Thyroid Function as a Predictor of Handgrip Strength Among Middle-Aged and Older Euthyroid Adults: The TCLSIH Cohort Study

Postmenopausal women with higher TSH values within the normal range present improved handgrip strength: a pilot study

OBJECTIVE

To evaluate the possible association between thyroid function within the euthyroid range and musculoskeletal parameters as well as body composition in a sample of postmenopausal women.

METHODS

This cross-sectional study included 96 postmenopausal women with serum thyroid-stimulating hormone (TSH) within the normal laboratory reference range. Fasting venous blood samples were obtained for biochemical/hormonal assessment. Bone status and body composition were measured using Dual Energy X-ray absorptiometry (DXA). Physical activity was quantified using the International Physical Activity Questionnaire (IPAQ) index.

RESULTS

Serum TSH correlated with handgrip strength (HGS, r-coefficient = 0.233, p = .025), and total body bone mineral density (BMD) T-score values (r-coefficient = 0.321, p = .003). HGS measures were associated with BMD (r-coefficient = 0.415, p < .001), with bone mineral content (BMC, r-coefficient = 0.427, p < .001), and lean mass (r-coefficient = 0.326, p = .003). Women with low muscle strength, defined as HGS < 16 kg, had lower TSH levels than women with normal muscle strength (low vs. normal muscle strength, ANCOVA 1.13 ± 0.49 mU/L vs. 1.60 ± 0.83 mU/L, p = 0.024) independently of age, BMD, percentage of body fat or absolute lean mass. Multivariable linear regression analysis showed that HGS values were associated with TSH measurements (β-coefficient = 0.246, p = .014) and BMD T-score values (β-coefficient = 0.306, p = .002). All models were adjusted for age, body mass index (BMI), vitamin D, low-density lipoprotein cholesterol, current smoking, physical activity, and homeostasis model assessment of insulin resistance.

CONCLUSIONS

In this sample of postmenopausal women, lower serum TSH values, within normal range, were associated with lower muscle strength compared to higher normal TSH values. Further research is needed to elucidate the significance of our preliminary findings.

Association of added sugar intake and its forms and sources with handgrip strength decline among middle-aged and older adults: A prospective cohort study

PURPOSE

The consumption of added sugar has increased rapidly in recent years. Limited knowledge exists regarding the association between added sugar intake and muscle strength, although the latter is a predictor of physical disability in older adults. This study aimed to investigate the association between added sugar intake and longitudinal changes in handgrip strength among middle-aged and elderly Chinese adults.

METHODS

This prospective cohort study included 5298 adults aged 40 years and older (62.6% men) from the TCLSIH (Tianjin Chronic Low-grade Systemic Inflammation and Health) cohort study. Added sugar intake was obtained through a frequency questionnaire containing 100 items of food. Handgrip strength is measured annually using a handheld digital dynamometer. Multivariate linear regression models were used to examine the association between added sugars intake and the annual changes in handgrip strength and weight-adjusted handgrip strength.

RESULTS

In the fully adjusted model, the annual change in handgrip strength for one unit increase in total added sugar, solid added sugar, and liquid added sugar intake was -0.0353 kg, (95% confidence intervals (CI) -0.000148, -0.0000164; P = 0.01), -0.0348 kg (95% CI: -0.000227, -0.0000269; P = 0.01) and -0.0189 kg (95% CI -0.000187, 0.0000338; P = 0.17), respectively. Added sugar from bread and biscuits sources were remarkably associated with a decline in handgrip strength (β = -0.0498; 95%CI -0.00281, -0.000787) and (β = -0.0459; 95%CI 0.00158, 0.00733) (P < 0.01).

CONCLUSIONS

Our data suggest that the higher the intake of solid added sugars, but not liquid sugars, were associated with the declined handgrip strength in the Chinese middle-aged and elderly population. In addition, the consumption of added sugars from bread and biscuits sources was also associated with a decline in grip strength.

