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

Heart rate response to graded exercise test of elderly subjects in different ranges of TSH levels

OBJECTIVE

Life expectancy is increasing worldwide and studies have been demonstrating that elevated serum thyroid stimulating hormone (TSH) concentration in elderly is associated with some better health outcomes. This elevation is somewhat physiological as aging. The aim of this study was to investigate the heart rate (HR) response during a graded exercise test and its recovery in healthy elderly, comparing subjects within serum TSH in the lower limit of reference range to those within the TSH in the upper limit.

SUBJECTS AND METHODS

A cross-sectional study was conducted with 86 healthy elderly aged 71.5 ± 5.1 years, with serum TSH between 0.4 - 4.0 mUl/mL. The participants were divided into two groups according to TSH level: < 1.0 mUl/mL (n = 13) and ≥ 1.0 µUI/mL (n = 73). All participants performed an ergometric test on a treadmill. The HR was recorded and analyzed at rest, during exercise and during the three minutes immediately after exercise.

RESULTS

No differences were observed in relation to HR at peak of exercise (TSH < 1.0 µUI/mL: 133.9 ± 22.5 bpm vs. TSH ≥ 1.0 µUI/mL: 132.4 ± 21.3 bpm; p = 0.70) and during the first minute of recovery phase (TSH < 1.0 µUI/mL: 122.3 ± 23.1 bpm vs. TSH ≥ 1.0 µUI/mL: 115.7 ± 18.4 bpm p = 0.33). The groups also presented similar chronotropic index (TSH < 1.0 µUI/mL: 78.1 ± 30.6 vs. TSH ≥ 1.0 µUI/mL: 79.5 ± 26.4; p = 0.74).

CONCLUSION

In this sample studied, there were no difference between lower and upper TSH level concerning HR response during rest, peak of exercise and exercise recovery.

Long-term treatment-related morbidity in differentiated thyroid cancer: a systematic review of the literature

Background

Differentiated thyroid cancer (DTC) occurs in relatively young patients and is associated with a good prognosis and long survival. The management of this disease involves thyroidectomy, radioiodine therapy, and long-term thyroid-stimulating hormone suppression therapy (THST). The long-term effects of the treatment and the interaction between subclinical hyperthyroidism and long-term hypoparathyroidism are poorly understood. This review sought to examine the available evidence.

Methods

A PubMed search was carried out using the search terms “Thyroid Neoplasms” AND (“Thyroxine” OR “Hypocalcemia” OR “Thyrotropin”). Original English language articles published in the last 30 years studying the morbidity from thyroid-stimulating hormone (TSH) suppression and hypoparathyroidism following a surgery for DTC were retrieved and reviewed by 2 authors.

Results

Of the 3,000 results, 66 papers including 4,517 patients were selected for the present study. Studies reported on a range of skeletal (included in 34 studies, 1,647 patients), cardiovascular (17 studies, 957 patients), psychological (10 studies, 663 patients), and other outcomes (10 studies, 1,348 patients). Nine of 26 studies on patients who underwent THST showed a reduction in bone density, and 13 of 23 studies showed an increase in bone turnover markers. Skeletal effects were more marked in postmenopausal women. There was no evidence of increased fracture risk, and only little data were available on hypoparathyroidism. Four of five studies showed an increased left ventricular mass index on echocardiography, and one study showed a higher prevalence of atrial fibrillation (AF). There was little difference in basic physiological parameters and limited literature regarding symptoms or significant events. Six studies showed associations between long-term TSH suppression and impaired quality of life. Impaired glucose metabolism and prothrombotic states were also found in DTC patients.

Conclusion

There is limited literature regarding long-term DTC treatment-related morbidity, particularly regarding the effects of long-term hypocalcemia. Most studies have focused on surrogate markers and not on clinical outcomes. A large prospective study on defined clinical outcomes would help characterize the morbidity of treatment and stimulate research on tailoring treatment strategies.

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

OBJECTIVE

Investigate the differences in cardiopulmonary (CP) capacity and Quality of Life (QOL) between healthy elderly (≥ 65 years) with different TSH levels (< 1.0 and ≥ 1.0 μIU/mL) both within the normal range. Also, evaluate the effects of TSH elevation on CP test and QOL, by administering methimazole to subjects with initial lower-normal TSH, in order to elevate it to superior-normal limit.

MATERIALS AND METHODS

Initially, a cross-sectional study was performed to compare CP capacity at peak exercise and QOL (using WHOQOL-OLD questionnaire) between healthy seniors (age ≥ 65 years) with TSH < 1.0 μIU/mL vs. TSH ≥1.0 μIU/mL. In the second phase, participants with TSH < 1.0 μIU/mL were included in a non-controlled-prospective-interventional study to investigate the effect of TSH elevation, using methimazole, on QOL and CP capacity at peak exercise.

RESULTS

From 89 elderly evaluated, 75 had TSH ≥ 1 μIU/mL and 14 TSH < 1 μIU/mL. The two groups had similar basal clinical characteristics. No difference in WHOQOL-OLD scores was observed between groups and they did not differ in terms of CP function at peak exercise. QOL and CP variables were not correlated with TSH levels. Twelve of 14 participants with TSH < 1.0 μIU/mL entered in the prospective study. After one year, no significant differences in clinical caracteristics, QOL, and CP variables were detected in paired analysis before and after methimazole intervention.

