First presentation of Addison's disease as hyperkalaemia in acute kidney injury.

Addison's disease is a rare endocrine disorder that frequently presents with non-specific symptoms, but may deteriorate rapidly into life-threatening Addisonian crisis if left untreated. Diagnosis can be difficult in patients without a suggestive medical history. We describe a case of a 37-year-old man who was admitted with acute kidney injury and hyperkalaemia, resistant to treatment with insulin/dextrose and calcium gluconate. On clinical examination, he was found to be hyperpigmented; a subsequent random serum cortisol of 49 nmol/L affirmed the preliminary diagnosis of Addison's disease. The patient's hyperkalaemia improved on treatment with hydrocortisone, and a follow-up morning adrenocorticotropic hormone of 1051 ng/L confirmed the diagnosis.