Longitudinal association between soft drink consumption and handgrip strength in adults: a prospective analysis from the Tianjin Chronic Low-Grade Systemic Inflammation and Health (TCLSIH) cohort study

Soft drink consumption has become a highly controversial public health issue. Given the pattern of consumption in China, sugar-sweetened beverage is the main type of soft drink consumed. Due to containing high levels of fructose, a soft drink may have a deleterious effect on handgrip strength (HGS) due to oxidative stress, inflammation and insulin resistance. However, few studies show an association between soft drink consumption and HGS in adults. We aimed to investigate the association between soft drink consumption and longitudinal changes in HGS among a Chinese adult population. A longitudinal population-based cohort study (5-year follow-up, median: 3·66 years) was conducted in Tianjin, China. A total of 11 125 participants (56·7 % men) were enrolled. HGS was measured using a handheld digital dynamometer. Soft drink consumption (mainly sugar-containing carbonated beverages) was measured at baseline using a validated FFQ. ANCOVA was used to evaluate the association between soft drink consumption and annual change in HGS or weight-adjusted HGS. After adjusting for multiple confounding factors, the least square means (95 % CI) of annual change in HGS across soft drink consumption frequencies were -0·70 (-2·49, 1·09) for rarely drinks, -0·82 (-2·62, 0·97) for < 1 cup/week and -0·86 (-2·66, 0·93) for ≥ 1 cup/week (Pfor trend < 0·05). Likewise, a similar association was observed between soft drink consumption and annual change in weight-adjusted HGS. The results indicate that higher soft drink consumption was associated with faster HGS decline in Chinese adults.

Biomarkers of frailty

Several biomarkers have been proposed to identify frailty, a multisystemic age-related syndrome. However, the complex pathophysiology and the absence of a consensus on a comprehensive and universal definition make it challenging to pinpoint a singular biomarker or set of biomarkers that conclusively characterize frailty. This review delves into the main laboratory biomarkers, placing special emphasis on those associated with various pathways closely tied to the frailty condition, such as inflammation, oxidative stress, mitochondrial dysfunction, metabolic and endocrine alterations and microRNA. Additionally, we provide a summary of different clinical biomarkers encompassing different tools that have been proposed to assess frailty. We further address various imaging biomarkers such as Dual Energy X-ray Absorptiometry, Bioelectrical Impedance analysis, Computed Tomography and Magnetic Resonance Imaging, Ultrasound and D3 Creatine dilution. Intervention to treat frailty, including non-pharmacological ones, especially those involving physical exercise and nutrition, and pharmacological interventions, that include those targeting specific mechanisms such as myostatin inhibitors, insulin sensitizer metformin and with special relevance for hormonal treatments are mentioned. We further address the levels of different biomarkers in monitoring the potential positive effects of some of these interventions. Despite the availability of numerous biomarkers, their performance and usefulness in the clinical arena are far from being satisfactory. Considering the multicausality of frailty, there is an increasing need to assess the role of sets of biomarkers and the combination between laboratory, clinical and image biomarkers, in terms of sensitivity, specificity and predictive values for the diagnosis and prognosis of the different outcomes of frailty to improve detection and monitoring of older people with frailty or at risk of developing it, being this a need in the everyday clinical practice.

Correlation of subclinical hypothyroidism with sarcopenia and its components in the Chinese older adults

OBJECTIVE

To identify the correlation of thyroid function and subclinical hypothyroidism (SCH) with sarcopenia and its components in the older Chinese adults.

METHODS

Older adults were recruited and divided into SCH group and non-SCH group. Free triiodothyronine (FT3), free thyroxine (FT4) and thyroid-stimulating hormone (TSH) were measured by electrochemiluminescence. Appendicular skeletal muscle mass (ASM) was measured, and skeletal muscle index (SMI) was further calculated. Grip strength was measured. Physical performance was graded by the Short Physical Performance Battery (SPPB) scores of the gait speed test, chair stand test and balance test.

