The relationship between subclinical thyroid dysfunction and the risk of fracture or low bone mineral density: a systematic review and meta-analysis of cohort studies

Bone geometry in older adults with subclinical hypothyroidism upon levothyroxine therapy: A nested study within a randomized placebo controlled trial

The effect of levothyroxine (LT4) therapy for subclinical hypothyroidism (SHypo) on appendicular bone geometry and volumetric density has so far not been studied. In a nested study within the randomized, placebo-controlled Thyroid Hormone Replacement for Subclinical Hypothyroidism (TRUST) trial, we assessed the effect of LT4 therapy on bone geometry as measured by peripheral quantitative computed tomography (pQCT). In the TRUST trial, community-dwelling adults aged ≥65 years with SHypo were randomized to LT4 with dose titration vs. placebo with mock titration. We analyzed data from participants enrolled at the TRUST site in Bern, Switzerland who had bone pQCT measured at baseline and at 1 to 2 years follow-up. The primary outcomes were the annual percentage changes of radius and tibia epi- and diaphysis bone geometry (total and cortical cross-sectional area (CSA) and cortical thickness), and of volumetric bone mineral density (bone mineral content (BMC) and total, trabecular and cortical volumetric bone mineral density (vBMD)). We performed linear regression of the annual percentage changes adjusted for sex, LT4 dose at randomization and muscle cross-sectional area. The 98 included participants had a mean age of 73.9 (±SD 5.4) years, 45.9% were women, and 12% had osteoporosis. They were randomized to placebo (n = 48) or LT4 (n = 50). Annual changes in BMC and vBMD were similar between placebo and LT4-treated groups, without significant difference in bone geometry or volumetric bone mineral density changes, neither at the diaphysis, nor at the epiphysis. For example, in the placebo group, epiphyseal BMC (radius) decreased by a mean 0.2% per year, with a similar decrease of 0.5% per year in the LT4 group (between-group difference in %ΔBMC 0.3, 95% CI -0.70 to 1.21, p = 0.91). Compared to placebo, LT4 therapy for an average 14 months had no significant effect on bone mass, bone geometry and volumetric density in older adults with subclinical hypothyroidism. TRIAL REGISTRATION: The trial was registered on ClinicalTrials.gov numbers NCT01660126 (TRUST Thyroid trial) and NCT02491008 (Skeletal outcomes).

Effects of thyroid dysfunction and thyroid stimulating hormone levels on the Atrial fibrillation risks: a systematic review and dose-response meta-analysis from cohort studies

OBJECTIVE

To explore the relationship between thyroid dysfunction, thyroid stimulating hormone (TSH) levels and risks of atrial fibrillation (AF) in studies as well as to conduct a dose-response meta-analysis on the correlation between TSH levels and AF risks.

METHODS

13 studies from five databases with 649,293 subjects (mean age 65.1 years) were included. The dose-response meta-analysis was conducted by comparing the Risk Ratios (RRs) and 95% Confidence Intervals (CI) for incident AF associated with different levels of TSH (vs TSH=0 mU/L) across studies. Data were collected until Oct 25, 2021.

RESULTS

Subclinical hyperthyroidism, subclinical hypothyroidism, clinical hyperthyroidism were associated with the increased risk of AF respectively (RR=1.70, 95% CI: 1.11-2.62; RR=1.23, 95% CI:1.05-1.44; RR=2.35, 95% CI:1.07-5.16), while clinical hypothyroidism was not found associated with the significantly increased risk of AF (RR=1.20, 95% CI: 0.72-1.99). A non-linear relationship was observed in two models (crude model: P_nonlinear<0.001; adjusted model: P_nonlinear =0.0391) between the TSH concentrations and the risks of AF.

CONCLUSIONS

Our study indicated that subclinical hyperthyroidism, subclinical hypothyroidism, clinical hyperthyroidism were associated with the risk of AF, and the results for TSH levels and AF risk were mixed which showed a U-shaped relationship.

