Pulmonary function testing and chest tomography in patients with acromegaly

Abstract

Background: Despite the gradual improvement in treatment procedures and cure rates of acromegaly, a steady increase in the mortality rate due to respiratory disease has been documented in recent decades. In this study, our objectives were to describe the abnormalities in lung structure and function that occur in acromegalic patients and to correlate these changes with hormonal levels.

Methods: This cross-sectional study included 20 acromegalic patients and 20 age-and height-matched control subjects, all non-smokers. All subjects underwent spirometry, whole body plethysmography, carbon monoxide diffusing capacity, and respiratory muscle strength. Acromegalic patients also performed high-resolution computed tomography (HRCT).

Results: Most patients were female (65%), with a mean age of 52.5 ± 13 years. Acromegalic patients showed lower values of maximum expiratory pressure (55.9 ± 17.1 vs. 103.7 ± 19.2%; p < 0.001) and maximum inspiratory pressure (71.4 ± 27.8 vs. 85.3 ± 24.1%; p = 0.005) compared to control subjects. The values of forced vital capacity (107.1 ± 15.9 vs. 98.9 ± 21.4%; p = 0.028), total lung capacity - TLC (107.3 ± 12.9 vs. 93.7 ± 7.60%; p = 0.002), residual volume (114.1 ± 22.7 vs. 90.0 ± 14.6%; p < 0.001), and airways' resistance (3.82 vs. 2.31 cmH2O/L/s; p = 0.039) were greater in acromegalic patients than in control subjects. The difference between the TLC measured by plethysmography and the VA (alveolar volume) measured during the DLCO maneuver was higher in acromegalic patients than in control subjects (0.69 ± 0.46 vs. 0.19 ± 0.61 L; p = 0.021). The main findings in HRCT in acromegalic patients were air trapping, airway calcification and bronchiectasis, which were observed in 60%, 40% and 35% of cases, respectively. There was no significant correlation between the levels of growth hormone and insulin-like growth factor I, the lung function and the air trapping.

Conclusions: Acromegalic patients show changes consistent with the involvement of the small airways and ventilation inhomogeneity, both in terms of lung function and structure. However, air trapping cannot be explained either by hormone levels or changes in lung function.

Figure 1

Bronchiectasis and air trapping in a 56-year-old man with acromegaly who had an RV value of 126% of predicted and a Raw value of 5.23 cm H₂O/L/s. (a) Inspiratory, transverse, thin-section CT scan obtained through the lower lung zone shows bronchiectasis (arrows). (b) Expiratory, transverse, thin-section CT scan obtained through the lower lung zone reveals diffuse air trapping (arrowheads).

Figure 2

Air trapping in a 57-year-old man with acromegaly who had a RV value of 173% of predicted and a Raw value of 3.47 cm H₂O/L/s. (a) Inspiratory, transverse, thin-section CT scan obtained through the lower lung zone shows no abnormal findings. (b) Expiratory, transverse, thin-section CT scan obtained through the lower lung zone reveals diffuse air trapping (arrows).

Figure 3

Airway calcification in a 49-year-old woman with acromegaly who had an RV value of 120% of predicted and a Raw value of 2.95 cm H₂O/L/s. (a) Axial unenhanced CT scan (mediastinal window) shows tracheal calcifications (arrows). (b) Axial unenhanced CT scan (mediastinal window) shows bronchial calcifications (arrows).