Primary adrenal insufficiency, also known as Addison’s disease, is a rare but serious condition where the adrenal glands—two small organs sitting atop the kidneys—fail to produce enough of the essential hormones cortisol and aldosterone, which the body needs to survive and function properly.
Understanding Primary Adrenal Insufficiency
The adrenal glands may be small, but they play a mighty role in keeping us alive and well. These triangle-shaped organs produce hormones that are absolutely essential for life. When the adrenal glands themselves become damaged and can no longer make enough cortisol (a hormone that helps the body respond to stress, maintain blood pressure, and control blood sugar) and aldosterone (a hormone that regulates salt and water balance in the body), the result is primary adrenal insufficiency.[1]
This condition differs from secondary adrenal insufficiency, which starts with a problem in the pituitary gland at the base of the brain rather than in the adrenal glands themselves. In primary adrenal insufficiency, the damage happens directly to the outer layer of the adrenal glands, called the adrenal cortex, which is responsible for making these critical steroid hormones.[4]
The term “Addison’s disease” honors Thomas Addison, a physician who first described this group of patients more than 150 years ago. He noticed they had anemia and diseased adrenal glands at autopsy. Today, we understand this condition much better, but it remains a challenging diagnosis that requires lifelong treatment and careful management.[11]
How Common Is Primary Adrenal Insufficiency?
Primary adrenal insufficiency is considered a rare condition. In the United States, it affects approximately one in every 100,000 people. This rarity means that many doctors may not see a case very often in their practice, which can sometimes lead to delays in diagnosis.[2]
The condition can affect people of all ages, from children to the elderly. However, it most commonly appears in adults between the ages of 30 and 50 years old. Unlike some diseases that favor one gender over another, Addison’s disease can affect both men and women, though some studies suggest a slightly higher occurrence in women.[2]
The prevalence of primary adrenal insufficiency has been estimated at about one in 8,000 people in developed nations, making it more common than some other rare diseases but still uncommon enough that raising awareness among both doctors and the public remains important.[8]
What Causes Primary Adrenal Insufficiency?
The leading cause of primary adrenal insufficiency in the United States and other developed countries is autoimmune disease. In this situation, the body’s immune system—which normally protects us from infections and foreign invaders—mistakenly identifies the cells of the adrenal cortex as enemies and attacks them. This is called autoimmune adrenalitis. The immune system makes antibodies against the adrenal tissue and slowly destroys it over months to years. More than 90 percent of people with recent-onset Addison’s disease have these antibodies, particularly ones targeting an enzyme called 21-hydroxylase.[5][11]
Before the mid-20th century, tuberculosis was the leading cause of Addison’s disease. The bacteria that cause tuberculosis can spread to the adrenal glands and destroy them. While tuberculosis is now a less common cause in developed countries, it remains important in regions where the disease is more prevalent. Other infections, including fungal infections and the CMV virus (especially in people with AIDS), can also damage the adrenal glands.[5]
Other causes of primary adrenal insufficiency include bleeding into the adrenal glands during severe illness or shock, invasion by cancer cells that have spread from elsewhere in the body (such as breast cancer), and surgical removal of both adrenal glands. Rare genetic conditions can also lead to adrenal failure. In some cases, no clear cause can be identified.[5][8]
It’s worth noting that the destruction of the adrenal glands needs to be quite extensive before symptoms appear. Typically, about 90 percent of the adrenal cortex must be destroyed before the condition becomes clinically apparent. This gradual process explains why symptoms often develop slowly and can be easily overlooked in the early stages.[8]
Who Is at Higher Risk?
