Addison vs Cushing: Two Sides of the Same Gland
Students lose points on adrenal questions for one reason: they try to memorize two separate lists of symptoms. You don’t need two lists. You need one list and a mirror.
Addison’s disease is too little adrenal cortex hormone. Cushing’s syndrome is too much cortisol. Once you know what cortisol and aldosterone normally do, every sign, lab, and nursing intervention falls out on its own. Flip the direction and you have the other disease.
The Addison vs Cushing comparison shows up on the NCLEX in a few predictable ways. You’ll be asked to match a set of labs to the right disorder, recognize an adrenal crisis, pick the priority action, or catch a client who is about to make a dangerous mistake with their steroids. We’ll hit all four.
If you want this topic in context with thyroid storm, SIADH, and the diabetic emergencies, the Endocrine Emergencies Made Simple lesson puts the whole family side by side.
Start With What the Adrenal Cortex Actually Does
The adrenal cortex makes three groups of hormones. A classic memory hook: “salt, sugar, sex.”
- Salt (mineralocorticoids, mainly aldosterone): holds onto sodium and water, gets rid of potassium. Keeps blood volume and blood pressure up.
- Sugar (glucocorticoids, mainly cortisol): raises blood glucose, helps you handle stress, suppresses inflammation and immunity, and helps maintain vascular tone.
- Sex (androgens): contributes to body hair, libido, and some secondary sex characteristics, especially in women.
Cortisol is controlled by a feedback loop. The hypothalamus releases CRH, the pituitary releases ACTH, and ACTH tells the adrenal cortex to make cortisol. When cortisol is high, the loop shuts down. When cortisol is low, the pituitary pushes out more ACTH. Hold onto that ACTH detail. It explains the bronze skin in Addison’s.
Addison’s = everything Down except potassium. Cushing’s = everything Up except potassium. Sodium, glucose, blood pressure, and weight all fall in Addison’s while potassium climbs. In Cushing’s, sodium, glucose, blood pressure, and weight all rise while potassium drops. Potassium is the rebel in both.
Addison’s Disease: Running on Empty
Addison’s disease is primary adrenal insufficiency. The adrenal cortex itself is damaged, most often by autoimmune destruction in the US. Other causes include TB, other infections, adrenal hemorrhage, and metastatic cancer. Because the whole cortex is affected, the client usually loses both cortisol and aldosterone.
Secondary adrenal insufficiency is a different animal. The problem is upstream (pituitary or hypothalamus), or it’s caused by long-term steroid use that shut the axis down. These clients are low on cortisol, but aldosterone is usually preserved because it’s driven mainly by the renin-angiotensin system, not ACTH. That matters on the exam, and we’ll come back to it.
What You’ll See
- Fatigue and weakness that slowly gets worse over months
- Weight loss, anorexia, nausea, vomiting, and abdominal pain
- Hypotension, often orthostatic, with dizziness when standing
- Salt craving
- Hyperpigmentation: the famous “bronze” or tanned look, darkest in skin creases, knuckles, scars, nipples, and gums
- Decreased body hair in women, from lost adrenal androgens
- Depression, irritability, or trouble concentrating
Why the bronze skin? Low cortisol tells the pituitary to crank out more ACTH. ACTH is cut from the same precursor molecule (POMC) as melanocyte-stimulating hormone, so high ACTH darkens the skin. No high ACTH, no bronzing. That’s why a client with secondary adrenal insufficiency typically looks pale, not tan.
The Labs
- Hyponatremia: no aldosterone, so sodium (and water) leak out through the kidneys
- Hyperkalemia: no aldosterone, so potassium stays in
- Hypoglycemia: no cortisol to support glucose production during fasting or stress
- Elevated BUN from volume depletion, and sometimes mild hypercalcemia
- Low serum cortisol with high ACTH in primary disease
The confirmation test you’ll most often see named is the ACTH stimulation test (cosyntropin). Synthetic ACTH is given, and cortisol is checked afterward. In Addison’s, cortisol barely budges because the gland can’t respond.
Hyperkalemia and hyperpigmentation point to primary adrenal insufficiency. A client whose adrenal insufficiency comes from stopping long-term prednisone usually has low cortisol and possible hypoglycemia, but potassium is often normal and the skin isn’t bronze. Don’t force the full Addison’s picture onto every low-cortisol client.
Cushing’s Syndrome: Too Much of a Good Thing
Cushing’s syndrome is any state of prolonged excess cortisol. Here’s the part students forget: the most common cause by far is taking glucocorticoid medications, like long-term prednisone for asthma, COPD, lupus, rheumatoid arthritis, or after a transplant. That’s called exogenous or iatrogenic Cushing’s.
