Relation of Thyroid Disfunction, Thyroid Autoantibodies, and Renal Function

Correlation of serum thyrotropin and thyroid hormone levels with diabetic kidney disease: a cross-sectional study

OBJECTIVE

The relationship between thyrotropin (TSH), free triiodothyronine (FT3), free thyroxine (FT4) and diabetic kidney disease (DKD) is still controversial, and this study analyzed the correlation between TSH, FT3, FT4 and DKD in patients with type 2 diabetes mellitus (T2DM).

METHODS

T2DM patients (1216) were divided into five groups based on serum TSH, FT3, and FT4 levels, differences in urinary albumin excretion rate (UACR), estimated glomerular filtration rate (eGFR) were compared. Binary logistic regression verified independent correlations among TSH, FT3, FT4 and UACR, eGFR. TSH and FT3 predictive values for DKD were analyzed using receiver operating characteristic (ROC) curves.

RESULTS

The prevalence of albuminuria with decreased eGFR was higher in T2DM patients with subclinical hypothyroidism and overt hypothyroidism than that in patients with normal thyroid function. TSH positively correlated with UACR (r = 0.133, p < 0.001) and positively correlated with eGFR (r = -0.218, p < 0.001), FT3 negatively correlated with UACR (r = -0.260, p < 0.001) and positively correlated with eGFR (r = 0.324, p < 0.001). With the change from the lower normal level to the increased level of TSH and the change from the higher normal level to the reduced level of FT3, the prevalence of albuminuria gradually increased, the prevalence of decreased eGFR gradually increased in TSH groups and FT3 groups. After adjusting for age, BMI, duration of diabetes, TPOAb, TGAb, smoking, drinking, hypertension, the use of anti-diabetic medications (metformin, sodium-glucose cotransporter 2 inhibitors), HbA1c, CRP, TC, TG, LDL-C, and HDL-C, both TSH and FT3 correlated with increased UACR (TSH: OR 1.253, p = 0.001; FT3: OR 0.166, p < 0.001) and decreased eGFR (TSH: OR 1.245, p < 0.001, FT3: OR 0.579, p < 0.001), but this correlation of TSH with eGFR < 60 mL/min/1.73 m2 was not found in male. The area under the ROC curve (AUC) for FT3 was greater than that for TSH (FT3: 0.64; TSH: 0.61).

CONCLUSIONS

Increased TSH and reduced FT3 levels were associated with DKD in T2DM patients, but in a sex-dependent manner. FT3 had a higher predictive value for DKD.

The predictive value of free thyroxine combined with tubular atrophy/interstitial fibrosis for poor prognosis in patients with IgA nephropathy

Background

IgA nephropathy (IgAN), the most common type of glomerulonephritis, has great individual differences in prognosis. Many studies showed the relationship between thyroid hormones and chronic kidney disease. However, the relationship between free thyroxine (FT4), as a thyroid hormone, and IgAN is still unclear. This study aimed to evaluate the impact of FT4 on IgAN prognosis.

Methods

This retrospective study involved 223 patients with biopsy-proven IgAN. The renal composite outcomes were defined as: (1) ESRD, defined as eGFR < 15 ml/(min·1.73 m2) or initiation of renal replacement therapy (hemodialysis, peritoneal dialysis, renal transplantation); (2) serum creatinine doubled from baseline; (3) eGFR decreased by more than 50% from baseline. The predictive value was determined by the area under the curve (AUC). Kaplan-Meier and Cox proportional hazards analyses assessed renal progression and prognosis.

Results

After 38 (26-54) months of follow-up, 23 patients (10.3%) experienced renal composite outcomes. Kaplan-Meier survival curve analysis showed that the renal survival rate of the IgAN patients with FT4<15.18pmol/L was lower than that with FT4≥15.18pmol/L (P < 0. 001). Multivariate Cox regression model analysis showed that FT4 was a protective factor for poor prognosis of IgAN patients, whether as a continuous variable or a categorical variable (HR 0.68, 95%CI 0.51-0.90, P =0.007; HR 0.04, 95%CI 0.01-0.20, P <0.001). ROC curve analysis showed that FT4 combined with t score had a high predictive value for poor prognosis of IgAN patients (AUC=0.881, P<0.001).

Conclusion

FT4 was a protective factor for IgAN. In addition, FT4 combined with tubular atrophy/interstitial fibrosis had a high predictive value for poor prognosis of IgAN.

Symmetric dimethylarginine concentrations in dogs with hypothyroidism before and after treatement with levothyroxine

OBJECTIVES

To evaluate the serum symmetric dimethylarginine (SDMA) and serum creatinine concentrations in a population of hypothyroid dogs at the time of diagnosis and after treatment.

MATERIALS AND METHODS

Serum SDMA and serum creatinine were measured in serum samples of 24 healthy dogs and 24 hypothyroid dogs, at the time of diagnosis (T0) and after supplementation with levothyroxine (T1).

RESULTS

The mean SDMA concentrations (reference intervals [RI] <18 μg/dL and <14 μg/dL depending on the source) were 11.7 ± 3.5 μg/dL, 13.8 ± 3.1 μg/dL and 11.83 ± 2.87 μg/dL in healthy dogs, and in the hypothyroid dogs at T0 and T1, respectively. The SDMA concentrations were higher in the hypothyroid dogs at T0 in comparison with the healthy dogs. Of the hypothyroid dogs, 1 out of 24 had an SDMA concentration above 18 μg/dL and 12 out of 24 above 14 μg/dL at T0. At T1, none of the hypothyroid dogs had SDMA concentrations above 18 μg/dL and two of them had SDMA concentrations above 14 μg/dL. The serum creatinine concentration was higher in the hypothyroid dogs at T0 as compared to the healthy dogs. At T0, 8 out of 24 hypothyroid dogs had serum creatinine concentrations above the RI (>1.4 mg/dL). In all but one dog, serum creatinine normalised after treatment.

