Relationship between plasma antioxidants and thyroid hormones in chronic obstructive pulmonary disease

Exp Clin Endocrinol Diabetes. 2012 Nov;120(10):623-8. doi: 10.1055/s-0032-1323808. Epub 2012 Oct 16.

Abstract

Background: A low-T₃ syndrome is observed in chronic diseases, but its treatment is still debated. Chronic obstructive pulmonary disease (COPD) has not been conclusively studied under this aspect. COPD is a complex condition, which cannot be considered a lung-related disorder, but rather a systemic disease also associated to increased oxidative stress. We evaluated thyroid hormones and antioxidant systems, the lipophilic Coenzyme Q10 (CoQ₁₀) and total antioxidant capacity (TAC) in COPD patients to reveal the presence of a low-T₃ syndrome in COPD and investigate the correlation between thyroid hormones, lung function parameters and antioxidants.

Methods: We studied: 32 COPD patients and 45 controls, evaluating thyrotropin (TSH), free-triiodotyronine (fT₃), free-tetraiodotyronine (fT₄), CoQ₁₀ (also corrected for cholesterol) and TAC. CoQ₁₀ was assayed by HPLC; TAC by the metmyoglobin-ABTS method and expressed as latency time (LAG) in radical species appearance.

Results: We found significantly lower LAG values, fT₃ and fT₄ levels and significantly higher TSH in COPD patients vs. controls. LAG values significantly correlated with fT₃ concentration. 12 out of 32 patients exhibited fT₃ levels lower than normal range. So we divided COPD patients in 2 groups on the basis of the fT₃ concentration (normal fT₃ COPD and low fT₃ COPD). We observed lower LAG values in normal fT₃-COPD, compared to healthy subjects, with a further significant reduction in low fT₃-COPD patients. Moreover higher TSH concentration was present in normal fT₃-COPD, compared to healthy subjects, with a further significant increase in low fT₃-COPD patients. CoQ₁₀/cholesterol ratio was higher in low fT₃-COPD vs. normal fT₃-COPD, with a nearly significant difference.

Conclusions: These data seem to indicate an increased oxidative stress in low fT₃-COPD and a role of fT₃ in modulating antioxidant systems. However low fT₃ levels are joined to metabolic indexes of true hypothyroidism, suggesting that elevated CoQ₁₀ expresses a reduced tissue utilization. These data might suggest the need of thyroid replacement therapy in such a condition.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Antioxidants / analysis*
  • Cholesterol / blood
  • Female
  • Humans
  • Hypothyroidism / complications
  • Hypothyroidism / epidemiology
  • Italy / epidemiology
  • Lung / physiopathology
  • Male
  • Middle Aged
  • Oxidative Stress*
  • Prevalence
  • Pulmonary Disease, Chronic Obstructive / blood*
  • Pulmonary Disease, Chronic Obstructive / complications
  • Pulmonary Disease, Chronic Obstructive / physiopathology
  • Regression Analysis
  • Thyroid Hormones / blood*
  • Thyroid Hormones / deficiency
  • Thyrotropin / blood
  • Thyrotropin / deficiency
  • Thyroxine / blood
  • Thyroxine / deficiency
  • Triiodothyronine / blood
  • Triiodothyronine / deficiency
  • Ubiquinone / analogs & derivatives
  • Ubiquinone / blood

Substances

  • Antioxidants
  • Thyroid Hormones
  • Triiodothyronine
  • Ubiquinone
  • Thyrotropin
  • Cholesterol
  • coenzyme Q10
  • Thyroxine