RESULTS

Of the 240 older adults included, 48 (20.00%) presented with SCH. The prevalence of sarcopenia in SCH group was higher than that in non-SCH group (33.33% v.s. 18.75%). Grip strength was significantly lower in patients with SCH than those without sarcopenia. In terms of physical performance, 6-meter gait speed and SPPB score were lower in subjects with SCH than those without SCH, while 5 sit-to-stand movements was longer score in subjects with SCH than those without SCH. SCH was significantly correlated with sarcopenia, while FT3, FT4, and TSH levels were not. SCH was significantly correlated with low muscle strength and low muscle mass, but not with low physical performance. FT3 level was positively correlated with grip strength and SMI. TSH level was negatively correlated with grip strength, 6-meter gait speed, and SPPB score, but positively correlated with the time of 5 sit-to-stand movements.

CONCLUSION

SCH is a risk factor for sarcopenia in the older adults and correlated with low muscle strength and low muscle mass, but not with low physical performance. FT3, FT4 and TSH levels are associated with sarcopenia components, but not with sarcopenia.

Serum FT3/FT4, but not TSH is associated with handgrip strength in euthyroid U.S. population: evidence from NHANES

Objective

Although several studies have examined the relationship between thyroid function and muscle strength, their population primarily derived from Asian areas, and their results were controversial. Thus, this study aimed to explore the association between thyroid function and handgrip strength (HGS) in the U.S. population.

Methods

A total of 1,067 participants from NHANES were categorized into three different age groups including young (<45 years), middle (45~64 years), and old (≥65 years) age groups. Thyroid function was measured by the competitive binding immune-enzymatic assays, while HGS was examined by a trained evaluator using a dynamometer. The weighted multiple linear regression models were used to examine the association between thyroid function and handgrip strength. The restricted cubic splines were employed to explore the non-linear relationship between these two variables. All statistical analyses were performed using the SPSS version 20.0 and R software.

Results

After adjustment for potential covariates, FT3/FT4, but not TSH was positively associated with HGS in middle age group (β=0.091, t=2.428, P=0.016). The subgroup analysis by sex revealed that the positive association between FT3/FT4 and HGS was observed in the middle age group for both male and female participants (β=0.163, t=2.121, P=0.035; β=0.157, t=2.180, P=0.031). The RCS analysis showed a statistically significant non-linear association between FT3/FT4 and HGS in overall population (P for non-linear=0.026). After adjustment for covariates, men with low HGS had a significant lower FT3/FT4 than those without low HGS in old age group (P=0.013). There was a significant increase in TSH level for female participants with low HGS in old age group compared to those with normal HGS (P=0.048).

Conclusions

This study demonstrated FT3/FT4, but not TSH, was positively associated with HGS in middle age group, and the different association was observed in men in middle age group when participants were stratified by sex. Future longitudinal cohort study should be conducted to reveal the causal relationship between thyroid function and muscle strength.

Anti-inflammatory dietary pattern is associated with handgrip strength decline: a prospective cohort study

BACKGROUND AND AIMS

Skeletal muscle strength decline is strongly associated with inflammation. While previous research has confirmed that diet can modulate chronic inflammation, little is known about the relationship between an anti-inflammatory dietary pattern and muscle strength. The aim of this study was to investigate the association between an anti-inflammatory dietary pattern and handgrip strength decline in a large-scale adult population.

METHODS

During a median follow-up period of 3 years, this prospective cohort study was carried out between 2013 and 2018 and included 2840 participants (60.2% men). Dietary intake was assessed using a validated food frequency questionnaire at baseline, and handgrip strength was measured annually with a handheld digital dynamometer. The dietary inflammatory potential score was calculated using white blood cell count and hypersensitive C-reactive protein as inflammatory markers, and was determined using reduced rank regression and stepwise linear regression. Multivariable linear regression models were used to estimate the association between the dietary inflammatory potential score and the annualized change in handgrip strength and weight-adjusted handgrip strength.

RESULTS

After adjusting for multiple confounding factors, significant associations between the dietary inflammatory potential score and the annualized change in handgrip strength and weight-adjusted handgrip strength in women, with values of - 0.8322 kg (95% confidence interval [CI] - 1.6405, - 0.0238; P < 0.0408) and - 0.0171 kg/kg (95% CI - 0.0310, - 0.0032; P < 0.0158), respectively. However, no significant differences were observed between the dietary inflammatory potential score and the annualized change in handgrip strength and weight-adjusted handgrip strength in men, with values of 0.1578 kg (95% CI - 0.6107, 0.9261; P < 0.6874) and - 0.0014 kg/kg (95% CI - 0.0115, 0.0088; P < 0.7933), respectively.

