Association of thyroid functional disease with mortality in a national cohort of incident hemodialysis patients

Exploring Thyroid Function after Kidney Transplantation: The Complex Interplay Unacknowledged in Post-Transplant Care

Background/Objectives: The interplay between thyroid function and kidney graft function following kidney transplantation remains incompletely understood. Thyroid disorders are more prevalent in kidney transplant recipients than in the general population and are associated with poorer outcomes. Methods: This prospective, single-center study was designed to estimate thyroid function (thyroid-stimulating hormone (TSH), triiodothyronine (T3), free triiodothyronine (FT3), thyroxine (T4), free thyroxine (FT4), as well as anti-thyroid peroxidase antibody (anti-TPO), anti-thyroglobulin antibody (anti-Tg), and thyroid-stimulating immunoglobulin (TSI)) and its influence on kidney graft function among a cohort of 23 kidney transplant recipients during a follow-up period of 12 months. Results: Significantly increased levels of T4 and T3 were observed 12 months post-transplantation, with FT3 levels increasing significantly after 6 months. The prevalence of immeasurably low anti-Tg antibodies rose during follow-up. Initially, 8% of patients showed positive TSI, which turned negative for all after 6 months. A statistically significant correlation was found between the initial TSH and the estimated glomerular filtration rate (eGFR) value 6 months after transplantation (p = 0.023). The graft function was stable. Proteinuria was statistically significantly lower 12 months after transplantation. Conclusions: Identifying additional risk factors, understanding their impact on kidney graft function, and recognizing cardiovascular comorbidities could enhance patient care. Notably, this study marks the first prospective investigation into thyroid function after kidney transplantation in Croatia, contributing valuable insights to the global understanding of this complex interplay.

Subclinical hypothyroidism predicts outcome in heart failure: insights from the T.O.S.CA. registry

Subclinical hypothyroidism (SH), defined as increased serum thyroid-stimulating hormone (TSH) with normal free T4 (fT4) levels, is frequently observed in the general population. Prevalence ranges from 0.6% to 1.8% in the adult population, depending on age, sex, and iodine intake. Several studies reported a worse prognosis in patients with heart failure with reduced ejection fraction (HFrEF) and SH, but they considered heterogeneous populations suffering mainly from severe SH. Aim of this study was to evaluate if SH was independently associated with the occurrence of cardiovascular death considering 30 months of follow-up. 277 HFrEF patients enrolled in the prospective, multicenter, observational T.O.S.CA. (Terapia Ormonale Scompenso CArdiaco) registry, were included in this analysis. Patients were divided into two groups according to the presence of SH (serum TSH levels > 4.5 mIU/L with normal fT4 levels). Data regarding clinical status, echocardiography, and survival were analyzed. Twenty-three patients displayed SH (87% mild vs 13% severe), while 254 were euthyroid. No differences were found in terms of age, sex, HF etiology, and left ventricular ejection fraction. When compared with the euthyroid group, SH patients showed higher TSH levels (7.7 ± 4.1 vs 1.6 ± 0.9, p < 0.001), as expected, with comparable levels of fT4 (1.3 ± 0.3 vs 1.3 ± 0.3, p = NS). When corrected for established predictors of poor outcome in HF, the presence of SH resulted to be an independent predictor of cardiovascular mortality (HR: 2.96; 5-95% CI:1.13-7.74; p = 0.03). Since thyroid tests are widely available and inexpensive, they should be performed in HF patients to detect subclinical disorders, evaluate replacement therapy, and improve prognosis.

Impact of Thyroid Status on Incident Kidney Dysfunction and Chronic Kidney Disease Progression in a Nationally Representative Cohort

OBJECTIVE

To examine the relationship between thyroid status and incident kidney dysfunction/chronic kidney disease (CKD) progression.

PATIENTS AND METHODS

We examined incident thyroid status, ascertained by serum thyrotropin (TSH) levels measured from January 1, 2007, through December 31, 2018, among 4,152,830 patients from the Optum Labs Data Warehouse, containing deidentified retrospective administrative claims data from a large national health insurance plan and electronic health record data from a nationwide network of provider groups. Associations of thyroid status, categorized as hypothyroidism, euthyroidism, or hyperthyroidism (TSH levels >5.0, 0.5-5.0, and <0.5 mIU/L, respectively), with the composite end point of incident kidney dysfunction in patients without baseline kidney dysfunction and CKD progression in those with baseline CKD were examined using Cox models.

RESULTS

Patients with hypothyroidism and hyperthyroidism had higher risk of incident kidney dysfunction/CKD progression in expanded case-mix analyses (reference: euthyroidism): adjusted hazard ratios (aHRs) (95% CIs) were 1.37 (1.34 to 1.40) and 1.42 (1.39 to 1.45), respectively. Incrementally higher TSH levels in the upper reference range and TSH ranges for subclinical, mild overt, and overt hypothyroidism (≥3.0-5.0, >5.0-10.0, >10.0-20.0, and >20.0 mIU/L, respectively) were associated with increasingly higher risk of the composite end point (reference: TSH level, 0.5 to <3.0 mIU/L): aHRs (95% CIs) were 1.10 (1.09 to 1.11), 1.37 (1.34 to 1.40), 1.70 (1.59 to 1.83), and 1.70 (1.50 to 1.93), respectively. Incrementally lower TSH levels in the subclinical (<0.5 mIU/L) and overt (<0.1 mIU/L) hyperthyroid ranges were also associated with the composite end point: aHRs (95% CIs) were 1.44 (1.41 to 1.47) and 1.48 (1.39 to 1.59), respectively.

CONCLUSION

In a national cohort, TSH levels in the upper reference range or higher (≥3.0 mIU/L) and below the reference range (<0.5 mIU/L) were associated with incident kidney dysfunction/CKD progression.

Subclinical Hypothyroidism in Patients with Obesity and Metabolic Syndrome: A Narrative Review

The literature on the connection between obesity, metabolic syndrome, and subclinical hypothyroidism is critically analyzed in this narrative review. These conditions are frequently observed among adult populations and various studies and meta-analyses have assessed their association. The prevalence of subclinical hypothyroidism in obese individuals is higher than in non-obese subjects and this trend is more pronounced in unhealthy obesity phenotypes. However, the diagnosis and treatment of subclinical hypothyroidism can be difficult in obese patients. Exaggerated body fat is linked to thyroid hypoechogenicity as evident through ultrasonography and euthyroid obese people have greater TSH, FT3, and FT3/FT4 ratios than non-obese individuals in a euthyroid condition. Moreover, a reduced expression of the TSH receptor and altered function of deiodinases has been found in the adipose tissue of obese patients. Current data do not support the necessity of a pharmacological correction of the isolated hyperthyrotropinemia in euthyroid obese patients because treatment with thyroid hormone does not significantly improve weight loss and the increase in serum TSH can be reversible after hypocaloric diet or bariatric surgery. On the other hand, obesity is linked to elevated leptin levels. Inflammation can raise the risk of Hashimoto thyroiditis, which increases the likelihood that obese patients will experience overt or subclinical hypothyroidism. Both metabolic syndrome and subclinical hypothyroidism are associated with atherosclerosis, liver and kidney disease. Hence, the association of these two illnesses may potentiate the adverse effects noted in each of them. Subclinical hypothyroidism should be identified in patients with obesity and treated with appropriate doses of L-thyroxine according to the lean body mass and body weight. Randomized controlled trials are necessary to verify whether treatment of thyroid deficiency could counteract the expected risks.

Thyroid function analysis after roxadustat or erythropoietin treatment in patients with renal anemia: a cohort study

PURPOSE

This cohort study was designed to explore whether roxadustat or erythropoietin could affect thyroid function in patients with renal anemia.

METHODS

The study involved 110 patients with renal anemia. Thyroid profile and baseline investigations were carried out for each patient. The patients were divided into two groups: 60 patients taking erythropoietin served as the control group (rHuEPO group) and 50 patients using roxadustat served as the experimental group (roxadustat group).

RESULTS

The results indicated that there were no significant differences in serum total thyroxine (TT4), total triiodothyronine (TT3), free triiodothyronine (FT3), free thyroxine (FT4) or thyroid stimulating hormone (TSH) between the two groups at baseline. After treatment, TSH, FT3, and FT4 were significantly lower in the roxadustat group than in the rHuEPO group (p < 0.05). After adjusting for age, sex, dialysis modality, thyroid nodules and causes of kidney disease, Cox regression showed that roxadustat was an independent influencing factor on thyroid dysfunction (HR 3.37; 95% CI 1.94-5.87; p < 0.001). After 12 months of follow-up, the incidence of thyroid dysfunction was higher in the roxadustat group than in the rHuEPO group (log-rank p < 0.001).

CONCLUSION

Roxadustat may lead to a higher risk of thyroid dysfunction, including low TSH, FT3 and FT4, than rHuEPO in patients with renal anemia.

Development and Validation of a Prediction Model for Incident Hypothyroidism in a National Chronic Kidney Disease Cohort

CONTEXT

Hypothyroidism is a common yet under-recognized condition in patients with chronic kidney disease (CKD), which may lead to end-organ complications if left untreated.

