Abstract:

Objective To investigate the changes of thyroid hormones in patients with chronic obstructive pulmonary disease（COPD） and infection and the correlation with low triiodothyronine（T₃） syndrome. Methods Totally，58 patients with COPD and infection were enrolled. The results of thyroid hormones，including thyroid-stimulating hormone（TSH），total triiodothyronine（TT₃），free triiodothyronine（FT₃），total thyroxine（TT₄） and free thyroxine（FT₄），were collected. The rate of low T₃ syndrome in patients with COPD and infection was evaluated based on the reference change value（RCV） and reference intervals. Results Compared with control group，COPD patients with infection showed lower TT₃ and FT₃ levels（P<0.05）. TT₃ and TSH after treatment were higher than those before treatment（P<0.05），which TT₃ was still lower than that in control group（P<0.05）. There was no statistical significance for TT₄ and FT₄ among the groups（P>0.05）. Based on the reference intervals，29 of 58 COPD patients with infection were diagnosed as low T₃ syndrome before infection （50.0%）. After infection control，21 cases had low T₃ syndrome （36.2%）. Based on the RCV，12 of 58 patients had low T₃ syndrome （20.8%）. The incidence rate of low T₃ syndrome based on the RCV was lower than that based on the reference intervals （P<0.05）. Conclusions The patients with COPD and infection has high low T₃ syndrome rate ，and the levels of thyroid hormones should be monitored. The results based on the RCV should be good choice for clinicians to recognize low T₃ syndrome cases.

Key words: Thyroid hormone, Low triiodothyronine syndrome, Chronic obstructive pulmonary disease, Infection