Uremic encephalopathy Quiz: Ace Your Exams

A 61-year-old man presents to the emergency department for altered mental status. A family member found him unresponsive at home in bed this morning and called for an ambulance. The family reports that the patient receives dialysis for chronic kidney disease, and his last appointment was three days ago. He has otherwise been in his usual state of health. He has a history of osteoarthritis and recently had an MRI of the hip with gadolinium contrast. Additional past medical history includes hypertension, diabetes, hyperlipidemia. Temperature is 37.2°C (99°F), blood pressure is 177/95 mmHg, pulse is 98/min, respiratory rate is 18/min, and O2 saturation is 98% on room air. BMI is 34 kg/m2. The patient is responsive to painful stimuli only and responds with moaning. He is moving all extremities spontaneously. A thrill is palpable over a right upper extremity fistula. Abdominal examination is within normal limits. Initial laboratory findings are detailed below. ECG demonstrates normal sinus rhythm and peaked T waves. Which of the following is the most likely cause of this patient's condition?  

Laboratory value	Result
Serum chemistry
Sodium	141 mEq/L
Potassium	5.9 mEq/L
Chloride	99 mEq/L
Creatinine	12.2 mg/dL
HCO3	30 mEq/L
Glucose	232 mg/dL
BUN	101