Thyroid UK
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Cortisol trsting

Hi could someone tell me the best way to privately tests cortisol binding globulin levels please? I want blood tests done (not saliva) that will tell me my cortisol plus the cbg levels because I'm suspecting my symptoms of low cortisol are caused by high cbg levels prob caused by high estrogen. I also can't seem to find private blood tests for free cortisol levels.

However I'm having difficulty determining the best way to test this. I'm going to do several tests over my monthly cycle to compare my 'well' days and 'unwell' days. I live in the UK.

Your help with this is much apreciated. Thankyou

7 Replies


Welcome to our forum.

Your logic is good but I haven't heard of this test being available privately in the UK. I don’t think it even conducted alongside a stim ACTH test (but others may be better informed ? ? ..) ...

...leading me to wonder if this is because of the supposedly modest amount of free cortisol required for well being. Also a small amount of cortisol (about quarter I think) binds to another large protein carrier called albumin (along with other hormones) indicating this would need to be tested as well.

Doctors focus on thyroid hormone because CBG goes down (leaving more free cortisol) as thyroid hormone becomes optimal. More cortisol is released from CBG as body temperature rises, and body temperature correlates positively with optimal thyroid levels. .... ..Or oestrogens as elevated levels will increase CBG together with SHBG & TBG (to an extent). Ask your GP to test sex hormones.


Addison’s Disease Network


Just for interesting info the link below discusses CBG receptors & gene polymorphisms that may show “normal” amounts of serum cortisol but giving the free a reduced ability to work in the tissues. Also CBG deficiency caused by insulin resistance or caloric restriction.


Hi Thankyou for your welcome and reply😊

Yes Iv never had it done alongside a stim test.

I am suspecting if I should do saliva to see my free cortisol levels, but I do prefer blood because I'm used to my cortisol being tested this way and understand the levels better. But my concern is I have the level by blood but I'm not actually seeing what I actually have free to use.

Please can you further explain...

When you say The supposedly modest amount of free cort for wellbeing

And the The thyroid cbg connection... As my thi Kings always been treat cortisol first thyroid second but from reading what you said it looks like treating thyroid first my help cortisol problems to.

Also I'm looking to monitor my free thyroids but am I wrong in believing that the levels don't change much in blood under 6 weeks? Because I'm also suspected high thyroid binding globulin again by estrogen and would like to see if these levels are changing throughout the month I'm trsting.

My menstrual cycle is 35 days long and my symptoms most definetly fluctuate during certain times. I'm going to order oestradiol and progesterone bloods to do throughout the 35 days alongside looking at cortisol and thyroid levels however I'm paying and it's costing a lot so I want to ensure I don't waste money or test the wrong things.

Many thanks



When the thyroid hormone has been low for many years and the adrenals glands become so compromised, there is thought they must be supported as thyroid hormone is replaced, or the hormone balance will be further divided as the metabolism increases.

It is a balance and we are all different so there is no laid down formula but optimal thyroid hormone will help improve adrenal health and will also optimise "free" cortisol so improving further health all round.

My GP stuck me on 100mcg Levo and over the following four years my already failing adrenals suffered further as did everything else !.

Serum blood will only measure the total cortisol but saliva measures the free and DHEA which must be kept in balance. The DHEA result can also give an indication of the advanced state of the adrenal fatigue. - link below

I read we actually only require a small amount of “free” to function well (with other balanced hormones). The larger “total” amount is like an emergency supply for when have ongoing stress or make too much when it then becomes a storage hormone (similar to T4). I also read that a high CBG can affect the cortisol response to ACTH as well as binding too much cortisol..

If you have bad or unusual periods, your GP should test oestrogen, progesterone and SHGB but if more comprehensive testing is required, you would (probably) have to pay…

I used Nordic Labs who gave me a really comprehensive overview including metabolism patterns of the three oestrogens, progesterone, testosterone and DHEA. Knowing this info has allowed me to supplement deficiencies and feel better.

Thyroid hormones take six weeks for the full affect to be felt. Therefore, it is unwise to test before.

If you click on the "reply" button, the person will be notified.


Saliva Stress Test (test ref END01)

Four saliva tests that measure the available "active" cortisol (& DHEA) secreted at set times over a 24 hours period. The results will allow you to see any imbalances in the daily circadian pattern so enabling use of correcting supplements to aid your adrenal health. Unfortunately this test is not generally used or recognised by GP's.

