Skeletal muscle function and body composition of patients with hyperthyroidism

Effect of radioiodine treatment on muscle mass in hyperthyroid cats

BACKGROUND

Approximately 75% of hyperthyroid cats lose muscle mass as accessed with a muscle condition scoring (MCS) system. After treatment, MCS improves as the cats regain muscle mass.

OBJECTIVES

To quantify the degree of muscle loss in hyperthyroid cats using ultrasonography and evaluate changes in muscle mass after treatment.

ANIMALS

Forty-eight clinically normal cats and 120 cats with untreated hyperthyroidism, 75 of which were reevaluated after radioiodine-131 therapy.

METHODS

Prospective cross-sectional and before-after studies. All cats underwent ultrasonography and measurement of epaxial muscle height (EMH), with subsequent calculation of vertebral and forelimb epaxial muscle scores (VEMS and FLEMS). A subset of hyperthyroid cats underwent repeat muscle imaging 6 months after treatment.

RESULTS

Untreated hyperthyroid cats had a lower EMH than did clinically normal cats (median [25th-75th percentile], 0.98 [0.88-1.16] cm vs 1.34 [1.23-1.58] cm, P < .001). Seventy-seven (64.2%) untreated cats had subnormal EMH. Similarly, compared to normal cats, hyperthyroid cats had lower VEMS (0.93 [0.84-1.07] vs 1.27 [1.18-1.39], P < .001) and FLEMS (1.24 [1.10-1.35] vs 1.49 [1.39-1.63], P < .001). After treatment, EMH increased (1.03 [0.89-1.03] cm to 1.33 [1.17-1.41] cm, P < .001), with abnormally low EMH normalizing in 36/41 (88%). Both VEMS (0.94 [0.87-1.10] to 1.21 [1.10-1.31], P < .001) and FLEMS (1.31 [1.17-1.40] to 1.47 [1.38-1.66], P < .001) also increased after treatment.

CONCLUSIONS AND CLINICAL IMPORTANCE

Almost two-thirds of hyperthyroid cats have abnormally low muscle mass when measured quantitatively by ultrasound. Successful treatment restores muscle mass in >85% of cats. EMH provided the best means of quantitating muscle mass in these cats.

Evaluation of Body Weight, Body Condition, and Muscle Condition in Cats with Hyperthyroidism

Background

The contribution of fat loss versus muscle wasting to the loss of body weight seen in hyperthyroid cats is unknown.

Objectives

To investigate body weight, body condition score (BCS), and muscle condition score (MCS) in hyperthyroid cats.

Animals

Four hundred sixty‐two cats with untreated hyperthyroidism, 117 of which were reevaluated after treatment.

Methods

Prospective cross‐sectional and before–after studies. Untreated hyperthyroid cats had body composition evaluated (body weight, BCS, and MCS). A subset of these cats were reevaluated 3–12 months after treatment when euthyroid.

Results

Pretreatment body weight (median, 4.36 kg; IQR, 3.5 to 5.2 kg) was lower than premorbid weight (5.45 kg; IQR, 4.6 to 6.4 kg, P < .0001) recorded 1–2 years before diagnosis. 154 (35.3%) cats were thin or emaciated; 357 (77.3%) had loss of muscle mass. Cats showed increases in body weight (median, 4.1 kg to 5.0 kg), BCS (median, 3/5 to 3.5/5), and MCS (2/3 to 3/3) after treatment (P < .001), but mild‐to‐moderate muscle wasting persisted in 45% of treated cats.

Conclusions and Clinical Importance

Most hyperthyroid cats lose body weight but maintain an ideal or overweight BCS, with only a third being underweight. As in human hyperthyroid patients, this weight loss is associated with muscle wasting, which affects >75% of hyperthyroid cats. Successful treatment leads to weight gain and increase of BCS in most cats, but almost half fail to regain normal muscle mass.

