science Lab Test

Adrenal Panel: What Your Results Mean

The adrenal glands — small organs sitting above each kidney — produce hormones essential for life, including cortisol (the stress hormone), aldosterone (which controls sodium and potassium balance), and adrenaline. An adrenal panel assesses adrenal function by measuring cortisol alongside sodium and potassium, the two electrolytes most directly regulated by adrenal hormones. This combination is a practical first-line screen for both adrenal insufficiency (Addison's disease) and adrenal excess (Cushing's syndrome), as both conditions produce characteristic patterns in these three markers.

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What It Tests

This panel measures cortisol (the primary glucocorticoid hormone produced by the adrenal cortex, which regulates stress response, blood sugar, inflammation, and metabolism), sodium (regulated by aldosterone, the adrenal mineralocorticoid — low sodium is a hallmark of adrenal insufficiency), and potassium (aldosterone promotes potassium excretion, so high potassium suggests aldosterone deficiency, while low potassium may indicate excess aldosterone or Cushing's syndrome).

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Why It's Ordered

An adrenal panel is ordered to investigate symptoms of adrenal insufficiency (profound fatigue, weight loss, salt craving, low blood pressure, skin darkening), Cushing's syndrome (central obesity, stretch marks, high blood pressure, easy bruising), hyperaldosteronism (resistant hypertension, low potassium), or to monitor adrenal function in patients on long-term corticosteroid therapy who are being tapered.

Markers in This Test

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Cortisol
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Potassium
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Sodium
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Frequently Asked Questions

What is the classic electrolyte pattern in Addison's disease? expand_more
Primary adrenal insufficiency (Addison's disease) causes low cortisol and low aldosterone. Without aldosterone, the kidneys cannot retain sodium or excrete potassium. The classic electrolyte pattern is hyponatraemia (low sodium) combined with hyperkalaemia (high potassium). This combination with low cortisol on a morning blood test is a strong indicator warranting an ACTH stimulation test to confirm the diagnosis.
What is the classic electrolyte pattern in Cushing's syndrome? expand_more
In Cushing's syndrome, excess cortisol has mild mineralocorticoid activity and can cause sodium retention and potassium wasting. The pattern tends to be normal to slightly elevated sodium and low to normal potassium. Blood pressure is often elevated. When Cushing's is caused by ectopic ACTH production (such as from a lung tumour), hypokalaemia can be severe.
Should cortisol always be measured in the morning? expand_more
Yes. Cortisol follows a strong circadian rhythm — it peaks between 6 and 9 AM and falls to its lowest at midnight. A morning cortisol below 3 µg/dL is strongly suggestive of adrenal insufficiency, while a morning level above 18–20 µg/dL largely excludes it. Tests done at other times of day are difficult to interpret and are used only for specific purposes such as a midnight cortisol to screen for Cushing's.
What further tests confirm adrenal insufficiency? expand_more
If a morning cortisol is low or borderline, the gold standard confirmatory test is the short Synacthen (ACTH stimulation) test. A small dose of synthetic ACTH is given and cortisol is measured 30–60 minutes later. A normal adrenal gland rises to above 18–20 µg/dL. Failure to respond confirms adrenal insufficiency. ACTH levels then help distinguish primary (high ACTH) from secondary (low ACTH) insufficiency.
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