CLINICAL SIGNIFICANCE

The SDMA and serum creatinine concentrations were higher in hypothyroid dogs at diagnosis as compared to healthy dogs. Serum creatinine concentrations were increased in one-third of the hypothyroid dogs and in the majority of cases normalised after levothyroxine supplementation. SDMA concentrations were rarely above the upper limit of the RI when the higest (<18 μg/dL) cut-off was employed. The diagnostic accuracy of SDMA in dogs with thyroid dysfunction requires additional evaluation.

Hypothyroidism and Kidney Function: A Mendelian Randomization Study

Background: Uncertainty in the mechanism and directionality of observational associations between thyroid function and kidney function may be addressed by genetic analysis with an instrumental variable method termed bidirectional Mendelian randomization (MR). Methods: In the Women's Genome Health Study (WGHS), observational associations between thyroid measures and kidney function were evaluated. Genetic instruments for MR were from recent genome-wide association studies (GWAS) of hypothyroidism, thyrotropin (TSH), and free thyroxine (fT4) concentrations within the reference range, thyroid peroxidase antibodies (TPOAb), estimated glomerular filtration rate from creatinine (eGFR_crea), eGFR from cystatin C (eGFR_cys), and chronic kidney disease (CKD). In WGHS individual-level data, these instruments were used for bidirectional MR between thyroid (N = 3336) and kidney (N = 23,186) functions. To increase power, MR was also performed using GWAS summary statistics from the Chronic Kidney Disease Genetics Consortium (CKDGen) for eGFR_crea (N = 567,460), eGFR_cys (N = 24,063), CKD [N(total) = 480,698, N(cases) = 41,395], and urinary albumin/creatinine ratio (UACR/N = 54,450). Results: In the WGHS, hypothyroidism was observationally associated with decreased eGFR_crea [beta (standard error, SE): -0.024 (0.009) ln(mL/min/1.73 m²), p = 0.01]. By MR, hypothyroidism was associated with decreased eGFR_crea in the WGHS [beta (SE): -0.007 (0.002) per doubled odds hypothyroidism, p = 1.7 × 10^-3] and in CKDGen [beta (SE): -0.004 (0.0005), p = 2.0 × 10^-22], and robust to sensitivity analysis. Hypothyroidism was also associated by MR with increased CKD in CKDGen (odds ratio, OR [confidence interval, CI]: 1.05 [1.03-1.08], p = 3.3 × 10^-5), but not in the WGHS (OR [CI]: 1.02 [0.95-1.10], p = 0.57). Increased TSH within the reference range had an MR association with increased eGFR_crea in the WGHS [beta (SE): -0.018 (0.007) ln(mL/min/1.73 m²)/standard deviation, SD, p = 6.5 × 10^-3] and CKDGen [beta (SE): -0.008 (0.001) ln(mL/min/1.73 m²)/SD, p = 6.8 × 10^-17], and with CKD in CKDGen (OR [CI]: 1.10 [1.04-1.15], p = 3.1 × 10^-4). There were no MR associations of hypothyroidism or TSH with eGFR_cys or UACR, and MR associations of fT4 in the reference range with kidney function were inconsistent in both the WGHS and CKDGen. However, by MR in CKDGen, TPOAb were robustly associated with decreased eGFR_crea [beta (SE): -0.041 (0.009), p = 6.2 × 10^-6] and decreased eGFR_cys [beta (SE): -0.294 (0.065), p = 6.2 × 10^-6]. TPOAb were less robustly associated with CKD but not associated with UACR. In reverse MR in the WGHS, kidney function was not consistently associated with thyroid function. Conclusions: Bidirectional MR supports a directional association from hypothyroidism, increased TSH, and TPOAb, but not fT4, to decreased eGFR_crea and increased CKD.

Thyroid Parameters and Kidney Disorder in Type 2 Diabetes: Results from the METAL Study

OBJECTIVE

Diabetic kidney disease is one of the most common microvascular complications of diabetes mellitus. We aimed to analyze the association of thyroid parameters with kidney disorders, especially in euthyroid participants.

METHODS

The data were obtained from a cross-sectional study, the METAL study. Thyroid parameters, including thyroid-stimulating hormone (TSH), free triiodothyronine (FT₃), free thyroxine (FT₄), triiodothyronine (T₃), thyroxin (T₄), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb), of 4136 participants with type 2 diabetes were measured. Two structure parameters of thyroid homeostasis, including the sum activity of step-up deiodinases (SPINA-G_D) and thyroid secretory capacity (SPINA-G_T), and two pituitary thyrotropic function indices, including Jostel's TSH index (TSHI) and the thyrotroph thyroid hormone resistance index (TTSI), were also calculated. Kidney disorders were described according to the presence of reduced estimated glomerular filtration rate (eGFR) and/or higher urinary albumin to creatinine ratio (UACR).

