What Causes Adrenal Insufficiency Unveiling the Mystery
Adrenal insufficiency happens when cortisol stays too low from adrenal damage or low ACTH signals. Learn causes, tests, and care options—no referral.
Adrenal insufficiency is when your body cannot make enough cortisol, the hormone that helps you keep your blood pressure, blood sugar, and stress response steady. The “mystery” usually comes down to one of two problems: your adrenal glands are damaged, or the brain signals that tell them to work are too weak. If you have been feeling wiped out, lightheaded, nauseated, or like you “crash” after minor illnesses, it can be scary because the symptoms are real but not specific. This guide walks you through what adrenal insufficiency feels like, what commonly causes it (including steroid medication withdrawal), how doctors confirm it with the right timing of tests, and what treatment looks like day to day. If you want help sorting symptoms and next steps quickly, PocketMD can help you prepare questions for your clinician, and VitalsVault labs can support the diagnostic workup when testing is appropriate.
Symptoms and signs that point to low cortisol
Deep fatigue that rest doesn’t fix
This is not just “tired.” With low cortisol, your body has trouble keeping energy available between meals and during stress, so you can feel drained from the moment you wake up. You might notice you can push through one day, but then you pay for it with a hard crash the next.
Dizziness when you stand up
Cortisol helps your blood vessels respond to standing, and another adrenal hormone called aldosterone helps you hold onto salt and water. When either is low, your blood pressure can drop when you get up, which can make you see stars or feel like you might faint. If you actually pass out, or you cannot keep fluids down, that needs urgent medical attention.
Nausea, belly pain, or poor appetite
Low cortisol can make your gut feel “off,” which can show up as nausea, cramping, or a sudden lack of appetite. The tricky part is that stomach bugs can also trigger a dangerous worsening of adrenal insufficiency, so persistent vomiting is a big deal. If you have known adrenal insufficiency and you are vomiting or have severe diarrhea, you may need emergency steroid dosing and IV fluids.
Unexplained weight loss and weakness
When cortisol is low, your body struggles to maintain normal metabolism and muscle function, so you can lose weight without trying and feel weaker than usual. You may notice stairs feel harder or your legs feel shaky after routine activity. This matters because weakness can worsen quickly during infections or after surgery if cortisol is not replaced.
Skin darkening in scars or creases
If the problem starts in the adrenal glands themselves, your brain often responds by sending louder “work” signals (ACTH), and that signal can also stimulate skin pigment. You might see darker knuckles, gums, or old scars, even without extra sun exposure. That clue points more toward primary adrenal insufficiency (Addison disease) than steroid withdrawal or pituitary causes.
If you’re evaluating fatigue, low blood pressure, or suspected hormone issues, VitalsVault lab ordering can support your workup
starting from $99 panel with 100+ tests, one visit
Results in days
Clear next steps
HSA / FSA
What causes adrenal insufficiency (and who is at risk)
Autoimmune damage to the adrenal glands
The most common cause of primary adrenal insufficiency is when your immune system mistakenly attacks your adrenal glands. Over time, the glands cannot make enough cortisol, and they often cannot make enough aldosterone either, which is why salt cravings and low blood pressure can be prominent. People with other autoimmune conditions, like thyroid disease or type 1 diabetes, have a higher chance of this pattern.
Stopping steroids too quickly
If you have taken steroid medicines like prednisone, dexamethasone, or high-dose inhaled steroids for a while, your brain can “turn down” its own cortisol signaling because it senses steroids already in your system. When steroids are reduced too fast, your body may not restart cortisol production in time, which can leave you feeling awful and, in severe cases, dangerously ill. This is one reason taper plans matter, even when you are eager to be done with the medication.
Pituitary or brain signaling problems
Sometimes the adrenal glands are capable, but the signal from your pituitary gland (a small hormone center at the base of your brain) is too low. This is called secondary adrenal insufficiency, and it can happen after pituitary tumors, surgery, radiation, or bleeding into the gland. Because aldosterone is usually preserved, you may have fewer salt-and-water symptoms, which can make the condition easier to miss.