CONCLUSION

Our findings suggest that consuming an anti-inflammatory dietary pattern could be a protective strategy against the decline in skeletal muscle strength in women.

Higher Peripheral Thyroid Sensitivity Is Linked to a Lower Risk of Heart Failure After Acute Myocardial Infarction

CONTEXT

It is still not clear how the free triiodothyronine (FT3) to free thyroxine (FT4) ratio affects the prognosis of acute myocardial infarction (AMI), especially the risk of heart failure (HF) subsequent to AMI.

OBJECTIVE

The purpose of this study was to see how peripheral sensitivity to thyroid hormones, as measured by the FT3/FT4 ratio, affected HF and mortality after AMI.

METHODS

Our study was a retrospective cohort study. The primary endpoint was HF after AMI during and after hospitalization. The secondary endpoints were all-cause death and cardiovascular death after hospitalization.

RESULTS

The main sample included 3648 inpatients with AMI with a median age of 61.0 years; 68.9% were male. In the fully adjusted model, compared with patients in the lowest Q1 of the FT3/FT4 ratio, the risk of in-hospital HF in the highest Q4 patients was reduced by 44% (OR 0.56, 95% CI 0.44-0.72, P trend < .001), the risk of out-of-hospital HF was reduced by 37% (HR 0.63, 95% CI 0.48-0.84, P trend < .001), and the risks of all-cause and cardiovascular death were also significantly reduced. The analysis of different subgroups is consistent with the overall results. Furthermore, the sensitivity analysis of the euthyroid sample of 2484 patients was consistent with the main sample. Mediation analysis showed that altered levels of amino-terminal pro-B-type natriuretic peptide were mediators between the FT3/FT4 ratio and all endpoints in our study.

CONCLUSION

The thyroid hormone peripheral sensitivity of the FT3/FT4 ratio is an independent predictor of HF and mortality after AMI.

Relationship between Euthyroidism and Muscle Mass and Strength: A Systematic Review

Thyroid hormones play a crucial role in skeletal muscle development, suggesting that thyroid function may influence muscle mass and muscle strength, which are both fundamental health-related indicators of several age-related consequences. However, whether there is a relationship between thyroid hormones, muscle mass, and muscle strength in individuals without thyroid dysfunctions is still unknown. Therefore, this systematic review aims to investigate whether thyroid hormones are related to muscle mass and strength parameters in euthyroid individuals. Three databases were searched (PubMed, Scopus, Web of Science) up to February 14, 2022, for peer-reviewed papers published in English. The search results were conducted independently by two different reviewers. The review included 13 studies with a total of 241,044 participants. All studies were observational: twelve studies measured thyroid stimulating hormone, ten and thirteen studies measured free triiodothyronine and free thyroxine, four studies analyzed the thyroid hormone ratio. The assessment methods for muscle mass were computed tomography, dual-energy X-ray absorptiometry and bioimpedance analysis, whereas hand dynamometer for muscle strength. Low levels within the normal range of free triiodothyronine, high levels within the normal range of free thyroxine, and lower thyroid hormone ratio may contribute to a reduced muscle function, which seems more evident in older males.

Higher thyroid hormone has a negative association with lower limb lean body mass in euthyroid older adults: Analysis from the Baltimore Longitudinal study of aging

