Is there such thing as a blood test for aldosterone or is my dr just bullsheeting me?

i was diagnosed with cushing's syndrome a few years ago (i had a tumor on my adrenal gland that was causing me to produce too much cortisol) and had the tumor removed. i've been ok for 2 years; then i started feeling reeeeally sick again and getting new stretch marks on my legs when i haven't gained any weight, and a ton of other odd symptoms, almost all to having excess aldosterone.

i went to 2 doctors, and neither of them want to test for high aldosterone, even though it could quite be a possibility. i went to my pediatric endocrinologist at dartmouth hitchcock hospital, and he told me he would check it, but he DIDN'T. and his nurse lied to me and said that it was fine. when my regular doctor went to look it up, it wasn't there. so they never did it.

now my regular doctor isn't convinced with the aldosterone thing either, and he said that he was gonna take a blood test for it. but all the tests i've read about online are urine. is my doctor bullsheeting me? what should i do?

I know for a fact you can get a blood test for it, but I will find you a link to let you read.