Adrenal insufficiency is a condition where your adrenal glands don’t produce enough of the hormones your body needs to regulate blood pressure, metabolism, and stress responses. It affects roughly 300 out of every million people. The condition ranges from mild and manageable with daily medication to life-threatening during an acute crisis, but with proper treatment most people live full, active lives.
The Three Types of Adrenal Insufficiency
Your body produces cortisol through a chain of command: the hypothalamus in your brain signals the pituitary gland, which signals the adrenal glands (small organs sitting on top of your kidneys) to release cortisol. Adrenal insufficiency can result from a breakdown at any point in that chain, and where the problem occurs determines which type you have.
Primary adrenal insufficiency (also called Addison’s disease) means the adrenal glands themselves are damaged. Because the glands are directly affected, you lose production of both cortisol and aldosterone, a hormone that controls sodium and potassium balance. This distinction matters because it leads to symptoms the other types don’t cause, like severe salt cravings, high potassium levels, and skin darkening.
Secondary adrenal insufficiency stems from the pituitary gland failing to send enough of its signaling hormone to the adrenals. The adrenal glands are structurally fine but don’t receive the message to work. Because aldosterone production is controlled through a separate pathway, it stays largely intact. This is the more common form, with hospital admission rates nearly three times higher than primary adrenal insufficiency.
Tertiary adrenal insufficiency originates one step further back, at the hypothalamus. The most common cause, by far, is the use of steroid medications like prednisone. When you take these drugs for an extended period, your hypothalamus dials down its signaling because external steroids are doing cortisol’s job. If you stop the medication abruptly, the whole chain can’t restart quickly enough.
What Causes It
In developed countries, up to 90% of primary adrenal insufficiency cases are autoimmune. Your immune system produces antibodies that attack the adrenal cortex, the outer layer of the gland responsible for hormone production. This destruction is gradual, and symptoms often don’t appear until about 90% of the cortex is damaged. Less commonly, infections like tuberculosis, tumors in the adrenal glands, or genetic conditions such as X-linked adrenoleukodystrophy can be the cause.
Secondary adrenal insufficiency typically results from pituitary tumors, pituitary surgery, or radiation to the head. Tertiary adrenal insufficiency is overwhelmingly caused by steroid medications, and it’s the fastest-growing form. Hospital admissions for secondary and tertiary adrenal insufficiency rose by nearly 92% over a recent study period, driven largely by widespread steroid prescribing.
Steroid Medications and Adrenal Suppression
Many people don’t realize how quickly steroid medications can suppress your body’s natural cortisol production. Taking 20 mg or more of prednisone (or an equivalent dose of another steroid) daily for more than three weeks will probably suppress the system. Even doses under 5 mg per day have been shown to alter adrenal function in some people, and treatment lasting less than four weeks can do it too. After about four to six weeks of insufficient signaling, the cortisol-producing layers of the adrenal gland begin to physically shrink, making recovery slower.
This is why doctors taper steroid doses gradually rather than stopping all at once. A typical tapering schedule can stretch over weeks or even months, with progressively smaller reductions as you approach lower doses. The final steps, going from 5 mg down to zero, often require the smallest decreases (0.5 mg at a time) over two to four weeks per step.
How It Feels
The symptoms of adrenal insufficiency are notoriously vague, which is one reason diagnosis is often delayed. Fatigue is the hallmark complaint, but not ordinary tiredness. People describe a bone-deep exhaustion that sleep doesn’t fix. Other common symptoms include unintentional weight loss, nausea, vomiting, abdominal pain, muscle and joint aches, and dizziness when standing up.
Primary adrenal insufficiency has a few distinctive signs. Hyperpigmentation, a darkening of the skin especially in skin creases, scars, gums, and areas exposed to friction, occurs because the pituitary overproduces its signaling hormone in an attempt to stimulate the failing adrenals. That same hormone triggers pigment-producing cells. Salt cravings are another hallmark, driven by the loss of aldosterone and the resulting sodium wasting through the kidneys. Some people also develop vitiligo, patches of skin that lose their pigment entirely.
Low blood pressure is common across all types, though it tends to be more severe in primary adrenal insufficiency. Cortisol normally helps your blood vessels respond to the hormones that maintain blood pressure. Without enough cortisol, vessels become less reactive, and blood pressure drops, particularly when you stand up quickly. Psychiatric symptoms, including depression and difficulty concentrating, are also well-documented.
