Cortisol saliva vs blood serum

[Incoguto]

Hey all, Did anyone find out anywhere why some of us have high cortisol or normal in blood serum, but suboptimal in saliva? Potentially something to do with transporters, but for the life of me, I cannot find anything anywhere and I can't test CBG where I am (binding globulin for cortisol).

I have done an iron IV to see if it helps me with tolerating medication, but it doesn't seem to be the answer.

Next thing to check is cortisol.

My blood serum is top range, by saliva is low morning, then normal midmorning, the dipping to go up to normal afternoon and evening (59-65% range).

All my other cofactors, vits, ferritin are optimal, so I've ruled that out.

Thank you 😊

[TiggerMe Ambassador]

You're probably right about it being bound hence low frees... I would suggest you try dosing when your cortisol is in a good place rather than first thing to see if that helps with uptake 🤗

[Incoguto in reply to TiggerMe]

Thank you! Do you mean dosing when my cortisol is higher, e.g. 10 am rather than first thing? I take my dose in one go.

[TiggerMe Ambassador in reply to Incoguto]

I would give it a go cortisol is needed for good uptake, if you can work it around your eating times 🤗

Edit... If this helps then you might then want to try this option to realign your cortisol rhythm.... dosing during the night which for some kicks your cortisol into action earlier in the day.... paulrobinsonthyroid.com/the....

[TiggerMe Ambassador in reply to TiggerMe]

I've added a bit about CT3M 🤗

[Blissful]

The serum cortisol test is testing TOTAL cortisol whereas the saliva test shows FREE cortisol. I think you need the SHBG ( Sex Hormone Binding Globulin) test to determine the FREE cortisol element.

Many processes happen via the liver - (just speculating) - your iron IV may have transiently interfered with processes).

[Incoguto in reply to Blissful]

Thank you! My SHBG at the time of taking saliva test was just below midrange. Would this mean anything?My iron infusion was weeks after the saliva test.

[gabkad in reply to Incoguto]

Blissful is on the right track. Salivary cortisol is always free cortisol not bound to albumen or any other protein because large protein molecules can't get into saliva. It is probably better to stimulate saliva flow as well but the test instructions I've read don't tell the person to do that.

It says only about 5% of serum cortisol is free or unbound to proteins. If you check 1/20 of serum cortisol level to saliva cortisol level, how do they compare?

I f your doctor thinks total serum cortisol is equivalent to salivary cortisol, there is a gap in education. Your saliva cortisol needs to be multipled by about 20 to compare it to serum total cortisol. Then it might not appear so disparate.

This is along the same lines as measuring total T4 and free T4. Total is way way higher.

[andyjs2 in reply to gabkad]

I believe CBG (cortisol binding globulin) binds to cortisol and not SHBG.

From an article I just read:

“SHBG is a protein made by your liver. It binds tightly to 3 sex hormones found in both males and females. These hormones are estrogen, dihydrotestosterone (DHT), and testosterone. SHBG carries these 3 hormones throughout your blood.”

[annabianca in reply to andyjs2]

CBG is also called transcortin.

[Incoguto in reply to gabkad]

That's really interesting. So the ranges they have for salivary cortisol do they take it into account or not really?

[annabianca]

Blood cortisol is mostly a screening test. Excess (Cushings's) and insufficient (Addison's) cortisol require appropriate different tests. Milder forms of these conditions are extremely hard to diagnose, as the cortisol levels still overlap with the normal ranges.

Testing for free cortisol in the blood is complex and expensive. Salivary and urinary cortisol measure free cortisol, so, in many cases, these tests can be used if necessary. There are a few cases when doctor would like to have a quick way to test for free cortisol, usually in urgent care and this is still an issue, but apparently not important enough to develop appropriate standard testing.

The main issue with cortisol binding globulin is when it is low, either from genetic conditions or medical issues, as it can lead to a wrong diagnosis of adrenal insufficiency. High binding globulin should be compensate by the pituitay-adrenal axis. There could be some reasons for this to be inadequate, but this suboptimal regulation would be very hard to diagnose.