Possible adrenal crisis? Use your prescribed emergency plan and seek emergency medical care. Adrenal crisis

02 Secondary AI

Secondary adrenal insufficiency

When the pituitary does not send enough ACTH—the signal the adrenal glands need to make cortisol.

What this type is

Secondary adrenal insufficiency is often described as a signaling problem. The pituitary gland may not produce enough adrenocorticotropic hormone, or ACTH. ACTH is the message that tells the adrenal glands to make cortisol. If that message is too low, cortisol production can fall even when the adrenal glands themselves are not the original site of the problem.

That is different from primary AI / Addison’s disease, where the glands themselves fail, and from tertiary or steroid-induced AI, which involves hypothalamic CRH signaling or HPA-axis suppression after glucocorticoid (steroid) exposure. Ask your clinician which type fits you.

How this type is typically acquired

Secondary AI happens when pituitary ACTH output is too low. Causes fall into several groups:

Pituitary tumors and their treatment. Growths in or near the pituitary, and the surgery, radiation, or other treatments used for them, can reduce ACTH production. Other pituitary hormones may be affected at the same time.
Pituitary surgery. Operations in the pituitary region can interrupt ACTH-producing cells or their connections.
Radiation. Radiation that includes the pituitary or nearby structures can later reduce hormone production, sometimes after a delay.
Trauma. Head injury and related trauma can affect pituitary function, including ACTH.
Infiltration and other pituitary disease. Infiltrative, inflammatory, infectious, vascular, or developmental pituitary disease can impair ACTH. Hypophysitis (inflammation of the pituitary) is one example your team may discuss.
Empty sella and other structural findings. Imaging may show structural changes. Your clinician interprets those findings in context; not every finding means secondary AI.
Medications. Some medications can suppress ACTH. Opioids are among the classes discussed in clinical care. Ask the prescribing clinician which of your medicines, if any, they want reviewed before you start, stop, or change anything.
Other causes your clinician identifies. Additional pituitary and hypothalamic–pituitary pathway problems exist. Isolated ACTH deficiency is sometimes a specific pattern. Your team names the cause that fits you.

Science: the HPA axis when ACTH is the missing message

The hypothalamus–pituitary–adrenal (HPA) axis is a communication loop:

The hypothalamus releases corticotropin-releasing hormone (CRH).
CRH tells the pituitary to release ACTH.
ACTH tells the adrenal glands to make cortisol.

In secondary AI, the break is at the pituitary ACTH step. The glands may still be able to make cortisol if they receive ACTH, but they are not being asked to do so at a sufficient level. Over time, glands that are not stimulated can also become less responsive in testing. Your clinician interprets those results.

Mineralocorticoids such as aldosterone are more relevant in primary AI, where the gland itself is damaged. Aldosterone is driven more by the renin–angiotensin system than by ACTH. In secondary AI, care often emphasizes glucocorticoid (cortisol) replacement more than mineralocorticoid replacement. Your prescriptions are still individualized. Salt and volume problems can still happen for other reasons (illness, vomiting, medications, heart or kidney disease).

People with secondary AI can still experience adrenal crisis when cortisol demand outstrips supply. Crisis education lives on the adrenal crisis page.

Testing your team may discuss

Your team may discuss tests such as:

A morning cortisol blood test
An ACTH level, often discussed together with cortisol to help distinguish secondary from primary AI
Cosyntropin (ACTH stimulation) testing
Other pituitary hormone tests (for example thyroid, growth hormone, gonadotropins, prolactin, and posterior pituitary / water-balance evaluation) when the clinician is looking at the pituitary as a whole
MRI of the pituitary and surrounding structures when the clinician orders imaging
Review of medicines, including opioids and other drugs the clinician thinks may suppress ACTH
Additional stimulation or specialist tests if the first results are unclear

Your clinician decides which tests to use, in what order, and what the results mean.

Questions to ask your medical team

Bring these to your visit:

Do I have secondary adrenal insufficiency, and what in my history and testing supports pituitary ACTH deficiency rather than primary or tertiary AI?
Should we evaluate other pituitary hormones, and do I need imaging?
What is my everyday glucocorticoid plan, and what is my sick-day or stress-dosing plan for fever, vomiting, injury, or a procedure?
Will you train me (and a caregiver) on an emergency glucocorticoid injection, and what belongs in my kit?
What should I tell emergency responders and the ER, and do I have a letter or protocol to carry?
Should I wear medical identification, and what wording do you recommend?
Which of my medicines (including pain medicines) should you know about because they can affect ACTH or cortisol?
If I have a pituitary tumor or had surgery or radiation, who coordinates follow-up, and how often?
Do I need mineralocorticoid replacement, or is that not part of secondary AI care in my case?