The results of the low-dose dexamethasone suppression test confirm pituitary-dependent hyperadrenocorticism (i.e. 4-hour cortisol concentration < 50% of baseline and 8-hour cortisol > 1.4 µg). Further diagnostics are not necessary. Starting therapy with trilostane is, therefore, the most appropriate option for this patient.
This patient was started on 10 mg trilostane once daily. The dose was increased over the next 3 months to 30 mg once daily, based on clinical response, baseline cortisol values, and ACTH stimulation test results. Eight months after diagnosis, Indi’s coat was essentially normal (see below).