CONCLUSIONS

We found no differences in CP capacity and QOL between health elderly with different TSH levels within normal range and no impact after one year of methimazole treatment. More prospective-controlled-randomized studies are necessary to confirm or not the possible harm effect in normal low TSH.

A systematic review of randomized controlled trials for management of persistent post-treatment fatigue in thyroid cancer survivors

BACKGROUND

Fatigue that persists post-treatment is commonly reported by thyroid cancer (TC) survivors.

METHODS

A systematic review of published English language randomized controlled trials (RCTs) on interventions for management of persistent post-treatment fatigue in TC was conducted. This review excluded studies on short-term interventions used in preparation for radioactive iodine diagnostic scans or treatment. An electronic search was executed in six databases and supplemented by a hand search. Two reviewers independently reviewed all citations from the electronic search and relevant full-text studies. Two abstractors independently critically appraised included studies and abstracted the data. The data were qualitatively summarized.

RESULTS

A total of 1086 unique citations and 25 full-text studies were reviewed. Four studies summarizing the results of three RCTs were included. The interventions included: combination triiodothyronine with levothyroxine (L-T4) therapy compared to L-T4 alone (one RCT), reduction in degree of thyrotropin (TSH) suppression using L-T4 compared to maintenance of TSH suppression (one RCT), and supervised exercise compared to inactivity (two RCTs examining different fatigue outcomes in same population). Trial duration ranged from 10 weeks to six months. All trials had limitations, and the number of TC survivors included in respective RCTs ranged from 15 to 36. Hormonal treatment RCTs had mixed fatigue outcome results within respective trials. However, multiple measures suggesting improvement in fatigue were reported following the exercise intervention.

CONCLUSIONS

There is paucity of RCTs to guide evidence-based management of persistent post-treatment fatigue in TC survivors. RCTs of interventions for prevention or treatment of fatigue in TC survivors are needed.

Exercise is associated with better quality of life in patients on TSH-suppressive therapy with levothyroxine for differentiated thyroid carcinoma

Objective : To evaluate if a supervised exercise training program improves the quality of life (QoL) of differentiated thyroid carcinoma (DTC) patients on TSH-suppressive therapy with levothyroxine (L-T4).Subjects and methods : Initially, a cross-sectional study was performed to compare the QoL and the health-related quality of life (HRQoL) between subclinical hyperthyroidism (SCH) patients (n = 33) and euthyroid subjects (EU; n = 49). In the prospective phase of the study, SCH patients were randomized in a non-blinded fashion to either participate (SCH-Tr = trained patients; n = 16) or not (SCH-Sed = untrained patients; n = 17) in a supervised exercise training program. The exercise program consisted of 60 minutes of aerobic and stretching exercises, twice a week, during twelve weeks. The QoL was assessed by the application of the WHOQOL-Bref, and the SF-36 was used to assess the HRQoL.Results : SCH patients had statistically lower scores than EU on the “physical” domain of WHOQOL-Bref, besides “physical function”, “role-physical”, “bodily pain”, “general health”, “vitality”, “role-emotional”, and “mental-health” domains of SF-36. After three months, SCH-Tr patients showed improvement in the “physical” and “psychological” domains of WHOQOL-Bref (p < 0.05), and in the “physical function”, “role-physical”, “bodily pain”, “vitality” and “mental health” domains of SF-36.Conclusion : Patients on TSH-suppressive therapy with L-T4 for DTC had impaired QoL and HRQoL compared to EU, but it was improved after 3-months of an exercise training program. Exercise seems to play an important role in the follow-up of DTC patients, since it seems to minimize the adverse effects of the treatment on QoL and HRQoL. Arq Bras Endocrinol Metab. 2014;58(3):274-81

Hyperthyroidism and cardiovascular complications: a narrative review on the basis of pathophysiology

Cardiovascular complications are important in hyperthyroidism because of their high frequency in clinical presentation and increased mortality and morbidity risk. The cause of hyperthyroidism, factors related to the patient, and the genetic basis for complications are associated with risk and the basic underlying mechanisms are important for treatment and management of the disease. Besides cellular effects, hyperthyroidism also causes hemodynamic changes, such as increased preload and contractility and decreased systemic vascular resistance causes increased cardiac output. Besides tachyarrythmias, impaired systolic ventricular dysfunction and diastolic dysfunction may cause thyrotoxic cardiomyopathy in a small percentage of the patients, as another high mortality complication. Although the medical literature has some conflicting data about benefits of treatment of subclinical hyperthyroidism, even high-normal thyroid function may cause cardiovascular problems and it should be treated. This review summarizes the cardiovascular consequences of hyperthyroidism with underlying mechanisms.

Exercise and its interactions with various aspects of man and animal lives

To review recently published papers in the Brazilian Scientific press on the general subject of physical exercise. All articles published in 2010/2011 found through the keyword exercise were collected from 11 Brazilian Journals. They were hand filtered to exclude all but original research papers. They were grouped according to subject categories and subcategories. A brief summary of all included articles was produced, comparing similar articles between them. The most commonly found interactions refer to exercise vs. the cardiovascular system, metabolism and the locomotor system, in this order. The volume of scientific research in the field is high and of sufficient quality to justify highlighting.