OBJECTIVE

We developed a prediction tool to identify CKD patients at risk for incident hypothyroidism.

METHODS

Among 15 642 patients with stages 4 to 5 CKD without evidence of pre-existing thyroid disease, we developed and validated a risk prediction tool for the development of incident hypothyroidism (defined as thyrotropin [TSH] > 5.0 mIU/L) using the Optum Labs Data Warehouse, which contains de-identified administrative claims, including medical and pharmacy claims and enrollment records for commercial and Medicare Advantage enrollees as well as electronic health record data. Patients were divided into a two-thirds development set and a one-third validation set. Prediction models were developed using Cox models to estimate probability of incident hypothyroidism.

RESULTS

There were 1650 (11%) cases of incident hypothyroidism during a median follow-up of 3.4 years. Characteristics associated with hypothyroidism included older age, White race, higher body mass index, low serum albumin, higher baseline TSH, hypertension, congestive heart failure, exposure to iodinated contrast via angiogram or computed tomography scan, and amiodarone use. Model discrimination was good with similar C-statistics in the development and validation datasets: 0.77 (95% CI 0.75-0.78) and 0.76 (95% CI 0.74-0.78), respectively. Model goodness-of-fit tests showed adequate fit in the overall cohort (P = .47) as well as in a subcohort of patients with stage 5 CKD (P = .33).

CONCLUSION

In a national cohort of CKD patients, we developed a clinical prediction tool identifying those at risk for incident hypothyroidism to inform prioritized screening, monitoring, and treatment in this population.

Thyroid, Gonadal and Adrenal Dysfunction in Kidney Transplant Recipients: A Review for the Clinician

While chronic kidney disease-associated mineral and bone disorders (CKD-MBD) prevail in the endocrinological assessment of CKD patients, other endocrine abnormalities are usually overlooked. CKD is associated with significant thyroid, adrenal and gonadal dysfunction, while persistent and de novo endocrinological abnormalities are frequent among kidney transplant recipients (KTR). Low T3 levels prior to transplantation may help identify those at risk for delayed graft function and are often found in KTR. Thyroid surveillance after kidney transplantation should be considered due to structural anomalies that may occur. Despite the rapid recovery of gonadal hormonal secretion after renal transplantation, fertility is not completely restored. Testosterone may improve anemia and general symptoms in KTR with persistent hypogonadism. Female KTR may still experience abnormal uterine bleeding, for which estroprogestative administration may be beneficial. Glucocorticoid administration suppresses the hypothalamic-pituitary-adrenal axis in KTR, leading to metabolic syndrome. Patients should be informed about signs and symptoms of hypoadrenalism that may occur after glucocorticoid withdrawal, prompting adrenal function assessment. Clinicians should be more aware of the endocrine abnormalities experienced by their KTR patients, as these may significantly impact the quality of life. In clinical practice, awareness of the specific endocrine dysfunctions experienced by KTR patients ensures the correct management of these complications in a multidisciplinary team, while avoiding unnecessary treatment.

Prevalence and Determinants of Hypothyroidism in Patients on Routine Hemodialysis in Somalia: A Cross-Sectional Study

Introduction

In recent decades, the relationship between thyroid and kidney disease has drawn considerable attention. We aim to assess the prevalence and the determinants of hypothyroidism in hemodialysis patients in Somalia.

Materials and Methods

This is a cross-sectional study which was conducted in the hemodialysis unit of Mogadishu Somalia Turkish Training and Research Hospital, between June 1 and July, 31 2022. A total of 301 patients who are routinely going to hemodialysis were included in the study. Demographic data including age, gender, and data regarding hemodialysis were extracted from hospital information system (HIS). All participants had their thyroid function test measured before hemodialysis sessions.

Results

A total of 301 patients were examined. Their ages ranged from 40 to 66 years, with the median age being 54 (IQR= 40-66). Males were 167 (55.5%) compared to females 134 (44.5%). Hypertension was the most common comorbidity among the patients with 137 (45.5%). Diabetic kidney disease was the most common cause of renal failure in 138 patients (45.84%) followed by hypertensive kidney disease 100 (33.22%). The prevalence rate of hypothyroidism in hemodialysis patients in our study was 28%. In hypothyroidism patients 57.8% had subclinical hypothyroidism and 42.2% had overt hypothyroidism. 70.8% of our patients were in euthyroid status. Subclinical hypothyroidism was commonly seen in patients with diabetes, hypertension, and heart disease. We found that increasing age, decreased albumin level were related to higher risk of subclinical hypothyroidism. We also found that increasing creatinine levels were associated with lower risk of overt hypothyroidism.

Conclusion

The prevalence rate of hypothyroidism in hemodialysis patients was 28%, with 57.8% showing subclinical hypothyroidism and 42.2% overt hypothyroidism. Increased age and low albumin level was associated with the prevalence of subclinical hypothyroidism in hemodialysis patients. Also low creatinine level was observed in overt hypothyroidism patients.

Clinicopathological features and prognosis of idiopathic membranous nephropathy with thyroid dysfunction

BACKGROUND

Thyroid dysfunction is common in patients with kidney disease. However, the relationship between thyroid dysfunction and idiopathic membranous nephropathy (IMN) remains unclear. This retrospective study aimed to investigate the clinicopathological characteristics and prognosis of patients with IMN and thyroid dysfunction compared to patients with IMN and without thyroid dysfunction.

METHODS

A total of 1052 patients with IMN diagnosed by renal biopsy were enrolled in this study, including 736 (70%) with normal thyroid function and 316 (30%) with abnormal thyroid function. We analyzed the clinicopathological features and prognostic data between the two groups, using propensity score matching (PSM) to reduce the bias. Logistic regression analysis was performed to investigate the risk factors for IMN combined with thyroid dysfunction. Kaplan-Meier curves and Cox regression analysis were used to evaluate the association between thyroid dysfunction and IMN.

RESULTS

Patients with IMN and thyroid dysfunction exhibited more severe clinical features. Female sex, lower albumin level, higher D-dimer level, severe proteinuria, and decreased estimated glomerular filtration rate were predictors of thyroid dysfunction in patients with IMN. After PSM, 282 pairs were successfully matched. Results from the Kaplan-Meier curves indicated that the thyroid dysfunction group had a lower complete remission rate (P = 0.044), higher relapse rate (P < 0.001), and lower renal survival rate (P = 0.004). The multivariate Cox regression analysis revealed that thyroid dysfunction was an independent risk factor for complete remission [hazard ratio (HR) = 0.810, P = 0.045], relapse (HR = 1.721, P = 0.001), and composite endpoint event (HR = 2.113, P = 0.014) in IMN.

CONCLUSIONS

Thyroid dysfunction is relatively common in patients with IMN, and the clinical indicators are more severe in these patients. Thyroid dysfunction is an independent risk factor for poor prognosis in patients with IMN. More attention should be paid to thyroid function in patients with IMN.

Kidney disease and thyroid dysfunction: the chicken or egg problem

Patients with non-dialysis-dependant chronic kidney disease (NDD-CKD) and dialysis-dependant chronic kidney disease (DD-CKD) frequently also suffer from thyroid disorders, especially hypothyroidism which is found two to five times more often among them compared to the general population. Emerging research has illustrated the potential prognostic implications of this association as NDD-CKD and DD-CKD patients with hypothyroidism have been shown to have higher mortality rates, and treatment of subclinical hypothyroidism in NDD-CKD patients has been reported to attenuate the decline of glomerular filtration rate over time. This review illustrates the bidirectional, multi-layered interplay between the kidneys and the thyroid gland explaining how pathologies in one organ will affect the other and vice versa. Additionally, it outlines the impact of thyroid disorders on routine parameters of kidney function (especially serum creatinine and serum cystatin C) that nephrologists should be aware of in their clinical practice. Lastly, it summarizes the emerging evidence from clinical studies on how treatment of subclinical hypothyroidism in NDD-CKD and DD-CKD patients may potentially have beneficial effects on kidney function as well as mortality. While most of the research in this area has been performed on adult patients, we specifically discuss what is currently known about thyroid dysfunctions in paediatric CKD patients as well and provide management suggestions. The evidence accumulated so far clearly indicates that further, prospective studies with meticulous methodology are warranted to refine our understanding of thyroid disorders in paediatric and adult CKD patients and establish optimal treatment pathways.

Elevated serum thyrotropin levels and endothelial dysfunction in a prospective hemodialysis cohort

INTRODUCTION

Thyroid dysfunction is a highly prevalent yet under-recognized complication in hemodialysis patients. In the general population, hypothyroidism has been associated with endothelial dysfunction due to impaired vasodilator synthesis and activity. Little is known about the association of serum thyrotropin (TSH), the most sensitive and specific single biochemical metric of thyroid function, with endothelial function in hemodialysis patients.

METHODS

In a secondary analysis of 99 patients from the Anti-inflammatory and anti-oxidative nutrition in hypoalbuminemic dialysis patients (AIONID) trial, we examined measurements of serum TSH and endothelial function ascertained by fingertip digital thermal monitoring (DTM), a novel method used to measure micro-vascular reactivity, collected within a 90-day period. DTM was used to measure changes in fingertip temperature during and after an ischemic stimulus (blood pressure cuff occlusion) as an indicator of changes in blood flow, and two DTM indices were assessed, namely adjusted (a) Temperature Rebound (TR), defined as the maximum temperature rebound post-cuff deflation, and adjusted (b) Area Under the Temperature Curve (TMP-AUC), defined as area under the curve between the maximum and minimum temperatures. We examined the relationship between serum TSH with impaired TR (separately) and TMP-AUC (both defined as less than the median level of observed values) using multivariable logistic regression.

