[Impairment of muscle vasodilation during mental stress in women with subclinical hypothyroidism].
OBJECTIVE
To test the hypothesis that women with subclinical hypothyroidism (SH) have forearm vascular conductance (FVC) impaired during mental stress.


METHODS
We evaluated 20 women with SH and 21 euthyroid (Control group), matched for age (p = 0.699) and body mass index (p = 0.462). Muscle blood flow (MBF) was assessed by venous occlusion plethysmography and blood pressure by Dixtal2023. Both variables were recorded simultaneously for 3 minutes of baseline followed by 3 minutes of mental stress. The FVC was calculated by dividing MBF by mean arterial pressure. Significant differences were assumed at p < 0.05.


RESULTS
The SH group had higher concentrations of thyroid stimulating hormone (7.57 ± 3.17 vs. 2.10 ± 0,88 mU/L, p < 0.001). At baseline, the SH and control groups were similar for MBF (2.50 ± 0.79 vs. 2.55 ± 0,71 mL/ min/100 mL, p = 0.905, respectively) and FVC (2.80 ± 0.90 vs. 2.92 ± 0.88 units, p = 0.952, respectively). Throughout the mental stress test the SH and Control groups increased the MBF (time effect, p < 0.001) and FVC (time effect, p < 0.001) compared to baseline protocol. However, these variables were lower in SH group during the first (MBF: 3.66 ± 0.96 vs. 4.66 ± 1,61 mL/min/100 mL, p = 0.018, FVC: 3.95 ± 1.08 vs. 5.19 ± 1,96 units, p = 0.010) and second (MBF: 3.55 ± 1.01 vs. 4.62 ± 2,27 mL/min/100 ml, p = 0.018; FVC: 3.75 ± 1.07 vs. 4.92 ± 2,37 units, p = 0.020) minutes of mental stress test.


CONCLUSIONS
Women with SH have reduced muscle vasodilatatory response during mental stress.
Unidade de Investigação Cardiovascular e Fisiologia do Exercício, Hospital Universitário.
Fabiana de Faria
Fde F
Ghetti
Unidade de Investigação Cardiovascular e Fisiologia do Exercício, Hospital Universitário.
Rafaela Pinheiro
RP
Lacerda
Centro Desportivo, Universidade Federal de Ouro Preto, Ouro Preto, MG, Brasil.
Francisco Zacaron
FZ
Wernek
Centro Desportivo, Universidade Federal de Ouro Preto, Ouro Preto, MG, Brasil.
Emerson Filipino
EF
Coelho
Hospital Universitário Clementino Fraga Filho.
Mário
M
Vaisman
Unidade de Investigação Cardiovascular e Fisiologia do Exercício, Hospital Universitário.
Jorge Roberto Perrout de
JR
Lima
Unidade de Investigação Cardiovascular e Fisiologia do Exercício, Hospital Universitário.
Daniel Godoy
DG
Martinez
Unidade de Investigação Cardiovascular e Fisiologia do Exercício, Hospital Universitário.
Mateus Camaroti
MC
Laterza
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D016022:Case-Control Studies; D005260:Female; D005542:Forearm; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics; D006801:Humans; D007037:Hypothyroidism / Q000503:physiopathology*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply*; D013315:Stress, Psychological / Q000503:physiopathology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014664:Vasodilation / Q000502:physiology*
D013972:Thyrotropin; D013974:Thyroxine