Exercise Performance in Young and Middle-Aged Female Patients with Subclinical Hyperthyroidism

Abstract

Subclinical hyperthyroidism (SH) may be responsible for many cardiovascular changes, including an impaired exercise performance. The aim of our study was to evaluate the response to the treadmill cardiopulmonary test in patients with SH. We studied 14 female patients from our endocrine clinic with exogenous SH, free from cardiovascular diseases, with mean age of 38.6 +/- 10.2 years, body mass index (BMI) of 24.4 +/- 4.0 kg/m(2), and disease duration of 4.9 +/- 4.9 years. The mean serum thyrotropin (TSH) was 0.03 +/- 0.03 mU/L, serum free thyroxine (FT(4)), 1.72 +/- 0.21 ng/dL, and serum triiodothyronine level, 137 +/- 32 ng/dL. The control group comprised 15 euthyroid, healthy women, with mean age of 35.4 +/- 7.4 years and BMI of 27.3 +/- 5.9 kg/m(2). Both groups had a sedentary lifestyle and underwent the cardiopulmonary test using a treadmill with the Balke protocol. Gas concentrations and the respiratory outflow were measured and the electrocardiogram (ECG) was registered in real time. We calculated the minute ventilation (V(E)), the oxygen consumption (peak VO(2)), the carbonic gas exhalation (peak VCO(2)) and the anaerobic threshold (AT). The heart rate (HR) at rest (90.9 +/- 15.7 versus 78.9 +/- 8.7 beats per minute; p = 0.03) was higher in the patients from our clinic. There was no difference between groups regarding age, BMI, fat percentage, blood pressure, peak HR, exercise duration, mean treadmill peak inclination, V(E), peak VO(2), peak VCO(2), and AT. There was no correlation between peak VO(2) and FT(4), TSH, or disease duration. Our results show that exercise capacity in young and middle-aged female patients is not significantly affected by exogenous SH.

Impaired functional and hemodynamic response to graded exercise testing and its recovery in patients with subclinical hyperthyroidism

“…This finding is in accordance with two population-based surveys that showed that SCH is not associated with changes in blood pressure (32,33). SCH also seems to be unassociated with peak blood pressure during exercise, since no differences were found in both SBP and DBP between SCH patients and euthyroid subjects, as reported by other studies (24,26).…”

“…Their patients however, were younger than ours (median = 40.5 years; interquartile range = 28.6 -48.0) and they also presented lower median disease duration (3.0 years; interquartile range = 1.2 -7.3). It may be hypothesized that age and time in TSH suppressive therapy may contribute to abnormalities in cardiopulmonary function in SCH (26).…”

Endogenous subclinical thyroid disorders, physical and cognitive function, depression, and mortality in older individuals

“…The prevalence of subclinical hyperthyroidism ranges from 1 to 15% and of subclinical hypothyroidism from 3 to 16% in individuals aged 60 years and older (1). Although overt thyroid disorders do negatively influence physical and cognitive function (2), associations of subclinical thyroid disorders with these outcome measures are less clear and studies demonstrate contradictory results (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). A systematic review of the literature rated the evidence as insufficient to confirm or refute an association of subclinical thyroid disorders with clinical symptoms (2).…”

Does low serum TSH within the normal range have negative impact on physical exercise capacity and quality of life of healthy elderly people?

“…Most of these studies have important limitations, like the restricted sectional design (17,34,35) and, even in a prospective way, the absence of a control group like the present one (33). The inclusion of subclinical and overt hypo or hyperthyroidism in the same sample is also reported by some studies (33).…”

“…Few studies have evaluated exercise performance in thyroid dysfunctions (17,21,(31)(32)(33)(34)(35)(36) and the minority applied ergospirometry to quantify cardiopulmonary capacity during exercise (17,21,31,32,35,36). Most of these studies have important limitations, like the restricted sectional design (17,34,35) and, even in a prospective way, the absence of a control group like the present one (33).…”