The cost is £77.00 which is a discounted price for THyroidUK when code A42AQ is used.


Private labs for thyroid testing


Thanks again..very informative..

Re the thyroid bloods, I'm not going to be taking any thyroxin.. I just want to monitor the changes in my thyroid over a 30 day period. To see if the free levels change. However I don't know if this can actually be done with thyroid bloods, if changes will show up as they would with say cortisol.

I want to basically find the best way to test my thyroid and cortisol several times during a 30 day period and be able to see what the free levels are and also if my tbg and cbg are higher therefore effecting my free levels...I will also measure my oestrogen levels to see if there is low frees on cortisol and thyroid on higher estrogen days which is what I'm suspecting.

Can you suggest an effective way to get these readings at all please?

Re the other hormones tests you done you say it showed metabolism patterns of these hormones, can you explain please what this means and what the results can show you?

Many thanks



My test was urine samples taken at specific times over 3 days.

In blood, I thought most hormones are bound to binding proteins and free hormone is not readily found in urine, except for cortisol and cortisone because they are more water soluble. (However, I read of some members using thyroid urine test so perhaps I am wrong here ? ) .

All hormones have to be manufactured, processed, converted (if applicable), directed and carried to the right part of the body. They are then excreted via urine (& faeces). If there is any part of the process that under//over performs, then all the rest will be out of balance.

For instance, I showed a low "total" cortisol level but my "free" was in range indicating slow cortisol clearance, by showing a falsely elevated "free" level in spite of low overall production.

Possible causes could be low thyroid hormone or a slow response between the HPA Axis, or when the body experiences a hormone excess (whether produced by the body or introduced by hormone therapy) and the liver can not physically process the hormone(s) quickly or efficiently enough.

Are you saying you are going to have bloods say, every few days for the duration of 30 ? ? ... .. Well, thyroid hormone is usually tested as total and free. It is useful to get FT3 which is the biological hormone.

The HPA axis is influenced by so many factors, I don’t know if this would give you accurate results as although roughly about 5 –10% of circulating cortisol is free, 75% is bound to CBG, and the remainder bound to albumin, cortisol can change back to its inactive form of cortisone.

Everything is further influenced by other sex hormones, thyroid hormones, possible thyroid antibodies effect on the immune system, elevated//deficient TBG, CBG and SHBG, eating//sleeping patterns, etc ...etc ..... .

SHGB elevates with high oestrogen and may additionally bind thyroid hormone but I don't know if this happens immediately ... say on days 1-14 of your cycle or whether it has a cumulative effect.

I consider a cortisol blood serum test is useful for measuring the adrenals ability in secreting hormones but a saliva test is better to ascertain if enough (or too much) “free” cortisol is available.

If you have a possible thyroid issue, post any test results complete with ranges (numbers in brackets) for members to comment .. (although perhaps not all 30 ..!! .. ... ;o))) ...) .. ..

You may be interested in the following links even if you don't have Hashimotos as they explain how thyroid function effects the menstrual cycle & vice versa.


Hashimotos and a Woman's Cycle.


Thyroid/Adrenal/Ovarian Systems



Thanks again

It's interesting about your cortisol tests for total and free, did you do blood for total and saliva for free and do them at same time? Coz this is something I want to find out... I then suppose this will in turn show me in another way if cbg is higher or lower looking at the differences between the total and free. I would prefer a direct measurement of cbg though.

I'm going to do the testing every two days from day 1 to day 35 and everyday during ovulation for about 4 days. I'm also going to do several cortisols on my days when I'm really unwell and when I'm feeling my best. On these days I would also like to test my thyroid to.

I've had many thyroids and cortisols ferritin etc done over the years but all are random days and I feel I will get a good picture hopefully of what's causing the changes in my symptoms over the month because I have a clear change in symptoms over certain times of the month.

I'm also wanting to test dheas and parathyroid but need to determine the best time to do these.

Do you think there Are any other things I should test during these days, I don't want to miss anything hormonaly wise.




Cbg testing is not available in the UK - my nutritionist checked for me. My cortisol is low even though my adrenals make enough of the stuff. The feedback I had was that. It might be due to excessive clearance of cortisol from my system by the liver. There are a variety of reasons for this including the use of steroids. All these findings came about following my taking a"DUTCH" adrenal test which measures cortisol, cortisone, Dhea and metabolites. Try googling it to find out more.


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