Monitoring cortisol production and basic blood chemistries (most notably potassium and sodium levels) are the most important tools. Historically, ACTH stimulation testing has been the preferred method for monitoring cortisol and it is still the most common method in the U.S. However, an alternative method has recently been introduced and is growing in favor, especially in the U.K. and Europe. It involves testing the baseline cortisol alone, right before a dose of trilostane is scheduled to be given. I think either monitoring method is fine — it’s just important to do one or the other in order to check adrenal function. Here’s a post that describes the newer “pre-pill” method in greater detail:
https://www.k9cushings.com/forum/sho...=1252#post1252
The importance of also monitoring potassium and sodium is because trilostane has the potential to lower the production of another adrenal hormone, aldosterone, as well as cortisol. Aldosterone controls the proper balance of potassium and sodium in the body, and it’s the other “half” of concern over an Addisonian condition. If either cortisol or aldosterone — or both — drop too low, an Addison’s crisis can be induced. But any basic blood chemistry panel ought to include potassium and sodium levels.
I truly believe that you are seeking only the best for your boy, especially after the rough life he led before you rescued him. You saved his life then, and you are trying your hardest to give him the best quality of life now. We are all grateful to you for what you are doing for him. In that vein, if the trilostane is not really helping him, even if his cortisol level is OK, you might want to give him a trial period to see whether he’s better or worse without it at all. I agree with you that at his age, comfort is the most important thing. So if the trilostane isn’t making him feel any better, you might want to just forget about it. That way, you wouldn’t have to worry about any negative side effects or the need for the monitoring blood draws. Just a thought. But who knows, maybe the cortisol testing will show that his cortisol is actually remaining too high to expect good symptom control. As you say, it’s possible that he may have an aggressive adrenal tumor that is really ramping up the cortisol production. When used diagnostically, the ACTH stimulation test frequently doesn’t return a “positive” result in the face of adrenal (vs. pituitary) tumors. So that might explain his original equivocal test result. All in all, we’ll surely be anxious to hear what the current testing shows!
Marianne