FINDINGS

In unadjusted and case-mix analyses, higher serum TSH levels (defined as the three highest quartiles) were associated with lower (worse) TR (ref: lowest TSH quartile): ORs (95% CI) 2.64 (1.01-6.88) and 2.85 (1.08-7.57), respectively. In unadjusted and case-mix analyses, higher TSH levels were associated with lower (worse) TMP-AUC: ORs (95% CI) 2.64 (1.01-6.88) and 2.79 (1.06-7.38), respectively.

DISCUSSION

In HD patients, higher serum TSH levels were associated with worse micro-vascular reactivity measured by DTM. Further studies are needed to determine if thyroid hormone supplementation improves endothelial function in hemodialysis patients with lower levels of thyroid function.

The Role of Thyroid in Renovascular Function: Independent Association of Serum TSH With Renal Plasma Flow

CONTEXT

There are well-established interactions between the thyroid and the kidney. Thyroid hypofunction is associated with reduced renal plasma flow (RPF), and hypothyroidism is highly prevalent in chronic kidney disease; however, less is known about the thyroid-kidney axis in the euthyroid state.

OBJECTIVE

This work aimed to study the association of thyroid function with renovascular parameters in a well-phenotyped cohort of euthyroid normotensive and hypertensive individuals.

METHODS

This cross-sectional, multicenter study of the HyperPATH Consortium took place in 5 US and European academic institutions. A total of 789 individuals, aged 18 to 65 years, with serum thyrotropin (TSH) 0.4 to 5.5 mIU/L, participated; individuals with uncontrolled or secondary hypertension or on medication affecting the hypothalamus-pituitary-thyroid axis were excluded. Hemodynamic parameters including RPF, thyroid function testing, and the Thr92Ala deiodinase 2 (D2) polymorphism were assessed in the setting of a liberal and restricted salt diet. We searched for associations between thyroid function and renovascular parameters and accounted for confounding factors, such as older age, hypertension, and diabetes.

RESULTS

Serum TSH was inversely associated with RPF assessed in the setting both of liberal and restricted salt diets. This association remained significant and independent when accounting for confounding factors, whereas free thyroxine index (fTI) and the Thr92Ala polymorphism, associated with lower D2 catalytic activity and disrupted thyroid hormone tissue availability, were not independently associated with RPF. Serum TSH remained an independent predictor of RPF on a liberal salt diet when the analysis was restricted to healthy young individuals.

CONCLUSION

Serum TSH levels, but not fTI nor the Thr92Ala D2 polymorphism, were independently inversely associated with RPF in individuals of the HyperPATH Consortium. These findings suggest a direct interconnection between TSH and renovascular dynamics even with TSH within reference range, warranting further investigation.

Subclinical Hypothyroidism: Prevalence, Health Impact, and Treatment Landscape

Subclinical hypothyroidism (sHypo) is defined as normal serum free thyroid hormone levels coexisting with elevated serum thyroid-stimulating hormone (TSH) levels. sHypo is a common condition observed in clinical practice with several unique features. Its diagnosis should be based on an understanding of geographic and demographic differences in biochemical criteria versus a global reference range for TSH that is based on the 95% confidence interval of a healthy population. During the differential diagnosis, it is important to remember that a considerable proportion of sHypo cases are transient and reversible in nature; the focus is better placed on persistent or progressive forms, which mainly result from chronic autoimmune thyroiditis. Despite significant evidence documenting the health impacts of sHypo, the effects of levothyroxine treatment (LT4-Tx) in patients with sHypo remains controversial, especially in patients with grade 1 sHypo and older adults. Existing evidence suggests that it is reasonable to refrain from immediate LT4-Tx in most patients if they are closely monitored, except in women who are pregnant or in progressive cases. Future research is needed to further characterize the risks and benefits of LT4-Tx in different patient cohorts.

Thyroid function, renal events and mortality in chronic kidney disease patients: the German Chronic Kidney Disease study

BACKGROUND

Hypothyroidism and low free triiodothyronine (FT3) syndrome [low FT3 levels with normal thyroid-stimulating hormone (TSH)] have been associated with reduced kidney function cross-sectionally in chronic kidney disease (CKD) patients with severely reduced estimated glomerular filtration rate (eGFR) or end-stage kidney disease (ESKD). Results on the prospective effects of impaired thyroid function on renal events and mortality for patients with severely reduced eGFR or from population-based cohorts are conflicting. Here we evaluated the association between thyroid and kidney function with eGFR (cross-sectionally) as well as renal events and mortality (prospectively) in a large, prospective cohort of CKD patients with mild to moderately reduced kidney function.

METHODS

Thyroid markers were measured among CKD patients from the German Chronic Kidney Disease study. Incident renal endpoints (combined ESKD, acute kidney injury and renal death) and all-cause mortality were abstracted from hospital records and death certificates. Time to first event analysis of complete data from baseline to the 4-year follow-up (median follow-up time 4.04 years) of 4600 patients was conducted. Multivariable linear regression and Cox proportional hazards models were fitted for single and combined continuous thyroid markers [TSH, free thyroxine (FT4), FT3] and thyroid status.

RESULTS

Cross-sectionally, the presence of low-FT3 syndrome showed a significant inverse association with eGFR and continuous FT3 levels alone showed a significant positive association with eGFR; in combination with FT4 and TSH, FT3 levels also showed a positive association and FT4 levels showed a negative association with eGFR. Prospectively, higher FT4 and lower FT3 levels were significantly associated with a higher risk of all-cause mortality (N events = 297). Per picomole per litre higher FT3 levels the risk of reaching the composite renal endpoint was 0.73-fold lower (95% confidence interval 0.65-0.82; N events = 615). Compared with euthyroid patients, patients with low-FT3 syndrome had a 2.2-fold higher risk and patients with hypothyroidism had a 1.6-fold higher risk of experiencing the composite renal endpoint.

CONCLUSIONS

Patients with mild to moderate CKD suffering from thyroid function abnormalities are at an increased risk of adverse renal events and all-cause mortality over time.

The Interplay Between Thyroid Dysfunction and Kidney Disease

Hypothyroidism is a highly prevalent endocrine complication in chronic kidney disease (CKD) patients. A large body of evidence has shown that there is a bidirectional relationship between thyroid dysfunction and kidney disease, yet there are many remaining gaps in knowledge in regards to the clinical management of CKD patients with hypothyroidism, including those receiving hemodialysis and peritoneal dialysis. Given that hypothyroidism has been associated with many deleterious outcomes including a higher risk of (1) mortality, (2) cardiovascular disease, (3) impaired health-related quality of life, and (4) altered body composition in both non-CKD and CKD patients, future research is needed to establish the appropriate screening, diagnosis, and treatment approaches in these populations.

Hemodilution Impacts Assessment of Thyroid Status before and after Hemodialysis in Patients with End-Stage Renal Disease

BACKGROUND

To elucidate the role of hemodilution in the alteration of thyroid hormone levels in end-stage renal disease (ESRD), we compared thyroid function before and after hemodialysis (HD).

METHODS

Twenty-three male ESRD patients (age <65 years) with either chronic glomerulonephritis (CGN) or diabetic nephropathy (DN), who were enrolled between June 2019 and August 2019, were included in the study. The free thyroxine (fT4), free tri-iodothyronine (fT3), and thyroid-stimulating hormone (TSH), thyroxine-binding globulin (TBG), and thyroglobulin (Tg), measured before and after HD in 12 patients with CGN (48.7 ± 11.8 years [mean ± standard deviation]) and 11 patients with DN (57.6 ± 6.5 years), were compared with 45 healthy controls (52.5 ± 11.9 years).

RESULTS

The fT4, fT3, and TBG were significantly low before HD and increased in parallel with an increase in hematocrit and albumin after HD in both ESRD subgroups. The TSH was high before HD and decreased significantly after HD, while Tg remained almost unchanged. In DN, the fT4 levels were nearly identical, while fT3 was lower with slightly higher TSH, compared with CGN. The TSH/fT4 ratios before HD were significantly higher in both subgroups, and the fT3/fT4 ratios after HD were significantly lower in DN than the control.

CONCLUSIONS

Our findings suggest that the low fT4 and fT3 levels found in ESRD are due to hemodilution before HD, resulting in a slightly higher TSH level but almost unchanged Tg level, and that DN is associated with decreased T4-to-T3 conversion.

A Pilot Trial on the Effect of Levothyroxine on Proteinuria in Patients With Advanced CKD

INTRODUCTION

Thyroid hormones can directly affect kidney function; elevated levels of thyroid-stimulating hormone (TSH) and chronic kidney disease (CKD) are associated with proteinuria, decreased estimated glomerular filtration rate (eGFR), and progression to end-stage renal disease. Our hypothesis is that in patients with CKD and TSH at levels considered to be in the low subclinical hypothyroidism (SCH) range, lowering TSH with levothyroxine (LVX) improves the clinical parameters of renal function.

