Adrenal Insufficiency Explained

Adrenal insufficiency is the broad term for the adrenal glands not making enough of certain essential hormones, chiefly cortisol. Because cortisol supports energy, blood pressure, and the body's response to stress, a shortage can cause vague but important symptoms. Blood tests are central to recognising it, and identifying the underlying cause guides care.

What adrenal insufficiency is

The adrenal glands are two small, triangular glands that sit one above each kidney. Their outer layer produces cortisol, a hormone that helps regulate blood sugar, blood pressure, and the way the body copes with stress and illness. The same region also makes aldosterone, which helps the body balance sodium, potassium, and fluid, and it contributes androgen precursors. In adrenal insufficiency, the supply of one or more of these hormones falls below what the body needs, and the consequences depend on which hormones are affected and how severely.

Clinicians describe the condition by where the problem lies, because this shapes both the symptoms and the testing. In primary adrenal insufficiency, the adrenal glands themselves are damaged and cannot respond even when the body signals them strongly; Addison's disease is the best-known primary cause, and both cortisol and aldosterone are commonly affected. In secondary adrenal insufficiency, the adrenal glands are intact but the pituitary gland does not release enough adrenocorticotropic hormone (ACTH) to stimulate them, so cortisol falls while aldosterone is usually preserved. A closely related situation, sometimes grouped as tertiary, is suppression of the hypothalamic signal that drives the pituitary; this is most often seen after long courses of glucocorticoid medicine, especially when such medicine is stopped abruptly. A sudden, severe shortage of cortisol, called an adrenal crisis, is a medical emergency.

Common signs and symptoms

Symptoms usually develop slowly and can be easy to overlook, because tiredness and a reduced appetite are easy to attribute to a busy or stressful period. They may include:

• Persistent tiredness and weakness that does not improve with rest
• Loss of appetite and unintentional weight loss
• Low blood pressure, sometimes with dizziness or light-headedness on standing
• Nausea, vomiting, or abdominal discomfort
• Salt cravings, more typical of the primary form
• Darkening of the skin, particularly in primary adrenal insufficiency, often most noticeable on scars, knuckles, gums, and skin creases
• Low mood, irritability, and difficulty concentrating
• Muscle or joint aches

An adrenal crisis presents differently and more dramatically. It can include severe weakness, confusion, vomiting and diarrhoea, abdominal or back pain, a sharp drop in blood pressure, and collapse. It is often triggered by an infection, injury, surgery, or another physical stress in a person whose cortisol cannot rise to meet the demand.

What causes it

The causes differ by type. Primary adrenal insufficiency is often autoimmune, in which the immune system mistakenly attacks the adrenal cortex; Addison's disease is the main primary cause and may occur alongside other autoimmune conditions. Other primary causes include certain infections, bleeding into the glands, the spread of disease into the adrenals, and some inherited conditions that affect how the glands develop or make hormones.

Secondary adrenal insufficiency usually relates to problems with the pituitary gland that reduce ACTH, such as a pituitary tumour, surgery or radiation to the region, injury, or inflammation. The most common cause overall, however, is suppression that can follow prolonged glucocorticoid medicine. When such medicine is taken for a long time, the body's own production may quieten, and stopping suddenly can leave a temporary gap before the glands recover. This is why glucocorticoid medicines should only be changed under medical guidance.

How it is diagnosed

Diagnosis combines symptoms with blood tests that assess cortisol and the signals controlling it. Because cortisol follows a daily rhythm, peaking in the morning and falling overnight, timing matters, and a dynamic test is often needed to confirm the picture. Common tests include:

• Morning cortisol — a low early-morning level raises suspicion of insufficiency, while a clearly normal level makes it less likely.
• ACTH — helps distinguish primary from secondary forms; it is typically high in primary disease, where the pituitary is straining against unresponsive glands, and low or inappropriately normal in secondary disease.
• An ACTH stimulation test — measures how cortisol responds to a dose of synthetic ACTH, and is a key confirmatory test when the diagnosis is uncertain.
• Electrolytes — sodium and potassium can be abnormal, especially when aldosterone is low in the primary form.
• Antibody and other tests — to look for an autoimmune cause or another underlying problem, sometimes with imaging of the adrenal glands or pituitary.

The following table outlines, in general terms, how the common forms tend to differ. These are typical patterns rather than firm rules, and interpretation always rests with a clinician.

The patterns above are illustrative and can vary by person, by laboratory method, and by the timing of the test. For background on the cortisol test, see the source below and our blood tests and hormones sections. Related adrenal and pituitary topics are summarised in our conditions overview.

How it is generally managed

Adrenal insufficiency is generally managed by replacing the hormones the adrenal glands can no longer make adequately, under the ongoing care of a clinician, with the specifics depending on the cause and on which hormones are affected. In the primary form, both cortisol and the salt-balancing hormone may need attention, whereas in the secondary form the focus is usually on cortisol alone. The aim is to mirror the body's natural pattern as closely as is practical and to keep the person well day to day.

A central part of living with the condition is preparing for times of extra demand. Because the body normally produces more cortisol during illness, injury, or surgery, people with adrenal insufficiency are usually taught how care may need to be adjusted during such "stress" periods, and how to recognise the warning signs of an adrenal crisis. Many are advised to carry medical identification so that, in an emergency, others know cortisol replacement may be urgently needed. General treatment principles are described in our treatments section, and our symptoms overview covers related complaints. This page is educational and is not a substitute for personalised medical advice.

Complications and when to seek care

The most serious complication is adrenal crisis, which can be life-threatening if not treated promptly. It deserves urgent medical attention when a person known to have adrenal insufficiency, or suspected of having it, develops severe vomiting, confusion, fainting, or a sudden, severe decline during an illness. Beyond the crisis itself, undertreated insufficiency can leave a person persistently unwell, while the underlying cause, such as a pituitary tumour, may need its own monitoring. Anyone with unexplained ongoing tiredness, weight loss, and low blood pressure is reasonable to have assessed by a clinician.

Living with adrenal insufficiency

With diagnosis and steady follow-up, many people with adrenal insufficiency manage daily life well. Understanding the condition, keeping in touch with the care team, attending review appointments, and knowing what to do during illness are the practical cornerstones. Questions about work, travel, exercise, and managing other conditions are common and are best discussed with the clinician who knows the individual's situation.