RESULTS

The prevalence of kidney disorders increased with decreasing FT₃ or T₃ and increasing FT₄ or T₄ quartile levels (all P < 0.05). After full adjustment, linear regression showed that UACR levels were negatively associated with FT₃ and T₃ (P < 0.001). In addition, eGFR was positively associated with FT₃ and T₃ and was negatively associated with TSH and FT₄ levels and TgAb positivity (all P < 0.05). By using binary logistic regression, higher TSH and FT₄ and lower FT₃ and T₃ were associated with kidney disorders (all P < 0.05). Similar results were seen in sensitivity analyses, which were performed in 3035 euthyroid diabetic participants; however, TSH was no longer related to them. The area under the receiver operating characteristic curve (AUROC) of lower FT₃ for existing kidney disorder was greater than that for any other thyroid hormones (all P < 0.001). The cutoff value of FT₃ for reduced eGFR was 4.39 pmol/L. Regarding thyroid homeostasis parameters, SPINA-G_D was negatively associated with three statuses of kidney disorders, and TSHI and TTSI were positively associated with reduced eGFR (all P < 0.05).

CONCLUSIONS

Among patients with type 2 diabetes, elevated TSH and FT₄ (or T₄), lower FT₃ (or T₃), TgAb positivity, lower SPINA-G_D, and higher TSHI and TTSI were associated with kidney disorders. The lower FT₃, even within the normal range (<4.38 pmol/L), may be the factor most related to reduced eGFR compared with other thyroid hormones in diabetic patients.

The hepcidin concentration decreases in hypothyroid patients with Hashimoto's thyroiditis following restoration of euthyroidism

The purpose of the study was to measure the hepcidin concentration and evaluate Fe homeostasis indices in a prospective study on patients with newly diagnosed hypothyroidism in the course of Hashimoto’s thyroiditis (HT) and following successful therapy. The prospective observational study consisted of 34 patients. The clinical evaluation and laboratory tests were performed at diagnosis (T0) and after restoration of euthyreosis 12 weeks later (T1). The median level of hepcidin was significantly lower (p = 0.002) after recovery (7.7 [6.2–13.0] ng/mL) than that before treatment (17.4 [7.6–20.4] ng/mL), while creatinine (p = 0.011) and GFR (p < 0.001) significantly improved after euthyroidism was achieved. A positive correlation was observed between hepcidin and fT3 (p = 0.033, r = 0.465) at T0. In the females, the level of hepcidin positively correlated with ferritin concentration before (p < 0.001, r = 0.928) and after treatment (p < 0.001, r = 0.835). A statistically significant difference was observed in RDW-CV (red blood cell distribution width - coefficient of variation) between the hypothyroid and euthyroid states. In conclusion, a decrease in hepcidin concentration during the transition from the hypothyroid state to euthyroidism in patients with HT is associated with the observed dynamics in iron homeostasis, mainly reflected by improvement in RDW-CV and significant correlations between ferritin and hepcidin as well as between hepcidin and fT3.

Evaluation of thyroid dysfunction in patients with nephrotic syndrome

Background

Thyroid and kidney are interdependent on each other in many ways for optimal functioning of either organs. Proteinuria causes urinary loss of thyroid hormones and thyroid binding globulins in substantial amount resulting in subclinical/overt hypothyroidism. Autoimmunity, which can attack both the organs simultaneously, may also contribute considerably to the abnormal functioning of both organs.

Aims and objectives

To study the effect of proteinuria on the thyroid function and its association with autoimmunity.

Methods

The study was carried out on a total number of 60 patients with nephrotic range proteinuria attending the kidney and dialysis clinic PGIMS, Rohtak, India. Thyroid profile and baseline investigations along with Anti-TPO antibodies and renal biopsy were carried out on each patient. Patients were allocated to 2 groups based on Anti TPO antibody results: group A comprising 25 Anti-TPO Ab positive patients and group B comprising 35 Anti-TPO Ab negative patients.

Results

Group A patients with Anti TPO antibody positivity had more elevated TSH levels (p<0.0001), proteinuria (p=0.0011) and serum creatinine (p=0.0137) as compared to group B patients. Group A patients had more diminished eGFR (p=0.0127) and serum albumin (p=0.0056) than patients in group B. TSH levels were positively correlated with proteinuria r=0.55 (p<0.0001, 95% CI 0.35 to 0.70) and serum creatinine levels r=0.56 (p<0.0001, 95% CI 0.36 to 0.71). TSH levels were negatively correlated with serum albumin levels r=−0.52 (p<0.0001, CI −0.68 to −0.31) and glomerular filtration rate r=−0.54 (p<0.0001, CI −0.69 to −0.33). On histopathology, membranous nephropathy - 29 out of 60 patients, 48% - was the most common finding in both the groups.

Conclusions

Nephrotic range proteinuria leading to thyroid dysfunction is a common entity but the association with autoimmunity causes an exaggerated effect on both these organs. Our study established a significant correlation between thyroid autoimmunity and nephrotic syndrome. Thus, a high index of suspicion should be kept in all patients with nephrotic syndrome to look for any associated antibodies against thyroid antigens. Autoimmunity causes more proteinuria and more elevations of thyrotropin leading to clinical hypothyroidism; however, the occurrence of overt hypothyroidism necessitating treatment needs further study.

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.

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.