Certain groups of people face a higher risk of developing primary adrenal insufficiency. People who have other autoimmune conditions are more likely to develop autoimmune adrenalitis. These conditions include type 1 diabetes, pernicious anemia (a condition where the body can’t absorb enough vitamin B12), Graves’ disease and chronic thyroiditis (conditions affecting the thyroid gland), vitiligo (a skin condition causing loss of pigment), and myasthenia gravis (a condition causing muscle weakness).[2]
Individuals with autoimmune polyendocrine syndrome are at particularly high risk. This is a rare, inherited condition in which the immune system attacks multiple hormone-producing glands and organs. People with this syndrome are much more likely to develop Addison’s disease, often along with other autoimmune problems.[2]
Having one autoimmune condition increases the risk of developing others. In fact, up to 50 percent of patients with primary adrenal insufficiency develop another autoimmune disorder during their lifetime. This makes it important for doctors to remain vigilant and screen for other autoimmune diseases in people diagnosed with Addison’s disease.[11]
Family history can also play a role, as some genetic factors increase susceptibility to autoimmune conditions. Certain human leukocyte antigen (HLA) genes, particularly HLA-B8, DR3, and DR4, confer increased risk for developing autoimmune adrenalitis.[11]
Recognizing the Symptoms
The symptoms of primary adrenal insufficiency typically develop gradually over months or even years as the adrenal glands are slowly destroyed. Because they come on so slowly and can be vague, they are often mistaken for other conditions or dismissed as just being tired or stressed. This gradual onset makes the condition challenging to diagnose early.[3]
Chronic, steadily worsening fatigue is the most common symptom. This isn’t just ordinary tiredness—it’s an overwhelming, persistent exhaustion that doesn’t improve with rest. People often describe feeling completely drained of energy and unable to carry out their normal daily activities.[2][5]
Another hallmark sign is hyperpigmentation, or darkening of the skin. This occurs particularly in areas that are already naturally darker, such as skin creases in the palms, around scars, on the elbows and knees, and on the gums inside the mouth. The darkening happens because of elevated levels of ACTH, the hormone the pituitary gland makes to try to stimulate the failing adrenal glands. ACTH can trigger increased melanin production in the skin. This symptom may be harder to notice in people with naturally darker skin tones.[2][5]
Digestive problems are very common and include loss of appetite, nausea, vomiting, diarrhea, and abdominal pain. These symptoms can lead to unintentional weight loss, which is another frequent feature of the disease.[2][5]
Low blood pressure is typical in primary adrenal insufficiency, and it often drops further when a person stands up from sitting or lying down. This is called postural hypotension or orthostatic hypotension, and it causes dizziness, lightheadedness, and sometimes fainting. The low blood pressure occurs because aldosterone, which helps regulate blood volume and pressure, is deficient.[3][5]
Many people with Addison’s disease develop intense cravings for salty foods. This happens because the body is losing too much salt in the urine due to the lack of aldosterone. The body tries to compensate by making people seek out salt.[2]
Muscle weakness, muscle cramps, and joint pain are also common complaints. People may find that tasks requiring physical effort become increasingly difficult. Low blood sugar, or hypoglycemia, can occur because cortisol helps maintain blood sugar levels.[2][5]
Changes in mood and mental state are frequently reported. People may experience irritability, depression, poor concentration, and anxiety. These psychological symptoms can sometimes be mistaken for primary mental health conditions.[2]
Women with primary adrenal insufficiency may experience abnormal or missed menstrual periods, loss of body hair, and decreased sexual drive. These symptoms occur because the adrenal glands also produce small amounts of androgens (male-type hormones), which are affected by the disease.[2]
Preventing Primary Adrenal Insufficiency
Unfortunately, there is no known way to prevent primary adrenal insufficiency when it is caused by autoimmune disease or other spontaneous conditions. The autoimmune process that leads to destruction of the adrenal glands cannot currently be stopped or prevented. Scientists do not yet fully understand what triggers the immune system to attack the adrenal glands in the first place, though both genetic and environmental factors are thought to play a role.[4]
However, once someone has been diagnosed with primary adrenal insufficiency, there are critical steps that can prevent complications and life-threatening crises. The most important preventive measure is taking prescribed hormone replacement medications consistently and correctly every day. Missing doses can lead to dangerous drops in hormone levels.[9]