Background: Hyperthyroidism is associated with lower lean body mass, as a result of catabolic actions of thyroid hormone. Therefore, higher thyroid hormone levels could be a factor in the development of sarcopenia and age associated functional decline. The relationship between thyroid hormone and muscle mass in ambulatory, euthyroid older adults is not known. Method: We used mixed-effects models to estimate the cross-sectional relationships (accounting for inter-person variability) between thyroid axis hormone measures and lower limb composition or sarcopenia at visits in the Baltimore Longitudinal Study of Aging (BLSA) at which DEXA scans were available and both thyrotropin (TSH) and free thyroxine (FT4) were in the reference range. Analyses were adjusted for levothyroxine use, age, race, sex, BMI, smoking, alcohol intake, cholesterol, and systolic blood pressure. Results: 1442 euthyroid participants (median age 68, 50% female, and 69% white) contributed to 5306 visits from 2003 to 2019. FT4 was negatively associated with lower limb lean mass (beta: 88.49; 95% Confidence Interval (CI): 122.78, -54.20; p < 0.001) and positively associated with sarcopenia (OR: 1.11%, 95% CI: 1.01, 1.22) in the whole cohort. Additionally, higher FT4 was associated with lower leg lean mass (beta: 66.79; 95% CI: 102.24, -31.33; p < 0.001) and sarcopenia (OR:1.09%, 95% CI:1.01, 1.18) in older adults, but not in younger adults alone. Conclusion: In euthyroid older adults, higher FT4 is associated with lower leg lean mass and higher odds of sarcopenia. Understanding the relationship between thyroid hormone and sarcopenia is needed to improve clinical decision-making and avoid functional decline from excess thyroid hormone use in older adults.

Exploring biomarkers of osteosarcopenia in older adults attending a frailty clinic

Osteosarcopenia is a new definitional approach that can increase the risk of falls and fractures in elderly compared with that of osteoporosis and sarcopenia alone. However, biomarkers for osteosarcopenia have not been well identified. Thus, we aimed to explore the biomarkers of osteosarcopenia, including bone, muscle, and geriatric markers. Outpatients attending a frailty clinic were enrolled in the study. Osteosarcopenia was defined as the coexistence of osteoporosis and sarcopenia. Osteoporosis was defined according to the criteria of the Japan Osteoporosis Society. Sarcopenia was defined according to the Asian Working Group for Sarcopenia consensus (2019). We selected 35 blood/serum pathological parameters, including bone, inflammation, nutritional, and aging markers for the study. Logistic regression analysis for osteosarcopenia was performed to explore the biomarkers of osteosarcopenia. Of the total 600 patients with a mean age of 76.6 years, 595 were enrolled in the registry during the study period. Logistic regression analysis for osteosarcopenia showed that elevated thyroid-stimulating hormone (TSH) (odds ratio [OR]:1.375; 95 % confidence interval [CI]: 1.092-1.731), bone-specific alkaline phosphatase (BAP) (OR: 1.059; 95 % CI: 1.002-1.120), and estimated glomerular filtration rate (eGFR) (OR: 1.029; 95 % CI: 1.007-1.053) increased the likelihood of osteosarcopenia. On the other hand, elevated 25-hydroxyvitamin D (25OHD) (OR: 0.905; 95 % CI: 0.841-0.974), blood urea nitrogen (BUN) (OR: 0.895; 95 % CI: 0.829-0.966) and K (OR: 0.241; 95 % CI: 0.081-0.717) decreased the likelihood of osteosarcopenia. It is worthwhile to examine these biomarkers for older adult outpatients attending a frailty clinic for screening osteosarcopenia. Further studies are needed to investigate the effects of other markers of bone metabolism.

A Low Free T3 to Free T4 Ratio Is Associated with Sarcopenia in Euthyroid Patients with Type 2 Diabetes Mellitus

BACKGROUND

This research evaluated the link between normal thyroid hormone levels and sarcopenia in patients with type 2 diabetes mellitus (T2DM).

METHODS

This cross-sectional study enrolled 312 euthyroid patients with T2DM from Qilu Hospital of the Shandong University, China. Body composition, grip strength, and physical performance were assessed as per the 2019 consensus guidelines of the Asian Working Group for Sarcopenia. Binary logistic regression was used to examine the correlation between thyroid hormone levels and sarcopenia and its components.

