Hyperkalemia: a clue to the diagnosis of adrenal insufficiency.

A 54-year-old man with childhood-onset type I diabetes mellitus who had preserved renal function but blindness secondary to his diabetes mellitus presented with a 5-day history of malaise and diarrhea. On admission, he was dehydrated, hypotensive, and hypo-thermic (96.1ºF/35.6ºC). Initial laboratory values showed a potassium level of 9.2 (N, 3.6–5.0) mmol/L, and a sodium level of 122 (N, 137–145) mmol/L. The potassium level was confirmed on arterial samples. The initial ECG showed a regular idioventricular rhythm with bizarre, broad QRS complexes, and a frequency of 32 beats per minute (Figure A). Over a 5-hour period, on correction of the hyperkalemia, he converted to sinus rhythm (Figure B and C) initially with a first-degree atrioventricular block (Figure B). Furthermore, the characteristic peaking of the T waves related to the hyperkalemia normalized (Figure C). On follow-up, an increased level of adrenocorticotropic hormone, the absence of response to synthetic adrenocorti-cotropic hormone, and strongly positive adrenal antibodies revealed that the patient had developed autoimmune adrenal insufficiency (Addison disease). Thomas Addison recognized the potential effects of adrenal insufficiency on the heart, and he described one of the marked features of the condition as " a remarkable feebleness of the hearts action " in his original monograph from 1855. 1 To this day, adrenal insufficiency is a condition that cardi-ologists should be aware of because of the common occurrence of hypoaldosteronism-mediated hyperkalemia, and because it is a differential diagnosis in patients with shock or circulatory collapse. Conditions predisposing to adrenal insufficiency are tumors, hemorrhage, or infections affecting the pituitary or the adrenal glands; iatrogenous adrenal insufficiency attributable to long-term glucocorticoid therapy; other autoim-mune diseases; or, more rarely, hereditary diseases. In some developing countries, tuberculous adrenalitis is still common, whereas an autoimmune diathesis accounts for most cases in the Western world. 2,3 Common clinical findings in patients with adrenal insuffi-ciency include malaise, lethargy, abdominal discomfort, hypo-tension, hypothermia, and sometimes hyperpigmentation or signs of a predisposing state (eg, other autoimmune diseases, carcinomas, or glucocorticoid therapy). The occurrence of hypoglycemia, metabolic acidosis, affected kidney function, or the classic—but not invariably present—combination of hyponatremia and hyperkale-mia may be other clues to the tentative diagnosis of adrenal insufficiency. 2–4 Acute adrenal insufficiency or addisonian crisis is a life-threatening condition, and, on suspicion, the administration of intravenous glucocorticoid, rehydration with saline, and treatment directed toward the triggering condition (eg, infections) should be initiated promptly. The glucocorticoid of choice has classically been hydrocortisone …