THYROID HORMONE REPLACEMENT REDUCES THE RISK OF CARDIOVASCULAR DISEASES IN DIABETIC NEPHROPATHY PATIENTS WITH SUBCLINICAL HYPOTHYROIDISM

Systematic Review to Gauge the Effect of Levothyroxine Substitution on Progression of Diabetic Nephropathy in Patients With Hypothyroidism and Type 2 Diabetes Mellitus

Diabetes mellitus (DM) and thyroid dysfunction are two disorders that are closely related. This systematic review aimed to investigate the effect of levothyroxine supplementation on diabetic nephropathy in type 2 diabetic patients with co-existing thyroid dysfunction. We explored medical databases such as PubMed, Medline, Multidisciplinary Digital Publishing Institute (MDPI), and Cochrane Library for relevant medical literature. The papers were screened, and 12 research papers involving 10,371 patients were identified after applying eligibility criteria and quality assessment using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The included papers analyzed the effect of aberrant thyroid profile on kidney disease in diabetic individuals and the role that achieving euthyroid status with levothyroxine supplementation could play in diabetic nephropathy. Reduced free triiodothyronine (FT3) was the most common independent factor associated with diabetic microvascular and macrovascular complications. Levothyroxine (LT4) regimen was more effective than the placebo in lowering urinary albumin excretion rate (UAER), low-density lipoprotein cholesterol, and uric acid and decreasing oxidative stress overall. However, replacement therapy's effect may differ in the short and long terms. Thyroid hormone replacement therapy (THRT) may reduce the risk of diabetic nephropathy and cardiovascular disease (CVD) development in hypothyroid patients, but more randomized trials are needed to confirm the effect of THRT.

Association between thyroid function and diabetes peripheral neuropathy in euthyroid type 2 diabetes mellitus patients

Previous studies disclosed that a high thyroid stimulating hormone level is an independent risk factor for diabetes peripheral neuropathy (DPN) in subclinical hypothyroidism (SCH) patients with type 2 diabetes mellitus (T2DM). However, whether thyroid metabolism has an effect on DPN in euthyroid T2DM patients remains unknown. The aim of this study was to identify the association between thyroid function and DPN in euthyroid T2DM patients. A set of 580 euthyroid T2DM patients was enrolled in the current study and stratified into DPN and Non-DPN groups. Mann-Whitney U test was performed to analyze the continuous variables of biochemical and thyroid metabolism indicators, and the Chi-square test was used to compare the categorical variables. Spearman correlation analysis was performed to analyze the relationship between clinical indicators and free thyroxine (FT4). By using the logistic regression analysis, the prevalence of DPN in different thyroid function indicators were evaluated. T2DM patients with DPN had obviously lower levels of aspartate aminotransferase (AST), alpha-hydroxybutyric dehydrogenase (α-HBDH), superoxide dismutase (SOD), calcium (Ca), creatinine (Cr), uric acid (UA), retinol binding protein (RBP), total protein (TP), albumin (ALB), alanine aminotransferase (ALT) and FT4 than the T2DM patients without DPN (P < 0.05). FT4 was associated with TP, prealbumin (PA), ALB, SOD, anion gap (AG), Ca, chlorine (Cl), UA, RBP, apoprotein A (Apo A), apoprotein B (Apo B), apoprotein E (Apo E), and total cholesterol (TC). According to the FT4 quartile, participants were sequentially divided into four groups to compare the prevalence of DPN between each group. The data suggested that the prevalence of DPN in these four groups was 53.79%, 53.28%, 54.97%, 38.10%, respectively. Moreover, compared with quartile 4, patients in quartile 1, 2, 3 all had a significantly higher risk of DPN (P = 0.007, P = 0.011, P = 0.004). The level of FT4 was negatively correlated with the prevalence of DPN in euthyroid T2DM patients.

