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Syncathin Test - stop prednisolone?

I am just about to start reducing Pred to 7mg by the slow method. I have an appointment with the rheumy in two weeks. I was going to ask her about having a syncathin test, but see (on a website) that you have to stop taking prednisolone 24 hours previously, which sounds very risky. I was dx with GCA nearly three years ago. Has anyone had this test?

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Not sure about stopping pred,im on 8mg pred .I had syncathin test about 10 years ago where I was told I had addisons disease ,I already had type 1 diabetes,ive GCA PMR dx 1 year ago.Im not sure why docs or you would want test,have you been told to have a test done ?.Im no doctor but I wouldn't be doing anything on your own without consultation .!


It should be done for exactly the reason you had one done - they suspected your adrenal glands weren't working properly so checked to see and they weren't. So you were told you had Addison's disease and, I assume, were put onto a low dose of pred, usually somewhere between 5 and 10mg/day.

When you take pred long term your adrenal glands don't produce cortisol themselves because the feedback system tells them they don't need to because there is a corticosteroid present in the blood - it doesn't care whether it is cortisol or pred. It's very complicated so I won't describe it. Once you are at a dose below about 8mg your body has to start to produce some itself because cortisol is essential for life. Sometimes it can't and as you reduce the artificial corticosteroid you effectively develop Addisons.

Many endocrinologists feel it is a good idea to check on this before pushing a patient who has been on pred for a long time to reduce to zero but making them feel rather ill in the meantime. It used to be thought you could only do the test once the patient had stopped taking pred altogether - that isn't true, you just have to stop any corticosteroid tablets for 24 hours before the test. There are different sorts and some people take their tablets more than once a day.

Once you know the patient's adrenal glands will be able to produce cortisol you can carry on reducing slowly so the body has time to get into the swing again.

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Since we almost all only take our tablets once a day it isn't much of a problem to stop taking it for the 24 hours up to the test. The test has to be done at 9am so you take your pred the morning before the test and then DON'T take the dose the next morning until after you have had the test. You go to the clinic where it is to be done, have the baseline blood sample taken at 9am and then you are given an injection of synacthen to stimulate the adrenal glands. Then they take a blood sample a short time later for the "short" synacthen test which is the usual version. If they want to do the "long" synacthen test it is a few hours later for another blood sample. Then as soon as they are finished you can take your tablets.

Don't tell me you haven't forgotten your tablets at least once? ;-) Everyone does at some time or other and you often have to do so or at least take them late for certain tests.

In fact, a synacthen test is to be included in a PMR study and the protocol is exactly as I've described above. The only problem might be that people are a bit stiff when going to the clinic for the test to be done but that is the only disadvantage or problem. One way of taking pred is to take a double dose on every second day - it reduces the side effects and for many people in many illnesses works well. The anti-inflammatory effect of pred lasts for 12-36 hours so if you are one of the lucky people for whom it is 36 hours it is fine.

So, no worries about having a synacthen test - especially at such low doses and you get to take the tablets just a few hours late. You won't go into adrenal failure because of missing one dose whatever level it is.

I'm sure Sambucca and polkadotcom won't mind me saying have both had the test since they have mentioned it on the forums - Sambucca was fine, polkadotcom will need a low dose of pred for life.

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Trenny, being on long term steroids and still around the 7.5mg dose could certainly skew the results of a Synacthen test. When following the slowly slowly method of reduction, once on the very low doses if our adrenal glands have been suppressed by the steroids, they should start returning to their normal pre-Pred production of natural steroid (cortisol), ie the equivalent of around 7.5mg of Pred.

You say that you are just about to embark on reducing to 7mg, so just around the point where your adrenals should be starting to wake up again. Not a point at which the Synacthen test would normally be considered.....or, in fact, approved by your rheumy, I'm sure. So do continue slowly, and give those adrenals a chance to get going! And reserve the Synacthen test for when you are much lower, if necessary, ie if you find you are continually having problems reducing from the tiny doses, without symptoms returning.


Celtic - sorry to disagree, but this is actually exactly the point it should be done to avoid future problems! I know it seems counter-intuitive but you need to know if the adrenals are going to be able to start functioning when you take away the artificial corticosteroid. It is too late when you have taken the dose down too low in someone with impaired adrenal function and made them develop secondary Addison's syndrome.

It does skew the results slightly - which is why the patient shouldn't take pred in the 24 hours up to the test and why the person looking at the results needs to know that this is a patient on regular pred.

Leeds is intending doing synacthen tests on patients as part of a study - doing it in exactly the way I described.

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PMRPro, having read quite a few articles over the years that say the results of the synacthen test can be skewed when on long term, higher dose Pred, I was always led to believe the test would only give a really accurate result at the very low doses. One such article from the Royal Derby Hospital states:

"It should be noted that Prednisolone and hydrocortisone cross react with cortisol assays, but the short synacthen test is suitable for patients that have recently started steroid replacement or are on low dose steroids. For these patients, the steroid dose should be omitted the evening before the test (if possible) and on the morning of the test.