METHODS

This was a double-blind, randomized, pilot clinical trial in patients with proteinuric CKD (eGFR <60 ml/min per 1.73 m2 and proteinuria >150 mg/d) performed at the Hospital Civil de Guadalajara, with the intention of lowering TSH (levels of 1.25-2.5 μIU/l) in patients with TSH (levels of 2.6-9.9 μIU/ml with FT4 in the range of 0.7-1.8 ng/dl). Patients were randomized 1:1 to receive LVX or placebo for 12 weeks. The primary objective was to evaluate absolute levels of proteinuria at the beginning compared to the end of the study and, as a secondary objective, the changes in serum creatinine (sCr), eGFR, cholesterol, triglycerides, low-density lipoprotein (LDL), and blood pressure, and to assess the tolerability and safety of LVX.

RESULTS

Between March and November 2018, a total of 163 patients were assessed for eligibility; 119 patients did not meet the inclusion criteria or were excluded, and 32 patients were randomized. The demographic and clinical characteristics of the 2 study groups were essentially not different. Subjects were 66.87 (SD 12.19) years of age, 62.5% were female, 75% were diabetes mellitus, eGFR was 23.55 (±12.91) ml/min per 1.73 m2, TSH was 5.37 ± 2.13 μIU/ml, proteinuria in 24-hour urine collection was 1.52 ± 1.12, and all of them were taking angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs). Proteinuria at 12 weeks in the LVX group was 0.89 SD ± 1.28 g/d, and in the placebo group it was 1.35 SD ± 0.85 g/d; when compared to placebo, LVX showed a significant decrease in proteinuria of 1.1 g/d (P = 0.0011). The eGFR in the LVX group showed an improvement of 4 ml/min/1.73 m2 (P = 0.049); in the placebo group, there was a decrease of 1.98 ml/min per 1.73 m2. The sCr, cholesterol, triglycerides, low-density lipoprotein, systolic blood pressure, and diastolic blood pressure were not different between groups. Adverse events were reported in the LVX group in 7.14% of patients and in 11.11% of patients in the placebo group; none left the study because of adverse effects, and there were no serious adverse events.

CONCLUSION

This single-center, randomized, double-blind, placebo-controlled pilot clinical trial in patients with advanced proteinuric CKD who already used ACEIs or ARBs demonstrated that administering LVX to obtain a TSH range close to 2.5 μIU/ml decreased proteinuria and improved eGFR. Future research is needed to confirm our results and to determine whether our findings generalize to patient groups not explicitly enrolled in this small pilot trial.

Association of Hypothyroidism and Mortality in the Elderly Population: A Systematic Review and Meta-Analysis

CONTEXT

The evidence of whether hypothyroidism increases mortality in the elderly population is currently inconsistent and conflicting.

OBJECTIVE

The objective of this meta-analysis is to determine the impact of hypothyroidism on mortality in the elderly population.

DATA SOURCES

PubMed, Embase, Cochrane Library, Scopus, and Web of Science databases were searched from inception until May 10, 2019.

STUDY SELECTION

Studies evaluating the association between hypothyroidism and all-cause and/or cardiovascular mortality in the elderly population (ages ≥ 60 years) were eligible.

DATA EXTRACTION

Two reviewers independently extracted data and assessed the quality of the studies. Relative risk (RR) was retrieved for synthesis. A random-effects model for meta-analyses was used.

DATA SYNTHESIS

A total of 27 cohort studies with 1 114 638 participants met the inclusion criteria. Overall, patients with hypothyroidism experienced a higher risk of all-cause mortality than those with euthyroidism (pooled RR = 1.26, 95% CI: 1.15-1.37); meanwhile, no significant difference in cardiovascular mortality was found between patients with hypothyroidism and those with euthyroidism (pooled RR = 1.10, 95% CI: 0.84-1.43). Subgroup analyses revealed that overt hypothyroidism (pooled RR = 1.10, 95% CI: 1.01-1.20) rather than subclinical hypothyroidism (pooled RR = 1.14, 95% CI: 0.92-1.41) was associated with increased all-cause mortality. The heterogeneity primarily originated from different study designs (prospective and retrospective) and geographic locations (Europe, North America, Asia, and Oceania).

CONCLUSIONS

Based on the current evidence, hypothyroidism is significantly associated with increased all-cause mortality instead of cardiovascular mortality among the elderly. We observed considerable heterogeneity, so caution is needed when interpreting the results. Further prospective, large-scale, high-quality studies are warranted to confirm these findings.

Prevalence of Hypothyroidism among Dialysis Patients in Palestine: A Cross-Sectional Study

Introduction

The kidney affects the thyroid gland causing various derangements in its function whenever the kidney is impaired, even with a minor imperfection in its job, and this makes dialysis patients more prone to thyroid disorders with subsequent increase in mortality and morbidity. This study aims to assess the prevalence of thyroid disease (hypo- and hyperthyroidism) among dialysis patients and their associated factors.

Methods

This cross-sectional study was conducted in the dialysis unit of An-Najah National University Hospital. 209 dialysis patients (60% were male, 57.6 ± 14.5 years, mean age) meeting our inclusion criteria were tested for thyrotropin (TSH) and free thyroxine (FT4) in addition to routine laboratory tests. Findings. The prevalence of hypothyroidism was assessed as 16.3% (95% CI = 11.29% to 21.3%), overt hypothyroidism was 9.1%, and subclinical hypothyroidism was 7.2%. Subclinical hyperthyroidism prevalence was 1%, and no overt hyperthyroidism cases were reported. We observed no significant association between thyroid state and age, gender, duration of dialysis, or weight. Discussion. Hypothyroidism (both subclinical and overt type) is commonly seen in dialysis patients, and its symptoms are ordinary complains even in euthyroid dialysis patients, and this warrants screening programs and more studies on the efficacy of thyroid hormone supplements.

Association of thyroid status prior to transition to end-stage renal disease with early dialysis mortality

BACKGROUND

Advanced chronic kidney disease (CKD) patients, including those receiving dialysis, have a high prevalence of thyroid dysfunction. Although hypothyroidism is associated with higher death risk in end-stage renal disease (ESRD) patients, no studies have examined whether thyroid status in the pre-ESRD period impacts mortality after dialysis initiation.

METHODS

Among US veterans with CKD identified from the national Veterans Affairs database that transitioned to dialysis over the period from October 2007 to September 2011, we examined the association of pre-ESRD serum thyrotropin (TSH) levels averaged over the 1-year pre-dialysis ('prelude') period with all-cause mortality in the first year following dialysis initiation.

RESULTS

Among 15 335 patients in the 1-year prelude cohort, TSH levels >5.0 mIU/L were associated with higher mortality in expanded case-mix Cox models (reference: TSH 0.5-5.0 mIU/L): adjusted hazard ratio (aHR) [95% confidence interval (CI) 1.20 (1.07-1.33). Similar findings were observed for TSH >5.0 mIU/L and mortality in the 2- and 5-year cohorts: aHRs (95% CI) 1.11 (1.02-1.21) and 1.15 (1.07-1.24), respectively. Analyses of finer gradations of TSH in the 1-year prelude cohort demonstrated that incrementally higher levels >5.0 mIU/L were associated with increasingly higher mortality in expanded case-mix models (reference: TSH 0.5-3.0 mIU/L): aHRs (95% CI) 1.18 (1.04-1.33) and 1.28 (1.03-1.59) for TSH levels >5.0-10.0 mIU/L and >10.0 mIU/L, respectively. In the 2- and 5-year cohorts, mortality associations persisted most strongly for those with TSH >10.0 mIU/L, particularly after laboratory covariate adjustment.

CONCLUSIONS

Among new ESRD patients, there is a dose-dependent relationship between higher pre-ESRD TSH levels >5.0 mIU/L and post-ESRD mortality. Further studies are needed to determine the impact of TSH reduction with thyroid hormone supplementation in this population.

