Theory · 56. Hypocorticism (Addison Disease)

Covers adrenal insufficiency, separating primary Addison disease from secondary causes, with the main aetiologies such as autoimmune adrenalitis and tuberculosis. It then walks through the pathogenesis, glucocorticoid and mineralocorticoid symptoms, the acute adrenal crisis, laboratory and stimulation tests, and chronic replacement therapy. A mnemonic of five features closes the note.

Inside: 8 sections · 3 labelled pictures · 14 flashcards · 2 min

Topic 53 of 88 in the MU Sofia syllabus for Internal Diseases (Dental Medicine, Year 4). The free AceMed note covers it in 8 sections, about 340 words (2 min of reading), with 14 flashcards.

Definition

Hypocorticism refers to adrenal insufficiency, which may be:

Primary: Direct destruction or dysfunction of the adrenal cortex (→ Addison disease).
Secondary: Due to hypothalamic-pituitary axis dysfunction leading to decreased ACTH.

Etiology

Primary (Addison disease):

Autoimmune adrenalitis – Most common cause in developed countries.
Tuberculosis – Most common in developing countries.
Other causes:
Bilateral adrenal hemorrhage (e.g., Waterhouse–Friderichsen syndrome)
Infiltrative diseases (e.g., amyloidosis, hemochromatosis)
Metastatic cancer
Surgical removal of adrenal glands
Fungal infections (e.g., histoplasmosis)
Cytomegalovirus (especially in immunosuppressed)

Secondary:

Sudden withdrawal of long-term glucocorticoid therapy
Hypopituitarism
Pituitary gland surgery or radiation

Pathogenesis

1. Destruction of adrenal cortex → ↓ cortisol, aldosterone, and adrenal androgens.
2. ↓ Cortisol → loss of negative feedback → ↑ ACTH.
3. ↑ ACTH has melanocyte-stimulating hormone (MSH) activity → skin hyperpigmentation.
4. ↓ Aldosterone → ↓ sodium and water retention, ↑ potassium → hypovolemia and hyperkalemia.
5. ↓ Cortisol and aldosterone contribute to poor stress tolerance → risk of adrenal crisis.