For the assessment of adrenal status in patients receiving long term steroid treatment who are having difficulty coming off steroids, referral to the Endocrine team is suggested.

Certain drugs, particularly steroids (Hydrocortisone and Prednisolone) may interfere with cortisol estimation."

I suppose a lot depends on different people's opinions of what is classed as "low dose steroids", but how can the test be carried out successfully on a patient on high dose steroids to see if their adrenal glands are producing sufficient natural cortisol at the time when that natural cortisol supply is being suppressed by high dose Pred. Am I being thick?!! I'm assuming it's all down to the scientific way they carry out the test.

The Leeds study sounds interesting and will hopefully provide more answers.


No, not being thick at all but the understanding has changed in the last few years - it really is quite recently that endocrinologists looked at it and realised that it was perfectly possible to get a lot of the information they needed. And what that says is slightly different, they are talking about absolute values not changes in values.

Prednisolone is excreted from the body quite quickly and even when you are on fairly high doses after 24 hours the level present in the body will be quite low. Even so, if you try to estimate absolute values of cortisol you WILL get the wrong answer, it will be falsely high, but in the case of the synacthen test all it really means is that you are starting from a different baseline and what you are looking for is an increase from that baseline in response to the synacthen injection. There are figures for a "normal" change in the level and in someone with some pred already there that change will be different. As long as you bear that in mind it is perfectly possible to do the synacthen test and decide whether there is enough function there for the patient to be OK even without any dose of pred. For completeness you would then get your patient to complete their reduction to zero in their own time and then repeat the test to see how complete their adrenal function is. But older people usually do have poorer adrenal function than younger people.


Well thanks for bringing me up-to-date and explaining all that! I now understand.......or at least I think I do, considering the metal posts of my wall-hung washing line just attacked me on the head whilst sweeping all the leaves from under it!!


Yes I have and it was done while I was on 20mg Pred. As far as I was concerned it simply confirmed what I already knew (that I had no adrenal function). I am due another test in the middle of January and I am currently on 5mg Pred.

I think the information you found might be out of date? There didn't seem to be any problems with it for me, tedious but straightforward.


I thoroughly enjoyed myself, best 4 hours I ever spent in a hospital.

Went at 8am and took a book, sat down in a very comfortable chair and warm room. Opened my book read one page and fell asleep. They woke me up 3 hours later and said, 'Your done'.

I was off pred when the test was done, I had the test because I was still suffering from fatigue and my GP thought that the adrenals could be part of the problem. As it turned out they were fully functioning.

I have been advising people on the three forums I use to push for this test once down to 7.5mg and below and am very pleased that Leeds are doing it as part of a study.


I am still not clear - it *was* a blood test, wasn't it? Why do you have to go to hospital? How long did you stay in for? Is it painful?


You usually go to a hospital because they have facilities to do tests like this which require more than just taking a single sample of blood. They are looking at a baseline level of something in the blood, giving you a substance in an injection and then looking at the blood level a certain time afterwards to see if that baseline figure has changed. They often put in a cannula because they need to take a few samples of blood and it saves sticking several needles into your vein which doesn't do it any good at all.

So they do that and take a first sample of blood and then give you an injection into the vein through the cannula. Then they have to wait to take a blood sample again after half an hour. Sometimes they do another a couple of hours later as they did for Sambucca - and because there was a cannula in they didn't have to wake her up!

The timing is quite important so they want you to hang around not wander off to the coffee shop and forget to come back on time. They also don't want you getting all excited or drinking/eating things that might interfere with the test - you are in a controlled environment and they know what you have been doing.

In addition, when you are being given injections of many substances they like to keep an eye on you in case you react badly - it is very unlikely but even if only one person in 2,000 went off into town and came over all funny and needed an ambulance that is one person too many. You never know how a patient will react to such things - better to keep them where you can see them.

Sometimes a GP will do the test in the practice - but in the unlikely event of the patient being poorly as a result they would have to call an ambulance. Longer times and an extra, very expensive resource required - do it handy to the facilities and do a whole load at the same time. Then the lab gets the whole lot of bloods all at the same time and just has one batch to run through - instead of doing 2 today and 2 on Friday and 2 next week.

It isn't any more painful than having any sample of blood taken - just one needle put into the vein and taped in place, used a few times and then removed. It is a smallish needle - not a big one like they use for a drip and won't be in as long probably.


You go to hospital or a clinic because it is a long test on average 3 to 4 hours.

No you do not 'stay in'.

No it does not hurt at all. As I said I fell asleep.

There were about 8 or 10 comfortable armchairs and each chair had a person in it.


Thankyou all for taking the time to answer so fully. I really appreciate it. I am a lot wiser now.


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