Factors associated with post-operative delirium in hip fracture patients: what should we care

Background

The postoperative delirium is a common yet serious complication in elderly patients with hip fracture. We aimed to evaluate the potential risk factors of delirium in patients with hip fracture, to provide reliable evidence to the clinical management of hip fracture.

Methods

This study was a retrospective design. Elderly patients who underwent hip fracture surgery in our hospital from June 1, 2019 to December 30, 2020 were selected. The characteristics and treatment data of delirium and no delirium patients were collected and compared. Multivariate logistic regression analysis was performed to analyze the influencing factors affecting postoperative delirium in elderly patients with hip fracture.

Results

A total of 245 patients with hip fracture were included, the incidence of postoperative delirium in patients with hip fracture was 13.06%. There were significant differences in the age, BMI, history of delirium, estimated blood loss and duration of surgery (all p  < 0.05). There were significant differences in the albumin and TSH between delirium and no delirium group (all p < 0.05), Logistics analyses indicated that age ≥ 75 years (OR 3.112, 95% CI 1.527–5.742), BMI ≥ 24 kg/m² (OR 2.127, 95% CI 1.144–3.598), history of delirium (OR 1.754, 95% CI 1.173–2.347), estimated blood loss ≥ 400 mL (OR 1.698, 95% CI 1.427–1.946), duration of surgery ≥ 120 min (OR 2.138, 95% CI 1.126–3.085), preoperative albumin ≤ 40 g/L (OR 1.845, 95% CI 1.102–2.835) and TSH ≤ 2 mU/L (OR 2.226, 95% CI 1.329–4.011) were the independent risk factors of postoperative delirium in patients with hip fracture(all p < 0.05).

Conclusions

Postoperative delirium is very common in elderly patients with hip fracture, and it is associated with many risk factors, clinical preventions targeted on those risk factors are needed to reduce the postoperative delirium.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-022-00660-9.

Study protocol to develop a core outcome set for thyroid dysfunction to bridge the unmet needs of patient-centred care

INTRODUCTION

Thyroid dysfunctions (TD) are common medical conditions affecting all global populations. Improved healthcare leading to increasing survival rates and delayed diagnosis rendered significant burden of the disease in the increasing number of patients with TD with comorbid illnesses. Therefore, reducing the burden of TD and improving the quality of care are crucial. Existing poor-quality data that guide evidence-based decisions only provide a fragmented picture of clinical care. The different outcomes across studies assessing the effectiveness of treatments impede our ability to synthesise results for determining the most efficient treatments. This project aims to produce a core outcome set (COS), which embeds the multiple complex dimensions of routine clinical care for the effectiveness studies and clinical care of adult patients with TD.

METHODS AND ANALYSIS

This mixed-method project has two phases. In phase 1, we will identify a list of patient-reported and clinical outcomes through qualitative research and systematic reviews. In phase 2, we will categorise the identified outcomes using the Core Outcome Measures in Effectiveness Trials taxonomy of core domains and the International Classification of Functioning, Disability and Health. We will develop questionnaires from the list of outcomes identified from each domain for the two-round online Delphi exercise, aiming to reach a consensus on the COS. The Delphi process will include patients, carers, researchers and healthcare participants. We will hold an online consensus meeting involving representatives of all key stakeholders to establish the final COS.

ETHICS AND DISSEMINATION

The study has been reviewed and approved by the Ethics Committee for Research Involving Human Subjects, Universiti Putra Malaysia and the Research Ethics Committee, National University of Malaysia. This proposed COS in TD will improve the value of data, facilitate high-quality evidence synthesis and evidence-based decision-making. Furthermore, we will present the results to participants, in peer-reviewed academic journals and conferences.

REGISTRATION DETAILS

Core Outcome Measures in Effectiveness Trials (COMET) Initiative database registration: http://www.comet-initiative.org/studies/details/1371.