Thyroid Pathology in End-Stage Renal Disease Patients on Hemodialysis

Objectives: Chronic kidney disease is a rising cause of morbidity and mortality in developed countries, including end-stage renal disease (ESRD). The prevalence of thyroid comorbidities in persons with chronic kidney disease is documented higher than in normal population. The study aims to investigate the prevalence of morphological and functional thyroid disorders in patients with chronic kidney disease, with renal replacement therapy (hemodialysis). Methods: A cross-sectional study was performed on 123 consecutive patients with chronic kidney disease stage 5, on hemodialysis during a period of one month (May 2019–June 2020). All patients were enrolled for maintenance hemodialysis in B Braun Hemodialysis Center Timisoara and were examined on conventional 2B ultrasound. Thyroid blood tests were done, including serum free thyroxin (FT4), free triiodothyronine (FT3) and thyroid-stimulating hormone (TSH) at the time of starting hemodialysis. Results: We evaluated 123 patients (male to female ratio 70/53) mean age 62.2 ± 11.01, mostly above 65 years old, enrolled in the end-stage renal disease program, on renal replacement therapy. From the cohort, 76/123 presented thyroid disease, including autoimmune hypothyroidism, nodular goiter or thyroid cancer. Among them, 63 patients presented nodular goiter, including 3 thyroid cancers, confirmed by surgery and histopathological result, 22 patients had thyroid autoimmune disease. The serum thyroid-stimulating hormone levels found in the cohort was 3.36 ± 2.313 mUI/mL, which was in the normal laboratory reference range. The thyroid volume was 13 ± 7.18 mL. A single patient in the cohort presented Graves Basedow disease, under treatment and three patients present subclinical hyperthyroidism. We have found that thyroid disease risk is increased by 3.4-fold for the female gender and also the increase of body mass index (BMI) with one unit raises the risk of developing thyroid disease with 1.083 times (p = 0.018). Conclusion: To conclude, this study aimed to quantify the prevalence of thyroid disease in end-stage kidney disease population, especially nodular goiter, important for differential diagnosis in cases with secondary hyperparathyroidism. Thyroid autoimmune disease can be prevalent among these patients, as symptoms can overlap those of chronic disease and decrease the quality of life. We have found that thyroid disease has a high prevalence among patients with end-stage renal disease on hemodialysis. Thyroid goiter and nodules in ESRD patients were more prevalent than in the general population. Clinical surveillance and routine screening for thyroid disorders can improve the quality of life in these patients.

Association of Subclinical Hypothyroidism and Cardiovascular Disease With Mortality

IMPORTANCE

Subclinical hypothyroidism is a common clinical entity among US adults associated in some studies with an increase in the risk of cardiovascular disease (CVD) and mortality. However, the extent to which CVD mediates the association between elevated serum thyrotropin (TSH) and mortality has not yet been well established or sufficiently quantified.

OBJECTIVE

To elucidate the extent to which subclinical hypothyroidism, elevated serum TSH and normal serum free thyroxine, or high-normal TSH concentrations (ie, upper normative-range TSH concentrations) are associated with mortality through CVD among US adults.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study relied on representative samples of US adults enrolled in the National Health and Nutrition Examination Survey in 2001 to 2002, 2007 to 2008, 2009 to 2010, and 2011 to 2012 and their mortality data through 2015. Data were analyzed from January to August 2019.

MAIN OUTCOMES AND MEASURES

Cox proportional hazards regression models were used to investigate associations between the TSH concentration category (subclinical hypothyroidism or tertiles of serum TSH concentrations within the reference range; low-normal TSH, 0.34-1.19 mIU/L; middle-normal TSH, 1.20-1.95 mIU/L; and high-normal TSH, 1.96-5.60 mIU/L) and all-cause mortality. Mediation analysis was used within the counterfactual framework to estimate natural direct associations (not through CVD) and indirect associations (through CVD).

RESULTS

Of 9020 participants, 4658 (51.6%) were men; the mean (SD) age was 49.4 (17.8) years. Throughout follow-up (median [interquartile range], 7.3 [5.4-8.3] years), serum thyroid function test results consistent with subclinical hypothyroidism and high-normal TSH concentrations were both associated with increased all-cause mortality (subclinical hypothyroidism: hazard ratio, 1.90; 95% CI, 1.14-3.19; high-normal TSH: hazard ratio, 1.36; 95% CI, 1.07-1.73) compared with the middle-normal TSH group. Cardiovascular disease mediated 14.3% and 5.9% of the associations of subclinical hypothyroidism and high-normal TSH with all-cause mortality, respectively, with the CVD mediation being most pronounced in women (7.5%-13.7% of the association) and participants aged 60 years and older (6.0%-14.8% of the association).

CONCLUSIONS AND RELEVANCE

In this study, CVD mediated the associations of subclinical hypothyroidism and high-normal TSH concentrations with all-cause mortality in the US general population. Further studies are needed to examine the clinical benefit of thyroid hormone replacement therapy targeted to a middle-normal TSH concentration or active CVD screening for people with elevated TSH concentrations.

Thyroid disease in end-stage renal disease

PURPOSE OF REVIEW

Hypothyroidism is a highly prevalent endocrine disorder in the end-stage renal disease (ESRD) population, yet many cases may remain latent and undiagnosed.

RECENT FINDINGS

Epidemiologic data show that there is a nearly five-fold higher prevalence of hypothyroidism in advanced chronic kidney disease (CKD) patients vs. those without CKD. Given that the metabolism, degradation, and excretion of thyroid hormone and its metabolites, as well as the regulation of the hypothalamic-pituitary-thyroid axis may be altered in ESRD, certain considerations should be made when interpreting thyroid functional tests in these patients. Growing evidence shows that hypothyroidism and other thyroid functional test derangements are associated with higher risk of cardiovascular disease, worse patient-centered outcomes, and survival in the advanced CKD population, including those with ESRD. Although limited data examining treatment of hypothyroidism suggests benefit, further studies of the efficacy and safety of thyroid hormone supplementation, including clinical trials and rigorous longitudinal observational studies are needed to inform the management of thyroid dysfunction in CKD.

SUMMARY

Given the high burden of hypothyroidism in ESRD patients, and potential ill effects on their cardiovascular health, patient-centered outcomes, and survival, further research is needed to inform the optimal management of thyroid dysfunction in this population.

Subclinical Hypothyroidism: A Review

IMPORTANCE

Subclinical hypothyroidism, defined as an elevated serum thyrotropin (often referred to as thyroid-stimulating hormone, or TSH) level with normal levels of free thyroxine (FT4) affects up to 10% of the adult population.

OBSERVATIONS

Subclinical hypothyroidism is most often caused by autoimmune (Hashimoto) thyroiditis. However, serum thyrotropin levels rise as people without thyroid disease age; serum thyrotropin concentrations may surpass the upper limit of the traditional reference range of 4 to 5 mU/L among elderly patients. This phenomenon has likely led to an overestimation of the true prevalence of subclinical hypothyroidism in persons older than 70 years. In patients who have circulating thyroid peroxidase antibodies, there is a greater risk of progression from subclinical to overt hypothyroidism. Subclinical hypothyroidism may be associated with an increased risk of heart failure, coronary artery disease events, and mortality from coronary heart disease. In addition, middle-aged patients with subclinical hypothyroidism may have cognitive impairment, nonspecific symptoms such as fatigue, and altered mood. In the absence of large randomized trials showing benefit from levothyroxine therapy, the rationale for treatment is based on the potential for decreasing the risk of adverse cardiovascular events and the possibility of preventing progression to overt hypothyroidism. However, levothyroxine therapy may be associated with iatrogenic thyrotoxicosis, especially in elderly patients, and there is no evidence that it is beneficial in persons aged 65 years or older.

CONCLUSIONS AND RELEVANCE

Subclinical hypothyroidism is common and most individuals can be observed without treatment. Treatment might be indicated for patients with subclinical hypothyroidism and serum thyrotropin levels of 10 mU/L or higher or for young and middle-aged individuals with subclinical hypothyroidism and symptoms consistent with mild hypothyroidism.

Hypothyroidism is associated with all-cause mortality in a national cohort of chronic haemodialysis patients

AIM

The prevalence of hypothyroidism is high in haemodialysis (HD) patients and hypothyroidism increases all-cause mortality in HD patients. Comorbidities are common in HD patients and are associated with both mortality and hypothyroidism. The aim of the study is to explore the effect of the interactions of comorbidities and hypothyroidism on all-cause mortality in HD patients.

METHOD

Patients with hypothyroidism (ICD-9-CM 244.0, 244.1, and 244.9) and matched patients without hypothyroidism in the Registry for Catastrophic Illness Patient Database of Taiwan Health Insurance from 2000 to 2010 were analyzed. The association of hypothyroidism and risk of all-cause mortality was analyzed using Cox proportional hazard regression.

RESULT

Nine hundred and eight HD patients with hypothyroidism and 3632 sex-, age-, gender- matched HD patients without hypothyroidism were analyzed. Hypothyroidism was associated with increased all-cause mortality with an adjusted hazard ratio of 1.22 [95% confidence interval (CI): 1.10-1.36, P < 0.001]. TRT may decrease mortality associated with hypothyroidism (P < 0.001). There was a significant interaction (P = 0.04) between diabetes and hypothyroidism. There was no significant interaction found in hypothyroidism and the following comorbidities: hyperlipidaemia, hypertension, chronic obstructive pulmonary disease, coronary artery disease, stroke, peripheral arterial disease, asthma, congestive heart failure and cancer.

CONCLUSION

Hypothyroidism is associated with increased all-cause mortality in chronic HD patients. The interaction of hypothyroidism and diabetes, but not other common comorbidities in HD patients, has an effect on mortality risks.

High-normal thyroid-stimulating hormone in euthyroid subjects is associated with risk of mortality and composite disease endpoint only in women

INTRODUCTION

The aim of the study was to evaluate whether serum thyroid-stimulating hormone (TSH) within the normal range in euthyroid subjects (having normal free triiodothyronine (fT3) and thyroxine (fT4)) is related to the risk of overall mortality or a composite endpoint of death and nonfatal events.

MATERIAL AND METHODS

In 614 middle-aged adult hospital screenees, free of uncontrolled diabetes at baseline, the association of sex-specific TSH tertiles with death was prospectively assessed using Cox regression, with the composite endpoint assessed using logistic regression in adjusted analyses, stratified by gender.

