So I have a pituitary tumor that I’ve had for years. I just recently got tested for Cushing’s but unfortunately my blood test got messed up, and I just recently had to get re-tested. Thankfully I was able to get the 24 hour urine test done correctly. My question is what is the likelihood that my blood test will come back high for cortisol since my urine test came back so high? I have many of the other symptoms of Cushing’s and we are just waiting for the last test result.
Hi! Thanks for the question.
The good news is that the 24 hour urine captures a longer period of time than the blood test does – 24 hours vs. a momentary snapshot of the cortisol level at the moment your blood is drawn. Both test results can be used to support the overall diagnosis, but most doctors consider the 24 hour urine much more accurate to begin with. If, for example, you had sleep apnea-induced Cushing’s Syndrome, an 8am blood draw would probably show a low cortisol level because the high cortisol readings would be happening overnight.
Are you familiar with incidentalomas? There is plenty of research out there to consider about their prevalence and how, when, and why to follow up on them periodically even if they’re not currently causing problems. This is just one of many that addresses this issue, albeit from the adrenal standpoint: https://www.ncbi.nlm.nih.gov/pubmed/30412278.
Since you have symptoms, hopefully your doctors are knowledgeable and will help you get the appropriate diagnosis as soon as possible.
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