High alkaline phosphatase from corticosteroids in dogs
7-year-old Labrador on prednisone 1 mg/kg/day for 4 weeks for allergic dermatitis. Clinically well, not icteric.
| Parameter | Result | Reference |
|---|---|---|
| Alkaline phosphatase (ALP) | 1,380 U/L | 20–150 |
| ALT | 140 U/L | 10–100 |
| GGT | 18 U/L | 0–10 |
| Total bilirubin | 0.3 mg/dL | 0–0.5 |
What is the most likely interpretation?
chevron_right Show answer and explanation
A. Extrahepatic biliary obstruction
A biliary obstruction with this ALP increase would come with hyperbilirubinaemia and icterus, plus clinical signs (abdominal pain, vomiting, anorexia).
B. Chronic active hepatitis
Chronic hepatitis is characterised by predominant ALT increases (hepatocellular damage). Here ALT is barely raised while ALP is up 9-fold.
C. Glucocorticoid enzyme induction
Correct. In dogs, glucocorticoids induce a specific ALP isoenzyme and also GGT, with a mild ALT rise (vacuolar hepatopathy). With normal bilirubin and a healthy patient, this is most likely. Recheck after tapering the steroid: it can take weeks to months to normalise.
D. Artefact from sample haemolysis
Haemolysis can interfere with some assays, but it does not explain an ALP nine times above the upper limit or the matching GGT rise.
lightbulb Key takeaway
Cats have no corticosteroid-induced ALP isoenzyme and ALP has a very short half-life: any ALP increase in a cat is significant (hepatic lipidosis, cholangitis, hyperthyroidism).
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.