Effects of hyperthyroidism on hand grip strength and function

Hyperthyroidism is a pathologic condition in which the body is exposed to excessive amounts of circulating thyroid hormones. Skeletal muscle is one of the major target organs of thyroid hormones. We evaluated hand grip strength and function in patients with overt hyperthyroidism. Fifty-one patients newly diagnosed with hyperthyroidism and 44 healthy controls participated in this study. Age, height, weight, and dominant hand of all participants were recorded. The diagnosis of hyperthyroidism was confirmed by clinical examination and laboratory tests. Hand grip strength was tested at the dominant hand with a Jamar hand dynamometer. The grooved pegboard test (PGT) was used to evaluate hand dexterity. The Duruöz Hand Index (DHI) was used to assess hand function. No significant differences were found in terms of clinical and demographic findings between the patients with hyperthyroidism and healthy controls (p > 0.05). Significant differences were found between the patients with hyperthyroidism and healthy controls regarding PGT and DHI scores (p < 0.05). Hyperthyroidism seemed to affect hand dexterity and function more than hand grip strength and seemed to be associated with reduced physical function more than muscle strength. This may also indicate that patients with hyperthyroidism should be evaluated by multidisplinary modalities.

Lower extremity mobility limitation and impaired muscle function in women with ulcerative colitis

BACKGROUND AND AIM

Fatigue, weakness and musculoskeletal manifestations are associated with IBD. An impaired nutritional status and a reduced physical activity can contribute to these clinical outcomes, impacting quality of life and increasing disability. This study aims to assess muscle strength and lower limb physical performance in female UC patients, taking into consideration disease activity, body composition and habitual physical activity.

METHODS

A case-control study was performed including 23 UC female outpatients and 23 age- and BMI-matched healthy women as controls. Quadriceps strength (QS), handgrip strength (HGS), physical performance based measures (five repetitions sit-up test and 4meter gait speed test), body composition (bioelectrical impedance analysis, anthropometry), and habitual physical activity (HPA) levels were assessed.

RESULTS

UC group had decreased QS (-6%; P=0.012), slower sit-up test (-32%; P=0.000), slower gait speed (-17% P=0.002) and decreased HPA level (-30%, P=0.001) compared with controls. No difference in HGS was observed between groups. Logistic regression showed that UC was an independent factor for decreased QS and slower sit-up test, while HPA was a protective factor for impaired gait speed. Multivariate linear regression showed that BMI was independently associated with an improved QS and slower sit-up test in the UC group.

CONCLUSION

Women with UC had decreased lower limb strength and mobility limitations, which were associated with BMI and the level of physical activity. Early evaluation of nutritional status and performance of the lower limbs could identify UC patients with pre-clinical disability who may benefit from earlier health lifestyle modifications.

Changes in body composition in women following treatment of overt and subclinical hyperthyroidism

OBJECTIVE

To determine changes in weight, body composition, and bone density after treatment of overt hyperthyroidism (OH) and subclinical hyperthyroidism (SCH) in women.

METHODS

Women with OH and SCH referred to the Mayo Clinic Thyroid Clinic were recruited. Hyperthyroid patients and euthyroid control women were matched for age (within decade) and body mass index. Patients with OH and SCH were treated to normalize thyroid function test results and were restudied after 6 months of normal thyroid function. Baseline and posttreatment studies included measurement of height, weight, bone density, lean mass, fat mass, and thigh muscle cross-sectional area. All participants had normal thyroid function test results for at least 6 months before completion of the posttreatment studies.

RESULTS

Twenty-four patients with OH, 21 patients with SCH, and 36 control patients were studied. In the OH group, fat-free mass increased from a mean of 36.8 kg (95% confidence interval [CI], 34.8-38.8) to 40.4 kg (95% CI, 38.5-42.3); in the SCH group, fat-free mass increased from a mean of 40.3 kg (95% CI, 38.1-42.5) to 42.2 kg (95% CI, 39.7-44.7). In both groups, fat mass increased to approximately the same extent, and both groups experienced significant weight gain with no change in percent body fat. Thigh muscle cross-sectional area increased in both groups -- from 100.6 cm(2) (95% CI, 92.7-108.5) to 113.3 cm(2) (95% CI, 105.5-121.1) in the OH group and from 106.1 cm(2) (95% CI, 96.7-115.5) to 112.2 cm(2) (95% CI, 102.0-122.4) in the SCH group. Bone density increased in patients with OH (P<.01) and in patients with SCH (P<.05).

