Nursing care
Primary vs secondary adrenal insufficiency: skin, potassium and ACTH
Written and reviewed by Nicole Ramirez, BSN, RN, CMSRN · 4 min read · Updated November 2026
Short answer
Primary adrenal insufficiency, or Addison disease, is failure of the adrenal glands, so cortisol and aldosterone both fall and ACTH rises. That brings darkened skin and high potassium. Secondary adrenal insufficiency is a lack of pituitary ACTH, often after long-term steroids are stopped, so cortisol falls but aldosterone is spared: no hyperpigmentation, and potassium usually stays normal.
The single best clue: skin color
When the adrenal glands fail, cortisol drops and the pituitary responds by releasing more ACTH. MSD Manuals explains that ACTH and a related pituitary hormone stimulate pigment cells, so skin and mucous membranes darken. NIDDK lists this darkening, seen on scars, skin folds and pressure points, as the symptom specific to Addison disease.
In secondary adrenal insufficiency the problem lies with the pituitary, so ACTH is low rather than high and the skin does not darken. A tired, weak, hypotensive client with bronzed skin points to primary disease; the same picture with ordinary skin color points to secondary disease, especially if the client recently stopped steroid tablets.
Why potassium usually stays normal in secondary disease
In primary disease the whole adrenal cortex is damaged, so aldosterone falls along with cortisol. MSD describes the result: the kidneys lose sodium and hold on to potassium, giving hyponatremia, hyperkalemia and dehydration. Salt craving, which NIDDK mentions, fits this sodium loss.
In secondary disease the adrenal glands are intact and keep making aldosterone, so MSD describes electrolytes as often normal or only mildly deranged. A high potassium in a client with suspected adrenal insufficiency therefore points toward the adrenal gland itself, and mineralocorticoid replacement such as fludrocortisone is part of primary disease treatment. The full potassium mechanism has its own page.
Causes, and the history question that matters most
Autoimmune damage causes most cases of Addison disease, according to NIDDK, with tuberculosis, HIV-related infection, cancer and genetic disorders among the other causes. Secondary disease comes from anything that stops the pituitary making ACTH, such as tumors, bleeding, infection or head injury. NIDDK also names sudden withdrawal of long-term corticosteroids as the most common cause of adrenal insufficiency overall.
Steroid tablets suppress the body's own signal, and recovery needs a gradual taper over weeks or months. So the key nursing question is the steroid history. A client admitted with an infection who took prednisone for months and stopped it is at risk even with no adrenal diagnosis. Nurses confirm that home steroids are continued or tapered as prescribed and teach clients not to stop them abruptly.
Shared danger: adrenal crisis
Both forms can tip into adrenal crisis during illness, injury or surgery, when the body needs more cortisol than it can make. NIDDK notes that symptoms sometimes appear for the first time during a crisis. Watch for severe weakness, vomiting, abdominal pain, confusion and low blood pressure, and treat a client on long-term steroids who becomes acutely unwell with that risk in mind.
MSD warns that delaying glucocorticoid treatment in adrenal crisis may be fatal, so the nurse escalates early, prepares IV access and fluids as ordered, and gives the prescribed steroid without waiting for confirmatory results. Hyperkalemia is a bigger concern in primary disease, so cardiac monitoring for rhythm changes carries more weight there.
Hypothetical practice scenario
Hypothetical scenario, not a real exam item: a client stopped long-term prednisone two weeks ago because of weight gain and now reports fatigue, nausea and dizziness on standing. The skin is not darkened, sodium is slightly low and potassium is normal. Which finding best supports secondary rather than primary adrenal insufficiency: the nausea, the normal potassium, or the dizziness on standing?
The normal potassium, together with the absence of hyperpigmentation, fits spared aldosterone in secondary disease. Nausea and dizziness on standing are tempting because they are genuine adrenal insufficiency findings, but they occur in both forms and cannot separate them. The nurse reports the stopped steroid and the symptoms to the prescriber promptly.
Sources and further reading
MSD Manual Professional Version: Addison Disease. ACTH-driven hyperpigmentation absent in pituitary-related disease, aldosterone loss causing sodium wasting and potassium retention, electrolytes often normal in secondary disease, fludrocortisone replacement, delay in glucocorticoid in crisis may be fatal.
NIDDK: Symptoms and Causes of Adrenal Insufficiency and Addison's Disease. Autoimmune and other causes of Addison disease, pituitary causes of secondary disease, sudden steroid withdrawal as the most common cause overall, skin darkening specific to Addison disease, salt craving, symptoms first appearing in crisis.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our endocrine practice questions are the closest set to what this page covers.
Common questions
Why is there hyperpigmentation only in primary adrenal insufficiency?
Because only primary disease raises ACTH. The failing adrenal glands make little cortisol, the pituitary releases more ACTH and a related hormone, and these stimulate skin pigment cells. In secondary disease the pituitary makes too little ACTH, so the skin does not darken.
Is Addison disease primary adrenal insufficiency?
Yes. Addison disease is the name for primary adrenal insufficiency, where the adrenal glands themselves are damaged, most often by autoimmune disease. Secondary adrenal insufficiency comes from the pituitary or from stopping long-term steroid medicine too quickly.
Why is potassium normal in secondary adrenal insufficiency?
The adrenal glands are intact, so they keep making aldosterone, the hormone that makes the kidneys excrete potassium and retain sodium. Only cortisol is short. Sodium can still drift low, but marked hyperkalemia points toward primary disease.