The prevalence and determinants of hypothyroidism in hospitalized patients with type 2 diabetes mellitus

The purpose of this study was to investigate the prevalence of hypothyroidism among hospitalized patients with type 2 diabetes mellitus and its related factors, and to assess the prevalence of macrovascular and microvascular diseases among type 2 diabetes mellitus inpatients with hypothyroidism and euthyroidism. A total of 1662 type 2 diabetes mellitus inpatients hospitalized at the Metabolic Diseases Hospital, Tianjin Medical University from 1 January 2008 to 1 March 2013 were included in this study. Information on demographic and anthropometric factors and additional variables related to hypothyroidism were collected from medical records. Prevalence rates were calculated and standardized using direct method based on the age-specific and sex-specific structure of all participants. Data were analyzed using binary logistic regression with adjustment for potential confounders. The prevalence of hypothyroidism among type 2 diabetes mellitus inpatients was 6.8 %, and 77.0 % of the patients with hypothyroidism had subclinical hypothyroidism. The prevalence of hypothyroidism increased with age, and was higher in women (10.8 %) than in men (3.4 %). Older age (odds ratio, 1.74; 95 % confidence interval, 1. 05 to 2.89), female gender (odds ratio, 2.02; 95 % confidence interval, 1.05 to 3.87), and positive thyroid peroxidase antibody (odds ratio, 4.99; 95 % confidence interval, 2.83 to 8.79) were associated with higher odds of hypothyroidism among type 2 diabetes mellitus inpatients. The type 2 diabetes mellitus inpatients with hypothyroidism had higher prevalence of cerebrovascular diseases than those with euthyroidism after adjustment for age and gender. The prevalence of hypothyroidism among type 2 diabetes mellitus inpatients was 6.8 %, and most patients had subclinical hypothyroidism. Older age, female gender, and positive thyroid peroxidase antibody could be indicators for detecting hypothyroidism in type 2 diabetes mellitus inpatients.

The correct renal function evaluation in patients with thyroid dysfunction

Thyroid dysfunction induces several renal derangements involving all nephron portions. Furthermore, dysthyroidism is a recognized risk factor associated with the development of chronic kidney disease. Current data, in fact, demonstrate that either subclinical or overt thyroid disease is associated with significant changes in creatinine, estimated glomerular filtration rate, measured glomerular filtration rate and Cystatin C. Herein, we systematically reviewed several relevant studies aiming at the identification of the most sensitive and specific parameter for the correct renal function evaluation in patients with thyroid dysfunction, that are usually treated as outpatients. Our systematic review indicates that estimated glomerular filtration rate, preferably with CKD-EPI equation, appears to be the most reliable and wieldy renal function parameter. Instead, Cystatin C should be better used in the grading of thyroid dysfunction severity.

Effects of Thyroid Hormone Withdrawal and Recombinant Human Thyrotropin on Glomerular Filtration Rate During Radioiodine Therapy for Well-Differentiated Thyroid Cancer

BACKGROUND

Renal function is related to thyroid hormonal status, and glomerular filtration rate (GFR) seems to be impaired in patients with hypothyroidism. The aim of this work was to evaluate quantitatively the effect of hypothyroidism on GFR using a (51)Cr-EDTA radioisotope assay.

METHODS

Twenty-eight patients without known renal disease or dysfunction who had been referred for radioiodine therapy (RIT) after total thyroidectomy were enrolled in this study and divided into two groups. Group A underwent thyroid hormone withdrawal (THW) resulting in hypothyroidism, while group B underwent recombinant human thyrotropin (rhTSH) stimulation and hence remained euthyroid. GFR was assessed by (51)Cr-EDTA before and after THW or rhTSH.

RESULTS

No clinical differences were observed between the two groups. The mean ± SD GFRs were 94 ± 19 mL/min/1.73 m(2) before THW and 76 ± 16 mL/min/1.73 m(2) after THW for group A (p = 0.009), and 91 ± 18 mL/min/1.73 m(2) before rhTSH and 93 ± 15 mL/min/1.73 m(2) after rhTSH for group B (p = 0.613). The percent decrease in GFR during hypothyroidism is approximately 18-22%.

CONCLUSION

GFR decreases in patients with normal kidney function during THW for RIT, and rhTSH preserves GFR in these patients. This GFR impairment following thyroidectomy is related to hypothyroidism due to a significant reduction in thyroid hormone levels and is not due to a rise in the TSH level.

Can levothyroxine treatment reduce urinary albumin excretion rate in patients with early type 2 diabetic nephropathy and subclinical hypothyroidism? A randomized double-blind and placebo-controlled study

OBJECTIVE

To investigate the effect of levothyroxine (LT4) therapy on urinary albumin excretion rate (UAER) in early type 2 diabetic nephropathy (DN) and subclinical hypothyroidism (SCH) patients with mildly increased thyroid stimulating hormone (TSH) levels and serum thyroid peroxidase antibody (TPO-Ab) positivity.

METHODS

Application of randomized double-blind and placebo-controlled methods. A total of 136 normotensive patients with early type 2 DN and SCH (TSH 4.0-7.0 mIU/L and TPO-Ab positive) were selected, and were randomly divided into two groups for LT4 or placebo treatments, respectively. Changes in UAER, serum creatinine, glomerular filtration rate (GFR), blood pressure, serum uric acid and lipids in patients before and after 48 weeks of treatment were examined and compared between groups.

RESULTS

There were no statistically significant differences in the baseline characteristics of study participants between two treatment groups (p > 0.05 for all). After 48 weeks of treatment, compared to the placebo treatment, the LT4 treatment was more effective in reducing total cholesterol (p < 0.05). Further comparison of therapy-related differences between groups showed that the LT4 treatment was better in reducing UAER, low-density lipoprotein cholesterol and uric acid than the placebo group (p < 0.01 for all).