Low glomerular filtration rate values are associated with higher TSH in an elderly population at high cardiovascular disease risk

Background

Hypothyroidism is associated with impaired glomerular filtration rate (GFR), a recognized cardiovascular disease (CVD), and mortality risk factor. In older adults, this association remains unexplored. We aimed to determine the relationship of elevated TSH with GFR in an elderly population at high CVD risk.

Methods

Older adults (age>65ys) with high CVD risk defined by two or more CVD risk factors: smoking (S), high blood pressure (HBP), high total cholesterol, low HDL cholesterol, diabetes (DM), metabolic syndrome or previous cardiovascular event, were prospectively included at our ambulatory Endocrine Clinic. Patients under levothyroxine or thyroid disease were excluded. TSH> 6mU/l defined subclinical hypothyroidism (ScH) with normal free T4 levels. Estimated GFR was calculated by the Berlin-Initiative Study (BIS)-1 formula for elderly population. Urinary albumin to creatinine ratio (uACR), IL-6 and TNF-α, and Carotid intima-media thickness (CIMT) were also determined. The U Mann-Whitney test, the Spearman test, and multiple linear regression were used as statistical tests.

Results

Finally 246 patients (68% females) were included and 20 (8%) had ScH. This group, was older (median, Q1-Q3: 77,72-78; 72,68-77 years, p=0.01) and DM was less frequent than in the euthyroid group (35 vs 58%, p=0.039). Lower fasting glucose (-20%,p=0.01), GFR (-14%,p=0.01) and freeT4 (-10%,p<0.001) were found compared to euthyroid patients. A higher prevalence of Kidney failure was found in ScH (80 vs. 46%, p=0.003) vs. euthyroid individuals. Significant correlations with GFR were detected: age (r-0.482,p<0.001), TSH (r-0.172,p=0.004), IL-6 (r-0.150,p=0.047), TNF-α (r-0.274,p<0.001), uACR (r-0.170,p=0.009) and CIMT(r-0.189,p=0.004). By multiple linear regression, in a model adjusted by age, sex, BMI, uACR, S, DM, TNF-α and HBP, TSH (Bst -0.14, p=0.023, R2 = 0.25) was found an independent predictor of GFR.

Conclusion

In older adults with high CVD risk, ScH is associated with lower renal function, and this relationship is present regardless of other cardiometabolic risk factors. These results suggest that ScH could contribute to low GFR and excess CVD risk, although this hypothesis should be addressed in longitudinal studies.

Prevalence and Predictors of Thyroid Dysfunction Among Type 2 Diabetic Patients: A Case-Control Study

Background

Type 2 diabetes mellitus (T2DM) and thyroid disorders are common endocrine disorders. This case–control study aims to determine the prevalence and predictors of thyroid disorders in T2DM patients.

Methods

A total of 998 T2DM patients attending a tertiary hospital were included and underwent investigations for thyroid function: thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3); and glycated hemoglobin (HbA1c). They were compared with 343 non-diabetic subjects as controls.

Results

A total of 1341 participants were included in the study. The mean age ± SD was 60.14 ± 12.21, and 47.9% were females. Among T2DM patients, 140 (14%) were known to have thyroid disorders; and as a direct result of screening, 126 (12.6%) new cases of thyroid disorder were diagnosed. Thus, the overall prevalence of thyroid disorders was found to be 26.7% in T2DM patients which significantly higher than the controls (13.7%), (p˂0.001). Subclinical hypothyroidism was the most common one. Using logistic regression, after adjusting for age, gender, obesity, smoking, anemia, presence of goiter, disease duration, and poorly controlled, the risk factors for thyroid dysfunction among T2DM patients were an age of ≥50 years with an adjusted OR of 3.895 (95% CI 2.151–7.052, p<0.001); female gender (OR 1.757, 95% CI 1.123–2.747, p=0.013); goiter (OR 2.904, 95% CI 1.118–7.547, p=0.029), and HbA1c>7% (OR 2.553, 95% CI 1.472–4.429, p=0.001). However, there were no significant associations between thyroid disorders and complications or duration of diabetes (p>0.050).

