Unresolved subclinical hypothyroidism is independently associated with progression of chronic kidney disease

The relationship between thyroid dysfunction, cardiovascular morbidity and mortality in type 2 diabetes: The Fremantle Diabetes Study Phase II

AIMS

It is uncertain whether subclinical thyroid dysfunction is associated with cardiovascular disease (CVD) events and mortality in people with type 2 diabetes. The aim of this study was to determine whether undetected thyroid disease increases the risk of incident CVD and death in type 2 diabetes.

METHODS

One thousand two hundred fifty participants with type 2 diabetes (mean age 65.3 years, 56.5% males, median diabetes duration 8.0 years) without known thyroid disease and not taking medications known to affect thyroid function were categorised, based on baseline serum free thyroxine (FT4) and thyrotropin (TSH) concentrations, as euthyroid, overt hypothyroid (increased TSH, low FT4), subclinical hypothyroid (increased TSH, normal FT4), overt thyrotoxic (decreased TSH, raised FT4) or subclinical thyrotoxic (decreased TSH, normal FT4). Incident myocardial infarction, incident stroke, all-cause and cardiovascular mortality were ascertained during a mean 6.2-6.7 years of follow-up.

RESULTS

Most participants with newly-detected thyroid dysfunction had subclinical hypothyroidism (77.2%) while overt/subclinical thyrotoxicosis was infrequent. Compared to participants with TSH 0.34-2.9 mU/L, those with TSH > 5.1 mU/L were not at increased risk of incident myocardial infarction (adjusted hazard ratio (95% confidence limits) 1.77 (0.71, 2.87)), incident stroke (1.66 (0.58, 4.78)), all-cause mortality (0.78 (0.44, 1.37)) or cardiovascular mortality (1.16 (0.38, 3.58)). Independent baseline associates of subclinical hypothyroidism included estimated glomerular filtration rate and systolic blood pressure.

CONCLUSIONS

Subclinical hypothyroidism was not independently associated with CVD events or mortality in community-dwelling people with type 2 diabetes despite its associations with CVD risk factors, questioning strategies to identify and/or treat mild thyroid dysfunction outside usual care.

Association between the use of allopurinol and risk of increased thyroid-stimulating hormone level

Allopurinol is the first-line agent for patients with gout, including those with moderate-to-severe chronic kidney disease. However, increased thyroid-stimulating hormone (TSH) levels are observed in patients with long-term allopurinol treatment. This large-scale, nested case-control, retrospective observational study analysed the association between allopurinol use and increased TSH levels. A common data model based on an electronic medical record database of 19,200,973 patients from seven hospitals between January 1997 and September 2020 was used. Individuals aged > 19 years in South Korea with at least one record of a blood TSH test were included. Data of 59,307 cases with TSH levels > 4.5 mIU/L and 236,508 controls matched for sex, age (± 5), and cohort registration date (± 30 days) were analysed. An association between the risk of increased TSH and allopurinol use in participants from five hospitals was observed. A meta-analysis (I² = 0) showed that the OR was 1.51 (95% confidence interval: 1.32-1.72) in both the fixed and random effects models. The allopurinol intake group demonstrated that increased TSH did not significantly affect free thyroxine and thyroxine levels. After the index date, some diseases were likely to occur in patients with subclinical hypothyroidism and hypothyroidism. Allopurinol administration may induce subclinical hypothyroidism.

Prevalence of hypothyroidism in Japanese chronic kidney disease patients

Background

Major symptoms of progressive chronic kidney disease (CKD) are similar to those of hypothyroidism. Hidden symptoms of hypothyroidism underlying CKD are often observed in clinical practice. This study aimed to ascertain the frequency of hypothyroidism complicated by CKD, and to analyze factors impacting thyroid function.

Methods

During the period from April 2012 through October 2016, 510 CKD patients at our outpatient clinic were measured thyroid and kidney function for diagnosing hypothyroidism (overt hypothyroidism, OH; subclinical hypothyroidism, SH; non-thyroidal illness, NTI) and evaluating the stage of CKD. All patients were over 15 years of age.

Results

There were significant differences in age, estimated glomerular filtration rate (eGFR), urinary protein (UP), and serum albumin (Alb) among patients with OH, SH, and NTI compared to the normal group in univariate and multivariate analyses. UP showed the highest odds ratio of OH, SH, and NTI but no differences were recognized in gender in each group. Frequency distribution showed that the prevalence of thyroid dysfunction was greater among more severe stage of CKD with higher amount of UP. OH and SH did not show high positive ratio of anti-thyroglobulin antibody (TgAb) and anti-thyroid peroxidase antibody (TPOAb). NTI and normal subjects showed higher positive ratio as 50.0% and 42.9% of TgAb and TPOAb than OH and SH.

Conclusions

Hypothyroidism complicated by CKD exhibited a high prevalence. Age, eGFR, UP, and serum Alb were related to the prevalence of hypothyroidism, whereas gender was not and this was contradicted to the prevalence of hypothyroidism in general population. The prevalence of OH and SH was higher among patients with higher stage of CKD with increased UP. Hypothyroidism complicated by CKD may involve different onset mechanisms unrelated to antithyroid antibodies (ATAb). In CKD patients, assessments of OH and SH, as well as NTI, are needed for proper diagnosis.

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.

Influence of low free thyroxine on progression of chronic kidney disease

BACKGROUND

Hypothyroidism is highly prevalent in patients with chronic kidney disease (CKD) and has been associated with poorer clinical outcomes, including faster decline of kidney function. However, there is no consensus whether low free thyroxin (LFT) affects the rate of estimated glomerular filtration rate (eGFR) decline and how the presence of proteinuria influences the progression of renal dysfunction in hypothyroidism.

