0.5 mL serum in red top or serum separator tube for baseline sample (labeled PRE) and 0.5 serum in red top or serum separator tube for post sample (labeled POST).
Test Description
Cortisol Assay, 2 Samples: PRE (Baseline) and POST ACTH Stimulation.
This is an ACTH stimulation test that requires two samples: one PRE, one POST. Results include baseline cortisol and one POST‑ACTH cortisol.
Interferences: Marked hemolysis may affect results, and marked lipemia (if unable to be cleared by centrifugation) may falsely decrease cortisol levels.
Collection Method Instructions:
Canine:
Using Cosyntropin (Cortrosyn):
1. Collect PRE‑sample. Label tube PRE.
2. Administer 5 micrograms/kg of Cosyntropin IV or IM (up to a total dose of 250 micrograms). A dose of 1 ug/kg (IV only) can be used when monitoring trilostane or mitotane treatment but is NOT recommended for diagnosing Cushing’s syndrome or Addison’s disease. If using the 1 ug/kg dose, it must be administered IV.
3. Collect 1-hour POST sample. Label 1-hour POST. If using compounded ACTH gel (not recommended), two POST samples are needed (1-hour and 2-hour POST sampling) and the ACTH3 test is required. See code ACTH3 (CT441) for testing detail.
Feline: (The ACTH stimulation test Is not recommended for the diagnosis of spontaneous Cushing’s syndrome in cats)
Using Cosyntropin (Cortrosyn):
1. Collect PRE‑sample. Label tube PRE.
2. Inject 0.125 mg Cosyntropin IV.
3. Collect 1‑hour POST‑sample. Label 1-hour POST. If using compounded ACTH gel (not recommended), two POST samples are needed (1-hour and 2‑hour POST sampling) and the ACTH3 test is required. See code ACTH3 (CT441) for testing detail.
For trilostane monitoring, ACTH testing should start 4‑6 hours after the morning dose of trilostane. The timing of the test is the same regardless of whether the patient is on SID (morning dose) or BID (morning and evening) and is always 4‑6 hours after medication. Trilostane MUST be administered with food, even on the morning that the ACTH stimulation test is going to be performed. Although we generally recommend an 8‑12 hour fast before blood draw (to avoid gross lipemia and hemolysis) this is NOT recommended when monitoring trilostane therapy.
The timing of the ACTH stimulation test does not matter in pets being treated with lysodren (aka mitotane).