Endogenous causes include a pituitary adenoma that over-secretes ACTH (that specific cause is called Cushing’s disease), an adrenal tumor, or an ectopic ACTH-producing tumor such as small cell lung cancer. Syndrome is the umbrella. Disease is the pituitary version.
What You’ll See
Cushing’s has the most “visual” presentation in all of endocrine. Exam writers love describing it.
- Moon face: round, full, often flushed (plethoric)
- Buffalo hump: fat pad on the upper back between the shoulders
- Truncal obesity with thin arms and legs from muscle wasting
- Purple striae (wide, dark stretch marks) on the abdomen, thighs, and breasts
- Thin, fragile skin, easy bruising, and poor wound healing
- Hypertension and fluid retention
- Osteoporosis and fractures
- Hirsutism, acne, and menstrual irregularities in women
- Mood swings, irritability, insomnia, even psychosis
- Frequent infections, with signs of infection that may be muted
The Labs
- Hyperglycemia: cortisol drives the liver to make glucose and blocks insulin’s effect
- Hypokalemia: high cortisol has mineralocorticoid effects at the kidney, so potassium gets wasted
- Sodium normal to high: sodium and water retention, though true hypernatremia is usually mild or absent
- Elevated cortisol on 24-hour urine free cortisol, late-night salivary cortisol, or a failed dexamethasone suppression test
- Possible elevated WBCs with low lymphocytes and eosinophils
On a dexamethasone suppression test, a healthy person’s cortisol drops after a dose of dexamethasone. In Cushing’s, it stays high because the feedback loop isn’t working.
The Side-by-Side Comparison Table
This is the table to study until you can rebuild it from memory. Cover one column and quiz yourself on the other.
| Feature | Addison’s Disease | Cushing’s Syndrome |
|---|---|---|
| Core problem | Too little cortisol and aldosterone | Too much cortisol |
| Most common cause | Autoimmune destruction of the adrenal cortex | Long-term glucocorticoid medication |
| Sodium | Low (hyponatremia) | Normal to high |
| Potassium | High (hyperkalemia) | Low (hypokalemia) |
| Blood glucose | Low (hypoglycemia) | High (hyperglycemia) |
| Blood pressure | Low, orthostatic | High |
| Fluid status | Dehydrated, volume depleted | Fluid retention, edema |
| Weight | Loss | Gain (central) |
| Skin | Bronze hyperpigmentation | Thin, bruises easily, purple striae |
| Body shape | Thin, wasted | Moon face, buffalo hump, thin limbs |
| ACTH (primary disease) | High | Depends on cause |
| Key diagnostic test | ACTH stimulation test | Dexamethasone suppression test, 24-hour urine cortisol |
| Emergency | Addisonian (adrenal) crisis | Rarely an emergency on its own |
| Treatment | Replace hormones for life | Remove the source or taper steroids |
Notice how much of this is about sodium, potassium, and fluid. If those shifts still feel shaky, review our fluid and electrolytes guide. The hypokalemia vs hyperkalemia breakdown also covers the ECG changes you’d expect at each end, which pair perfectly with this topic.
Addisonian Crisis: The One That Kills
Addisonian crisis (acute adrenal crisis) is a true emergency. The client’s body faces a stressor and has no cortisol to meet it. Blood pressure falls and stays down, even with fluids.
Common Triggers
- Infection, the most common trigger
- Surgery, trauma, or a major illness
- Abrupt withdrawal of long-term steroids
- Vomiting or diarrhea that keeps the client from absorbing their oral replacement
- Adrenal hemorrhage (for example, in sepsis or with anticoagulation)
Recognize It
- Severe hypotension and shock that responds poorly to fluids alone
- Severe abdominal, back, or leg pain
- Vomiting, profound weakness, confusion, or loss of consciousness
- Hyponatremia, hyperkalemia, and hypoglycemia on labs
- Fever is common, especially when infection is the trigger
A client with known adrenal insufficiency (or on chronic steroids) who becomes hypotensive, confused, and vomiting is in adrenal crisis until proven otherwise. Hydrocortisone should not wait for the lab to confirm a low cortisol. Draw the labs if you can do it quickly, then treat.
Emergency Care
Assess ABCs, place large-bore IV access, and start continuous cardiac monitoring. Hyperkalemia puts this client at risk for peaked T waves and dysrhythmias.
