Acth below normal but Cortisol normal

[lowcort]

I received my lab results and my Plasma Free Cortisol was 0.10 mcg/dl which they consider normal.  I don't know why they tested my Free instead of my Total it seems like everyone else has their Total cortisol tested.  They also tested my ACTH and that came back below normal at <10pg/ml.  

How could I have a normal cortisol reading but an abnormally low ACTH reading?  I thought ACTH stimulates the adrenals to release Cortisol so how is it stimulating them if it is below normal.  

I am totally confused.   Has anyone else had results like this?

[rumpled]

The ACTH could have been messed up in the lab - it is a fussy test. It has to be spun immediately, frozen right after spinning or it degrades.

Lab error is the answer but your doc is not going to pick up on it unless he is good.

[lowcort]

Maybe it is a lab error.  I just could not understand how it could be low but cortisol normal.  
I know that the lab technician put it in ice immediately after she drew it and then she said she had to freeze it to a certain temp.  

So is there no way that the ACTH could be low with a normal cortisol reading?

[rumpled]

She let it sit on ice - it degraded. She was better of spinning it. She needed to freeze it AFTER the spin. Sad...

The ACTH is what tells your adrenals to secrete cortisol. One or the other or both has to be abnromal in a certain sequence to let the doc know what is wrong where, and your tech goofed it up.

On the other hand, I had pituitary Cushing's with normal ACTHs (normally that is adrenal) so you really need a doc who knows their stuff to really test, know lab error and get to the bottom of it if they suspect something.

[lowcort]

Thank you for all your information.  I had another Cortisol test done yesterday and they tested my Total Cortisol instead of Free and it came back at 6.6 with a reference range of 8.7-22.41.  They did the test at 10:00 in the morning.  Now, the other day my free cortisol was normal but my ACTH was not.  My doctor called me today and said that it was low and they needed to do more testing.  
One thing I notice with me is that I am absolutely exhausted all day and just want to sleep and then about 7-8 at night I start getting energy and then I cannot get to sleep.  I end up having to take Benedryl every night just to fall asleep.  Could my cortisol levels be reversed?  Low in the morning and high at night?  With both the cortisol and the ACTH coming back low she said it could be secondary adrenal insufficiency.  Everywhere I have read says that with low Cortisol you lose weight and I have gained about 18 pounds in one month!  

[galliar]

You need to have the following the standard stimulation test.  It involves the following:

1. ACTH and Cortisol baseline draws
2. ACTH stimulation injection, get the IV method with a small amount of ACTH, it is safer.
3. 30min - Cortisol draw
4. 60min - Cortisol draw.

You can see about this test here.  Even though it is derived from Wikipedia, I check several other sources and it looks correct:  

http://www.acthstimulationtest.com/interpretation

Keep working for a diagnosis.  As for weight, you can still gain with this disease.  Some people like myself get very low blood sugar problems also, and if you have them you often tend to want to eat high refined carbohydrates to feel better.  These in fact over time make you gain weight and feel worse.  It is a cycle that is hard to quit!