CONCLUSIONS

Treatment of OH and SCH leads to increases in muscle area and bone density. Weight gain reflects increases in both fat and fat-free mass. While these results provide some support for actively treating SCH in women, further prospective studies are needed to determine whether the changes documented translate into real patient benefit.

Thyroxine therapy in euthyroid patients does not affect body composition or muscular function

OBJECTIVE

The main objective of the study was to evaluate the effects of small increments in thyroxine (T4) levels following levothyroxine (L-T4) administration on the body composition of women patients. The secondary objective was to assess the effect of the therapy on energy expenditure and muscular function.

METHODS

The prospective, randomized study consisted of a 12-month follow-up of 37 women with thyroid nodules. The patients were divided into two groups for comparison, one treated with L-T4 (20 women) and the other untreated (17 women). L-T4 dose was individually adjusted to obtain a serum thyroid-stimulating hormone in the lower portion of the normal range. Multiple tests, including bioelectrical impedance analysis, dual-energy X-ray absorptiometry, air displacement plethysmography, measurement of waist circumference, and skinfold anthropometry, were used to investigate the muscular, fat, and water compartments; energy expenditure and muscular function were assessed by cycle ergometry.

RESULTS

There were no significant differences in body composition, heart rate, energy metabolism, or muscular function between the group of women treated with L-T4 and the untreated group.

CONCLUSION

The controlled increase of circulating T4 does not appear to modify the body composition or muscular function in women patients.

Thigh muscle stiffness assessed with magnetic resonance elastography in hyperthyroid patients before and after medical treatment

PURPOSE

To measure the stiffness of the vastus medialis (VM) in hyperthyroid patients before and after treatment.

MATERIALS AND METHODS

A total of five healthy euthyroid patients and five hyperthyroid patients were tested using magnetic resonance elastography (MRE), which involves the induction of shear waves in the thigh muscles using a pneumatic driver at 90 Hz.

RESULTS

Among the pretreatment hyperthyroid cohort a lower stiffness was found when the muscle was relaxed (2.11 +/- 0.61 kPa) compared the stiffness following treatment of hyperthyroidism (5.52 +/- 1.52 kPa), which was accompanied by an improvement in the contractile function of the VM. Pretreatment muscle stiffness was also less than that of age matched healthy volunteers (4.56 +/- 0.40 kPa). The behavior of the waves was sensitive to the stage of this myopathy and to the amount of free thyroxine (FT4).

CONCLUSION

The MRE technique provides a new tool to gain new insights into pathophysiology of thyroid associated and other muscle diseases and their response to treatment.

Resistance Training Improves Muscle Function and Body Composition in Patients With Hyperthyroidism

OBJECTIVE

To evaluate the effect of resistance training on skeletal muscle performance and body composition in patients with medically treated hyperthyroidism.

DESIGN

Nonrandomized controlled trial.

SETTING

Large public tertiary hospital.

PARTICIPANTS

Sixteen sedentary patients with recent clinical diagnosis and laboratory confirmation of hyperthyroidism (7 men, 9 women; age, 38+/-11 y; weight, 58.4+/-2.6 kg; height, 1.6+/-0.3m) were assigned to the control group (medical therapy; n=9) or training group (medical therapy associated with resistance training; n=7). An age- and sex-matched healthy group served as controls (3 men, 5 women; age, 40+/-3 y; weight, 68.4+/-4.3 kg; height, 1.6+/-0.3m).

INTERVENTION

Resistance training twice a week for 16 weeks.

MAIN OUTCOME MEASURES

Peak muscular strength (by dynamometry and 1 repetition maximum method) and endurance (30% of peak force) for 7 movements and anthropometric measurements.