The commonly taught first dose is hydrocortisone 100 mg IV (IM if no IV), followed by ongoing dosing. Sources vary on the maintenance schedule, with options such as 50 mg every 6 hours or 200 mg per 24 hours as a continuous infusion. At high doses, hydrocortisone also has enough mineralocorticoid effect that fludrocortisone isn’t needed during the acute phase.
Infuse 0.9% normal saline rapidly, often about 1 L in the first hour for adults, then continue based on response. Dextrose (for example, D5NS) is added to treat or prevent hypoglycemia. Watch for fluid overload in older clients or anyone with heart failure.
Trend blood pressure, heart rhythm, glucose, sodium, and potassium closely. Hyperkalemia usually improves with fluids and hydrocortisone. Look for and treat the cause, especially infection. Keep the environment calm and limit unnecessary stress.
Once the client is stable, they transition to oral hydrocortisone, and fludrocortisone is restarted if they have primary disease. For more on spotting a crashing client early, our Recognizing Complications and Emergency Response lesson is a strong companion.
Nursing Care: Addison’s vs Cushing’s
The day-to-day care follows the mirror, too.
| Nursing Focus | Addison’s Disease | Cushing’s Syndrome |
|---|---|---|
| Fluids | Monitor for dehydration, orthostatic hypotension, daily weights | Monitor for fluid retention, edema, hypertension, daily weights |
| Diet | Adequate sodium, small frequent meals, avoid fasting | Low sodium, low calorie, high protein, potassium-rich, limit simple sugars |
| Glucose | Watch for hypoglycemia | Watch for hyperglycemia, may need insulin |
| Safety | Fall risk from dizziness and weakness | Fall and fracture risk from osteoporosis and muscle wasting |
| Skin | Expect hyperpigmentation | Gentle handling, protect fragile skin, watch wounds closely |
| Infection | Infection can trigger crisis | High infection risk, signs may be masked |
| Emotional support | Fatigue and depression | Body image changes, mood swings |
Treatment for Addison’s is lifelong replacement: hydrocortisone (or prednisone) for cortisol, plus fludrocortisone for aldosterone in primary disease. Treatment for Cushing’s depends on the cause. That can mean slowly tapering the steroid that caused it, surgery to remove a pituitary or adrenal tumor, or medications that block cortisol production. After an adrenalectomy or pituitary surgery, the client will need temporary or permanent steroid replacement, which brings them right back to the teaching below.
Steroid Teaching the NCLEX Loves
Whether a client is replacing missing cortisol in Addison’s or taking prednisone that could give them Cushing’s, the teaching points overlap. These are some of the most commonly tested education questions in all of pharmacology. For more on the drug class, see the NCLEX medications and pharmacology guide, and remember the drug suffix clue: “-sone” and “-olone” usually mean a corticosteroid.
Never Stop Abruptly
Long-term glucocorticoids suppress the HPA axis. The client’s own adrenal glands have been “on vacation” and can’t restart quickly. Stop the drug suddenly and you can trigger adrenal crisis. Courses longer than about 2 to 3 weeks are generally tapered, though the exact cutoff depends on dose and the provider.
Sick Day Rules (Stress Dosing)
- During fever or significant illness, the provider typically has the client double or triple the usual oral dose until recovered
- If the client is vomiting or can’t keep pills down, they use their emergency injectable hydrocortisone and seek care right away
- Surgery, dental procedures, and major trauma require extra (stress) dosing, so the client must tell every provider they take steroids
- Wear a medical alert bracelet and carry an emergency card
Infection Risk
- Steroids suppress immunity and can hide fever and inflammation
- Teach strict hand hygiene and avoiding sick contacts and crowds during high-dose therapy
- Report subtle signs: low-grade fever, new cough, sore throat, or a wound that isn’t healing
- Avoid live vaccines while on high-dose therapy unless the provider approves
Other Daily Habits
- Take oral glucocorticoids in the morning with food to mimic the body’s natural rhythm and protect the stomach
- Monitor blood glucose, blood pressure, and weight
- Get adequate calcium and vitamin D, and do weight-bearing exercise if approved, to protect bone
- Report black, tarry stools (GI bleeding risk)
When a teaching question asks which client statement shows a need for more teaching, look for the client who plans to skip doses when they feel sick, stop the pills once they feel better, or “cut back” on their own. Any statement that reduces steroid dosing during illness or stops it suddenly is the wrong one, every time.
Priority questions often put an adrenal client next to three other clients. Our prioritization and delegation guide shows how to rank them, and the Black Belt Recall mnemonic library has more endocrine memory hooks. For outside reading, the NIDDK has clear overviews of adrenal insufficiency and Addison’s disease and Cushing’s syndrome, and StatPearls covers adrenal crisis management in detail.