Personalized treatment for differentiated thyroid cancer: current data and new perspectives

More conservative and personalized treatment options have been developed in recent years to face the rising diagnosis of low-risk differentiated thyroid carcinoma (DTC). The present review describes the change towards a more risk-adapted management either in the treatment or in the follow-up of DTC. Particular attention is given to the innovations introduced by the latest guidelines for low-risk tumors, starting from the most appropriate extension of surgery up to the postoperative management. The emerging role of active surveillance for low-risk microcarcinoma is discussed, as well as the development of percutaneous strategies in the setting of malignant thyroid disease. The recent use of approved new systemic target therapies for advanced radioiodine refractory thyroid cancer is reported, together with the description of new compounds in trial. Finally, we provide some considerations to improve the risk evaluation in a presurgical setting, especially related to the rising role of genetics, to enable better risk-based cancer management and personalized treatment choices.

Subclinical thyroid dysfunction, bone mineral density, and osteoporosis in a middle-aged Korean population

Thyroid dysfunction is associated with the loss of bone density (osteoporosis). However, the connection between subclinical thyroid dysfunction and osteoporosis remains controversial. This study found no apparent association between subclinical hypothyroidism or subclinical hyperthyroidism and bone mineral density (BMD) in the lumbar spine and femur.

INTRODUCTION

The present study examined the relationship between subclinical thyroid dysfunction and BMD in healthy middle-aged adults.

METHODS

A total of 25,510 healthy Koreans with normal free thyroxine levels were enrolled from January 2011 to December 2016, and 91% of subjects visited only once. The average age of the 15,761 women was 45, and the average age of the 9749 men was 48. Levels of thyroid-stimulating hormone (TSH) and BMD were recorded in all subjects. BMD was measured using dual-energy X-ray absorptiometry.

RESULTS

No apparent association was found between subclinical thyroid dysfunction and BMD in the lumbar spine, femur-neck, and proximal femur sites compared with a euthyroid group. Age, body mass index (BMI), and postmenopausal status affected BMD in women, and only BMI affected BMD in men. Subclinical hypothyroidism was independently associated with a lower risk of osteoporosis (odds ratio 0.657, 95% confidence interval 0.464-0.930) in 4710 postmenopausal women.

CONCLUSIONS

No apparent association was found between subclinical hypothyroidism or subclinical hyperthyroidism defined on single TSH measurement and BMD at the lumbar spine and femur in a large cohort of middle-aged men and women. Subclinical hypothyroidism was independently associated with a lower risk of osteoporosis in postmenopausal women.

Association of subclinical thyroid dysfunction with bone mineral density and fracture: a meta-analysis of prospective cohort studies

PURPOSE

To comprehensively investigate the associations of subclinical thyroid dysfunction with BMD and fractures at various sites.

METHODS

Comprehensive electronic and manual searches of databases were systematically conducted to identify prospective cohort studies from the inception of the databases to May 2019. The summary results for fractures and BMDs at various sites were calculated by relative risks (RRs) and weighted mean differences (WMDs) with corresponding 95% confidence intervals (CIs) using the random-effects model.

RESULTS

Seventeen prospective cohorts from 24 studies were identified and 313,557 individuals were recruited in a final analysis. The summary RR indicated that subclinical hyperthyroidism was associated with an increased risk of any fracture (RR, 1.17; 95% CI, 1.08-1.26; P < 0.001), hip fracture (RR, 1.27; 95% CI, 1.09-1.48; P = 0.003), spine fracture (RR, 1.97; 95% CI, 1.31-2.97; P = 0.001), and non-spine fracture (RR, 1.19; 95% CI, 1.04-1.37; P = 0.014). However, there were no significant associations of subclinical hypothyroidism with the risk of any fractures (P = 0.166), hip fracture (P = 0.068), spine fracture (P = 0.818), and non-spine fracture (P = 0.277). Finally, subclinical hyperthyroidism was associated with lower distal forearm BMD in women, and ultradistal forearm BMD in both men and women, whereas subclinical hypothyroidism was associated with higher femur neck BMD in women.

