Your adrenal glands signal trouble through a specific set of symptoms and blood markers, not through vague tiredness alone. The most reliable way to know if they’re working is a morning blood cortisol test, where levels below 5 mcg/dL strongly suggest underactive adrenals and levels above 13 mcg/dL generally indicate normal function. But symptoms, physical signs, and follow-up testing all play a role in getting a clear answer.
What Your Adrenal Glands Actually Do
Your two adrenal glands sit on top of your kidneys and produce several hormones your body depends on. The outer layer (cortex) makes cortisol, which regulates blood sugar, metabolism, inflammation, and your stress response. It also produces aldosterone, a hormone that controls sodium and potassium balance in your blood. The inner layer (medulla) releases adrenaline during stressful moments to trigger the fight-or-flight response.
Cortisol production follows a chain of command. Your brain’s hypothalamus sends a signal to the pituitary gland, which then releases a hormone called ACTH that tells the adrenals to produce cortisol. Once cortisol levels rise high enough, the hypothalamus gets the message and stops sending signals. This feedback loop keeps cortisol levels in a healthy range throughout the day, peaking in the early morning and dropping to their lowest point around midnight.
Symptoms That Point to Underactive Adrenals
Adrenal insufficiency, where the glands don’t produce enough cortisol, causes a recognizable pattern of symptoms. The most common are chronic fatigue that doesn’t improve with rest, muscle weakness, loss of appetite, and unexplained weight loss. Abdominal pain, nausea, vomiting, and diarrhea are also frequent complaints.
Beyond these core symptoms, low adrenal output can cause blood pressure that drops when you stand up, leading to dizziness or fainting. You might notice strong cravings for salty foods (a sign your aldosterone is low), irritability, depression, joint pain, low blood sugar episodes, irregular periods, or reduced interest in sex. In Addison’s disease, the most severe form, skin darkening appears on scars, skin folds, elbows, knees, knuckles, lips, and the inside of the cheeks. That darkening happens because excess ACTH, which the pituitary keeps pumping out when cortisol stays low, stimulates pigment-producing cells in the skin.
Signs of Overactive Adrenals
Adrenal glands can also produce too much cortisol, a condition called Cushing’s syndrome. The symptoms look very different from insufficiency: weight gain concentrated in the face, upper back, and abdomen, while arms and legs stay thin. Purple stretch marks on the skin, easy bruising, slow wound healing, high blood sugar, high blood pressure, and thinning skin are hallmarks. Women may notice excess facial hair or irregular periods; men may experience reduced fertility.
The Morning Cortisol Blood Test
The first step your doctor will likely order is a simple blood draw between 7 and 9 AM, when cortisol naturally peaks. Normal morning cortisol falls in a broad range of 5 to 25 mcg/dL, which is part of why a single reading isn’t always conclusive. A morning level below 3 mcg/dL is a strong indicator of adrenal insufficiency according to Endocrine Society guidelines. Values below 5 mcg/dL are considered highly suspicious. On the other end, a level above 13 mcg/dL generally rules out insufficiency.
The tricky zone is between 5 and 13 mcg/dL. Stress, exercise, food intake, sleep quality, and medications can all shift your cortisol reading. If your result lands in this gray area, your doctor will move to a more definitive test.
The ACTH Stimulation Test
This is the gold standard for confirming whether your adrenal glands can respond to demand. A baseline blood sample is drawn, then you receive an injection of synthetic ACTH, the hormone that normally tells your adrenals to produce cortisol. Blood is drawn again at 30 and 60 minutes to see how your adrenals responded.
A peak cortisol level above 18.1 mcg/dL (500 nmol/L) at either the 30 or 60 minute mark means your adrenals are producing cortisol appropriately, and insufficiency is effectively ruled out. A response that falls short of that threshold confirms inadequate adrenal function. The test has about 92% sensitivity for detecting primary adrenal insufficiency, making it the most reliable single diagnostic tool available.