How It’s Diagnosed
The first step is usually a morning blood draw for cortisol, taken between 8 and 9 a.m. when cortisol naturally peaks. A level below 3 micrograms per deciliter strongly suggests adrenal insufficiency. A level above 14.5 micrograms per deciliter generally indicates normal function. Values in between are inconclusive and require further testing.
The standard confirmatory test is the ACTH stimulation test. You receive an injection of synthetic ACTH, the pituitary hormone that tells your adrenals to produce cortisol. Blood is drawn at 30 and 60 minutes afterward. If your cortisol rises to at least 18 micrograms per deciliter, adrenal insufficiency is effectively ruled out. A peak below that threshold confirms the diagnosis. During pregnancy, the cutoff values are higher, rising from 25 micrograms per deciliter in the first trimester to 32 in the third.
To distinguish primary from secondary adrenal insufficiency, doctors also measure ACTH itself. In primary adrenal insufficiency, ACTH levels are high because the pituitary is working overtime trying to stimulate damaged adrenals. In secondary adrenal insufficiency, ACTH levels are low or inappropriately normal, pointing to the pituitary as the source of the problem.
Daily Treatment
Treatment replaces the hormones your body can’t make on its own. For cortisol replacement, the Endocrine Society recommends 15 to 25 mg of hydrocortisone daily, taken in divided doses to mimic the body’s natural rhythm, with the largest dose in the morning and smaller doses later in the day. Some people do well on the lower end, while others need up to 30 mg. The effective range across individuals varies roughly sevenfold, from about 4 to 30 mg, which is why finding the right dose requires careful adjustment based on how you feel, your energy levels, and your weight.
People with primary adrenal insufficiency also need a mineralocorticoid replacement to compensate for lost aldosterone. The standard starting dose of fludrocortisone is 0.1 mg daily, which can be increased to 0.2 mg. If it causes high blood pressure, the dose is reduced. This medication helps your kidneys retain sodium and maintain blood pressure. People with secondary or tertiary adrenal insufficiency typically don’t need it because their aldosterone production remains intact.
Getting the dose right is a balancing act. Too little replacement leaves you fatigued, nauseated, and at risk for a crisis. Too much can cause weight gain, high blood sugar, bone thinning, and other effects of excess cortisol over time.
Adrenal Crisis
An adrenal crisis is the most dangerous complication and the reason everyone with adrenal insufficiency needs an emergency plan. It can be triggered by illness, surgery, injury, severe emotional stress, or missed medication doses. The body’s cortisol demand spikes during these situations, and if the adrenals can’t meet it, things deteriorate fast.
Early signs include worsening fatigue, nausea, vomiting, abdominal or back pain, dizziness, and fever. Without treatment, these can progress within hours to dangerously low blood pressure, confusion, loss of consciousness, and shock. Emergency treatment involves an injection of 100 mg hydrocortisone given intravenously or intramuscularly, followed by 200 mg over the next 24 hours.
People with adrenal insufficiency are typically taught “sick day rules,” which involve doubling or tripling their oral hydrocortisone dose during illness or physical stress. Many also carry an emergency injection kit for situations where they can’t keep oral medication down due to vomiting. Wearing a medical alert bracelet ensures that emergency responders know about the condition if you’re unable to communicate.
Living With Adrenal Insufficiency
Most people with adrenal insufficiency take their medication two or three times a day and lead relatively normal lives. The biggest adjustments tend to be logistical: always carrying medication, planning for travel across time zones, and learning to recognize the early signs that your body needs more cortisol. Exercise is not only safe but encouraged, though some people find they need a small extra dose before intense physical activity.
Stress dosing becomes second nature over time. A mild cold might call for doubling your dose. A stomach bug with vomiting might require your emergency injection. Surgery or a major injury means your medical team will administer higher doses through an IV. The goal is always the same: matching your cortisol intake to what a healthy body would produce under the same circumstances.
Fatigue remains the most persistent quality-of-life issue, even with optimized treatment. Current replacement strategies, while effective at preventing crises, don’t perfectly replicate the body’s minute-to-minute cortisol fluctuations. Newer formulations designed to release hydrocortisone more gradually are an option some people explore with their endocrinologist to better match the body’s natural cortisol curve.