Assessment of Functional Lung Impairment in Hypothyroidism

Abstract

Aims: To determine any functional lung impairment amongst patients diagnosed with hypothyroidism by spirometry. Methods: 21 hypothyroid subjects with TSH ≥10 mIU/L aged between 18-52 yrs were studied along with 21 healthy controls in the department of Physiology, Regional Institute of Medical Sciences (RIMS), Imphal. Hypothyroid subjects with other conditions/diseases which affect PFT were excluded. Spirometric parameters were conducted by means of computerised spirometer HELIOS 401/701(RMS, Chandigarh).The spirometric parameters studied are FVC, FEV 1 , FEV 1 /FVC, FEF 25-75%, PEFR. Unpaired T-test and Pearson correlation was used and P value <0.05 was taken as significance. Result: Hypothyroid subjects showed a reduction of the % predicted value of FVC, FEV 1 , FEF 25-75% , PEFR as compared to control subjects even though these values are within the normal values for their age, sex and gender. But the difference is statistically significant only for FVC. And the % predicted value for FEV 1 /FVC of hypothyroid subjects is found to be significantly increased than the controls. On analyzing and classifying only the hypothyroid subjects based on FVC values, 47% of the hypothyroid subjects were normal while 9% had mild restrictive lung impairment and the rest 43% had moderate to severe restrictive impairment. A negative correlation was found between TSH levels with the spirometric parameters FVC, FEV₁, FEV1/FVC and a positive correlation was found between T 4 levels with FVC, FEV₁, FEV 1 /FVC. But none of the findings were not statistically significant. Conclusion: The pulmonary functions can be affected in hypothyroidism and they show a restrictive pattern of lung impairment.