Approach to hypernatremia Quiz: Ace Your Exams

A 94-year-old man presents to the primary care physician for a routine evaluation accompanied by his son. He has no medical concerns and feels well, though he reports decreased urine output over the past 2 days. The patient was recently seen in the emergency department for a fall and closed head injury but has otherwise been living independently. He has a past medical history of hypertension, high cholesterol, and dementia. Temperature is 37°C (98.6°F), blood pressure is 136/64 mmHg, heart rate is 77 beats per minute, respiratory rate is 16 breaths per minute, and oxygen saturation is 99% on room air. On physical examination, the patient is in no acute distress. Cardiopulmonary and abdominal examination are within normal limits. Mucous membranes appear dry. The patient is alert and oriented to self and place, which is the patient's baseline. Laboratory results are displayed below. Which of the following is most likely to be found on further history?  

Laboratory value	Result
Serum chemistry
Sodium	151 mEq/L
Potassium	4.8 mEq/L
Chloride	97 mEq/L
Creatinine	1.2 mg/dL