RESULTS

In total, 64 deaths and additional incident nonfatal events in 141 cases were recorded at a mean 7.55 years' follow-up. Multivariable linear regression revealed TSH to be significantly associated among men with age (p = 0.006), but in women inversely with fT3 and fT4 (p < 0.001, and p = 0.024 respectively). In logistic regression analysis, adjusted for age, fT3, fT4, systolic blood pressure and serum total cholesterol, sex-specific baseline TSH tertiles were associated in men neither with the risk of death nor with composite endpoint. In contrast, in women, the highest compared with the bottom TSH tertile predicted the risk of composite endpoint (relative risk: 2.02, 95% CI: 1.07-3.82) and, much more strongly, the mortality risk, independently of fT4 increments.

CONCLUSIONS

The significant association of higher range of normal serum TSH in euthyroid middle-aged adults with the risk of death and nonfatal adverse outcomes in women alone cannot be accounted for by the action of thyroid hormone and is consistent with involvement of TSH in the pro-inflammatory state.

Impact of Hypothyroidism and Heart Failure on Hospitalization Risk

BACKGROUND

Prior studies suggest that the relationship between hypothyroidism and mortality is dependent on underlying cardiovascular risk. Little is known about the association of hypothyroidism with hospitalization risk, and how these associations are modified by cardiovascular status.

METHODS

This study examined the association of thyroid status, defined by serum thyrotropin (TSH), with hospitalization risk among patients who received care at a large university-based tertiary care center between 1990 and 2015. Thyroid status was categorized as hypothyroidism versus euthyroidism (TSH >4.7 vs. 0.3-4.7 mIU/L, respectively). The relationship between thyroid status and hospitalization risk stratified by cardiovascular status was examined using multivariable Cox models.

RESULTS

Among 52,856 patients who met eligibility criteria, 49,791 (94.2%) had euthyroidism and 3065 (5.8%) had hypothyroidism. In analyses stratified by congestive heart failure (CHF) status, compared to euthyroidism, hypothyroidism was associated with higher risk of hospitalization in those with CHF but slightly lower risk in those without CHF (adjusted hazard ratio [aHRs] = 1.86 [confidence interval (CI) 1.17-2.94] and HR = 0.95 [CI 0.92-0.99], respectively; p = 0.006). In sensitivity analyses accounting for death as a competing event, underlying coronary artery disease modified the hypothyroidism-hospitalization relationship, such that stronger associations were observed among those with versus without coronary artery disease. In competing risk analyses, hypothyroidism was associated with higher versus lower risk of hospitalization among those with versus without cerebrovascular disease, respectively.

CONCLUSIONS

Hypothyroidism is associated with higher hospitalization risk among patients with underlying cardiovascular disease. Future studies are needed to determine whether correction of thyroid status with replacement therapy ameliorates hospitalization risk in this population.

Thyroid Status and Death Risk in US Veterans With Chronic Kidney Disease

OBJECTIVE

Given that patients with non-dialysis-dependent chronic kidney disease (NDD-CKD) have a disproportionately higher prevalence of hypothyroidism compared with their non-CKD counterparts, we sought to determine the association between thyroid status, defined by serum thyrotropin (TSH) levels, and mortality among a national cohort of patients with NDD-CKD.

PATIENTS AND METHODS

Among 227,422 US veterans with stage 3 NDD-CKD with 1 or more TSH measurements during the period October 1, 2004, to September 30, 2012, we first examined the association of thyroid status, defined by TSH categories of less than 0.5, 0.5 to 5.0 (euthyroidism), and more than 5.0 mIU/L, with all-cause mortality. We then evaluated 6 granular TSH categories: less than 0.1, 0.1 to less than 0.5, 0.5 to less than 3.0, 3.0 to 5.0, more than 5.0 to 10.0, and more than 10.0 mIU/L. We concurrently examined thyroid status, thyroid-modulating therapy, and mortality in sensitivity analyses.

RESULTS

In expanded case-mix adjusted Cox analyses, compared with euthyroidism, baseline and time-dependent TSH levels of more than 5.0 mIU/L were associated with higher mortality (adjusted hazard ratios [aHRs] [95% CI], 1.19 [1.15-1.24] and 1.23 [1.19-1.28], respectively), as were baseline and time-dependent TSH levels of less than 0.5 mIU/L (aHRs [95% CI], 1.18 [1.15-1.22] and 1.41 [1.37-1.45], respectively). Granular examination of thyroid status showed that incrementally higher TSH levels of 3.0 mIU/L or more were associated with increasingly higher mortality in baseline and time-dependent analyses, and TSH categories of less than 0.5 mIU/L were associated with higher mortality (reference, 0.5-<3.0 mIU/L) in baseline analyses. In time-dependent analyses, untreated and undertreated hypothyroidism and untreated hyperthyroidism were associated with higher mortality (reference, spontaneous euthyroidism), whereas hypothyroidism treated-to-target showed lower mortality.

CONCLUSION

Among US veterans with NDD-CKD, high-normal TSH (≥3.0 mIU/L) and lower TSH (<0.5 mIU/L) levels were associated with higher death risk. Interventional studies identifying the target TSH range associated with the greatest survival in patients with NDD-CKD are warranted.

Hypothyroidism is a Risk Factor for Atrial Fibrillation after Coronary Artery Bypass Graft

INTRODUCTION

Few reports in the world have shown a differential effect of hypothyroidism in relation to morbidity and mortality following cardiac surgery.

OBJECTIVE

To determine the association between preoperative hypothyroidism, composite and disaggregated outcomes of mortality and complications in patients undergoing first-time isolated myocardial revascularization surgery.

METHODS

Historical cohort of patients undergoing myocardial revascularization between January 2008 and December 2014, with 626 patients included for evaluation of the composite and disaggregated outcomes of in-hospital mortality and complications (atrial fibrillation, surgical site infection and reoperation due to bleeding). A logistic regression model was used to determine the association between hypothyroidism and the onset of those outcomes.

RESULTS

Cohort of 1696 eligible patients for the study, with 1.8 mortality. Median age, female gender and prevalence of arterial hypertension were all significantly higher among hypothyroid patients. No differences were found in other preoperative or intraoperative characteristics. Hypothyroidism was associated with the presence of the composite outcome, RR 1.6 (1.04-2.4) and atrial fibrillation 1.9 (1.05-3.8). No association with mortality, infections or reoperation due to bleeding was found.

CONCLUSION

Hypothyroidism is a disease that affects females predominantly and does not determine the presence of other comorbidities. Hypothyroidism is a risk factor for the onset of postoperative fibrillation in patients undergoing myocardial revascularization surgery. Postoperative care protocols focused on the prevention of these complications in this type of patients must be instituted.

Association between Testosterone and Mortality Risk among U.S. Males Receiving Dialysis

BACKGROUND

Among the general population, low circulating testosterone levels are associated with higher risk of cardiovascular disease and death. While testosterone deficiency is common in dialysis patients, studies of testosterone and mortality in this population are ambiguous and overlapping. We hypothesized that lower testosterone levels are associated with higher mortality in male dialysis patients.

METHODS

We examined a nationally representative cohort of male dialysis patients from a large US dialysis organization who underwent one or more total testosterone measurements from 1/2007 to 12/2011. The association between total testosterone categorized as quartiles and all-cause mortality was studied using Cox models adjusted for expanded case-mix and laboratory covariates. We also examined total testosterone as a continuous predictor of all-cause mortality using restricted cubic splines.

RESULTS

Among 624 male dialysis patients, 51% of patients demonstrated testosterone deficiency (total testosterone <300 ng/dL); median (IQR) total testosterone levels were 297 (190-424) ng/mL. In expanded case-mix + laboratory adjusted Cox analyses, we observed a graded association between lower testosterone levels and higher mortality risk (ref: quartile 3): adjusted hazard ratios (95% CI) 2.32 (1.33-4.06), 1.80 (0.99-3.28), and 0.68 (0.32-1.42) for Quartiles 1, 2, and 4, respectively. In adjusted spline analyses, the lower testosterone-higher mortality risk association declined with higher testosterone levels until the value reached a threshold of 400 ng/dL above which risk plateaued.

CONCLUSION

Lower testosterone levels were independently associated with higher mortality risk in male dialysis patients. Further studies are needed to determine underlying mechanisms, and whether testosterone replacement ameliorates death risk in this population.

Thyroid Status, Quality of Life, and Mental Health in Patients on Hemodialysis

BACKGROUND AND OBJECTIVES

In the general population, there is increasing recognition of the effect of thyroid function on patient-centered outcomes, including health-related quality of life and depression. Although hypothyroidism is highly prevalent in hemodialysis patients, it is unknown whether thyroid status is a risk factor for impaired health-related quality of life or mental health in this population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We examined the association of thyroid status, defined by serum thyrotropin, with health-related quality of life and depressive symptoms over time in a prospective cohort of 450 patients on hemodialysis from 17 outpatient dialysis facilities from May of 2013 to May of 2015 who underwent protocolized thyrotropin testing, Short-Form 36 surveys, and Beck Depression Inventory-II questionnaires every 6 months. We examined the association of baseline and time-dependent thyrotropin categorized as tertiles and continuous variables with eight Short-Form 36 domains and Beck Depression Inventory-II scores using expanded case mix plus laboratory adjusted linear mixed effects models.

