Differential Diagnosis for Low ACTH Stim and Low Cortisol
- Single most likely diagnosis
- Adrenal insufficiency (primary or secondary): This is the most likely diagnosis because a low cortisol level with a low ACTH stim test suggests that the adrenal glands are not producing enough cortisol, and the pituitary gland is not stimulating them to do so.
- Other Likely diagnoses
- Pituitary apoplexy or hypopituitarism: These conditions can cause a decrease in ACTH production, leading to low cortisol levels.
- Adrenal gland damage or disease (e.g., Addison's disease): Damage to the adrenal glands can cause them to produce less cortisol, leading to low levels.
- Exogenous steroid use: Long-term use of steroid medications can suppress the body's natural production of cortisol, leading to low levels.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Septic shock: In severe sepsis, the adrenal glands may not produce enough cortisol, leading to low levels.
- Waterhouse-Friderichsen syndrome: This is a rare but life-threatening condition caused by adrenal gland failure due to severe infection.
- Sheehan syndrome: This is a rare condition caused by postpartum necrosis of the pituitary gland, leading to hypopituitarism and adrenal insufficiency.
- Rare diagnoses
- Congenital adrenal hyperplasia: This is a rare genetic disorder that affects the adrenal glands' ability to produce cortisol.
- Familial glucocorticoid deficiency: This is a rare genetic disorder that affects the adrenal glands' ability to produce cortisol.
- Tumors of the adrenal gland or pituitary gland: Rarely, tumors can cause adrenal insufficiency or hypopituitarism, leading to low cortisol levels.