Maturation of lung function in children with hypopituitarism.

To identify factors that bring about maturation of the respiratory system, we studied pulmonary function in 18 patients 9 to 19 yr of age with severe growth retardation caused by hypopituitarism. In 6 we measured pulmonary pressure-volume (P-V) curves before and after a 4 to 6 yr period of human growth-hormone-induced catch-up growth. Even when size-corrected according to total lung capacity (TLC), all measurements were more appropriate for height than for age. The ratio of functional residual capacity to TLC was low for age (less than 2 SD in 8 of 18 patients), and the ratio of closing capacity to TLC was slightly high for age (108% of predicted, p less than 0.05). The diffusion constant for carbon monoxide and the slope of the nitrogen washout alveolar plateau were both high for age. Lung elastic recoil was low for age; Pst(L) at 60% TLC was less than 2 SD in 3 of the 6 patients studied. During the period of catch-up growth, TLC increased appropriately for height, the slope of the alveolar plateau decreased (1.9 to 1.0% N2 L, p less than 0.01) and Pst(L) at 60% TLC increased (6.3 to 7.9 cm H2O, p less than 0.02). The P-V results indicate that growth of the lungs per se causes the increase in lung elastic recoil previously observed during childhood.