Adrenal Insufficiency Community
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AM Cortisol Test


I am due to have a 9am cortisol test in two days time.  I'm not sure if I should fast before or not as my doctor says I should but I have also read it isn't necessary.

Thanks alot for your help

5 Responses
757137 tn?1347200053
I am curious as to why it is a 9AM test. The one I had measured cortisol throughout the day. Normally cortisol is high in the morning and falls throughout the day. What my test showed was that my cortisol rose during the day. A single 9AM test would not have shown this. No doubt your doctor has a s special purpose in mind, but I am still curious. Why don't you ask him when you see him?
657231 tn?1453836403
You should fast before, as well, it should be 8am. Your doctor is not up on the protocol.
Avatar universal
I was wondering about this test my self I have had plenty of blood test and not sure if cortisol was one of them but do know that at no time during any of the blood test was I told I had to have an am test which I have read about when diagnoising adrenal issues. I was also wondering more about good testing for discovering adrenal problems. As I have read that it can be diagnoised late due to the kindney ect being able to cope right up till its about to fail. This concerns me a little since I've been struggleing to have quailty of life over the last year at least and recently (3 week ago) diagnoised with inappropriate sinus tachycardia. I'm currently on ivabradine for the tachycardia, which is helping but by no means is giving me an answer or making it easier on me.

I dont know if adreanal issues is whats causing my symptoms but I do know that I dont want to find out when it practicly too late anyway.
657231 tn?1453836403
Time of test is critical for cortisol. Cortisol varies greatly by time of day and there are only a few times of day where there are ranges. Cortisol is the diurnal or circadian rhythm of the body - wakes you up in the morning and puts you to bed at night so you have to test accordingly, test for the peaks and ebbs. My docs insist on 12 hour fasting.
Avatar universal
I have a 9 am cortisol test next week as well. This is a repeat one, although I do not know whether the original was high or low. I have been told to fast for 12 hours.
You should fast 12 hours before. In addition, DO NOT take any vitamin B's and Biotin ( found foods, beverages supplement--whey protein, vitamins, etc.) 4 days before the test because it will give false reading (not only on cortesol test, but thyroid test too. This information came directly from multiple Endocrinologists, Rheumatologist, Interna Specialists working together. Put on dexamethasone 4 day before test and stop Prednisone, but due not take dexamethasone morning of test. Also, should take if diagnosed with Adrenal insufficiency (Addisons, Cushing's, etc) in morning and / or afternoon as usually as doctors prescribed; but, not at bedtime (reported to keep person awake).
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657231 tn?1453836403
Northern, NJ
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