RESULTS

The hyperthyroid patients as a group had lower baseline overall strength values when compared with healthy subjects (200.3+/-16.0 kg vs 274.9+/-21.8 kg, respectively; P=.006). Overall absolute increases in strength (49 kg vs 91 kg, P<.05) and endurance (78.5x10(2)kg/s vs 176.9x10(2)kg/s, P<.05) were higher in the training group compared with the control group. Body weight increased in both groups, but the sum of muscular circumference increased only in the training group (training group, 92.6+/-3.3 cm vs 97.1+/-3.8 cm; control group, 94.6+/-2.2 cm vs 94.4+/-2.1cm; P<.05), with no change in the sum of skinfolds.

CONCLUSIONS

Resistance training accelerates the recovery of skeletal muscle function and promotes weight gain based on muscle mass improvement in patients with medically treated hyperthyroidism.

Autosomal-dominant non-autoimmune hyperthyroidism presenting with neuromuscular symptoms

AIM

Neuromuscular presentations are common in thyroid disease, although the mechanism is unclear. In the present study, we investigated the pathogenesis in a boy with autosomal-dominant hyperthyroidism presenting with neuromuscular symptoms.

METHODS

The TSHr gene was investigated by direct sequencing. Functional properties of the mutant TSHr were investigated during transient expression in COS-7 cells. Family members were investigated by clinical and biochemical examinations.

RESULTS

Sequence analysis revealed a previously reported heterozygous missense mutation Glycine 431 for Serine in the first transmembrane segment, leading to an increased specific constitutive activity. Three additional affected family members carried the same mutation. There was no indication of autoimmune disorder. All symptoms disappeared upon treatment with thacapzol and L-thyroxine and subsequent subtotal thyroidectomy.

CONCLUSION

The data imply that neuromuscular symptoms can be caused by excessive thyroid hormone levels rather than by autoimmunity.

Disfunção muscular esquelética e composição corporal no hipertireoidismo

O objetivo deste artigo é revisar os aspectos da disfunção muscular esquelética e composição corporal no hipertireoidismo. O hipertireoidismo está associado a uma fraqueza muscular generalizada que é parte da manifestação clínica inicial de cerca de 80% dos pacientes, comprometendo a realização de tarefas cotidianas e a qualidade de vida. Um fator que contribui para a redução da força é a atrofia muscular, que tende a afetar mais comumente os grupos musculares proximais. Além disso, o hipertireoidismo é acompanhado de perda ponderal associada à depleção de massa muscular e tecido adiposo. Estudos demonstram que o tratamento medicamentoso é capaz de recuperar a força e mais lentamente a resistência, definida como a capacidade de sustentar cargas submáximas por períodos prolongados, e que o treinamento contra resistência associado ao tratamento medicamentoso, é capaz de promover um maior ganho de força e de resistência muscular nestes pacientes. Embora não tenha sido estabelecido um padrão de composição corporal na recuperação do peso após o tratamento da doença, sabe-se que pacientes submetidos ao treinamento de força apresentam recuperação de peso acompanhado principalmente de ganho de massa muscular.

Muscle power increases after resistance training in growth-hormone-deficient adults

PURPOSE

To measure the effects of a resistance training (RT) program over muscle function and body composition of adults with GH deficiency without replacement.

METHODS

11 GH-deficient patients (39 +/- 11 yr) were evaluated in four occasions (two pretraining and at 6 and 12-wk of training). We performed anthropometric measurements and physical tests. Muscle power was measured by a specific tensiometer (Fitro, Bratislava, Slovakia) in five different exercises: seated chest press, rear lat pull-down, knee extension, standing upright row, and triceps press down. Muscle endurance was assessed by maximum number of sit-ups and maximum static strength by measurement with a handgrip dynamometer. A 12-wk home-based RT program was individually prescribed and consisted of 13 exercises, performed each other day, using simple material.

RESULTS

No significant differences occurred in body weight or limb circumferences ( > 0.05), although the sum of central skinfolds decreased with RT (111 +/- 9 vs 100 +/- 9 mm; < 0.05). RT induced significant gains in four of five exercises: rear lat pull-down (141 +/- 19 vs 198 +/- 20 W), standing upright row (134 +/- 22 vs 157 +/- 24 W), triceps press down (85 +/- 14 vs 123 +/- 21 W), and seated chest press (114 +/- 20 vs 143 +/- 21 W; < 0.05). Sit-up results also showed significant improvements, while handgrip did not ( > 0.05).