RESULTS

The prevalence of sarcopenia was 26.9%. Following adjustments for potential confounders, a high-normal serum free triiodothyronine (FT3) level (odds ratio (OR) = 0.522, 95% confidence interval (CI): 0.304-0.895, P = 0.018), a low-normal serum free thyroxine (FT4) level (OR = 1.126, 95% CI: 1.009-1.258, P = 0.034), and a heightened FT3/FT4 ratio (OR = 0.923, 95% CI: 0.879-0.969, P = 0.001) were linked to a low prevalence of sarcopenia. Considering the components of sarcopenia, FT3 concentration was positively associated with muscle strength (OR = 0.525, 95% CI: 0.305-0.902, P = 0.020) and physical performance (OR = 0.443, 95% CI: 0.259-0.758, P = 0.003), while FT4 concentration was negatively linked to muscle mass (OR = 1.114, 95% CI: 1.009-1.232, P = 0.036). The FT3/FT4 ratio was positively linked to muscle mass (OR = 0.943, 95% CI: 0.905-0.981, P = 0.006), muscle strength (OR = 0.945, 95% CI: 0.901-0.992, P = 0.021), and physical performance (OR = 0.934, 95% CI: 0.894-0.975, P = 0.002). Nevertheless, thyroid-stimulating hormone concentration was not associated with sarcopenia.

CONCLUSION

A high FT3/FT4 ratio was significantly linked to a lowered risk of sarcopenia in euthyroid patients with T2DM.

Persisting neuroendocrine abnormalities and their association with physical impairment 5 years after critical illness

Background

Critical illness is hallmarked by neuroendocrine alterations throughout ICU stay. We investigated whether the neuroendocrine axes recover after ICU discharge and whether any residual abnormalities associate with physical functional impairments assessed 5 years after critical illness.

Methods

In this preplanned secondary analysis of the EPaNIC randomized controlled trial, we compared serum concentrations of hormones and binding proteins of the thyroid axis, the somatotropic axis and the adrenal axis in 436 adult patients who participated in the prospective 5-year clinical follow-up and who provided a blood sample with those in 50 demographically matched controls. We investigated independent associations between any long-term hormonal abnormalities and physical functional impairments (handgrip strength, 6-min walk distance, and physical health-related quality-of-life) with use of multivariable linear regression analyses.

Results

At 5-year follow-up, patients and controls had comparable serum concentrations of thyroid-stimulating hormone, thyroxine (T₄), triiodothyronine (T₃) and thyroxine-binding globulin, whereas patients had higher reverse T₃ (rT₃, p = 0.0002) and lower T₃/rT₃ (p = 0.0012) than controls. Patients had comparable concentrations of growth hormone, insulin-like growth factor-I (IGF-I) and IGF-binding protein 1 (IGFBP1), but higher IGFBP3 (p = 0.030) than controls. Total and free cortisol, cortisol-binding globulin and albumin concentrations were comparable for patients and controls. A lower T₃/rT₃ was independently associated with lower handgrip strength and shorter 6-min walk distance (p ≤ 0.036), and a higher IGFBP3 was independently associated with higher handgrip strength (p = 0.031).

Conclusions

Five years after ICU admission, most hormones and binding proteins of the thyroid, somatotropic and adrenal axes had recovered. The residual long-term abnormality within the thyroid axis was identified as risk factor for long-term physical impairment, whereas that within the somatotropic axis may be a compensatory protective response. Whether targeting of the residual abnormality in the thyroid axis may improve long-term physical outcome of the patients remains to be investigated.

Trial registration ClinicalTrials.gov: NCT00512122, registered on July 31, 2007 (https://www.clinicaltrials.gov/ct2/show/NCT00512122).

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03858-1.

Ultra-processed food intake is associated with grip strength decline in middle-aged and older adults: a prospective analysis of the TCLSIH study

PURPOSE

Ultra-processed foods make up more than 50% of daily energy consumed in Western countries and are rapidly increasing in China. However, little is known about the association between ultra-processed food intake and muscle strength, a predictor for physical disability in senior years. We aimed to investigate the association of ultra-processed food intake with longitudinal changes in grip strength among middle-aged and older Chinese adults.

METHODS

This prospective cohort study included a total of 5409 adults aged 40 years and over (61.3% men). Ultra-processed food intake was obtained by means of a validated food frequency questionnaire and classified according to the NOVA classification system. Grip strength was measured annually using a handheld digital dynamometer. Multivariable linear regression models were used to examine the association between ultra-processed food intake and annualized change in grip strength and weight-adjusted grip strength.