CONCLUSION

The LT4 treatment may decrease UAER and exert kidney protection effects in early type 2 DN and SCH patients with mildly increased TSH levels and serum TPO-Ab positivity. However, due to the short duration of follow-up and small number of cases, the results of this study need future trials with larger numbers of patients and longer follow-up periods to verify whether such a strategy can provide durable benefits.

Subclinical hypothyroidism and the associations with macrovascular complications and chronic kidney disease in patients with Type 2 diabetes

AIMS

The prevalence of subclinical hypothyroidism (SCH) is high among patients with diabetes, although the relationship between SCH and diabetic vascular complications is unknown. This study aimed to determine the relationship between SCH and vascular complications in patients with Type 2 diabetes.

METHODS

In this cross sectional study, 991 patients with Type 2 diabetes were screened for thyroid function at their admission to the Second Affiliated Hospital of Chongqing Medical University. We compared the prevalence of coronary heart disease (CHD), ischaemic stroke and chronic kidney disease (CKD) with the prevalence of euthyroidism and SCH.

RESULTS

Among the 991 patients, 126 (12.7%) patients had SCH. The prevalence of CHD was significantly higher in the SCH group than in the euthyroid group (22.2% and 15.0%, respectively; P = 0.039). In the logistic regression analyses, SCH was associated with CHD [odds ratio (OR): 1.993; 95% confidence interval (CI): 1.135-3.497; P = 0.016]. This association was stronger in patients aged ≥ 65 years than in younger patients [2.474 (1.173-5.220); P = 0.017]. No significant association was found between SCH and ischaemic stroke. Patients with severe SCH had a high risk of CKD [1.842 (1.120-3.029); P = 0.016].

CONCLUSIONS

This study provides evidence that SCH in patients with Type 2 diabetes is associated with a high prevalence of CHD (and CKD in severe SCH), although not with ischaemic stroke.

Thyroid function modifies the association between ratio of triglyceride to high-density lipoprotein cholesterol and renal function: a multicenter cross-sectional study

Hypothyroidism was confirmed to be associated with both dyslipidemia and renal dysfunction. However, the impact of thyroid function on the relationship between serum lipid levels and renal function has never been given sufficient attention. In this large-scale multicenter cross-sectional study, the ratio of triglyceride to high-density lipoprotein cholesterol (TG/HDL) and the prevalence of hypothyroidism in CKD subjects were significantly higher than those in non-CKD ones (P < 0.001). After adjustment for potential confounding factors, TG/HDL was shown to be significantly associated with serum Cr levels (β = 0.551; 95%CI, 0.394–0.708), and eGFR (β = −0.481; 95%CI, −0.731–−0.230). The risk for CKD was significantly increased as TG/HDL ratio was elevated (adjusted odds ratio = 1.20; 95%CI, 1.11–1.27). These significant associations were found among subjects with euthyroidism and hypothyroidism rather than hyperthyroidism. Furthermore, the associations between TG/HDL and Cr or CKD status were significantly greater in hypothyroidism than those in euthyroidism (P < 0.05). These results suggested that elevated TG/HDL ratio was associated with renal dysfunction; it exhibited a significantly stronger association with Cr and CKD in hypothyroidism than in euthyroidism. Therefore, more attention should be paid on lipid profile to prevent or delay the occurrence and progression of renal dysfunction, especially for those with hypothyroidism.

A SAGE based approach to human glomerular endothelium: defining the transcriptome, finding a novel molecule and highlighting endothelial diversity

Background

Large scale transcript analysis of human glomerular microvascular endothelial cells (HGMEC) has never been accomplished. We designed this study to define the transcriptome of HGMEC and facilitate a better characterization of these endothelial cells with unique features. Serial analysis of gene expression (SAGE) was used for its unbiased approach to quantitative acquisition of transcripts.

Results

We generated a HGMEC SAGE library consisting of 68,987 transcript tags. Then taking advantage of large public databases and advanced bioinformatics we compared the HGMEC SAGE library with a SAGE library of non-cultured ex vivo human glomeruli (44,334 tags) which contained endothelial cells. The 823 tags common to both which would have the potential to be expressed in vivo were subsequently checked against 822,008 tags from 16 non-glomerular endothelial SAGE libraries. This resulted in 268 transcript tags differentially overexpressed in HGMEC compared to non-glomerular endothelia. These tags were filtered using a set of criteria: never before shown in kidney or any type of endothelial cell, absent in all nephron regions except the glomerulus, more highly expressed than statistically expected in HGMEC. Neurogranin, a direct target of thyroid hormone action which had been thought to be brain specific and never shown in endothelial cells before, fulfilled these criteria. Its expression in glomerular endothelium in vitro and in vivo was then verified by real-time-PCR, sequencing and immunohistochemistry.

Conclusions

Our results represent an extensive molecular characterization of HGMEC beyond a mere database, underline the endothelial heterogeneity, and propose neurogranin as a potential link in the kidney-thyroid axis.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-725) contains supplementary material, which is available to authorized users.