CONCLUSION

Subclinical hyperthyroidism could induce additional risk on fractures at any, hip, spine, and non-spine, whereas subclinical hypothyroidism did not have any impact on fractures. Moreover, BMD at the lower distal and ultradistal forearms might be affected by subclinical hyperthyroidism, and higher femur neck BMD could be affected by subclinical hypothyroidism.

Skeletal Effects of Levothyroxine for Subclinical Hypothyroidism in Older Adults: A TRUST Randomized Trial Nested Study

CONTEXT

Both thyroid dysfunction and levothyroxine (LT4) therapy have been associated with bone loss, but studies on the effect of LT4 for subclinical hypothyroidism (SHypo) on bone yielded conflicting results.

OBJECTIVE

To assess the effect of LT4 treatment on bone mineral density (BMD), Trabecular Bone Score (TBS), and bone turnover markers (BTMs) in older adults with SHypo.

DESIGN AND INTERVENTION

Planned nested substudy of the double-blind placebo-controlled TRUST trial. Participants with SHypo were randomized to LT4 with dose titration versus placebo with computerized mock titration.

SETTING AND PARTICIPANTS

196 community-dwelling adults over 65 years enrolled at the Swiss TRUST sites had baseline and 1-year follow-up bone examinations; 4 participants withdrew due to adverse events not related to treatment.

MAIN OUTCOME MEASURES

One-year percentage changes of BMD, TBS, and 2 serum BTMs (serum CTX-1 [sCTX] and procollagen type 1 N-terminal polypeptide [P1NP]). Student's t-test for unadjusted analyses and linear regression adjusted for clinical center and sex were performed.

RESULTS

Mean age was 74.3 years ± 5.7, 45.4% were women, and 19.6% were osteoporotic. The unadjusted 1-year change in lumbar spine BMD was similar between LT4 (+0.8%) and placebo-treated groups (-0.6%; between-groups difference +1.4%: 95% confidence interval [CI] -0.1 to 2.9, P = .059). Likewise, there were no between-group differences in 1-year change in TBS (-1.3%: 95% CI -3.1 to 0.6, P = .19), total hip BMD (-0.2%: 95% CI -1.1 to 0.1, P = .61), or BTMs levels (sCTX +24.1%: 95% CI -7.9 to 56.2, P = .14), or after adjustment for clinical centers and sex.

CONCLUSIONS

Over 1-year levothyroxine had no effect on bone health in older adults with SHypo.

REGISTRATION

ClinicalTrial.gov NCT01660126 and NCT02491008.

Thyroid replacement therapy, thyroid stimulating hormone concentrations, and long term health outcomes in patients with hypothyroidism: longitudinal study

OBJECTIVE

To explore whether thyroid stimulating hormone (TSH) concentration in patients with a diagnosis of hypothyroidism is associated with increased all cause mortality and a higher risk of cardiovascular disease and fractures.

DESIGN

Retrospective cohort study.

SETTING

The Health Improvement Network (THIN), a database of electronic patient records from UK primary care.

PARTICIPANTS

Adult patients with incident hypothyroidism from 1 January 1995 to 31 December 2017.

EXPOSURE

TSH concentration in patients with hypothyroidism.

MAIN OUTCOME MEASURES

Ischaemic heart disease, heart failure, stroke/transient ischaemic attack, atrial fibrillation, any fractures, fragility fractures, and mortality. Longitudinal TSH measurements from diagnosis to outcomes, study end, or loss to follow-up were collected. An extended Cox proportional hazards model with TSH considered as a time varying covariate was fitted for each outcome.