RESULTS

In categorical analyses, the highest baseline thyrotropin tertile was associated with a five-point lower Short-Form 36 domain score for energy/fatigue (P=0.04); the highest time-dependent tertile was associated with a five-point lower physical function score (P=0.03; reference: lowest tertile). In continuous analyses, higher baseline serum thyrotropin levels (+Δ1 mIU/L) were associated with lower role limitations due to physical health (β=-1.3; P=0.04), energy/fatigue (β=-0.8; P=0.03), and pain scores (β=-1.4; P=0.002), equivalent to five-, three-, and five-point lower scores, respectively, for every 1-SD higher thyrotropin. Higher time-dependent thyrotropin levels were associated with lower role limitations due to physical health scores (β=-1.0; P=0.03), equivalent to a three-point decline for every 1-SD higher thyrotropin. Baseline and time-dependent thyrotropin were not associated with Beck Depression Inventory-II scores.

CONCLUSIONS

In patients on hemodialysis, higher serum thyrotropin levels are associated with impaired health-related quality of life across energy/fatigue, physical function, and pain domains. Studies are needed to determine if thyroid-modulating therapy improves the health-related quality of life of hemodialysis patients with thyroid dysfunction.

Thyroid Status and Mortality in a Prospective Hemodialysis Cohort

CONTEXT AND OBJECTIVE

Compared with the general population, hemodialysis patients have a substantially higher risk of hypothyroidism, as defined by an elevated serum thyrotropin (TSH) level, and cardiovascular mortality. Whereas an elevated TSH is associated with cardiovascular disease and death in the general population, associations among dialysis patients have been inconsistent.

DESIGN, SETTING, PARTICIPANTS, AND MAIN OUTCOME

We examined 541 hemodialysis patients from 17 southern California dialysis centers in the prospective Hypothyroidism, Cardiovascular Health, and Survival study who underwent protocolized measurement of repeated serum TSH levels every 6 months from 2013 to 2015. Associations between TSH tertiles (<1.28, 1.28 to <2.14, and 2.14 to 86.7 mIU/L) and mortality were estimated using time-dependent Cox models with four adjustment levels. In sensitivity analyses, we excluded patients receiving thyroid hormone supplementation.

RESULTS

Compared with the lowest TSH tertile, the highest TSH tertile was associated with a 2.2- to 2.5-fold higher mortality risk in unadjusted, case-mix, expanded case-mix+laboratory, and expanded case-mix+laboratory+medication models [hazard ratios (95% confidence interval), 2.54 (1.32 to 4.89), 2.53 (1.30 to 4.93), 2.19 (1.11 to 4.32), and 2.28 (1.45 to 3.58), respectively]. We observed a consistent trend between higher TSH tertiles and numerically higher mortality risk across all models. Similar findings were observed in analyses excluding patients receiving thyroid hormone supplementation.

CONCLUSION

In time-dependent analyses, TSH levels in the high-normal to high range were independently associated with higher death risk in hemodialysis patients. Further studies are indicated to determine whether normalization of TSH levels with thyroid hormone supplementation improves survival in this population.

Thyroid function in end stage renal disease and effects of frequent hemodialysis

INTRODUCTION

End-stage renal disease (ESRD) is associated with perturbations in thyroid hormone concentrations and an increased prevalence of hypothyroidism. Few studies have examined the effects of hemodialysis dose or frequency on endogenous thyroid function.

METHODS

Within the Frequent Hemodialysis Network (FHN) trials, we examined the prevalence of hypothyroidism in patients with ESRD. Among those with endogenous thyroid function (without overt hyper/hypothyroidism or thyroid hormone supplementation), we examined the association of thyroid hormone concentration with multiple parameters of self-reported health status, and physical and cognitive performance, and the effects of hemodialysis frequency on serum thyroid stimulating hormone (TSH), free thyroxine (FT4), and free tri-iodothyronine (FT3) levels. Conventional thrice-weekly hemodialysis was compared to in-center (6 d/wk) hemodialysis (Daily Trial) and Nocturnal (6 nights/wk) home hemodialysis (Nocturnal Trial) over 12 months.

FINDINGS

Among 226 FHN Trial participants, the prevalence of hypothyroidism was 11% based on thyroid hormone treatment and/or serum TSH ≥8 mIU/mL. Among the remaining 195 participants (147 Daily, 48 Nocturnal) with endogenous thyroid function, TSH concentrations were modestly (directly) correlated with age (r = 0.16, P = 0.03) but not dialysis vintage. Circulating thyroid hormone levels were not associated with parameters of health status or physical and cognitive performance. Furthermore, frequent in-center and nocturnal hemodialysis did not significantly change (baseline to month 12) TSH, FT4, or FT3 concentrations in patients with endogenous thyroid function.

DISCUSSION

Among patients receiving hemodialysis without overt hyper/hypothyroidism or thyroid hormone treatment, thyroid indices were not associated with multiple measures of health status and were not significantly altered with increased dialysis frequency.

Thyroid dysfunction and kidney disease: An update

Thyroid hormones influence renal development, kidney hemodynamics, glomerular filtration rate and sodium and water homeostasis. Hypothyroidism and hyperthyroidism affect renal function by direct renal effects as well as systemic hemodynamic, metabolic and cardiovascular effects. Hypothyroidism has been associated with increased serum creatinine and decreased glomerular filtration rate. The reverse effects have been reported in thyrotoxicosis. Most of renal manifestations of thyroid dysfunction are reversible with treatment. Kidney disease may also cause thyroid dysfunction by several mechanisms. Nephrotic syndrome has been associated to changes in serum thyroid hormone concentrations. Different forms of glomerulonephritis and tubulointerstitial disease may be linked to thyroid derangements. A high prevalence of thyroid hormone alteration has been reported in acute kidney injury. Thyroid dysfunction is highly prevalent in chronic kidney disease patients. Subclinical hypothyroidism and low triiodothyronine syndrome are common features in patients with chronic kidney disease. Patients treated by both hemodialysis and peritoneal dialysis, and renal transplantation recipients, exhibit thyroid hormone alterations and thyroid disease with higher frequency than that found in the general population. Drugs used in the therapy of thyroid disease may lead to renal complications and, similarly, drugs used in kidney disorders may be associated to thyroid alterations. Lastly, low thyroid hormones, especially low triiodothyronine levels, in patients with chronic kidney disease have been related to a higher risk of cardiovascular disease and all-cause mortality. Interpretation of the interactions between thyroid and renal function is a challenge for clinicians involved in the treatment of patients with thyroid and kidney disease.

Plasma Gelsolin and Its Association with Mortality and Hospitalization in Chronic Hemodialysis Patients

Background: Human plasma gelsolin (pGSN) is an actin-binding protein that is secreted into the extracellular fluid, with the skeletal muscle and myocardial tissues being its major source. Depletion of pGSN has been shown to be related to a variety of inflammatory and clinical conditions. Methods: pGSN levels were prospectively determined in prevalent maintenance hemodialysis (HD) patients from 3 U.S. dialysis centers. Demographics (age, time since dialysis initiation, race, gender, body height and weight, comorbidities), inflammatory markers (C reactive protein, CRP; interleukin 6, IL-6), free triiodothyronine (fT3), and routine laboratory parameters were obtained. We performed Kaplan-Meier and Cox proportional hazard survival analysis for all-cause and cardiovascular mortality, and recurrent event survival analysis for hospitalization. Results: We studied 153 patients; mean age was 60.5 ± 14.7; 52% were males. The mean pGSN level was 6,617 ± 1,789 mU/ml. In univariate analysis, pGSN was positively correlated with body mass index (r = 0.2, p = 0.01), pre-HD serum albumin (r = 0.247, p = 0.002), and pre-HD serum creatinine (r = 0.381, p < 0.001), and inversely with age (r = -0.286, p < 0.001), CRP (r = -0.311, p < 0.001), and IL-6 (r = -0.317, p < 0.001). In the adjusted analysis, the associations with CRP and creatinine were retained. pGSN levels tended to be lower in patients who died (p = 0.08). There was no association with all-cause or cardiovascular mortality, or all-cause hospitalization. Of note, fT3 was lower in patients who died (p = 0.001). Conclusions: Even though pGSN was inversely correlated with age, CRP and IL-6, suggesting that inflammation may influence pGSN, lower pGSN levels were not associated with hospitalization, all-cause and cardio-vascular mortality in this patient population.