The value of red blood cell distribution width in subclinical hypothyroidism

Objective : Therefore, we evaluated the relationship between the subclinical hypothyroidism and red cell distribution width (RDW) levels in a healthy population. Subjects and methods : The medical records of 23,343 consecutive health subjects were reviewed. Subjects were classified into four thyroid stimulating hormone (TSH) groups to determine the correlation between TSH and other variables in detail (0.3 to < 2.5 mU/L, 2.5 to < 5 mU/L, 5 to < 7.5 mU/L, and ≥ 7.5 mU/L). Results : In the multivariate linear regression analysis, RDW was associated with TSH levels, and e-GFR was inversely associated with TSH levels, respectively (standardized beta coefficient = 0.102, -0.019; p < 0.001, p < 0.001). After adjusting for age and sex, in the four groups, TSH levels were significantly correlated with RDW, estimated glomerular filtration rate (e-GFR), and free thyroxine (fT4) levels in all groups. Furthermore in the 4 th group, RDW levels were more strongly associated with TSH levels than in the other groups (p = 0.006). Conclusions : RDW levels are correlated with euthyroid and subclinical thyroid status. Notably, RDW is more correlated with subclinical hypothyroidism than the euthyroid status. This study presents the relationship between the RDW levels and thyroid function using TSH level in a large healthy population.

Hypothyroidism presenting as reversible renal impairment: an interesting case report

We describe an interesting case of reversible renal impairment secondary to hypothyroidism. A 57-years-old man was referred from peripheral institution for evaluation of elevated serum creatinine. He had vague complaints of weakness, lethargy and muscle ache but no urinary symptoms. He was found to have hypothyroidism, and thyroid hormone replacement therapy (THRT) was started which resulted in reversal of the renal dysfunction. There was marked improvement in estimated glomerular filtration rate. 99mTc DTPA renal scans done before and after THRT suggested hypothyroidism responsible for this reversible renal impairment. Several studies have described the pathophysiology of diminished renal function in hypothyroidism. Few studies or case reports have shown total amelioration of renal impairment as seen in our patient. The etiology is presumed to be multifactorial, in which hemodynamic effects and a direct effect of thyroid hormone on the kidney play an important role. We suggest that patients with renal impairment of unknown cause have thyroid function tests undertaken as part of routine investigation.

Relationship between thyroid dysfunction and chronic kidney disease in community-dwelling older adults

OBJECTIVES

Renal function has been shown to be influenced by thyroid status in animal models and human studies. We aimed to assess the cross-sectional association between thyroid hormones and function with prevalence of chronic kidney diseases (CKD) in older adults.

STUDY DESIGN

1571 Blue Mountains Eye Study participants aged ≥ 60 years were analyzed in 2002-4. Thyroid dysfunction was defined using serum thyrotropin (TSH) screen, followed by serum free T4 (FT4) assessment. Baseline biochemistry including serum creatinine was measured. Moderate CKD was defined as estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m(2).

RESULTS

After adjusting for age, sex, receipt of pension payment, body mass index, smoking, hypertension and diabetes, persons with any thyroid dysfunction (hyperthyroidism or hypothyroidism) had 84% higher likelihood of having CKD, odds ratio, OR, 1.84 (95% confidence intervals, CI, 1.03-3.31). Participants in the highest versus lowest quartile (reference) of serum TSH and FT4 had a significantly greater odds of prevalent CKD, OR 1.82 (95% CI 1.22-2.71), and OR 1.64 (95% CI 1.10-2.45), respectively. Similarly, among participants not receiving treatment for their thyroid dysfunction (n=1329), those in the third and fourth quartiles of serum TSH had significantly greater odds of having prevalent CKD, OR 1.83 (95% CI 1.15-2.92) and OR 1.96 (95% CI 1.23-3.13), respectively, Ptrend=0.001. Significant associations were not observed between type of thyroid dysfunction (hyperthyroidism or hypothyroidism) and prevalent CKD.

CONCLUSIONS

Increasing serum TSH was associated with a greater likelihood of prevalent CKD among older adults, independent of the influence of age, diabetes and hypertension.

A literature review on the adverse effects of hypothyroidism on kidney function

Thyroid produce two important hormone of thyroxine or tetraidothyronine (T4) and triidothyronine (T3), which are involved in whole aspect of metabolism. T4 and T3 play vital role in all biochemical function, growth and development in human body. The basic metabolic pathways in kidney and every organ in human controlled by these hormones. T4 and T3 are involved in kidney function in health and diseases condition therefore the pathophysiology of kidney can be directly influenced and regulated by thyroid hormones. Kidney growth, haemodynamic, blood circulation, tubular, electrolyte balance and glomerular filtration rate (GFR) are among such crucial process. Hypothyroidism which accompanied with reduced thyroid hormone production adversely affect the renal functions, development and eventually leading to reduced weight, kidney vascular disorders, electrolyte, tubular transport imbalances, lower filtration rate and other adverse consequences of hypothyroidism. On other hand kidney diseases can also disrupt the thyroid function metabolism resulting in the subsequent hypothyroidism. It is an interesting subject in how thyroid and kidney in health and diseases closely interacted. For the ideal clinical follow up of either of thyroid and renal diseases the two organs should be simultaneously examined for a proper patient management. Close correlation of thyroid and kidney clinical teams are essential to check the cross reactions and adverse interactions which might be produced between these two vital organs to avoid misdiagnosis either of thyroid or kidney abnormalities.

