CORTISOL BLOOD TEST

My Rheumy has instructed me to have a cortisol blood before I take a further reduction in Pred. At present on 8 mg. Has anyone had this test and if so how did you prepare for it, eg did you fast and did you take your daily dose of Pred? My surgery seem very vague about it. I also believe that you should rest for at least 30 mins before the blood is taken. Advice would be appreciated.

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  • I presume you mean a synacthen test?

    patient.co.uk/health/synact...

    It is done - as that link tells you - whether your adrenal glands are still functioning normally. They sometimes don't after some time on pred. When you are down to 8mg you are at the level your body would make itself if you weren't taking pred but as you go lower there is a risk you won't have enough in the blood to cover "normal" everyday things if the adrenal glands don't respond. If you reduce very slowly it shouldn't be a problem (I take 6 weeks to reduce 1mg by just taking the new dose on one day a week at first and working up) unless your adrenals have stopped working altogether. I'm impressed - it is the first time I have heard of a rheumy doing it on a PMR patient!

    Normally you would have to stop taking pred for a day or so but I know of at least one specialist who dose them whilst the patient is still taking their normal dose. My 14-year-old granddaughter who has been on high steroids for severe asthma has had a couple done.

    As the link tells you - every hospital is a bit different so I can't tell you how yours will be done but usually you turn up at hospital fasting, have blood taken, are given an injection and then they take more blood later. If it is a "short" synacthen test you will be able to go home later on. If it is a "long" one you may have to stay overnight. Take a good book! You'll get a letter or a phone call from the hospital to tell you when and how.

  • Hi PMRPro. I am having mine done at my GPs surgery. They have given me no instructions, only to turn up for my first blood test at 0900 hrs and the second at 1000 hrs. I am wondering whether they know what they are doing.

  • I imagine they know how to do it yes :-) - it is a short test you're getting and it really is just a baseline blood sample, an injection and another blood test to see if your body has reacted and produced cortisol.

    This handout from a hospital explains it too, maybe more applicable for you:

    derbyhospitals.nhs.uk/easys...

    It is a standard test so won't be any different. 8mg of pred is a low dose (they mention that). I assume you just take it in the morning? So you can take it the day before and just leave it until you get home to take it that day. This hospital says you don't need to fast - all the info is quite clear there even for a lay person.

    Is that OK? Just ask again if anything isn't clear.

  • Many thanks for your reply. The link was excellent.

  • Yes, it does look as if they know what they are doing. It's a very simple but a very tedious test for the patient.

    I had mine done at the local hospital, but that's by no means necessary. Basically, you take your usual steroids for the day (I think I was on 15mg at the time) and have breakfast, fasting is not necessary. At the first appointment they take a baseline sample and give you an injection of something to kick-start the adrenals (I can never remember what it's called) then have you in an hour later to check if the stuff has had any effect. I had this done twice more, which was very boring as all I could do was wander the hospital or read.

    The end result of mine was as expected, I don't have any adrenal function so on 5mg steroid for life. It bothers me not!

  • Let me know how it goes. I should probably have one done as I have never had it done.

  • From what I have read in a"drugs" book,it can take up to 72 hours for Prednisolone to "leave"body.On can also do saliva test for same,to buy on line.I know nothing about it.Good Luck.Soo

  • Experienced doctors can still do a synacthen test and interpret the results without stopping the pred. The plasma half-life is only a couple of hours (the time taken for half of the drug to leave the body) so if you are having the test 24 hours after the last dose there will be hardly anything left of a dose of 8mg. The biological half life is much longer - the EFFECT will last up to 36 hours and that is why it is possible to take double doses on alternate days to reduce the side effects, the body has quite a long time not under the influence of pred.

  • Hi everyone. Had one cortisol blood test test at 9 am this morning. Nurse said they didn't carry out the synacthen test in the surgery because the samples had to be in the lab 10 minutes after they had been taken in order for the results to be accurate. She had phoned the Pathology lab who said one blood sample would be sufficient. The adrenal fatigue at present is horrendous but no can give me advice or help. Many thanks to everyone for their replies.

  • To PMRpro.Thanks for reply,how great to know so much about medicine,its always been an interest for me,as I workedfor years in Education with children with Special Needs.Regards,and hope grandchild keeps well.Soo.

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