Conclusion

A high prevalence of thyroid disorders was reported in T2DM patients. Therefore, we suggest that diabetic patients should be routinely screened for thyroid dysfunction. Old age, female gender, goiter, and poorly controlled diabetes found to be risk factors for thyroid dysfunction among T2DM patients. Consequently, appropriate management and control of diabetes may lower the risk of thyroid dysfunction and vice versa.

Impact of Hypothyroidism on Echocardiographic Characteristics of Patients With Heart Valve Disease: A Single-Center Propensity Score-Based Study

Background: Hypothyroidism is known to be correlated with multiple heart diseases. However, the influence of hypothyroidism on the patients with heart valve disease (HVD) is still unclear. The purpose of our study was to investigate the impact of hypothyroidism on echocardiographic characteristics of patients with heart valve disease. Methods: We conducted a retrospective cohort study which included 2,128 patients with HVD, and they were divided into euthyroid, subclinical hypothyroidism (SCHypoT), and overt hypothyroidism (OHypoT) group. Echocardiographic characteristics before and after valve surgery between groups were compared by using propensity score (PS) analysis. Kaplan-Meier analysis was used to compare the percent of recovery of left atrial (LA) enlargement between groups. Results: Overall, 463 patients had hypothyroidism (404 SCHypoT patients and 59 OHypoT patients), and 1,665 patients were euthyroid. At baseline, hypothyroidism was associated with significantly higher left atrial diameter (LAD), interventricular septum thickness, left ventricular posterior wall thickness, pulmonary artery systolic pressure, and lower left ventricular ejection fraction. After valve surgery, only LAD remained significantly higher in the patients with hypothyroidism. Additionally, patients with hypothyroidism had a significantly lower recovery rate of LA enlargement after valve surgery compared with euthyroid patients. Conclusion: Hypothyroidism was associated with a larger LAD in patients with HVD before and after surgery, which may suggest that hypothyroidism is a risk factor of LA enlargement of HVD. Besides, hypothyroidism was associated with a significantly lower recovery rate of LA enlargement after valve surgery.

Clinical Associations of Thyroid Hormone Levels with the Risk of Atherosclerosis in Euthyroid Type 2 Diabetic Patients in Central China

BACKGROUND

Thyroid function is associated with the etiology and pathogenesis of type 2 diabetes (T2D) and potentially contributes to the development of the complications of T2D. The association of thyroid hormones with atherosclerosis in euthyroid T2D patients is not clear.

PURPOSE

To investigate the association of thyroid hormone levels with the risk of developing atherosclerosis in euthyroid T2D patients in Central China.

METHODS

This cross-sectional study recruited 910 euthyroid T2D patients from Henan Provincial People's Hospital, China. Association among hemoglobin A1c (HbA1c), thyroid hormones, and the prevalence of atherosclerosis was assessed by multivariable Cox models after adjusting for covariates including age, BMI, duration of T2D, smoking status, SBP, TC, family history of T2D, and medications on hyperlipidemia.

RESULTS

Among all 910 subjects, 373 were diagnosed with atherosclerosis. There were 523 females and 387 males included in this study. The mean age was 51.9 years. The average BMI was 25.3 kg/m². Low-normal serum-free triiodothyronine (FT3) levels (3.50-4.17 pmol/L) were associated with a high prevalence of atherosclerosis. Comparing with low-normal FT3, the prevalence ratio in patients with mid- (4.17-4.83 pmol/L) and high-normal FT3 level (4.83-6.50 pmol/L) is 0.74 (95% CI 0.56 to 0.97, p=0.029) and 0.63 (95% CI 0.46 to 0.87, p=0.005) after adjusting for covariates. High level of free thyroxine (FT4) also had decreased risk for atherosclerosis. Thyroid-stimulating hormone (TSH) and FT3 to FT4 ratio did not show significant association with the development of atherosclerosis.

CONCLUSION

T2D patients with low but clinically normal FT3 level are more likely to develop macrovascular complications comparing with those with mid- and high-normal FT3 level.

