ACTH Stim test prep questions

[Judee]

My new endo seems very nice. She is sending me to do an ACTH stim test next week however, the nurse that schedules that doesn't really like me asking a lot of questions.

She says it can be scheduled morning or afternoon. That I don't need to fast or stop caffeine or my thyroid medicine. That I just need to be well hydrated.

What I am reading online says it is best to do the test as close to 8am as possible. (I do have sleep inversion so don't know if that would change that recommendation.) It says in some places to fast 6 hours, others 8 hours, some say I can eat a fat free meal, others say no fasting is necessary.

Some of those same sites say stop meds 24 hours before and that I absolutely should not have caffeine before the test.

I'm trying to figure out what is best. I think fasting would possibly put me into hypoglycemia and make me feel stressed which is supposed to be a no-no for the testing so I may eat a light food a few hours before.

I will stop caffeine and my thyroid meds 24 hours before. To me that seems to make basic sense.

The thing I'm most concerned about is the time of day especially with my skewed sleep schedule. I'm trying move my sleep schedule back (again!) but still don't get to sleep until around 2am and then wake up somewhere between 11am-1pm.

Please advise me on your experiences. For anyone with an abnormal test result, did you have it at a time other than 8am? For anyone with a normal test result in the afternoon, were you ever follow-up retested at 8am with an abnormal result?

One study I found that said it doesn't really matter, but they didn't seem to make sense to me on how they determined that there wouldn't have been more abnormals or normals either way.

 

[Moof]

I'm wondering if the conflicting advice is because there's more than one test? I don't know, but it's a possibility.

I'm in the UK, and was told to fast and to have the test done by 9am. This turned out to be difficult, as I can't retain enough fluid for my arteries to release any blood at that time of the morning! – but after two attempts at my GP surgery, they told me to go straight to the hospital phlebotomy clinic next time. They have vibrating heat pads, and were able to get my reluctant veins to part with enough blood for the test. (After all that faffing about, it was completely normal.)

 

[Judee]

This turned out to be difficult, as I can't retain enough fluid for my arteries to release any blood at that time of the morning! – but after two attempts at my GP surgery, they told me to go straight to the hospital phlebotomy clinic next time. They have vibrating heat pads, and were able to get my reluctant veins to part with enough blood for the test.

@Moof, it's funny that you mention that. Cfsremission.com has a lot of information on thick blood being a contributing disorder in ME/CFS. Here is a link in case you were interested.

From Fatigue to Fantastic by Dr Teitelbaum also mentions this as well.

 

[Revel]

@Judee, for a Short Synacthen Test, fasting is not usually necessary, unless they will be taking bloods for other tests at the same time (although it is recommended that you do not consume too much salt prior to the test as this can throw off the result). So, if you have been told not to fast, I would follow their recommendation. Like @Moof, I am in the UK, but did not have to fast prior to my test.

Steroids (eg prednisolone) should be stopped at least 24 hours before the test. Also, those taking oestrogen replacement or the oral contraceptive containing oestrogen should ideally stop 6 weeks prior to the test.

If your sleep pattern is inverted, then I would try to schedule a test as close to your normal waking time as possible.

About 15 minutes into the test, I developed uncontrollable shakes and a raised heart rate. They kept me in hospital for an additional hour after the second blood draw, until these symptoms subsided. In spite of this reaction, as per usual, my test result was "normal".