The Effect of Levothyroxin on Pulmonary Function Tests of Hypothyroid Patients

The aim of the present study was to determine the effect of levothyroxin on the pulmonary function of patients with hypothyroidism.
Materials and Methods: In this Quaziexperimental study, all patients who were diagnosed as hypothyroid for first time and had no history of known pulmonary disease or smoking or recent abdominal or chest surgery were recruited. Levothyroxin was prescribed for all patients (1.7 Ilglkg). Spirometry was done with the standard methods for all patients at the beginning of the study and again after at least 3 months of euthyroidism.
Results: 30 patients (24 females and 6 males) with a mean age of 37.5+12 years were studied. At the beginning of the study, 16 patients had mild restrictive pulmonary abnormalities and 10 patients had moderate restrictive pulmonary disease. 4 patients were normal. At the end of the study, the results of spirometry were normal in 12 patients and mild restrictive abnormalities were found in 14, and moderate restrictive abnormalities in 4 patients. Significant increases in FEVl, FVC and FEF25-75% were found after treatment with levothroxin (p<0.05), especially in patients over 40 years of age and those with a body mass index <30 kglm2.
Conclusion: This report shows that respiratory restrictive abnormalities are prevalent in hypothyroidism and may be reversible after treatment with levothyroxin.