Research on the potential mechanism of Chuanxiong Rhizoma on treating Diabetic Nephropathy based on network pharmacology

Background: Chuanxiong Rhizoma is one of the traditional Chinese medicines which have been used for years in the treatment of diabetic nephropathy (DN). However, the mechanism of Chuanxiong Rhizoma in DN has not yet been fully understood. Methods: We performed network pharmacology to construct target proteins interaction network of Chuanxiong Rhizoma. Active ingredients were acquired from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform. DRUGBANK database was used to predict target proteins of Chuanxiong Rhizoma. Gene ontology (GO) biological process analyses and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were also performed for functional prediction of the target proteins. Molecular docking was applied for evaluating the drug interactions between hub targets and active ingredients. Results: Twenty-eight target genes fished by 6 active ingredients of Chuanxiong Rhizoma were obtained in the study. The top 10 significant GO analyses and 6 KEGG pathways were enriched for genomic analysis. We also acquired 1366 differentially expressed genes associated with DN from GSE30528 dataset, including five target genes: KCNH2, NCOA1, KDR, NR3C2 and ADRB2. Molecular docking analysis successfully combined KCNH2, NCOA1, KDR and ADRB2 to Myricanone with docking scores from 4.61 to 6.28. NR3C2 also displayed good docking scores with Wallichilide and Sitosterol (8.13 and 8.34, respectively), revealing good binding forces to active compounds of Chuanxiong Rhizoma. Conclusions: Chuanxiong Rhizoma might take part in the treatment of DN through pathways associated with steroid hormone, estrogen, thyroid hormone and IL-17. KCNH2, NCOA1, KDR, ADRB2 and NR3C2 were proved to be the hub targets, which were closely related to corresponding active ingredients of Chuanxiong Rhizoma.

Correlation analysis of serum thyroid stimulating hormone with acute cerebrovascular disease

Background

Acute cerebrovascular disease (ACVD) could cause abnormal metabolism of thyroid hormones (TH), mostly represented as a euthyroid sick syndrome or low T3 syndrome. However, the changes in serum thyroid-stimulating hormone (TSH) are controversial. The aim of this study is to investigate the clinical significance of TSH alteration in patients with ACVD.

Method

Patients with ACVD admitted in our hospitals between January 2013 and September 2017 were enrolled in this study (n = 245, including 176 cerebral infarctions and 69 cerebral hemorrhages). Their thyroid hormones were measured and compared with healthy individuals (n = 75). The correlation of TSH with severity and prognosis of ACVD were analyzed by receiver operating characteristic curve.

Results

Serum TSH in ACVD group was higher than the control group (1.64 ± 1.08 vs. 1.26 ± 0.36 μIU/mL, P < 0.05). The TSH levels in intermediate and severe patients with ACVD were higher than in mild patients (1.72 ± 1.18 vs. 2.71 ± 0.93 vs. 1.02 ± 0.47 μIU/mL, P < 0.05). Receiver Operating Characteristic curve (ROC) of TSH in determining the severity of patients were 0.863 (Area under the curve, AUC), 1.496 μIU/L (optimal threshold), 76.5% (sensitivity) and 87.3% (specificity). TSH levels in improved and unchanged groups were significantly higher than the primarily healing group (2.27 ± 1.11 vs. 2.88 ± 1.07 vs. 0.86 ± 0.46 μIU/mL, P < 0.05). ROC of TSH in determining the prognosis of patients was 0.910 (AUC), 1.681 mIU/L (optimal threshold), 79.8% (sensitivity) and 90.5% (specificity) correspondingly.

Conclusion

Since elevated TSH in ACVD patients affects the outcome of thyroid function evaluation, it is preferable to re-check after the acute period. A correlation between a high TSH level and the severity and prognosis of ACVD was detected, but the mechanism of this correlation needs to be further studied.

