system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 44-year-old man is brought to the emergency department 45 minutes after being involved in a high-speed motor vehicle collision in which he was the restrained driver. On arrival, he has left hip and left leg pain. His pulse is 135/min, respirations are 28/min, and blood pressure is 90/40 mm Hg. Examination shows an open left tibial fracture with active bleeding. The left lower extremity appears shortened, flexed, and internally rotated. Femoral and pedal pulses are decreased bilaterally. Massive transfusion protocol is initiated. An x-ray of the pelvis shows an open pelvis fracture and an open left tibial mid-shaft fracture. A CT scan of the head shows no abnormalities. Laboratory studies show:
Hemoglobin 10.2 g/dL
Leukocyte count 10,000/mm3
Platelet count <250,000/mm3
Prothrombin time 12 sec
Partial thromboplastin time 30 sec
Serum
Na+ 125 mEq/L
K+ 4.5 mEq/L
Cl- 98 mEq/L
HCO3- 25 mEq/L
Urea nitrogen 18 mg/dL
Creatinine 1.2 mg/dL
The patient is taken emergently to interventional radiology for exploratory angiography and arterial embolization. Which of the following is the most likely explanation for this patient's hyponatremia?"
assistant
Physiologic ADH (vasopressin) secretion