A65-year-old man is brought to the ER due to recent dyspnea on exertion and generalized fatigue. He has a history of recurrent heart failure exacerbations last year. He has hypertension, myocardial infarction and hypercholesteromia. he has a 30-pack-yaer smoking history in addition to 15-year history of alcohol abuse. Physical examination reveals tachycardia, distended neck veins, bilateral crackles on lung auscultation, a third heart sound on cardiac auscultation, and pedal edema. The appropriate therapy is initiated. On the third day of hospitalization, his hematocrit level increases to 50%, up from 44% on admission. An arterial blood gas analysis shows an arterial O₂ partial pressure (PaO₂) of 70 mm Hg. A 51Cr-tagged red blood cell infusion indicates normal red blood cell mass. Which of the following is the most likely cause of this patient's polycythemia?

Question

Quizplus · Accepted Answer

Eductional Objective: Erythrocytosis is defined as a hematocrit level > 52% in men and > 48% in women.  Measurement of red blood cell mass is necessary to distinguish absolute from relative erythrocytosis.  A normal red blood cell mass indicates plasma volume contraction as the cause of polycythemia.

A65-Year-Old Man Is Brought to the ER Due to Recent