Acid-base homeostasis · USMLE Step 1

Which of the following represents a primary disturbance in respiratory acidosis?

  1. Low PaCO₂ due to hyperventilation
  2. High HCO₃⁻ due to renal compensation
  3. High PaCO₂ due to hypoventilation
  4. Low HCO₃⁻ due to metabolic loss
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Correct answer: High PaCO₂ due to hypoventilation

Respiratory acidosis begins with elevated PaCO₂ (hypoventilation), increasing carbonic acid and lowering pH; renal compensation (increased HCO₃⁻) may follow if chronic.

Difficulty: Medium Question 18 of 19

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