RESULTS

In the fully adjusted models, annualized changes in grip strength and weight-adjusted grip strength per 10% increment in the proportion of ultra-processed foods in the diet were - 0.3708 kg (95% confidence interval - 0.5687, - 0.1730; P < 0.001) and - 0.0057 kg/kg (95% confidence interval - 0.0086, - 0.0029; P < 0.0001), respectively. In analyses stratified by age, sex, body mass index, physical activity, hypertension, hyperlipidemia, diabetes, and healthy diet score, such associations were largely consistent in most subgroups (all P for interaction > 0.05).

CONCLUSIONS

Our data indicate that higher ultra-processed food intake was associated with faster grip strength decline in middle-aged and older Chinese adults.

Role of hormones in sarcopenia

Aging involves numerous changes in body composition that include a decrease in skeletal muscle mass. The gradual reduction in muscle mass is associated with a simultaneous decrease in muscle strength, which leads to reduced mobility, fragility and loss of independence. This process called sarcopenia is secondary to several factors such as sedentary lifestyle, inadequate nutrition, chronic inflammatory state and neurological alterations. However, the endocrine changes associated with aging seem to be of special importance in the development of sarcopenia. On one hand, advancing age is associated with a decreased secretion of the main hormones that stimulate skeletal muscle mass and function (growth hormone, insulin-like growth factor 1 (IGFI), testosterone and estradiol). On the other hand, the alteration of the IGF-I signaling along with decreased insulin sensitivity also have an important impact on myogenesis. Other hormones that decline with aging such as the adrenal-derived dehydroepiandrosterone, thyroid hormones and vitamin D seem to also be involved in sarcopenia. Adipokines released by adipose tissue show important changes during aging and can affect muscle physiology and metabolism. In addition, catabolic hormones such as cortisol and angiotensin II can accelerate aged-induced muscle atrophy, as they are involved in muscle wasting and their levels increase with age. The role played by all of these hormones and the possible use of some of them as therapeutic tools for treating sarcopenia will be discussed.

The relationship between dietary patterns and grip strength in the general population: the TCLSIH cohort study

PURPOSE

Previous studies have shown that many nutrients play an essential role in maintaining skeletal muscle strength. Hand grip strength (HGS) is frequently used as an objective and reliable method to evaluate overall body muscle strength and physical function. Some studies have demonstrated that some specific single nutrients such as PUFA, fiber, vitamin C, fruits and vegetables are associated with muscle strength. However, few studies have explored the relationship between dietary patterns and HGS in the adult population. The aim of this study was to investigate how dietary patterns are related to HGS in a large-scale Chinese population.

METHODS

A cross-sectional study (n = 35,175) was performed in Tianjin, China. Adherence to dietary patterns was measured by a valid self-administered food frequency questionnaire with 81 food items. Principal-components analysis was used to derive three major dietary patterns: "sweet", "healthy" and "animal food". HGS was measured using a handheld digital dynamometer. Analysis of covariance and multiple logistic regression were employed to explore the relationship between dietary patterns and HGS.

RESULTS

After adjustment for potential confounders, the means (95% confidence interval) of HGS for increasing quartile of dietary patterns were as follows: "sweet", 0.50 (0.49-0.51), 0.50 (0.49-0.51), 0.50 (0.49-0.51), 0.50 (0.48-0.51) (P value = 0.07); "healthy" 0.50 (0.49-0.51), 0.50 (0.49-0.51), 0.50 (0.49-0.51), 0.50 (0.49-0.51) (P value < 0.0001); "animal food" 0.51(0.50-0.52), 0.50 (0.49-0.51), 0.50 (0.49-0.51), 0.49 (0.48-0.51) (P value < 0.0001), respectively.

CONCLUSIONS

The present study demonstrated a slight improvement between healthy dietary pattern and HGS across the quartiles. On the contrary, this study also showed higher adherence to the animal food dietary pattern (i.e., higher quartile) had lower grip strength. A long-term prospective study or randomized trials are required to clarify this association.

