Extreme Hypernatremia with Markedly Increased Anion Gap.

During a routine visit for nail care and diabetic neuropathy evaluation, laboratory tests were ordered for a 64-year-old man with a history of diabetes mellitus and hypertension. At the time, he had no symptoms of any acute problem. A serum separator tube was received and revealed sodium 162 mmol/L, potassium 3.8 mmol/L, chloride 88 mmol/L, CO2 20 mmol/L, and anion gap 54 mmol/L with normal blood urea nitrogen (BUN), creatinine, and glucose.