CBC count, electrolyte levels, erythrocyte sedimentation rate, rheumatoid factor, liver function tests, and urinalysis were within normal ranges. Antimyeloperoxidase, anti-proteinase-3, anti-Ro, anti-La, anti-Smith, antiribonucleoprotein, anti-Jo-1, anti-Scl-70, and anticentromere antibodies were within the normal range. HIV serology, antinuclear antibody, and Mantoux skin test were all negative. Arterial blood gas measurements showed respiratory alkalosis and hypoxemia (pH, 7.49; Pco2, 32; Po2, 89 on room air). Pulmonary function test showed moderate obstruction, with an FEV1/FVC ratio of 60% and an FEV1 of 2.75 L or 65% predicted. Diffusion capacity was diminished, at 66%.