Relationship between plasma antioxidants and thyroid hormones in chronic obstructive pulmonary disease.
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.
Division of Endocrinology, Department of Internal Medicine, Catholic University of the Sacred Heart, Rome, Italy. mancini.giac@mclink.it
A
A
Mancini
G M
GM
Corbo
A
A
Gaballo
S
S
Raimondo
C
C
Di Segni
P
P
Gigliotti
A
A
Silvestrini
S
S
Valente
G P
GP
Littarru
A
A
Pontecorvi
E
E
Meucci
D000368:Aged; D000369:Aged, 80 and over; D000975:Antioxidants / Q000032:analysis*; D002784:Cholesterol / Q000097:blood; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000150:complications / Q000453:epidemiology; D007558:Italy / Q000453:epidemiology; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D012044:Regression Analysis; D013963:Thyroid Hormones / Q000097:blood* / Q000172:deficiency; D013972:Thyrotropin / Q000097:blood / Q000172:deficiency; D013974:Thyroxine / Q000097:blood / Q000172:deficiency; D014284:Triiodothyronine / Q000097:blood / Q000172:deficiency; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000097:blood
D000975:Antioxidants; D013963:Thyroid Hormones; D014284:Triiodothyronine; D014451:Ubiquinone; D013972:Thyrotropin; D002784:Cholesterol; C024989:coenzyme Q10; D013974:Thyroxine