Answer
It stimulates the adrenal cortex so that the cortisol response can be measured, helping investigate suspected adrenocortical insufficiency.
Sources for this answer
- Synacthen Depot Ampoules 1 mg/ml — Current selected SmPCemc · Summary of Product Characteristics
- NHSNHS · NHS medicine guidance
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.