Interactions between thyroid disorders and kidney disease

There are several interactions between thyroid and kidney functions in each other organ's disease states. Thyroid hormones affect renal development and physiology. Thyroid hormones have pre-renal and intrinsic renal effects by which they increase the renal blood flow and the glomerular filtration rate (GFR). Hypothyroidism is associated with reduced GFR and hyperthyroidism results in increased GFR as well as increased renin - angiotensin - aldosterone activation. Chronic kidney disease (CKD) is characterized by a low T3 syndrome which is now considered a part of an atypical nonthyroidal illness. CKD patients also have increased incidence of primary hypothyroidism and subclinical hypothyroidism. The physiological benefits of a hypothyroid state in CKD, and the risk of CKD progression with hyperthyroidism emphasize on a conservative approach in the treatment of thyroid hormone abnormalities in CKD. Thyroid dysfunction is also associated with glomerulonephritis often by a common autoimmune etiology. Several drugs could affect both thyroid and kidney functions. There are few described interactions between thyroid and renal malignancies. A detailed knowledge of all these interactions is important for both the nephrologists and endocrinologists for optimal management of the patient.

Unusual renal manifestations in a girl with hyperthyroidism

A 16-year-girl, a known case of hyperthyroidism since last 6 months, presented to the emergency with complaints of acute gastroenteritis of 5 days duration. At admission the child was found to be hypovolemic with acidotic breathing, which was thought to be due to dehydration. However, despite fluid correction she remained acidotic. A diagnosis of distal renal tubular acidosis (RTA) was suspected when her renal scan, for the cause of metabolic acidosis, revealed nephrocalcinosis. This was later confirmed by relevant investigations. She was started on treatment for distal RTA on which she symptomatically improved. The association of distal RTA and thyroid disorders is rarely reported in children. Till date there is only one report of distal RTA and hypothyroidism, but none with hyperthyroidism in this age group. The authors chose to report this case to highlight the fact that one should have a high index of suspicion for renal tubular disorders in children with thyroid hormone abnormalities, as these are treatable conditions if diagnosed early.

Biochemical and histopathological studies of the PTU-induced hypothyroid rat kidney with reference to the ameliorating role of folic acid

Thyroid hormones (THs) are essential for growth and development of the kidney. Also TH influences glomerular filtration and tubular functions. Hypothyroidism negative influences kidney function indirectly by affecting the cardiovascular system and the renal blood flow, and directly by affecting glomerular filtration, tubular functions and the structure of the kidney. The purpose of this study was to evaluate changes in biochemical markers, oxidative stress parameter and histological changes in kidney of hypothyroid rats before and after treatment with folic acid. Hypothyroidism was induced for 6 weeks by the administration of propylthiouracil in drinking water. Urea and creatinine were measured to evaluate the changes in kidney function. Also malondialdehyde, nitrite, nitrate and other oxidative stress parameter were measured in serum and kidney tissue as indicators of oxidative damage. Kidney function and oxidative stress parameters in hypothyroid rats were significantly changed compared to those in control rats. Treatment with folic acid helps in improving the adverse effect of hypothyroidism; the histological study also confirms this finding.

Measuring glomerular filtration rate in children; can cystatin C replace established methods? A review

Our aim was to evaluate published methods that use serum cystatin C (s-CysC) for measuring glomerular filtration rate (GFR) in children and to discuss advantages and limitations of s-CysC and of established GFR methods. A comprehensive literature review of clinical studies in children evaluating s-CysC or CysC-based formulas and plasma creatinine or creatinine-based formulas against an exogenous reference method using receiver operating characteristics (ROC) curves or Bland-Altman plots is presented. The comparison of s-CysC with plasma creatinine indicated that s-CysC was superior to plasma creatinine in five of 13 studies; four studies showed no difference, and, in four studies, no statistical comparison was made. Comparison of s-CysC and the Schwartz formula showed that s-CysC was superior to the Schwartz formula in two of seven studies; two studies demonstrated no difference, and, in one study, the Schwartz formula was superior to s-CysC. In two studies no statistical comparison was made. The CysC-based prediction equations all had high accuracy but low agreement when compared with a reference GFR, in the range of 30-40% at best. S-CysC is most likely superior to plasma creatinine and at least equal to creatinine-based formulas. CysC-based prediction equations are at least as good as creatinine-based formulas but cannot replace exogenous methods.

Thyroid dysfunction and kidney disease

Thyroid hormones (TH) are essential for an adequate growth and development of the kidney. Conversely, the kidney is not only an organ for metabolism and elimination of TH, but also a target organ of some of the iodothyronines' actions. Thyroid dysfunction causes remarkable changes in glomerular and tubular functions and electrolyte and water homeostasis. Hypothyroidism is accompanied by a decrease in glomerular filtration, hyponatremia, and an alteration of the ability for water excretion. Excessive levels of TH generate an increase in glomerular filtration rate and renal plasma flow. Renal disease, in turn, leads to significant changes in thyroid function. The association of different types of glomerulopathies with both hyper- and hypofunction of the thyroid has been reported. Less frequently, tubulointerstitial disease has been associated with functional thyroid disorders. Nephrotic syndrome is accompanied by changes in the concentrations of TH due primarily to loss of protein in the urine. Acute kidney injury and chronic kidney disease are accompanied by notable effects on the hypothalamus-pituitary-thyroid axis. The secretion of pituitary thyrotropin (TSH) is impaired in uremia. Contrary to other non-thyroidal chronic disease, in uraemic patients it is not unusual to observe the sick euthyroid syndrome with low serum triodothyronine (T(3)) without elevation of reverse T(3) (rT(3)). Some authors have reported associations between thyroid cancer and kidney tumors and each of these organs can develop metastases into the other. Finally, data from recent research suggest that TH, especially T(3), can be considered as a marker for survival in patients with kidney disease.

