Hypothyroidism linked to COPD exacerbation risk

Research shows that chronic obstructive pulmonary disease (COPD) patients with hypothyroidism have an elevated exacerbation frequency but, despite this, experience similar quality of life to patients with normal thyroid function.

The research team, led by Sevinc Sarinc Ulasli (Afyon Kocatepe University, Turkey), studied a group of 44 COPD patients with hypothyroidism, 44 with COPD and normal thyroid function, and 40 healthy controls.

They found that patients with hypothyroidism had significantly more acute exacerbations over the course of a year compared with euthyroid patients, at a mean of 1.50 versus 0.86.

And there was a significant linear relationship between increasing thyroid stimulating hormone (TSH) and rising exacerbation frequency. Furthermore, in multivariate analysis, TSH level was the only predictor for exacerbation frequency, while spirometry results were not.

Previous studies have found evidence of diaphragmatic dysfunction and decreased inspiratory and expiratory muscle strength in patients with hypothyroidism, Ulasli et al explain. In accordance, they report that patients with hypothyroidism and COPD in their study had significantly lower maximal expiratory pressure (MEP) than that of other COPD patients, at a mean of 25.6 cmH₂O versus 34.9 cmH₂O.

However, there was no association between hypothyroidism and maximal inspiratory pressure (MIP), nor were MEP and MIP associated with thyroid function, which the authors say may be due to the lack of patients with severe COPD in their study and the fact that their patients had similar forced expiratory volume in 1 second (FEV1) and disease stage.

Also in agreement with previous studies, the team found that patients with and without hypothyroidism had significantly decreased domain scores on the Short Form-36 compared with controls, which correlated with FEV1. However, there was no overall difference in quality of life between the COPD groups.

“Therefore we can conclude that hypothyroidism is not a factor affecting quality of life in COPD patients,” Ulasli et al comment in Multidisciplinary Respiratory Medicine, but add that it should be addressed in a larger sample size of patients.

However, the team concludes that, given the relationship between exacerbations and quality of life, the findings suggest “that the detection of impairment in thyroid function can decrease exacerbation number and improve quality of life in COPD patients.”

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