α1-Antitrypsin Deficiency

Abstract

The patient was a 37-year-old Japanese male with α1-antitrypsin (AAT) deficiency. He had a 3-year history of progressive dyspnea on exertion. He smoked 10 cigarettes daily from ages 15 to 20 and then 40 cigarettes daily until the age of 34 years when he quit because of dyspnea. He worked as an automobile parts salesman and denied any history of exposure to noxious gases. Family history was not contributory concerning emphysema, asthma, or other respiratory disorders. Physical examination on admission disclosed no cyanosis, tachypnea, or tachycardia. No clubbing of the fingers was present. Breath sounds were diffusely diminished in both lungs. Laboratory data such as blood cell count and results of routine biochemical screening tests were within the normal range except for mild erythrocytosis with an elevated hemoglobin value (17.8 g/dl) and red blood cell count (637 × 10⁴/μl). Liver function tests results were normal. Serum protein electrophoresis failed to detect a peak corresponding to α1-globulin; subsequent determination of serum levels of AAT disclosed severely decreased concentrations (20 mg/dl; normal range, 170–274; measured by nephelometry, SRL, Tokyo, Japan). Arterial blood gas levels sampled with the patient breathing room air showed moderate hypoxemia (PaO₂, 60 Torr; PaCO₂, 37.5 Torr). A chest roentgenogram disclosed hyperinflated lungs and bilaterally flattened hemidiaphragms (Fig. 16.1). Computed tomography of the chest demonstrated panlobular emphysema with lower lobe preponderance (Fig. 16.2). Pulmonary function tests indicated severe obstructive ventilatory impairment with forced expiratory volume in 1 sec (FEV₁) (1.13 L, 30.3% of the predicted value) and FEV₁/forced vital capacity (33.6%). Residual volume was increased (3.27 L; 228% of the predicted value), and the diffusing capacity of carbon monoxide was impaired (6.45 ml/min/mm Hg; 26.5% of the predicted value). The patient was diagnosed with severe pulmonary emphysema resulting from AAT deficiency, and home oxygen therapy was initiated to ameliorate hypoxemia.