RESULTS

162 369 patients with hypothyroidism and 863 072 TSH measurements were included in the analysis. Compared with the reference TSH category (2-2.5 mIU/L), risk of ischaemic heart disease and heart failure increased at high TSH concentrations (>10 mIU/L) (hazard ratio 1.18 (95% confidence interval 1.02 to 1.38; P=0.03) and 1.42 (1.21 to 1.67; P<0.001), respectively). A protective effect for heart failure was seen at low TSH concentrations (hazard ratio 0.79 (0.64 to 0.99; P=0.04) for TSH <0.1 mIU/L and 0.76 (0.62 to 0.92; P=0.006) for 0.1-0.4 mIU/L). Increased mortality was observed in both the lowest and highest TSH categories (hazard ratio 1.18 (1.08 to 1.28; P<0.001), 1.29 (1.22 to 1.36; P<0.001), and 2.21 (2.07 to 2.36; P<0.001) for TSH <0.1 mIU/L, 4-10 mIU/L, and >10 mIU/L. An increase in the risk of fragility fractures was observed in patients in the highest TSH category (>10 mIU/L) (hazard ratio 1.15 (1.01 to 1.31; P=0.03)).

CONCLUSIONS

In patients with a diagnosis of hypothyroidism, no evidence was found to suggest a clinically meaningful difference in the pattern of long term health outcomes (all cause mortality, atrial fibrillation, ischaemic heart disease, heart failure, stroke/transient ischaemic attack, fractures) when TSH concentrations were within recommended normal limits. Evidence was found for adverse health outcomes when TSH concentration is outside this range, particularly above the upper reference value.

Graves' disease, multinodular goiter and subclinical hyperthyroidism

Subclinical hyperthyroidism is a common clinical entity, defined by serum TSH below the reference range, with normal FT4 and FT3 levels in an asymptomatic patient. Whether or not subclinical hyperthyroidism should be treated remains a matter of debate. Cross-sectional and longitudinal population-based studies demonstrate association of subclinical hyperthyroidism with risk of atrial fibrillation and osteoporosis, and with cardiovascular and all-cause mortality. However, there are no randomized clinical trials addressing whether long-term health outcomes are improved by treating subclinical hyperthyroidism; in the absence of evidence one way or the other, it seems appropriate to use decision trees taking account of TSH concentration and presence of risk factors (age>65 years or post-menopause, osteoporosis and cardiac disease).

Hypothyroidism and related diseases: a methodological quality assessment of meta-analysis

OBJECTIVES

There is an increasing prevalence of hypothyroidism and there is a growing body of meta-analyses (MAs) on the association between hypothyroidism and other diseases. However, the methodological quality of the MAs significantly varies. Thus, this study aimed to evaluate and summarise data on the methodological quality of MAs on the associations between hypothyroidism and other diseases using the Assessment of Multiple Systematic Reviews (AMSTAR) scale, providing suggestions for clinical decision-making processes.

DESIGN

To assess the methodological quality of MAs using the AMSTAR scale.

DATA SOURCES

A systematic literature search was performed in PubMed, EMBASE, the Cochrane Library, web of science and Chinese Biomedicine Literature Database.

ELIGIBILITY CRITERIA

We included MAs that had assessed the association between hypothyroidism and other diseases in humans and that had full texts regardless of the publication status. No restriction applied on language or date.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently screened the titles and abstracts of all searched literature to acquire potentially eligible publications. The full texts of possible eligible publications were downloaded and assessed. Inconsistent comments were resolved through discussions with a third reviewer.

RESULTS

52 studies were included. The average AMSTAR score of the included articles was 8.6 (range: 5-10), and those of English and Chinese MAs were 8.8 and 7.0, respectively. A total of 52 MAs were evaluated, and 19 (36.5%) and 33 (63.5%) of these MAs were of moderate and high quality, respectively. None of the MAs were of low quality. Only two MAs had an a priori design. Items 3, 5 and 9 had the highest compliance (50/52, 96.2%), and aside from item 1, items 7 and 8 had the lowest compliance (33/52,63.5%). According to the results of these MAs, hypothyroidism was significantly associated with cardiovascular diseases, metabolic diseases, neuropsychiatric disorders, breast cancer and pregnancy outcome.