People with Addison’s disease need to learn to recognize situations that require increasing their medication dose temporarily. These “stress situations” include illnesses (especially those with fever), injuries, surgeries, dental procedures, and even severe emotional stress. During such times, the body needs more cortisol than usual. Patients are often taught to double or triple their usual cortisol dose when they are sick with a fever. Not adjusting medication during stress is a common cause of adrenal crises.[9]
Wearing a medical alert bracelet or necklace and carrying a steroid emergency card at all times is essential. These alert healthcare providers to the condition in case the person becomes unconscious or unable to communicate. Many patients are also given an emergency injection kit containing hydrocortisone that they or a family member can administer if needed.[7]
Regular follow-up with an endocrinologist (a doctor who specializes in hormone disorders) helps ensure that hormone replacement is adequate and that other autoimmune conditions are detected early if they develop.[4]
How the Body Changes in Primary Adrenal Insufficiency
To understand what goes wrong in primary adrenal insufficiency, it helps to know what the adrenal hormones normally do. The adrenal cortex produces three main types of steroid hormones. The outermost layer makes aldosterone, the middle layer makes cortisol, and the innermost layer makes weak androgens like DHEA. In primary adrenal insufficiency, the destruction of the adrenal cortex means all three types of hormones are deficient, though cortisol and aldosterone deficiency cause the most serious problems.[1]
Cortisol is sometimes called the “stress hormone” because it helps the body respond to physical stress such as illness, injury, or surgery. But cortisol does much more than that. It helps control blood pressure by making blood vessels respond properly to other hormones that constrict them. It helps control blood glucose by stimulating the liver to make sugar and by modifying how the body uses nutrients. It reduces inflammation throughout the body and helps control the amount of water in the body. Cortisol also affects the immune system, metabolism, and even mood and cognition. Without enough cortisol, all these processes are disrupted.[1][5]
Aldosterone is a mineralocorticoid that regulates the balance of sodium (salt) and potassium in the blood. It acts on the kidneys, telling them to hold onto sodium and get rid of potassium. When sodium is retained, water follows it, which helps maintain blood volume and blood pressure. When aldosterone is deficient, the kidneys lose too much sodium and water, leading to dehydration, low blood volume, and low blood pressure. At the same time, potassium levels in the blood can rise, which can affect heart rhythm and muscle function.[1][5]
Because cortisol production is low, the body tries to compensate. The pituitary gland increases production of ACTH, the hormone that normally signals the adrenal glands to make cortisol. In primary adrenal insufficiency, ACTH levels become very high because the damaged adrenal glands cannot respond. This elevated ACTH is actually useful for diagnosis, as it distinguishes primary from secondary adrenal insufficiency. The high ACTH also has a side effect—it stimulates melanin production in the skin, causing the characteristic darkening or hyperpigmentation seen in many patients.[6]
During times of physical stress—such as infection, surgery, or trauma—the body normally increases cortisol production several-fold to help cope. People with primary adrenal insufficiency cannot do this because their adrenal glands are destroyed. This is why stressful situations can rapidly trigger an adrenal crisis. The body simply cannot meet the increased demand for cortisol. Blood pressure drops dangerously low, blood sugar falls, and the person can go into shock. This is why increasing medication during illness is so critical.[8]
The deficiency of adrenal androgens like DHEA is less serious but may contribute to decreased libido, loss of body hair, and possibly depression and fatigue, particularly in women. In men, the testes produce most androgens, so adrenal androgen deficiency is less noticeable. In women, the adrenal glands are the main source of these hormones after menopause, so the loss may be more significant.[5]
The changes in hormone levels affect metabolism as well. Without adequate cortisol, the body may have difficulty mobilizing energy stores and maintaining blood sugar, especially between meals or during fasting. This can lead to episodes of low blood sugar with symptoms like shakiness, sweating, and confusion.[8]
The immune system is also affected. Cortisol normally helps modulate immune responses and inflammation. When cortisol is deficient, inflammatory processes may not be properly controlled, though the immune system’s ability to fight infections can also be impaired. This complex effect on immunity is one reason why people with untreated adrenal insufficiency may be more susceptible to certain infections.[8]
All these changes explain why primary adrenal insufficiency affects so many aspects of health and daily life. The symptoms—fatigue, low blood pressure, digestive problems, salt craving, mood changes, and darkened skin—all make sense when viewed through the lens of what these hormones normally do and what happens when they are missing.[8]