METHODS

We assessed thyroid status, proteinuria, and progression of eGFR by Modification of Diet in Renal Disease equation and CKD-EPI equation in a cohort of CKD patients followed in general nephrology clinics. We estimated the association of LFT levels, and the degree of proteinuria on progression of eGFR. We adjusted for other covariables: age, gender, body mass index, diabetes, hypertension, HbA1c, uric acid, cholesterol, and triglycerides levels..

RESULTS

One thousand six hundred ten patients (64 ± 15 years, 46.8% men, 25.3% diabetic) were included. At beggnining of follow up eGFR was between 45 and 60, 30-45 and 15-30 ml/min/1.73m2 in 479 (29.8%), 551(34.2%), and 580(36.0%) patients, respectively. LFT levels were available at initial evaluation in 288(17.9%) patients and 735(48.5%) had assessment of proteinuria (19.6% with LFT vs. 15.4% without LFT, p = 0.032). Median follow-up time was of 21 months, and 1223(76%) had at least 1 year of follow up. Overall, eGFR decline per month was - 0.05(- 0.26, 0.23) ml/min/1.73m2, reaching 1.7(1.3, 2.4) ml/min/1.73m2 by the end of study period. Similar results were obtained using CKD-EPI. Multivariable mixed linear analysis showed that proteinuria and age were independently associated with eGFR decline, with no effect of LFT, and no interaction between proteinuria and LFT. In patients without proteinuria, there was an improvement of eGFR despite the presence of LFT.

CONCLUSIONS

We confirmed a faster rate of eGFR declined in patients with proteinuria. However, despite the pathophysiological rational that hypothyroidism can lead to increased rate of CKD progression, we failed to demonstrate an association between LFT and rate of CKD progression. We conclude that the benefit of hypothyroidism treatment in CKD patients needs to be evaluate in prospective studies.

Relationship between Thyroid Function and Kidney Function in Patients with Type 2 Diabetes

PURPOSE

To determine if the TSH is related to estimated glomerular filtration rate (eGFR) in T2D patients without overt thyroid dysfunction.

METHODS

A cohort study of 5936 T2D patients was assessed for thyroid and kidney functions, in whom 248 with subclinical hyperthyroidism and 362 with subclinical hypothyroidism. Serum creatinine and 24-hour urine albumin excretion (UAE) were collected. Chronic kidney disease (CKD) was defined as eGFR < 60 ml/min/1.73 m².

RESULTS

Compared with euthyroid subjects, the patients with subclinical hypothyroidism had lower eGFR (82.7 ± 22.4 vs. 90.5 ± 22.4 ml/min/1.73 m², p < 0.01), higher UAE (114 ± 278 vs. 88 ± 229 mg/24 h, p < 0.05), and high incidence of CKD (16.0% vs. 10.1%, p < 0.05). The participants with a TSH level between 0.55 and 3.0 μIU/ml had a higher eGFR (91.4 ± 22.2 ml/min/1.73 m²) and a lower prevalence of CKD (9.5%) than those with higher TSH (3.01-4.78 μIU/ml, 85.6 ± 22.7 ml/min/1.73 m², p < 0.01 and 13.1%, p < 0.01). Linear logistic regression analysis showed that the eGFR was significantly negatively associated with TSH (OR: 0.519, 95% CI: 0.291-0.927, p < 0.05), after adjustment of confounders.

CONCLUSION

High TSH was independently associated with decreased eGFR in type 2 diabetes patients without overt thyroid dysfunction. Our findings indicate that doctors who treat T2D patients should routinely measure the thyroid function.

Thyrotropin levels are associated with chronic kidney disease among healthy subjects in cross-sectional analysis of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

BACKGROUND

Few studies have evaluated a possible relationship between thyrotropin levels and glomerular filtration rate (GFR) and albumin/creatinine ratio in euthyroid subjects. We aimed to analyze this association using baseline data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

METHODS

Cross-sectionally, we included subjects with normal thyroid function and with subclinical hypothyroidism (SCH). We excluded individuals using medications that affect thyroid function. Linear and logistic regression models evaluated GFR estimated by Chronic Kidney Disease Epidemiology Collaboration (CKD-Epi) and albuminuria/creatinine ratio as dependent variables and thyrotropin quartiles in individuals with euthyroidism and SCH as independent variables, adjusted for demographical characteristics and diseases related to CKD.

RESULTS

We included 13,193 subjects with a median age of 51 years [interquartile range, (IQR): 45-58], 6840 (51.8%) women, 12,416 (94.1%) euthyroid, and 777 (5.9%) with SCH. SCH subjects were characterized by higher age, triglycerides, frequency of white race, cardiovascular disease, CKD, and former smokers. In adjusted models, log-transformed TSH in euthyroid subjects was inversely and strongly associated with CKD (β = -2.181, 95% CI -2.714 to -1.648), P < 0.0001 for glomerular filtration rate and 4.528 (1.190-7.865) for albuminuria/creatinine ratio. Multivariate logistic models for euthyroid subjects showed an OR of 1.45 (95% CI 1.15-1.83) for GFR and of 1.95 (95% CI 1.08-3.54) for albuminuria/creatinine ratio in the fourth quartile of TSH using the first as the reference.

CONCLUSIONS

Thyrotropin levels are independently associated with CKD in euthyroid subjects.