Interactions between thyroid and kidney function in pathological conditions of these organ systems: a review

Thyroidal status affects kidney function already in the embryonic stage. Thyroid hormones influence general tissue growth as well as tubular functions, electrolyte handling and neural input. Hyper- and hypo-functioning of the thyroid influences mature kidney function indirectly by affecting the cardiovascular system and the renal blood flow, and directly by affecting glomerular filtration, electrolyte pumps, the secretory and absorptive capacity of the tubuli, and the structure of the kidney. Hyperthyroidism accelerates several physiologic processes, a fact which is reflected in the decreased systemic vascular resistance, increased cardiac output (CO), increased renal blood flow (RBF), hypertrophic and hyperplastic tubuli, and increased glomerular filtration rate (GFR). Renal failure can progress due to glomerulosclerosis, proteinuria and oxidative stress. Hypothyroidism has a more negative influence on kidney function. Peripheral vascular resistance is increased with intrarenal vasoconstriction, and CO is decreased, causing decreased RBF. The influence on the different tubular functions is modest, although the transport capacity is below normal. The GFR is decreased up to 40% in hypothyroid humans. Despite the negative influences on glomerular and tubular kidney function, a hypothyroid state has been described as beneficial in kidney disease. Kidney disease is associated with decreased thyroid hormone concentrations caused by central effects and by changes in peripheral hormone metabolism and thyroid hormone binding proteins. Geriatric cats form an animal model of disease because both hyperthyroidism and chronic kidney disease (CKD) have high prevalence among them, and the link between thyroid and kidney affects the evaluation of clinical wellbeing and the possible treatment options.

A case of autoimmune thyroiditis and membranoproliferative glomerulonephritis

Thyroid hormones play an important role in the growth of the kidney and maintenance of its functions. Prolonged hypothyroidism is known to be accompanied by changes in renal morphology such as thickening of the glomerular and tubular basement membranes as well as increased mesangial matrix. Increased transcapillary leakage of plasma proteins leading to proteinuria and generalized edema is also a known complication of hypothyroidism. In particular, autoimmune thyroiditis is associated with proteinuria. Most previous reports of autoimmune thyroiditis with nephrotic syndrome have demonstrated mixed pathological morphology marked by predominant membranous glomerulopathy. Here we present a patient whose initial presentation with profound hypothyroidism and autoimmune thyroiditis was dominated by nephrotic syndrome secondary to type 1 membranoproliferative glomerulonephritis (MPGN). The association of MPGN and autoimmune thyroiditis is very rare.

Rhabdomyolysis, renal failure, pericardial effusion, and acquired von Willebrand disease resulting from hypothyroidism in a 10-year-old girl

A 10-year-old girl manifested unexplained muscle aches and high creatine phosphokinase (CPK) concentrations attributed to rhabdomyolysis in association with severe hypothyroidism due to autoimmune thyroiditis. The response to therapy strongly suggested that hypothyroidism was the cause of rhabdomyolysis. Hypothyroidism is a rare cause of rhabdomyolysis. It should always be considered in a patient with muscular symptoms and elevated CPK concentrations. In addition, the patient developed other uncommon manifestations of hypothyroidism such as pericardial effusion, acute renal failure, and acquired von Willebrand disease. After thyroxine replacement, the symptoms and abnormal findings disappeared. The patient was also diagnosed as having celiac disease, which is often associated with autoimmune thyroiditis. Conditions accompanying autoimmune thyroid disease may result from altered thyroid function and from the presence of other autoimmune diseases. The butterfly-shaped thyroid gland has a tremendous impact on metabolism, which may be compared to a phenomenon termed the "Butterfly Effect".

Subclinical hypothyroidism is a risk factor for nephropathy and cardiovascular diseases in Type 2 diabetic patients

AIMS

The purpose of this study was to determine the relationship between subclinical hypothyroidism and prevalence of retinopathy and nephropathy, incident cardiovascular disease, and mortality in Type 2 diabetic patients without taking thyroid medication.

METHODS

Serum thyrotropin and free thyroxine concentrations were measured in 588 Type 2 diabetic subjects in Taipei Veterans General Hospital, Taiwan. In a cross-sectional study, we examined the prevalence of retinopathy and nephropathy. In a longitudinal study, we examined the risk of cardiovascular disease events, cardiovascular mortality and total mortality in the 4-year follow-up.

RESULTS

In the cross-sectional analysis, subclinical hypothyroidism was associated with a greater prevalence of diabetic nephropathy (odds ratio, 3.15 [95% CI, 1.48-6.69]) and did not show a high prevalence of diabetic retinopathy (odds ratio, 1.15 [95% CI, 0.59-2.26]) compare to euthyroid diabetics. During the 44.0 +/- 7.4 months of follow-up, 51 participants had cardiovascular events. The risk of cardiovascular events was significantly increased in Type 2 diabetics with subclinical hypothyroidism after adjustment for age, sex, A1C, other standard cardiovascular risk factors and medication (hazard ratio, 2.93; 95% CI, 1.15-7.48; P = 0.024), but it became nonsignificant after additional adjustment for urinary albumin-to-creatinine ratio (hazard ratio, 2.06; 95% CI, 0.67-6.36; P = 0.211). The rates of cardiovascular-related and total mortality did not significantly differ by thyroid status.

CONCLUSIONS

Type 2 diabetic patients with subclinical hypothyroidism are associated with an increased risk of nephropathy and cardiovascular events, but not with retinopathy. Our data suggest that the higher cardiovascular events in subclinical hypothyroidism with Type 2 diabetes may be mediated with nephropathy.