Preparation for a Cortisol blood test - Thyroid UK

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Preparation for a Cortisol blood test

ATVMWF profile image
7 Replies

Hello all you helpful people. Just a quick question about blood tests to check Cortisol levels.

I have developed hyperpigmentation on my arms so G.P. wants me to have this test. Already have Hashis, vitiligo and Sjogrens and feel exhausted most of the time, although, better since introducing T3 18 months ago.

Test booked for 8.50 a.m. anything I need to do meds wise beforehand to prepare?

TIA

ATVMWF

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ATVMWF
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humanbean profile image
humanbean

Do you know the name of the test you are having?

...

It is essential for ALL blood tests that you avoid biotin for 3 - 7 days before any blood sample is taken. Check all your supplements to see if they contain biotin. The higher the dose the longer you should give it up before any testing.

If you are having just a straightforward cortisol blood test done at your GP surgery with no other tests then I'm not aware of any special preparation. Fasting is not usually required.

However, if you are going to be having a cortisol blood test as well as thyroid testing or any other blood tests then the conditions for, say, a thyroid function test, are not the same as for a cortisol test.

Ideally, thyroid testing is done having fasted overnight, and having not taken Levo for 24 hours, and not taking T3 / NDT for 8 - 12 hours, but for cortisol testing you really need to be acting as close to normal as possible for the results to be representative of your true cortisol.

In my opinion, I think that on this occasion your cortisol test should take precedence over any thyroid testing or any other testing, since thyroid testing can be repeated fairly easily, but cortisol testing is rarely done.

If your test is not just a simple cortisol test and is being done at a hospital...

Take note of any preparation mentioned in the following document...

This document, called the Endocrine Bible and aimed at doctors but useful for patients too, gives you information about preparation, how tests are carried out, and how results should be interpreted for the tests that hospital endocrinology departments carry out in UK hospitals.

imperialendo.co.uk/Bible201...

Read the Important Note at the end of page 2.

Read pages on 25 - 34 on "Suspected Cushing's Disease". I doubt all the tests are relevant to a first test, but they may be useful for later.

...

Another test that might be done - but is usually done when low cortisol is suspected rather than high - is the Short Synacthen Test on pages 68 - 70.

...

Apart from any preparation given in the Endocrine Bible, and avoiding biotin, I would suggest that you stick to going about your normal routine including eating, drinking, taking thyroid hormones, etc

ATVMWF profile image
ATVMWF in reply to humanbean

Hi humanbean,Think it is just a cortisol blood test, no thyroid tests but you know what they are like for slipping them in on you unawares. It is at the G.P surgery not hospital so unlikely to get any more than the basic tests on this occasion.

Just another question on biotin always a bit confused on this issue. I take the usual VitD and K2after advice on this forum but also Seabuckthorm Oil an Methylfolate, do they contain biotin, or is that only VitB12?

Thanks for help

A TV WF

humanbean profile image
humanbean in reply to ATVMWF

I take the usual VitD and K2after advice on this forum but also Seabuckthorm Oil an Methylfolate, do they contain biotin, or is that only VitB12?

Biotin and B12 are different nutrients. You will see the word "biotin" in the ingredient lists of any supplement containing it. You'll usually find it as a separate supplement, or as part of a B Complex, or as part of a hair and nails supplement.

For example, Thorne Basic B contains biotin and it is mentioned in the ingredient list as a separate thing:

thorne.com/products/dp/basi...

ATVMWF profile image
ATVMWF in reply to humanbean

Once again thanks. I will check the ingredients on all the supplements to double check. Personally I don't think I have Addisons, I think it is connected to Sjogrens.Sorry for delay in replying by the way, flying back from holiday and phone switched off.

CoeliacMum1 profile image
CoeliacMum1

I assume this cortisol test is just a before 9-10am blood test, I had this a year ago no preparation I was told.

I was also have various other tests so I fasted and timed my thyroid meds, (wasn’t asked too) as thyroid was being looked at too. I wasn’t supplementing with anything at the time so nothing else for me to do. I had to sit rested on a hospital bed for short time, and then nurse took all my tests, but there was a lot being taken myopathy panels rheumatoid, Lupus too as well as all basics and inflammatory markers and more, so no idea if this applies to just a cortisol test.

I have read these cortisol blood tests aren’t all they cracked up to be and saliva ones are more accurate, however depending on what they’re looking for there is synacthen test again a blood test but a couple as they test before, then actually inject steroids in and measure again at intervals over few hours, you should know if your having this test (I don’t think GPs run these in primary care) you must come off any steroid medication, or it will skew the test, although I’m told if having hrt utrogestan and gel/patch you’re ok to still take. I’ve got to come off my long lasting asthma medication (Fostair) for a week before but Ventolin is ok.

So my story I have hyperpigmentation on both lower arms patches on neck, although my GP says there’s a chance my blood sugar levels can cause this (mines normal in range, but often the high end towards pre diabetes’) along with sun damage can cause it I’m told. My old endocrinologist ran this basic cortisol test and my cortisol sat perfectly in a good range (I haven’t those results to share at present I’m not with my results).

Now a new endocrinologist is suggesting my main concern with musculoskeletal issues isn’t thyroid but could be adrenal problems, so ruling out Addison’s which is low levels after the other endo was thinking it was high… but both barking up the wrong tree I feel but going along with this and he’s added an insulin tolerance test.

I have 3 autoimmune conditions (Coeliac disease, Hashimoto’s and Pernicious anaemia) and asthma so in his words as I’m autoimmuny with these poly glandular issues and before doing anything else for the thyroid, he’s looking at this, actually it’s in couple of weeks. I definitely fit more Cushing than Addison’s, it really took me by surprise…hopefully after this he will get to my thyroid and back on track, thyroid tests are being taken too.

Can I ask how you was diagnosed with Sjögrens?

Was it by a rheumatologist?

I’m wondering if I’d get further sorting with my muscular skeletal issues by seeing rheumatologist, my last endocrinologist was talking about it, but retired … my GP might once exhausted these hormone issues.

I’m aware not everyone with Sjögren's syndrome has these antibodies, a bit like pernicious anaemia (PA), I’m told, I didn’t have antibodies for PA but told I have it regardless by GP and last endocrinologist.

ATVMWF profile image
ATVMWF in reply to CoeliacMum1

Hi CoeliacMumI was diagnosed via the usual tests; Schirmers eye test; scan of parotid glands; blood tests-antiRo&La. and lip biopsy. All positive apart from Anti Ro

I also have Raynauds, Hashis,Vitiligo and not diagnosed as Coeliac but GF as gluten causes lots of digestive issues for me.

Like you my tests for diabetes have sometimes been flagged up but the next test is OK, very odd!🤔

Interesting that you mention polyglandular issues as I am aware that there is a rare set of conditions known as APS, not to be confused with Hughes. Think it is called autoimmune polyglandular syndrome. I think one of the admins on this site is diagnosed. Likely that most doctors won't even consider it as a diagnosis because do rare. Only rare because they don't recognize it....😏

ATVMWF

CoeliacMum1 profile image
CoeliacMum1 in reply to ATVMWF

Thanks for reply and information 😊

I will pass this on to a friend, who is struggling to be diagnosed but had thought she has this condition, she does tick few boxes and even a physiotherapist has mentioned it re suffering joint pain, amongst other things.

Re glucose situation I have had various hypos since teenager but my levels been normal or high end so think just ruling something else out obviously insulin & cortisol play a big part in metabolic conditions and helping these areas helps others.

Hope your tests are ok.

Merry Christmas

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