Lab marker · Low

Low Adrenocorticotropic hormone (ACTH): what it means

A Adrenocorticotropic hormone (ACTH) result below the normal range is considered low. Here is what a reduced Adrenocorticotropic hormone (ACTH) can point to, and when it is worth discussing with a doctor.

Reference range: ~7–63 pg/mL in the morning; strongly diurnal (highest on waking); only interpretable paired with a same-time cortisol

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What a low Adrenocorticotropic hormone (ACTH) can mean

  • With high cortisol — an adrenal tumour making cortisol directly, which suppresses pituitary ACTH.
  • With low cortisol — secondary adrenal insufficiency: the pituitary or hypothalamus is under-driving the adrenals, most commonly after long-term steroid medication suppresses the axis.
  • Exogenous steroid use.

When to discuss with a doctor

ACTH is never read alone — always with a same-time cortisol, because it is the pair that tells the story. It is the second step once cortisol testing suggests either Cushing's syndrome (too much cortisol) or adrenal insufficiency (too little), and it directs the search to the pituitary versus the adrenal. New adrenal insufficiency — fatigue, weight loss, low blood pressure, low sodium, high potassium, skin darkening — can be dangerous and needs prompt endocrine assessment, as can a suspected adrenal crisis (an emergency). Mediora.AI shows ACTH beside cortisol and the electrolyte pattern so the axis can be read together; the diagnosis and imaging belong with endocrinology.

Conditions this can relate to

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Mediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.