CONCLUSIONS

The methodological quality of the included MAs on the association between hypothyroidism and other diseases was moderate to high. MAs with high qualities confirmed that hypothyroidism was significantly associated with cardiovascular diseases, metabolic syndrome, preterm birth and neonatal outcomes. Consideration of scientific quality when formulating conclusions should be made explicit and more attention should be paid to improving the methodological quality of MAs, and increasing their applicability for clinical decision-making.

Thyroid Hormone Suppression Therapy

Thyroid hormone suppression therapy is designed to lower serum thyrotropin (TSH) levels using doses of thyroid hormone in excess of what would normally be required to maintain a euthyroid state. The basis of this therapy is the knowledge that TSH is a growth factor for thyroid cancer, so that lower serum TSH levels might be associated with decreased disease activity. However, clinical studies have not documented improved outcomes with TSH suppression, except in patients with the most advanced disease. Furthermore, there are a number of negative outcomes related to aggressive thyroid hormone therapy, including osteoporosis, fracture, and cardiovascular disease. Therefore, a graded approach to TSH suppression is recommended by the American Thyroid Association, based on initial risk and ongoing risk assessment.

The influence of thyroid disorders on bone density and biochemical markers of bone metabolism

Background Thyroid dysfunction, predominantly hyperthyroidism, has been previously linked to impaired bone mass density (BMD) and increased risk of fractures. On the other hand, data in the field of hypothyroidism (HT) are missing. The purpose of the present study was to investigate the impact of thyroid disorders on bone density serum and urine calcium (Ca) and phosphate (P) as well as serum osteocalcin and alkaline phosphatase and urine hydroxyproline in a series of post-menopausal women. Materials and methods The study was conducted in the Reproductive Endocrinology Outpatient Clinic of our hospital. A consecutive series of post-menopausal women was included, after excluding patients under hormone treatment (including levothyroxine supplementation) and those who received raloxifene, tamoxifen or tibolone during the study period as well as those who received treatment during the previous 12 months were excluded from the present study. Results Overall, 188 women were included in the present study. Among them, 143 women had normal thyroid function, 32 women had hyperthyroidism and 13 women had HT. Correlation of thyroid function indices with osteoporosis indices revealed statistically significant correlations between thyroxine (T4) and free triiodothyronine (T3) with T-, Z-scores and BMD. Logistic regression analysis concerning the impact of HT and hyperthyroidism on T-score, Z-score and bone mass density revealed that both pathological entities negatively affect bone health (p < 0.05). Conclusion The findings of our study suggest that not only hyperthyroidism, but also HT negatively affects BMD. Future studies should investigate this association and corroborate our findings.

Thyroid Stimulating Hormone and Bone Mineral Density: Evidence From a Two-Sample Mendelian Randomization Study and a Candidate Gene Association Study

With population aging, prevalence of low bone mineral density (BMD) and associated fracture risk are increased. To determine whether low circulating thyroid stimulating hormone (TSH) levels within the normal range are causally related to BMD, we conducted a two-sample Mendelian randomization (MR) study. Furthermore, we tested whether common genetic variants in the TSH receptor (TSHR) gene and genetic variants influencing expression of TSHR (expression quantitative trait loci [eQTLs]) are associated with BMD. For both analyses, we used summary-level data of genomewide association studies (GWASs) investigating BMD of the femoral neck (n = 32,735) and the lumbar spine (n = 28,498) in cohorts of European ancestry from the Genetic Factors of Osteoporosis (GEFOS) Consortium. For the MR study, we selected 20 genetic variants that were previously identified for circulating TSH levels in a GWAS meta-analysis (n = 26,420). All independent genetic instruments for TSH were combined in analyses for both femoral neck and lumbar spine BMD. In these studies, we found no evidence that a genetically determined 1-standard deviation (SD) decrease in circulating TSH concentration was associated with femoral neck BMD (0.003 SD decrease in BMD per SD decrease of TSH; 95% CI, -0.053 to 0.048; p = 0.92) or lumbar spine BMD (0.010 SD decrease in BMD per SD decrease of TSH; 95% CI, -0.069 to 0.049; p = 0.73). A total of 706 common genetic variants have been mapped to the TSHR locus and expression loci for TSHR. However, none of these genetic variants were associated with BMD at the femoral neck or lumbar spine. In conclusion, we found no evidence for a causal effect of circulating TSH on BMD, nor did we find any association between genetic variation at the TSHR locus or expression thereof and BMD. © 2018 The Authors. Journal of Bone and Mineral Research Published by WileyPeriodicals, Inc.