Association of TSH Elevation with All-Cause Mortality in Elderly Patients with Chronic Kidney Disease

Chronic kidney disease (CKD) is a widespread condition in the global population and is more common in the elderly. Thyroid-stimulating hormone (TSH) level increases with aging, and hypothyroidism is highly prevalent in CKD patients. However, the relationship between low thyroid function and mortality in CKD patients is unclear. Therefore, we conducted a retrospective cohort study to examine the relationship between TSH elevation and all-cause mortality in elderly patients with CKD. This retrospective cohort study included individuals ≥65 years old with CKD (n = 23,786) in Taipei City. Health examination data from 2005 to 2010 were provided by the Taipei Databank for Public Health Analysis. Subjects were categorized according to thyroid-stimulating hormone (TSH) level as follows: low normal (0.34<TSH<1.074 mIU/L), middle normal (1.074≤TSH≤2.46 mIU/L), high normal (2.46<TSH<5.2 mIU/L), elevated I (5.2≤TSH<10 mIU/L), and elevated II (TSH≥10 mIU/L). Risk of mortality was evaluated using a Cox proportional hazard regression model adjusted for sex, age, hypertension, diabetes mellitus, CKD stage, serum albumin, high-density lipoprotein cholesterol, uric acid, hemoglobin, body mass index, glutamic-pyruvic transaminase, smoking, alcohol consumption, and history of cardiovascular disease (coronary artery disease, congestive heart failure, cerebral vascular disease), history of cancer, and history of chronic obstructive pulmonary disease. Our results showed that compared to the reference group (middle normal TSH), the risk of all-cause mortality was increased in the elevated I group (hazard ratio [HR], 1.21; 95% confidence interval [CI], 1.02–1.45) and elevated II group (HR, 1.30; 95% CI, 1.00–1.69). We found a significant association between TSH elevation and all-cause mortality in this cohort of elderly persons with CKD. However, determining the benefit of treatment for moderately elevated TSH level (5.2–10 mIU/L) in elderly patients with CKD will require a well-designed randomized controlled trial.

Thyroid Functional Disease and Mortality in a National Peritoneal Dialysis Cohort

CONTEXT AND OBJECTIVE

End-stage renal disease patients have a higher risk of thyroid disease compared with those without kidney disease. Although thyroid dysfunction is associated with higher death risk in the general population and those undergoing hemodialysis, little is known about the effect of thyroid disease upon mortality in patients treated with peritoneal dialysis (PD).

DESIGN, SETTING, PARTICIPANTS, AND MAIN OUTCOME

We examined the association of thyroid status, assessed by serum TSH, with all-cause mortality among PD patients from a large national dialysis organization who underwent one or more TSH measurements over 5 years (January 2007 to December 2011). Thyroid status was categorized as overt-hyperthyroid, subclinical-hyperthyroid, low-normal, high-normal, subclinical-hypothyroid, and overt-hypothyroid range (TSH < 0.1, 0.1–<0.5, 0.5–<3.0, 3.0–<5.0, 5.0–<10.0, and ≥10.0 mIU/L, respectively). We examined the association between TSH and mortality using case mix–adjusted time-dependent Cox models to assess short-term thyroid function–mortality associations and to account for changes in thyroid function over time.

RESULTS

Among 1484 patients, 7 and 18% had hyperthyroidism and hypothyroidism, respectively, at baseline. We found that both lower and higher time-dependent TSH levels were associated with higher mortality (reference: TSH, 0.5-<3.0 mIU/L): adjusted hazard ratios (95% confidence intervals) 2.09 (1.08-4.06), 1.53 (0.87-2.70), 1.05 (0.75-1.46), 1.63 (1.11-2.40), and 3.11 (2.08-4.63) for TSH levels, <0.1, 0.1-<0.5, 0.5-<3.0, 3.0-<5.0, 5.0-<10.0, and ≥10.0 mIU/L, respectively.

CONCLUSION

Time-dependent TSH levels < 0.1 mIU/L and ≥ 5.0 mIU/L were associated with higher mortality, suggesting hyper- and hypothyroidism carry short-term risk in PD patients. Additional studies are needed to determine mechanisms underlying the thyroid dysfunction-mortality association, and whether normalization of TSH with treatment ameliorates mortality in this population.

The interaction between thyroid and kidney disease: an overview of the evidence

PURPOSE OF REVIEW

Hypothyroidism is highly prevalent in chronic kidney disease (CKD) patients, including those receiving dialysis. This review examines potential mechanistic links between thyroid and kidney disease; current evidence for hypothyroidism as a risk factor for de novo CKD and CKD progression; and studies of thyroid functional disorders, cardiovascular disease, and death in the CKD population.

RECENT FINDINGS

Epidemiologic data have demonstrated an incrementally higher prevalence of hypothyroidism with increasing severity of kidney dysfunction. Various thyroid functional test abnormalities are also commonly observed in CKD due to alterations in thyroid hormone synthesis, metabolism, and regulation. Although the mechanistic link between thyroid and kidney disease remains unclear, observational studies suggest that hypothyroidism is associated with abnormal kidney structure and function. Previously thought to be a physiologic adaptation, recent studies show that hypothyroidism is associated with higher risk of cardiovascular disease and death in CKD.

SUMMARY

A growing body of evidence suggests that hypothyroidism is a risk factor for incident CKD, CKD progression, and higher death risk in kidney disease patients. Rigorous studies are needed to determine the impact of thyroid hormone replacement upon kidney disease progression, cardiovascular disease, and mortality, which may shed light onto the causal implications of hypothyroidism in CKD.

Thyroid Function Test Derangements and Mortality in Dialysis Patients: A Systematic Review and Meta-analysis

BACKGROUND

We evaluated current evidence associating thyroid function test result derangements with risk for mortality in patients with chronic kidney failure treated by long-term dialysis.

STUDY DESIGN

Systematic review and meta-analysis of cohort studies.

SETTING & POPULATION

Dialysis patients.

SELECTION CRITERIA FOR STUDIES

We searched PubMed, Web of Science, Science Citation Index, Cochrane Library, and Embase databases from inception through December 2015.

PREDICTORS

Hypothyroidism (thyrotropin level greater than reference range) and low triiodothyronine (T₃) and thyroxine (T₄) levels.

OUTCOMES

All-cause and cardiovascular mortality.

RESULTS

12 studies involving 14,766 participants (4,450 deaths) were identified. Of those, 6 studies provided data for cardiovascular mortality (2,772 participants with 327 cardiovascular deaths). Overall, confidence in the available evidence was moderate. Pooled adjusted HRs for all-cause mortality associated with hypothyroidism, low T₃ level, and low T₄ level were 1.24 (95% CI, 1.14-1.34), 1.67 (95% CI, 1.23-2.27), and 2.40 (95% CI, 1.47-3.93), respectively. Pooled adjusted HRs for cardiovascular mortality associated with low T₃ and T₄ levels were 1.84 (95% CI, 1.24-2.74) and 3.06 (95% CI, 1.29-7.24), respectively.

LIMITATIONS

Fewer studies reporting on T₄ and thyrotropin outcomes.

CONCLUSIONS

In patients treated with long-term dialysis, (cardiovascular) mortality is consistently higher in the presence of thyroid function test result derangements.

Chronic Kidney Disease Distinctly Affects Relationship Between Selenoprotein P Status and Serum Thyroid Hormone Parameters

INTRODUCTION

Chronic kidney disease (CKD) impairs thyroid hormone (TH) metabolism and is associated with low serum triiodothyronine (T3) concentrations in patients with a low glomerular filtration rate (GFR). Whether this results from decreased T3 formation from thyroxine (T4) by impaired 5'-deiodinase (DIO) activity and/or enhanced degradation of T3 and increased reverse triiodothyronine (rT3) formation from T4 by elevated 5-DIO activity remains unclear. Both activating 5'- and the inactivating 5-deiodination of TH are catalyzed by three selenium (Se)-dependent DIO isoenzymes. Selenoprotein P (SePP) is the major constituent of serum selenium, and functions as Se transport protein from liver to kidney and several other organs. This study tested the hypothesis that serum SePP and TH status are associated with the degree of renal impairment in patients with CKD.

PATIENTS AND METHODS

A total of 180 CKD patients (stages 1-5) and 70 chronic hemodialysis (CHD) patients undergoing hemodialysis three times per week for at least two years were prospectively investigated for clinical data, parameters of renal function, serum TH profile (thyrotropin, T4, free thyroxine [fT4], T3, free triiodothyronine (fT3), rT3, thyroxine-binding globulin [TBG]), C-reactive protein (CRP), and serum SePP.

RESULTS

In CKD patients, renal function was negatively associated with SePP concentration (standardized β = -0.17, p = 0.029); that is, SePP concentrations increased in more advanced CKD stages. In contrast, significantly lower SePP concentrations were found in patients on hemodialysis compared with CKD patients (M ± SD = 2.7 ± 0.8 mg/L vs. 3.3 ± .9 mg/L; p < 0.001). Notably, in CKD patients, the SePP concentration was negatively associated with T4 (standardized β = -0.16, p = 0.039) and fT4 (standardized β = -0.16, p = 0.039) concentrations, but no association was found with T3, fT3, rT3, T3/T4, rT3/T3, rT3/T4, or TBG concentrations. The SePP concentration was also negatively associated with CRP levels (standardized β = -0.17, p = 0.029). In the CHD group, no association was detected between SePP and the investigated TH parameters.

SUMMARY AND CONCLUSION

Impaired renal function is positively correlated with serum concentrations of SePP. In patients undergoing CHD treatment, SePP concentrations were significantly reduced, but the TH profile remained unaffected. These findings indicate an important contribution of kidney function on serum SePP homeostasis, and consequently on Se status.