My Saliva Vs. Serum Cortisol Results

[sue1234]

I had mentioned a few weeks ago I was testing my saliva cortisol to see what's up. I had had some odd serum cortisol results last spring, so I was testing saliva to see if they correlate. Well, they really are almost polar opposites!

Serum:

cortisol a.m. 23 (5-25) (close, but guessing here on range)

ACTH a.m. 52 (5-60) (again, close but guessing on range)

I thought that was kind of odd to have an almost high cortisol, and the ACTH was high, too. Normally if one is high the other is low, and vice-versa.

Urine:

cortisol, 24 hr. 9.3 (3.5-45)

The urine seems to be on the low end, while serum is on the high end. I don't understand this. So, I decided to do a late-night saliva. It is a test that IS accepted by main-stream medicine in the help of diagnosing Cushing's disease. I felt like I was sitting close to it.

The salivary test comes in 4x a day testing (morning, noon, afternoon, late night). Well, because I was concerned about late-night, I tested my morning as usual, but all 3 of the remaining ones I did on different late nights. These are my results:

Saliva:

morning 3.4 (3.7-9.5)

night1 .3 (.4-1.0)

night2 .4

night3 .3

At least I was consistent at night!! I did NOT tell the lab that I had altered my test-taking time, so it looks like they didn't alter anything either. So, in blood I look like I'm almost high cortisol, yet on urine and saliva, I look low (especially saliva---low on all four tests).

Any ideas?

****I just edited the saliva night range to .4-1.0. I originally had .04-1.0, which was wrong.

[Bex]

Hi Sue

I'm a trainee clinical biochemist working in a pathology lab in the UK, so hopefully I will be able to give you some clues on what your results mean. We have different reference ranges and work in different units over here, but based on the ranges you have given I should be able to figure it out.

Your results look perfectly normal to me. I'm not sure exactly what you mean when you say you had some odd serum cortisol results in the past, but these results (urine, serum and saliva) are all within the reference ranges you have given. A person with Cushing's syndrome will usually have markedly abnormal results in at least one of these tests. No one test is 100% sensitive and specific for the diagnosis of Cushing's, so a combination of tests is usually required. A dexamethasone suppression test is usually one of the typical tests requested to rule out Cushing's. If you are particularly worried, I would suggest you have one of these done. However, I am almost 100% certain this would come back as normal.

As for your reference to the relationship between ACTH and cortisol, ACTH is released by the pituitary under the influence of CRH, which is released by the hypothalamus. ACTH drives the synthesis of cortisol in the adrenal glands. Cortisol has a negative feedback effect on the synthesis of ACTH, so you are right in saying that (in a healthy individual) if cortisol is high, ACTH should be low. However, if ACTH is high, it is not necessarily the case that cortisol should be low.

Cushing's DISEASE is caused by a pituitary tumour which secretes ACTH. This drives the adrenal glands to produce more and more cortisol - therefore, in this case both ACTH and cortisol will be high.

Cushing's SYNDROME is used to refer to any condition which increases the concentration of cortisol in the bloodstream (this can also, confusingly, refer to Cushing's DISEASE). Cushing's syndrome not caused by a pituitary tumour (i.e. not Cushing's DISEASE) can refer to adrenal tumours which secrete cortisol, adrenal hyperplasia, or other tumours which secrete ACTH (known as ectopic ACTH). In these cases (adrenal tumour, hyperplasia or ectopic ACTH), cortisol will be high, but due to the negative feedback effect of cortisol on the synthesis of ACTH, ACTH will be low.

I hope this has clarified your understanding of cortisol and ACTH, and therefore the relevance of your results. In interpretation of cortisol results (especially serum cortisol), you have to remember that the concentration is very variable, and depends on many factors, such as how stressed you are at the time of sampling. Also, when considering a diagnosis of Cushing's, you should also remember that depression, obesity and alcohol can give results that point to Cushing's - this is known as "pseudo-Cushing's".

Hope this has helped

Bex