Adrenal Insufficiency

Wednesday's morning report focussed on adrenal insufficiency and endocrine causes of syncope (adrenal insufficiency and hypoglycemia being the most common of these, though hypocalcemia can cause hypovolemia and thus presyncope).

With respect to adrenal insufficiency, it's useful to review the hypothalamic-pituitary-adrenal axis, in that the hypothal produces corticotropin releasing hormone, which stimulates pit production of corticotropin or ACTH, which stimulates the adrenal gland to produce cortisol and androgen (and short-lived aldosterone).

I had to review the anatomy of the adrenal cortex, but as a quick reminder the zones are (from outside in): GFR - zona glomerulosa, fasciculata, and reticularis, which produce mineralocorticoids, glucocorticoids, and androgens respectively (salt, suger, sex is a good way to remember it).

Here's a review article (a bit old, but useful) - see table 1 for the causes of primary/secondary insufficiency. Table 2 highlights the signs/symptoms of adrenal insufficiency, emphasizing that this is a nonspecific presentation that requires looking for other clues (ie high K or low Na, hyperpigmentation) and actually remembering the diagnosis as a possibility. Very easy to miss. Dynamic testing (ie cosyntropin stimulation test) is necessary to make the diagnosis, though AM cortisol can sometimes be useful (or at least practical) in people in whom you have a very low index of suspicion and you are just ruling it out (ie the asymptomatic patient who has euvolemic hyponatremia). Remember, patients with adrenal insufficiency on treatment should probably have medicalert bracelets - something you can give them info on before they go.