ABSTRACT
Context: Subclinical hypothyroidism (SCH) is defined by an elevated Thyroid stimulating hormone (TSH) level in presence of normal serum free T4 concentration. Thus serum TSH measurement is the necessary test for diagnosis of mild thyroid failure. Aims: Evaluation of the pulmonary function by spirometry in patients of SCH, correlate the pulmonary function with fT3, fT4, TSH level and assess any change in pulmonary function in patients of SCH following treatment. Settings and Design: Prospective case control study from December 2014 to November 2016 in tertiary medical college of eastern India Methods and Material: 70 patients and 35 age sex matched controls were included in the study. The main outcome measures of the study were based on a comparison of spirometric findings of subclinical hypothyroidism with the control group and change in spirometric parameters after 3 months follow up with levothyroxin replacement. Statistical analysis used:The statistical comparisons were done by SPSS software version 20. Pvalue was considered significant if <0.05. Results: The study population 90% were females and 10% males. The mean TSH of the patients with subclinical hypothyroidism was 11.49±8.44 and that of the control group was 3.22±0.79, it was statistically significant. Forced expiratory volume in 1 second of subclinical hypothyroidism patients was significantly lower than control group. The mean FEV1/FVC% was higher in subclinical hypothyroidism as compared with control. After 3 months of thyroid hormone replacement the TSH level was normalised. With improvement of TSH all the respiratory parameters improved significantly. Conclusions: Though mild restrictive pattern of respiratory function abnormality occurs in subclinical hypothyroidism, it cannot be ignored. Hence they should be evaluated and clinical approaches should be taken accordingly at the earliest.