don't pinpoint a specific diagnosis but help veterinarians narrow down possibilities and determine the next diagnostic steps.
Common Causes of Elevated Liver Enzymes
- High ALT: Hepatic lipidosis (fatty liver), inflammation, toxins, hyperthyroidism, liver tumors
- High ALP: Cholangitis, biliary obstruction, bone growth (in kittens), certain medications, cancer
- High AST: Liver disease, muscle trauma, hemolysis (red blood cell breakdown)
- High GGT: Bile duct obstruction, cholangitis, gallbladder or pancreatic disease
Confused by your cat's liver panel?
Upload results to VetLens for an instant, plain-English breakdown of ALT, ALP, AST, and GGT tailored to your cat's specific situation.
Try VetLens FreeSymptoms Pet Owners Might Notice
- • Weight loss despite normal eating
- • Poor appetite or complete food refusal
- • Vomiting or diarrhea
- • Increased thirst and urination
- • Lethargy or hiding behavior
- • Jaundice (yellowing of eyes, gums, or inner ears)
What Happens Next?
Your veterinarian may recommend:
- • Repeat bloodwork to confirm trends
- • Liver ultrasound to assess structure and look for masses
- • Bile acids test to evaluate liver function
- • Testing for hyperthyroidism (common in older cats)
- • Testing for pancreatitis which often occurs alongside liver issues
- • Fine needle aspirate or biopsy for definitive diagnosis
Key Takeaway:
Elevated liver enzymes are a signal, not a diagnosis. The pattern of elevation combined with your cat's history and clinical signs determines the next steps.
Want Liver Enzymes Explained for Your Cat?
Upload your cat's bloodwork into VetLens and get:
- ✓ A plain-English breakdown of ALT, ALP, AST, and GGT
- ✓ Context based on your cat's history and medications
- ✓ Suggested questions to ask your vet
- ✓ Tailored care recommendations
Frequently Asked Questions
Which enzyme is most commonly elevated in cats?
ALT is the most commonly elevated liver enzyme in cats, often indicating hepatocellular injury or inflammation.
Can medications raise liver enzymes?
Yes, certain medications including steroids, anticonvulsants, and some antibiotics can cause elevated liver enzymes.
Do high values always mean liver disease?
No. Hyperthyroidism, diabetes, muscle injury, and even stress can cause enzyme elevations without primary liver disease.
How are elevated liver enzymes treated?
Treatment depends on the underlying cause and may include dietary changes, medications, supplements like SAMe, or treating concurrent conditions.