Testing for Excess Cortisol
If the concern is too much cortisol rather than too little, different tests apply. A late-night salivary cortisol test takes advantage of the fact that cortisol should be at its lowest around 11 PM to midnight. You collect a saliva sample at that time, and levels above roughly 1.15 mcg/L suggest abnormal cortisol production. This test is highly accurate for detecting Cushing’s syndrome when timed correctly.
A 24-hour urine collection measures total cortisol output over a full day, smoothing out the natural fluctuations that make a single blood draw less reliable. Your doctor may also use a dexamethasone suppression test, which checks whether your feedback loop is working. You take a small dose of a synthetic steroid at night, and your cortisol is measured the next morning. In a healthy system, the synthetic steroid should signal the brain to stop cortisol production, bringing levels down. If cortisol stays elevated, something is overriding the normal feedback.
Clues From Routine Blood Work
A standard metabolic panel can reveal indirect signs of adrenal dysfunction even before specific hormone tests are ordered. Low sodium (hyponatremia) and high potassium (hyperkalemia) together are a classic pattern in adrenal insufficiency, because low aldosterone means your kidneys can’t properly excrete potassium or retain sodium. Normal potassium runs between 3.5 and 5.1 mmol/L, and values pushing above that range alongside low sodium should prompt further investigation. Low blood sugar readings on routine labs can also point toward insufficient cortisol, since cortisol helps maintain blood glucose between meals.
A Simple Check You Can Do at Home
While no home test replaces lab work, checking your blood pressure response to standing can offer a rough clue. Lie down for five minutes, take your blood pressure, then stand and measure again after two to three minutes. Normally, your blood pressure stays about the same or rises slightly when you stand. A drop of 20 points or more in the top number (systolic), or 10 points or more in the bottom number (diastolic), defines orthostatic hypotension. This pattern has many possible causes, but when combined with fatigue, salt cravings, and weight loss, it adds weight to the possibility of low adrenal function.
Medications That Affect Test Results
Several common medications can throw off adrenal testing. Birth control pills raise a protein that binds cortisol in the blood, making total cortisol levels appear artificially high. Corticosteroids, whether taken as pills, inhalers, creams, or injections, suppress your natural cortisol production and can make your adrenals appear underactive even when the glands themselves are healthy. Antiseizure medications can also alter results. If you’re on any of these, your doctor may ask you to stop them temporarily before testing, or will account for their effects when interpreting your numbers.
Why “Adrenal Fatigue” Is Not a Diagnosis
If you’ve searched online for adrenal symptoms, you’ve probably encountered the term “adrenal fatigue,” a proposed condition where chronic stress supposedly wears out your adrenal glands until they can’t keep up. The Endocrine Society, the leading professional organization for hormone specialists, has stated clearly that no scientific proof supports adrenal fatigue as a real medical condition. There is no validated test for it, and the saliva panels marketed by some alternative practitioners are not backed by good scientific studies.
This matters because accepting an unproven label can delay finding the actual cause of your symptoms. Chronic fatigue, weakness, and depression overlap with dozens of real, treatable conditions: thyroid disorders, sleep apnea, iron deficiency, depression, diabetes, and genuine adrenal insufficiency among them. The symptoms are real. The explanation just needs to come from proper testing rather than a category that lacks diagnostic criteria.
What Testing Typically Looks Like
If you bring these concerns to your doctor, expect a stepwise process. A morning cortisol level and basic metabolic panel are usually first. If morning cortisol is clearly normal (above 13 mcg/dL) and your electrolytes look fine, adrenal insufficiency is unlikely and your doctor will look at other explanations for your symptoms. If cortisol is low or borderline, an ACTH stimulation test follows. Depending on those results, imaging of the adrenal glands or pituitary gland may be ordered to identify the underlying cause, whether that’s an autoimmune process attacking the adrenals, a pituitary tumor affecting ACTH production, or damage from long-term steroid use.
The entire workup from first blood draw to a confirmed diagnosis typically takes a few weeks, depending on how quickly tests can be scheduled and whether results fall in a clear or ambiguous range.