Goodpasture Anti-GBM Pulmonary Renal Spirometry

A 24-year-old male smoker presents with a 10-day history of progressive hemoptysis, dyspnea, and dark tea-colored urine. Examination reveals respiratory distress, bilateral fine crackles, and hypertension. Laboratory studies show acute kidney injury, hematuria with dysmorphic RBCs and RBC casts, and positive anti-GBM antibodies. Chest imaging demonstrates diffuse bilateral ground-glass opacities consistent with diffuse alveolar hemorrhage (DAH). After stabilization on plasmapheresis and immunosuppression, spirometry is performed. The pattern marked **A** in the diagram shows reduced TLC and FVC with a preserved FEV1/FVC ratio and markedly elevated DLCO at 160% predicted. What is the pathophysiologic basis for the paradoxically elevated DLCO in this patient's pulmonary function pattern?