Thyroid hormones and frailty in persons experiencing extreme longevity

CONTEXT

The aging phenotype is quite heterogeneous, being the result of the capability of each individual to successfully or unsuccessfully response to stressors. The reduction of homeostatic reserve characterizing aging is accompanied by a remodeling of the endocrine system. Frailty has been indicated as a promising way for capturing the physiological decline as well as the biological aging of the individuals. In particular, the Frailty Index (FI), based on the assumption that health deficits tend to accumulate with aging, represents a quantitative measure of extreme interest.

OBJECTIVE

The study aims to correlate the thyroid hormone levels with FI in a population of centenarians and their offspring to capture the effects of thyroid remodeling in extreme longevity.

STUDY DESIGN

The study described 593 well-characterized Italian subjects, including 180 centenarians, as well as 276 centenarian's offspring and 137 age-matched controls.

RESULTS

FT3 levels and FT3/FT4 ratio were significantly lower (p < 0.001) and TSH levels higher (p < 0.001) in centenarians compared to the other groups, analysing both overall subjects and excluding subjects with hormone levels out of the normal ranges. In overall centenarians, we observed a negative correlation between FI and FT3 (ρ: -0.281, p < 0.001), FT3/FT4 (ρ: -0.344, p < 0.001) and TSH (ρ: -0.223, p 0.003) and a positive association between FI and FT4 (ρ: 0.189, p = 0.001). In centenarians with hormone levels within the normal ranges, similar negative correlations were observed between FI and FT3 (ρ: -0.201, p = 0.02) and FT3/FT4 (ρ: -0.264, p = 0.002). In this sub-analysis, FI positively correlated with FT4 and age (ρ: 0.167, p = 0.05; ρ: 0.219, p = 0.005, respectively). Conversely, no significant correlations were observed between hormone levels and FI in offspring and controls.

CONCLUSIONS

We found an association between thyroid hormone levels and frailty in centenarians, underlying the significant role of thyroid in the aging process and longevity.

Thyroid Function and Sarcopenia: Results from the ELSA-Brasil Study

OBJECTIVES

We aimed to investigate the association of subclinical thyroid disease and thyroid hormone levels with sarcopenia and its defining components in community-dwelling middle-aged and older adults without overt thyroid dysfunction.

DESIGN

Cross-sectional study.

SETTING

Active and retired employees from public institutions located in six Brazilian cities.

PARTICIPANTS

A total of 6974 participants from the ELSA-Brasil study's second wave, aged 50 years and older, without overt thyroid dysfunction and with complete data for exposure, outcome, and covariates.

METHODS

Serum levels of thyrotropin (TSH), free thyroxine, and free triiodothyronine (FT3) were measured and divided in quintiles for the analyses. Participants were classified with euthyroidism, subclinical hypothyroidism, and subclinical hyperthyroidism. Muscle mass was assessed by bioelectrical impedance analysis and muscle strength by handgrip strength. Sarcopenia was defined according to the Foundation for the National Institutes of Health criteria. Possible confounders included sociodemographic characteristics, clinical conditions, and lifestyle. Analyses were performed separately for middle-aged and older adults (≥65 y).

RESULTS

The frequencies of sarcopenia, low muscle mass, low muscle strength, subclinical hypothyroidism, and subclinical hyperthyroidism were 1.5%, 20.8%, 3.8%, 9.1%, and .9%, respectively. Subclinical thyroid dysfunction was not associated with sarcopenia and its defining components. Among older adults, TSH had a U-shaped association with sarcopenia and low muscle strength. The odds ratios (ORs) (95% confidence intervals [CIs]) for the associations of the first, second, fourth, and fifth quintile with sarcopenia, respectively, were 5.18 (1.47-18.28), 6.28 (1.82-21.73), 4.12 (1.15-14.76), and 4.81 (1.35-17.10), and with low muscle strength was (OR (95% CI) for the first, second, and fifth quintiles, respectively: 1.43 (1.16-5.07), 2.07 (1.24-4.70), and 2.18 (1.03-4.60). Additionally, FT3 had a negative association with muscle mass in both age strata.

CONCLUSION

Subtle thyroid hormone alterations are associated with sarcopenia or its defining components in middle-aged and older adults without overt thyroid dysfunction. J Am Geriatr Soc 68:1545-1553, 2020.