Infections, bleeding, or infiltration of the adrenals
Less commonly, the adrenal glands can be damaged by infections like tuberculosis, by bleeding into the glands during severe illness, or by diseases that infiltrate the tissue. These causes often come with other clues, such as a recent ICU stay, blood thinner use, or symptoms pointing to a chronic infection. The “so what” is urgency: adrenal failure from bleeding or severe infection can progress quickly and needs rapid treatment.
Cancer or certain medications affecting adrenal function
Cancers that spread to the adrenal glands can reduce hormone production, and some newer cancer immunotherapies can trigger autoimmune hormone problems. A few medications can also interfere with cortisol production or speed up cortisol breakdown, which can unmask borderline adrenal function. If symptoms started after a new medication or cancer treatment, it is worth bringing a full medication list to your clinician so they can connect the dots.
How adrenal insufficiency is diagnosed
Morning cortisol and ACTH blood tests
Cortisol follows a daily rhythm, so a morning blood draw is often the first step. A very low morning cortisol can strongly suggest adrenal insufficiency, while a borderline result usually needs confirmatory testing. Measuring the brain signal at the same time (ACTH) helps sort whether the issue is in the adrenal glands or in the pituitary signaling.
ACTH stimulation test (cosyntropin test)
This test checks whether your adrenal glands can respond when they are “asked” to make cortisol. You get a small dose of synthetic ACTH (cosyntropin), and cortisol is measured before and after to see if it rises appropriately. It is one of the clearest ways to confirm the diagnosis, especially when symptoms are significant but baseline labs are not definitive.
Electrolytes, glucose, and renin/aldosterone
Low sodium, high potassium, and low blood sugar can show up when adrenal hormones are low, and they help explain why you feel weak, shaky, or lightheaded. Renin and aldosterone testing can show whether your salt-and-water hormone system is affected, which is especially important in primary adrenal insufficiency. These results also guide treatment choices, because replacing aldosterone is a different medication than replacing cortisol.
When to treat as an emergency
If you have severe weakness, confusion, fainting, severe belly pain, or you cannot keep fluids down—especially with fever or infection—this can be an adrenal crisis. In that situation, clinicians often treat first with IV steroids and fluids and confirm the diagnosis after you are stable, because waiting can be dangerous. If you already carry an emergency steroid plan, this is the moment to use it and seek emergency care.
Treatment options that replace what your body is missing
Daily cortisol replacement
The core treatment is replacing cortisol with a steroid medicine in doses designed to mimic what your body would normally make. The goal is to feel steady—able to get through the day without crashes—without taking more than you need. Your clinician will adjust dosing based on symptoms, weight, blood pressure, and how you respond during stress.
Stress dosing during illness or surgery
When you are sick, injured, or having a procedure, your body normally makes extra cortisol, and adrenal insufficiency means you cannot do that on your own. “Stress dosing” is a planned temporary increase in steroid dose to prevent a crisis, and it is one of the most important skills to learn early. Having a written plan reduces panic because you know exactly what to do when fever, vomiting, or surgery happens.
Aldosterone replacement for primary disease
If your adrenal glands cannot make enough aldosterone, you may need a medication that helps your kidneys hold onto salt and maintain blood pressure. This can reduce dizziness, salt cravings, and dehydration that keeps coming back. Your clinician may monitor blood pressure and electrolytes to fine-tune the dose, because too little and you feel faint, but too much can raise blood pressure.
Emergency injection and medical ID
Many people with confirmed adrenal insufficiency are prescribed an emergency steroid injection for situations where you cannot take pills, such as vomiting. Wearing a medical ID and keeping an emergency kit where others can find it can be lifesaving, because in a crisis you may not be able to explain what is happening. This is not about being dramatic—it is about buying time until you can get IV fluids and care.
Treating the underlying cause when possible
If adrenal insufficiency is caused by steroid withdrawal, the plan may focus on a safer taper and supporting recovery of your body’s own hormone signaling. If the cause is pituitary disease, treating the pituitary problem can improve hormone output, although replacement is still often needed. When autoimmune disease is the cause, replacement therapy is usually long-term, and the focus shifts to consistent dosing and preventing crises.
Living with adrenal insufficiency day to day
Build a “sick day” routine now
It is much easier to follow a stress-dose plan when you are not already miserable. Ask your clinician for clear instructions for fever, stomach illness, and injuries, and keep them in your phone and on paper. Practice what you would do if you woke up vomiting, because that is when decision-making gets hardest.