Thyroid diseases and bone health

Thyroid hormones are essential for skeletal development and are important regulators of bone maintenance in adults. Childhood hypothyroidism causes delayed skeletal development, retarded linear growth and impaired bone mineral accrual. Epiphyseal dysgenesis is evidenced by classic features of stippled epiphyses on X-ray. In severe cases, post-natal growth arrest results in a complex skeletal dysplasia. Thyroid hormone replacement stimulates catch-up growth and bone maturation, but recovery may be incomplete dependent on the duration and severity of hypothyroidism prior to treatment. A severe phenotype characteristic of hypothyroidism occurs in children with resistance to thyroid hormone due to mutations affecting THRA encoding thyroid hormone receptor α (TRα). Discovery of this rare condition recapitulated animal studies demonstrating that TRα mediates thyroid hormone action in the skeleton. In adults, thyrotoxicosis is well known to cause severe osteoporosis and fracture, but cases are rare because of prompt diagnosis and treatment. Recent data, however, indicate that subclinical hyperthyroidism is associated with low bone mineral density (BMD) and an increased risk of fracture. Population studies have also shown that variation in thyroid status within the reference range in post-menopausal women is associated with altered BMD and fracture risk. Thus, thyroid status at the upper end of the euthyroid reference range is associated with low BMD and increased risk of osteoporotic fragility fracture. Overall, extensive data demonstrate that euthyroid status is required for normal post-natal growth and bone mineral accrual, and is fundamental for maintenance of adult bone structure and strength.

Relationship between Hypothyroidism and Non-Alcoholic Fatty Liver Disease: A Systematic Review and Meta-analysis

BACKGROUND

Previous studies propose that hypothyroidism might play a crucial role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD), but findings from published studies on the relationship between hypothyroidism and NAFLD are still controversial. Our study aimed to make a comprehensive evaluation of the relationship between hypothyroidism and NAFLD through a meta-analysis.

METHODS

PubMed, China Dissertation Database, and EMBASE databases were searched to find observational studies assessing the relationship between hypothyroidism and NAFLD. The pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated to evaluate the strength of the relationship between hypothyroidism and NAFLD through meta-analysis.

RESULTS

Thirteen articles were ultimately included in our meta-analysis. Meta-analysis of the 13 studies found a high correlation between hypothyroidism and NAFLD (OR = 1.52, 95% CI 1.24-1.87, P < 0.001). Meta-analysis of 9 studies providing adjusted ORs found that hypothyroidism was independently correlated with NAFLD (OR = 1.72, 95% CI 1.32-2.23, P < 0.001). Subgroup analysis found that both overt hypothyroidism and subclinical hypothyroidism were significantly correlated with NAFLD, and the pooled ORs were 1.70 (95% CI 1.23-2.36, P = 0.002) and 1.40 (95% CI 1.10-1.77, P = 0.006), respectively. Besides, meta-analysis of studies providing adjusted ORs also found that both overt hypothyroidism and subclinical hypothyroidism were independently correlated with NAFLD, and the pooled ORs were 1.81 (95% CI 1.30-2.52, P < 0.001) and 1.63 (95% CI 1.19-2.24, P = 0.002), respectively.

CONCLUSION

The meta-analysis provides strong epidemiological evidence for the relationship between hypothyroidism and NAFLD. Both individuals with subclinical and overt hypothyroidism are at higher risk for NAFLD than euthyroid subjects.