Hypoxemia and pulmonary function in acromegaly.

Pulmonary function was assessed in 11 patients with acromegaly, 8 of whom were previously treated by external pituitary irradiation. None of the patients had any overt respiratory ailment. Ventilatory function tests were normal in all patients and all had normal total lung capacity ranging from 75 to 123% (mean, 98.18 +/- 4.69%). Eight of ten patients (80%) had hypoxemia with a partial pressure of oxygen in arterial blood ranging between 58 and 90 mmHg (mean, 76.0 +/- 4.2). Calculated alveolar-arterial differences for oxygen ranged between 5.25 and 46.0 (mean, 26.0 +/- 4.7). In 4 of 5 patients in whom lung perfusion scans were performed, perfusion defects were found. There was a significant correlations (p < 0.05) between the presence of hypoxemia and the known duration of acromegaly, but not with the present growth hormone levels or previous therapy. The results indicate that pneumomegaly is not common in acromegaly. However, most patients have some degree of hypoxemia present usually as subclinical disease and it is probably due to a ventilation-perfusion derangement, which is probably a direct effect of the prolonged oversecretion of growth hormone.