Upper airflow obstruction and pulmonary function in acromegaly: relationship to disease activity

Pulmonary function and disease activity were assessed in a large series of patients with acromegaly (19 men and 16 women). Large lungs, defined as a vital capacity greater than 120 per cent of predicted normal occurred in six of 19 males and six of 16 females. Ten of the 12 patients with elevated vital capacity had active disease (growth hormone greater than 5 mU/l during a glucose tolerance test). There was no association with duration of disease. Diffusing capacity was normal overall but DLCO greater than 120 per cent occurred in six of 14 females and one of 18 males. Significant intrathoracic airflow obstruction occurred in eight of 35 patients, six of whom were nonsmokers. Upper (extrathoracic) airflow obstruction was the most common pulmonary function abnormality. A maximal expiratory/inspiratory flow ratio greater than 1.0 at 50 per cent vital capacity occurred in 13 of 18 males and four of 16 female patients, and there was an association with disease activity (17 of 25 subjects with active disease had upper airflow obstruction compared to one of nine in remission; p = 0.01). Nocturnal hypoxaemia occurred in three of 13 patients studied: six of this group had upper airways obstruction. They were all male with elevated growth hormone levels and upper airflow obstruction. In summary, in 35 acromegalics (26 with active disease), large lungs occurred in 12 patients (34 per cent) and upper airflow obstruction in 17 patients (50 per cent). The latter may develop nocturnal hypoxaemia--this was seen in three of six patients with upper airflow obstruction. Upper airways obstruction was more common in males (13 of 18 compared to four of 16 females; p = 0.04) and its presence in males should arouse suspicion of nocturnal hypoxaemia.