title: Effect of hormone replacement on exercise cardiopulmonary reserve and recovery performance in subclinical hypothyroidism.
abstract: Subclinical hypothyroidism (SH) patients present cardiopulmonary, vascular and muscle dysfunction, but there is no consensus about the benefits of levothyroxine (L-T₄) intervention on cardiopulmonary performance during exercise. The aim of the present study was to investigate the effects of L-T₄ on cardiopulmonary exercise reserve and recovery in SH patients. Twenty-three SH women, 44 (40-50) years old, were submitted to two ergospirometry tests, with an interval of 6 months of normalization of thyroid-stimulating hormone (TSH) levels (L-T₄ replacement group) or simple observation (TSH = 6.90 μIU/mL; L-T₄ = 1.02 ng/dL). Patients with TSH >10 μIU/mL were excluded from the study to assure that they would receive treatment in this later stage of SH. Twenty 30- to 57-year-old women with no thyroid dysfunction (TSH = 1.38 μIU/mL; L-T₄ = 1.18 ng/dL) were also evaluated. At baseline, lower values of gas exchange ratio reserve (0.24 vs 0.30; P < 0.05) were found for SH patients. The treated group presented greater variation than the untreated group for pulmonary ventilation reserve (20.45 to 21.60 L/min; median variation = 5.2 vs 25.09 to 22.45 L/min; median variation = -4.75, respectively) and for gas exchange ratio reserve (0.19 to 0.27; median variation = 0.06 vs 0.28 to 0.18; median variation = -0.08, respectively). There were no relevant differences in cardiopulmonary recovery for either group at baseline or after follow-up. In the sample studied, L-T₄ replacement improved exercise cardiopulmonary reserve, but no modification was found in recovery performance after exercise during this period of analysis.
authors.affiliation: Serviço de Endocrinologia, Hospital Universitário Clementino Fraga Filho, Departamento de Clínica Médica, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Brasil. miriam.mainenti@hotmail.com
authors.forename: M R M
authors.initials: MR
authors.lastname: Mainenti
authors.forename: P F S
authors.initials: PF
authors.lastname: Teixeira
authors.forename: F P
authors.initials: FP
authors.lastname: Oliveira
authors.forename: M
authors.initials: M
authors.lastname: Vaisman
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005080:Exercise Test / Q000379:methods*; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000503:physiopathology*; D007321:Inspiratory Reserve Volume / Q000502:physiology*; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D013147:Spirometry; D013974:Thyroxine / Q000627:therapeutic use*
chemical_list: D013974:Thyroxine