Evaluation of redox profiles in exogenous subclinical hyperthyroidism at two different levels of TSH suppression

• Published in: Archives of Endocrinology and Metabolism Vol. 62; no. 5; pp. 545 - 551
• Main Authors: Piazera, Bruna Karoline Lima, Gomes, Diego Viana, Vigário, Patrícia, Salerno, Verônica P., Vaisman, Mário
• Format: Journal Article
• Language: English
• Published: Brazil Sociedade Brasileira de Endocrinologia e Metabologia 01.10.2018; Brazilian Society of Endocrinology and Metabolism
• Subjects: Adult; antioxidants; Case-Control Studies; Catalase - blood; Cross-Sectional Studies; Female; Glutathione - blood; Glutathione Disulfide - blood; Humans; Hyperthyroidism - drug therapy; Hyperthyroidism - metabolism; Lipid Peroxidation - drug effects; Male; Middle Aged; Original; Oxidation-Reduction - drug effects; oxidative stress; Oxidative Stress - drug effects; Phenols - blood; Protein Carbonylation; Reference Values; Statistics, Nonparametric; Subclinical hyperthyroidism; Sulfoxides - blood; Thiobarbituric Acid Reactive Substances - analysis; thyroidectomy; Thyrotropin - antagonists & inhibitors; Thyroxine - pharmacology
• ISSN: 2359-3997; 2359-4292; 2359-4292
• DOI: 10.20945/2359-3997000000075

Evaluate the relationship between exogenous subclinical hyperthyroidism and oxidative stress through the analysis of the redox profile of patients with subclinical hyperthyroidism exogenous (SCH) grade I (TSH = 0.1 to 0.4 IU/mL) and grade II (TSH < 0.1 IU/mL). We analyzed 46 patients with SCH due to the use of TSH suppressive therapy with LT4 after total thyroidectomy along with 6 control euthyroid individuals (3M and 3W). Patients were divided into two groups, G1 with TSH ≥ 0.1-0.4 IU/mL (n = 25; and 7M 14W) and G2 with TSH < 0.1 IU/mL (n = 25; and 4M 21W). Venous blood samples were collected to measure the levels of markers for oxidative damage (TBARS, FOX and protein carbonylation), muscle and liver damage (CK, AST, ALT, GGT) and antioxidants (GSH, GSSG and catalase). Individuals in G2 showed a GSH/GSSG ratio ~ 30% greater than those in G1 (p = 0.004) and a catalase activity that was 4 times higher (p = 0.005). For lipid peroxidation, the levels measured in G2 were higher than both control and G1 (p = 0.05). No differences were observed for both protein carbonyl markers. G1 and G2 presented with greater indications of cell injury markers than the control group. TSH suppression therapy with LT4 that results in subclinical hyperthyroidism can cause a redox imbalance. The greater antioxidant capacity observed in the more suppressed group was not sufficient to avoid lipid peroxidation and cellular damage.