Lung function in acromegaly.

Lung function has been assessed by spirometry, body plethysmography, flow volume loops and single breath transfer factor in thirty patients with acromegaly. Having excluded eight patients with kyphosis and/or clinical or radiological evidence of pulmonary venous hypertension we have found a significant correlation between duration of acromegaly and lung size as assessed by total lung capacity. Excluding the same eight patients we have found evidence of small airways narrowing in eight patients, seven of these eight had had acromegaly for nine years or longer, and the duration of acromegaly was significantly longer in the patients with small airways narrowing than in those without. In the absence of other recognized causes it is possible that small airways narrowing in acromegaly is caused either by the increased whole blood volume with pulmonary vascular engorgement, or by increase in size of the soft tissues of the small conducting airways. Six of the eight patients with kyphosis and/or pulmonary venous hypertension also had evidence of small airways narrowing. Thus fourteen of the thirty patients with acromegaly had small airways narrowing. Five men had evidence of extra thoracic airway narrowing and in four the duration of acromegaly was ten years or longer. We conclude that the increase in total lung capacity, the incidence of small airways narrowing and the incidence of upper airway narrowing are all related to the duration of acromegaly. It seems that once duration exceeds eight years patients are very likely to develop abnormalities of lung function either primarily from the effects of acromegaly on the airways and lung or secondarily from the associated cardiovascular and thoracic skeletal abnormalities. It seems probable that the small airways and upper airway narrowing contribute to the morbidity and mortality of this disease. This study provides further evidence that acromegaly should be treated early.