A client with Addison’s disease who takes hydrocortisone and fludrocortisone is admitted with a 2-day history of vomiting. Vital signs: BP 78/44 mm Hg, HR 122/min. Labs: sodium 126 mEq/L, potassium 6.0 mEq/L, glucose 52 mg/dL. Which prescription should the nurse implement first?
- Administer oral fludrocortisone 0.1 mg
- Administer hydrocortisone 100 mg IV
- Administer sodium polystyrene sulfonate orally
- Obtain a 24-hour urine cortisol specimen
This client is in Addisonian crisis: hypotension, tachycardia, hyponatremia, hyperkalemia, and hypoglycemia after vomiting prevented absorption of oral replacement. IV hydrocortisone replaces the missing cortisol, supports blood pressure and glucose, and at this dose provides mineralocorticoid effect that helps correct sodium and potassium. Rapid IV saline with dextrose would run alongside it.
Why the other answers are wrong:
- A: The client is vomiting and can’t reliably absorb oral medication, and fludrocortisone alone doesn’t replace cortisol.
- C: Potassium usually corrects with fluids and hydrocortisone. An oral binder in a vomiting, hypotensive client doesn’t treat the cause.
- D: A 24-hour urine cortisol is a diagnostic test for Cushing’s syndrome, and testing should never delay treatment of a crisis.
Final Takeaway
Addison’s and Cushing’s are mirror images. Addison’s means too little cortisol and aldosterone: low sodium, high potassium, low glucose, low blood pressure, weight loss, and bronze skin. Cushing’s means too much cortisol: higher sodium, low potassium, high glucose, hypertension, moon face, buffalo hump, purple striae, and fragile skin.
Addisonian crisis is the emergency. Give IV hydrocortisone and IV saline with dextrose fast, and don’t wait on labs. For any client on steroids, the teaching is the same: never stop abruptly, increase the dose during illness as directed, and take infection risk seriously.
Train like a black belt. Think like a nurse. 🥋
Ready to Lock In Addison vs Cushing?
Test yourself on endocrine questions in the Proving Grounds practice exams, download our printable NCLEX cheat sheets, or work through more NCLEX practice questions.
FAQ: Addison vs Cushing
What is the easiest way to remember Addison vs Cushing?
Think of them as mirror images. Addison’s disease is too little adrenal hormone (cortisol and usually aldosterone), so everything trends down: low sodium, low glucose, low blood pressure, and low weight, with potassium as the one value that goes up. Cushing’s syndrome is too much cortisol, so sodium, glucose, blood pressure, and weight trend up, while potassium goes down.
Why does Addison’s disease cause hyperkalemia?
Aldosterone tells the kidneys to hold onto sodium and excrete potassium. In primary Addison’s disease, the adrenal cortex cannot make enough aldosterone, so the kidneys lose sodium and water and keep potassium. The result is hyponatremia, hyperkalemia, dehydration, and hypotension.
Why does Addison’s disease cause bronze skin?
When cortisol is low, the pituitary pumps out more ACTH to try to stimulate the adrenal glands. ACTH comes from the same precursor molecule as melanocyte-stimulating hormone, so high ACTH darkens the skin, especially in skin creases, scars, knuckles, and gums. This hyperpigmentation is seen in primary adrenal insufficiency, not in secondary adrenal insufficiency, where ACTH is low.
What is the first priority in Addisonian crisis?
Addisonian (adrenal) crisis is treated with rapid IV fluids (normal saline, often with dextrose) and IV hydrocortisone, commonly 100 mg IV or IM right away, followed by ongoing hydrocortisone dosing. Treatment should not be delayed for test results. The nurse also monitors blood pressure, glucose, potassium, and cardiac rhythm closely.
Why can’t corticosteroids be stopped abruptly?
Long-term steroid therapy suppresses the body’s own ACTH and cortisol production. If the medication is stopped suddenly, the adrenal glands cannot ramp back up fast enough, and the client can develop acute adrenal insufficiency with hypotension, hypoglycemia, and shock. Steroids taken for more than a couple of weeks are tapered under provider direction.
What are sick day rules for clients on steroid replacement?
Clients with adrenal insufficiency need more cortisol during physical stress. Common teaching is to double or triple the usual oral glucocorticoid dose during fever or significant illness, as directed by the provider, and to use an emergency injection and seek care if they are vomiting or cannot keep pills down. They should also wear a medical alert ID and tell all providers, including before surgery, that they take steroids.