Notice patterns that suggest under- or over-replacement
If you are consistently lightheaded, craving salt, or crashing in the afternoon, your dosing schedule may need adjusting. On the other hand, if you feel wired, have trouble sleeping, or are gaining weight quickly, you may be taking more steroid than your body needs. The point is not perfection—it is learning your body’s signals so you can have a more productive conversation at follow-up visits.
Plan for travel, work, and exercise
Travel and long workdays are doable, but you need redundancy because missed doses can hit hard. Carry extra medication in more than one place, and keep your emergency injection accessible rather than buried in luggage. With exercise, start slower than your ego wants, because your body may need time to relearn how to handle physical stress without a normal cortisol surge.
Support your blood pressure and hydration
Many people feel better when they are intentional about fluids, especially in heat or during stomach illness. If you have primary adrenal insufficiency, your clinician may also recommend specific salt strategies based on your blood pressure and labs. The practical takeaway is simple: when dizziness is part of your story, hydration is not optional—it is part of treatment.
Prevention and risk reduction (when you can’t prevent it entirely)
Use steroid medicines thoughtfully
Steroids can be lifesaving, but long courses or high doses can suppress your body’s own cortisol system. If you need steroids, ask early about the lowest effective dose and the expected taper plan, because that is where many preventable cases start. Never stop long-term steroids abruptly unless a clinician tells you to.
Prevent crises with early action during illness
Most adrenal crises are triggered by infections, vomiting, or dehydration that escalates. Treating fever, increasing fluids, and using your stress-dose plan early can keep a rough day from turning into an emergency. If you cannot keep medication down, that is your cue to use the emergency plan and seek urgent care.
Screen for related autoimmune conditions
If your adrenal insufficiency is autoimmune, other hormone glands can be involved over time. Periodic checks for thyroid function, blood sugar changes, and vitamin deficiencies can catch problems before they become a second mystery. This is less about “more tests” and more about not ignoring new symptoms that don’t fit your usual pattern.
Keep your plan visible to others
Adrenal insufficiency is one of those conditions where the right information in the wrong place does not help you. Share your emergency instructions with a partner, friend, or coworker you trust, and make sure they know where your injection kit is stored. In a true crisis, that preparation can matter more than any single lab result.
Frequently Asked Questions
What is the most common cause of adrenal insufficiency?
For primary adrenal insufficiency, the most common cause is autoimmune damage to the adrenal glands. For secondary adrenal insufficiency, a very common cause is suppression from steroid medications taken for weeks to months. Which one applies to you depends on your ACTH level and how your adrenal glands respond on stimulation testing.
Can stopping prednisone cause adrenal insufficiency?
Yes, especially if you have been on moderate-to-high doses or you have taken it for a long time. Your brain can reduce its own cortisol signaling while you are on steroids, and it may not restart fast enough when the medication is stopped. A taper plan is meant to give your body time to wake that system back up.
How do you know if it’s adrenal insufficiency or just stress and burnout?
Burnout can feel intense, but adrenal insufficiency often brings physical clues like low blood pressure when standing, low sodium, low morning cortisol, or symptoms that worsen sharply with illness. The only way to be sure is targeted testing done at the right time of day, often followed by an ACTH stimulation test. If you are having fainting, confusion, or persistent vomiting, treat it as urgent rather than assuming it is stress.
What labs are used to diagnose low cortisol?
A morning cortisol level is usually the starting point, and ACTH measured at the same time helps identify whether the problem is in the adrenal glands or in the brain signaling. Many clinicians confirm with an ACTH stimulation test, which checks whether cortisol rises appropriately after stimulation. Electrolytes and glucose often add helpful context because they show how low cortisol is affecting your body.
Is adrenal insufficiency curable?
Sometimes it improves, such as when it is caused by steroid suppression and your hormone signaling recovers over time. Primary adrenal insufficiency from autoimmune adrenal damage is usually lifelong, but it is very treatable with consistent hormone replacement and a clear stress-dose plan. The biggest quality-of-life shift often comes from learning how to prevent adrenal crisis during illness.