Review Question - QID 214592

A 34-year-old man is found in the desert of Arizona. He is confused and is not able to offer a history. He has a pack with him with many supplies and appears to have been in the desert for several days. His temperature is 98.5°F (36.9°C), blood pressure is 103/61 mmHg, pulse is 140/min, respirations are 21/min, and oxygen saturation is 97% on room air. Physical exam reveals a confused man who is moving all extremities and is protecting his airway. Laboratory studies are ordered as seen below.

Serum:
Na+: 165 mEq/L
Cl-: 102 mEq/L
K+: 4.3 mEq/L
HCO3-: 25 mEq/L
BUN: 39 mg/dL
Glucose: 77 mg/dL
Creatinine: 1.15 mg/dL

The patient is given 3 L of Ringer lactate. He then begins jerking his extremities and is not responding to commands. The episode lasts 3 minutes and terminates before medications can be given. The patient is subsequently somnolent. He then experiences another episode. Which of the following is the most likely underlying etiology of this patient's symptoms?