CONCLUSION

GH-deficient adults without GH replacement may improve their maximum muscle power when submitted to an individualized, simple, and short home-based RT program. Considering that limb girths did not significantly change, the gains were most likely due to improvements in neuromuscular components.

Função muscular esquelética e composição corporal de pacientes com hipertireoidismo submetidos ao treinamento contra resistência

O hipertireoidismo está associado a uma fraqueza muscular generalizada que é parte da manifestação clínica inicial de cerca de 80% dos pacientes. A recuperação da performance muscular esquelética durante o tratamento do hipertireoidismo depende tanto do aumento da massa muscular quanto da melhoria da função intrínseca da musculatura esquelética. Por outro lado, o treinamento contra resistência aumenta a força e a endurance muscular em diferentes grupos de indivíduos. O objetivo do presente trabalho foi avaliar o efeito deste tipo de treinamento sobre a recuperação da função muscular esquelética de pacientes portadores de hipertireoidismo. Os pacientes, atendidos no ambulatório de endocrinologia, diagnosticados clínica e laboratorialmente com doença de Graves, foram submetidos, antes do tratamento e quatro meses após, a medidas antropométricas e testes de força máxima e endurance musculares (sustentando 30% da carga máxima) de quatro movimentos [handgrip esquerdo (HE) e direito (HD), legpress (LEG), flexão plantar de tornozelo (FPT) e supino reto (SR)]. Após a avaliação inicial, os pacientes foram divididos em dois grupos: 1) controle (GC - tratamento medicamentoso) e 2) treinamento (GT - acrescentado treinamento contra resistência individualizado 2X/semana). Os resultados (GC, n = 3; GT, n = 4; todas do sexo feminino) mostram: <img src="/img/revistas/rbme/v7n1/a04tab01.gif"> Os autores concluem que o treinamento contra resistência parece favorecer aumento da massa e da performance muscular esquelética em pacientes com hipertireoidismo.

Neuromuscular findings in thyroid dysfunction: a prospective clinical and electrodiagnostic study

OBJECTIVES

To evaluate neuromuscular signs and symptoms in patients with newly diagnosed hypothyroidism and hyperthyroidism.

METHODS

A prospective cohort study was performed in adult patients with newly diagnosed thyroid dysfunction. Patients were evaluated clinically with hand held dynamometry and with electrodiagnosis. The clinical features of weakness and sensory signs and the biochemical data were evaluated during treatment.

RESULTS

In hypothyroid patients 79% had neuromuscular complaints, 38% had clinical weakness (manual muscle strength testing) in one or more muscle groups, 42% had signs of sensorimotor axonal neuropathy, and 29% had carpal tunnel syndrome. Serum creatine kinase did not correlate with weakness. After 1 year of treatment 13% of the patients still had weakness. In hyperthyroid patients 67% had neuromuscular symptoms, 62% had clinical weakness in at least one muscle group that correlated with FT4 concentrations, but not with serum CK. Nineteen per cent of the patients had sensory-motor axonal neuropathy and 0% had carpal tunnel syndrome. The neuromuscular signs developed rapidly, early in the course of the disorder and were severe, but resolved rapidly and completely during treatment (average time 3.6 months).

CONCLUSIONS

Neuromuscular symptoms and signs were present in most patients. About 40% of the hypothyroid patients and 20% of the hyperthyroid patients had predominantly sensory signs of a sensorimotor axonal neuropathy early in the course of thyroid disease. Weakness in hyperthyroidism evolved rapidly at an early stage of the disorder and resolved completely during treatment, suggesting a functional muscle disorder. Hand held dynamometry is sensitive for the detection of weakness and for the clinical evaluation of treatment effects. Weakness in hypothyroidism is more difficult to treat, suggesting myopathy.