The prevalence and incidence of thyroid dysfunction in patients with diabetes - a longitudinal follow-up study

BACKGROUND

Thyroid dysfunction (TD) occurs in 13.4% of diabetic patients, which has prompted recommendations for annual thyroid screening in patients with diabetes. However, recommendations for annual screening should be based on disease incidence rather than prevalence.

METHODS

In 1997-1998, seven hundred and thirty patients (618 type 2 diabetes, 55% male; 112 type 1 diabetes, 47% male) were sequentially screened for TD. The 639 patients with normal thyroid function were followed from 1999 to 2006, with annual thyroid function tests.

RESULTS

A total of 21/112 (19%) with type 1 diabetes (T1DM) and 70/618 (11%) with type 2 diabetes (T2DM) had TD. TD was more frequent in females (p < 0.05) and T1DM (p = 0.04). The mean annual rate of conversion to abnormal tests was 2.1%. At 8 years, there were 100 new cases of TD representing 15.6% of the cohort (17 T1DM and 83 T2DM). TD was more frequent in females (p < 0.05), but there was no difference in the incidence of new TD between T1DM and T2DM (p = 0.39).

CONCLUSIONS

Our data confirms the high prevalence of TD in diabetic patients, in concordance with the results from other series. We found only 25 treatable cases of new thyroid disease from 639 patients in the 8-year follow-up, less than 0.5% per year. The low incidence of treatable thyroid disease challenges the need for annual screening for thyroid abnormalities in patients with type 2 diabetes.

CASE FINDING FOR HYPOTHYROIDISM SHOULD INCLUDE TYPE 2 DIABETES AND METABOLIC SYNDROME PATIENTS: A LATIN AMERICAN THYROID SOCIETY (LATS) POSITION STATEMENT

OBJECTIVE

Latin American Thyroid Society (LATS) Hypothyroidism Clinical Practice Guidelines recommend case finding of hypothyroid patients in multiple and different situations that agree with other Society guidelines. However, the detection of hypothyroidism in type 2 diabetes mellitus (T2DM) or metabolic syndrome (MetS) patients is not mentioned in particular. In the recent years, several basic and epidemiologic studies have appeared showing that a lower thyroid function and MetS/T2DM are associated. Hence, the aim of this review is to manifest the LATS position on the diagnosis of hypothyroidism in both MetS and T2DM patients.

METHODS

A search was made in PubMed using the following terms: "hypothyroidism" AND "diabetes" OR "metabolic syndrome." The most relevant studies describing the prevalence and complications due to hypothyroidism in both MetS and T2DM patients were selected.

RESULTS

The current document reviews new information from studies that have shown that the prevalence of hypothyroidism is higher in T2DM patients (odds ratio [OR], 3.45; 95% confidence interval [CI], 2.5 to 4.7) and that diabetic complications are more prevalent in subclinical hypothyroidism (ScH). The incidence of T2DM is 1.09-fold higher with each doubling of thyroid-stimulating hormone (TSH) mIU/L (95% CI, 1.06 to 1.12), and the incidence of prediabetes increases 15% (hazard ratio, 1.15; 95% CI, 1.04 to 1.26) in patients with TSH >5 mIU/L. Similarly, MetS is more prevalent in ScH compared to euthyroid individuals (OR, 1.31; 95% CI, 1.08 to 1.60).

CONCLUSION

Thyroid function is affected in MetS and T2DM, and hypothyroidism is more common in these patients. Diabetic complications are more frequent in ScH patients. Therefore, LATS now recommends aggressive case finding of hypothyroidism in both MetS and T2DM patients.

ABBREVIATIONS

CI = confidence interval; GLUT4 = glucose transporter 4; HOMA-IR = homeostatic model assessment for insulin resistance; HR = hazard ratio; LATS = Latin American Thyroid Society; MetS = metabolic syndrome; OR = odds ratio; ScH = subclinical hypothyroidism; T2DM = type 2 diabetes mellitus; T3 = triiodothyronine; T4 = thyroxine; TSH = thyroid-stimulating hormone.