Reversibility of diffusion capacity abnormalities in patients with clinical hypothyroidism with establishment of euthyroid state

Background: Hypothyroidism is associated with significant reduction of parameters of diffusion capacity and slight peripheral obstruction. However, it is not quite clear whether these abnormalities are reversible. Aim: To evaluate the reversibility of diffusion capacity (D L,CO ) abnormalities in patients with clinical hypothyroidism with establishment of euthyroid state. Patients and methods: Sixteen patients with different forms of autoimmune thyroiditis in clinical hypothyroid state (male/female – 4/12; age = 43.0±13.4 (mean±SD), TSH=101.6±52.3 mIU.L -1 , FT4=4.9±3.8 pmol.L -1 ) and 14 age and sex matched controls were included in the study. Pulmonary function assessment included slow vital capacity, forced spirometry and diffusion measurements (MasterScreen Diffusion, E. Jaeger, Germany). Results: Most of the patients with hypothyroidism (13/16) revealed significantly reduced diffusion capacity for carbon monoxide (D L,CO %pred. = 70.5±6.7 vs 93.8±12.9 in controls; p -1 ) diffusion capacity was significantly improved (D L,CO =80.3±10.3 vs. 70.5±6.7 before treatment; p=0.020). No changes were aparent in the other pulmonary function parameters. Conclusions: Hypothyroidism is associated with significant reduction of diffusion capacity. Restoring euthyroid state reverses these abnormalities as seen by the substantial improvement of D L,CO .