Actually, caffeine pushes the adrenals to keep producing cortisol at high levels, and for adrenals that aren't functioning well, this can push them to very low levels of functioning.
And it depends on what type of a test a person has to check their adrenals. Blood tests are rarely performed properly. A saliva test, where there are 4 collection times in one day, is the most accurate - and may save you from serious adrenal issues.
Most doctors don't have a clue as to how to diagnose low adrenals, only when they are in the process of shutting down (Addisonian Crisis) - at which time your life is in danger - not just your health, but many things can be done long before they reach that point. For anyone that is interested in doing a few home tests for low adrenals and possibly ordering your own adrenal saliva test, see this page:
www.stopthethyroidmadness.com/adrenal-info/As for coffee and it's affect on adrenal glands, here are some articles that go into it a bit:
"What happens each time you drink a cup of coffee? Your brain sends a message to the pituitary gland, which releases a hormone that tells your adrenals to produce the stress hormones adrenaline and cortisol. In other words, you are triggering exactly the same kind of stress response that your body uses when you are in imminent physical danger."
adrenalfatiguesolution.com/caffeine/"Here’s the problem. Coffee stimulates the adrenal glands, which means that every time you drink coffee, you’re activating the body’s fight-or-flight response. But, instead of releasing adrenaline so the body can react to a true stressor, the adrenals are releasing this hormone in response to your coffee consumption.
What happens over time is that your adrenal glands start to burn out from overuse, which can lead to adrenal fatigue."
drjessechappus.com/the-impact-of-coffee-on-your-adrenal-glands/" Dr. Bruce Rind MD, a holistic endocrinologist whose talk focused on spotting and reversing thyroid and adrenal problems.
I learned from Dr. Rind that the health of the thyroid gland and the adrenal glands is inextricably linked. If one goes south, the other one probably will too and in very short order.
Adrenal problems can frequently masquerade as thyroid problems. As a result, if the adrenal glands are being stressed day in and day out by lack of sleep, too much sugar and caffeine in the diet and a rush rush lifestyle loaded with carbohydrate heavy processed foods, thyroid gland problems will eventually manifest along with the adrenal problems."
www.thehealthyhomeeconomist.com/6-little-known-signs-of-adrenal-fatigue/"Adrenal glands function to produce hormones essential to life. The adrenal medulla is the inner portion of the adrenal gland, and produces adrenaline and noradrenaline. The adrenal cortex is the outer portion of the adrenal gland, and produces cortisol, estrogen, progesterone and testosterone. Cortisol regulates other hormones, balances metabolism and manages immune function. Chronic stress, such as that incurred by daily consumption of caffeine, creates a situation of sustained high levels of cortisol."
www.livestrong.com/article/269199-caffeine-effects-on-the-adrenal-function/