Thyroid hormone upregulates Na,K-ATPase alpha and beta mRNA in primary cultures of proximal tubule cells

Association of Serum Thyroid Hormones with the Risk and Severity of Chronic Kidney Disease Among 3563 Chinese Adults

Background

Chronic kidney disease (CKD) is a global health problem with an increasing prevalence. We explored the association of serum thyroid hormones with the risk and severity of CKD among Chinese adults.

Material/Methods

This retrospective study involved 3563 participants. CKD was diagnosed according to the clinical practice guidelines of the 2012 Kidney Disease Improving Global Outcomes guidelines. Effect-size estimates are expressed as odds ratio (OR) and 95% confidence interval (CI).

Results

Given the strong magnitude of correlation, only 3 thyroid hormones were analyzed: free triiodothyronine (FT3), free thyroxin (FT4), and thyroid-stimulating hormone (TSH). After propensity score matching on age, sex, diabetes, and hypertension, per 0.2 pg/mL increase in FT3 was significantly associated with 35–38% reduced risk of CKD at stage 1–4, and per 0.3 ng/dL increase in FT4 was only significantly associated with 21% reduced risk of CKD at stage 5 (OR, 95% CI: 0.79, 0.69–0.89), and per 0.5 μIU/mL increment in TSH increased the risk of CKD stage 5 by 8% (1.08, 1.02–1.14). Importantly, 3 thyroid hormones acted interactively, particularly for the interaction between FT3 and FT4 in predicting CKD at stage 5 (OR, 95% CI: 1.81, 1.30–2.55 for high FT3-low FT4, 17.72, 7.18–43.74 for low FT3-high FT4, and 22.28, 9.68–51.30 for low FT3-low FT4).

Conclusions

Our findings indicate that serum FT3 can be used as an early-stage biomarker for CKD, and FT4 and TSH can be used as advanced-stage biomarkers among Chinese adults.

Relationship between perioperative thyroid function and acute kidney injury after thyroidectomy

Thyroid dysfunction may alter kidney function via direct renal effects and systemic haemodynamic effects, but information on the effect of thyroid function on postoperative acute kidney injury (AKI) following thyroidectomy remains scarce. We reviewed the medical records of 486 patients who underwent thyroidectomy between January 2010 and December 2014. Thyroid function was evaluated based on the free thyroxine or thyroid stimulating hormone levels. The presence of postoperative AKI was determined using the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. AKI developed in 24 (4.9%) patients after thyroidectomy. There was no association between preoperative thyroid function and postoperative AKI. Patients with postoperative hypothyroidism showed a higher incidence of AKI than patients with normal thyroid function or hyperthyroidism (19.4%, 6.7%, and 0%, respectively; P = 0.044). Multivariable logistic regression analysis showed that male sex (OR, 4.45; 95% CI, 1.80-11.82; P = 0.002), preoperative use of beta-blockers (OR, 4.81; 95% CI, 1.24-16.50; P = 0.016), low preoperative serum albumin levels (OR, 0.29; 95% CI, 0.11-0.76; P = 0.011), and colloid administration (OR, 5.18; 95% CI, 1.42-18.15; P = 0.011) were associated with postoperative AKI. Our results showed that postoperative hypothyroidism might increase the incidence of AKI after thyroidectomy.

Radioiodine ablation in thyroid cancer patients: renal function and external radiation dose rate at discharge according to patient preparation

BACKGROUND

An elevated thyroid stimulating hormone (TSH) level is essential for the uptake of radioiodine into thyroid remnants and residual thyroid cancer in patients undergoing high-dose radioiodine therapy (HD-RIT). Recently, the use of recombinant human thyroid stimulating hormone (rh-TSH) has increased in preference over the conventional method of thyroid hormone withdrawal (THW). However, the clinical influences of the two methods, aside from the therapeutic effects, have not been widely evaluated. The aim of this work was to investigate the influences of the two methods, particularly on the renal function and external radiation dose rate (EDR) from patients undergoing HD-RIT.

METHODS

From February 2012 to November 2016, 667 patients (M:F=138:529, mean age: 47.7±11.8 years), who underwent first HD-RIT (120, 150, or 180 mCi, 1 mCi=37 MBq) for ablation of remnant thyroid tissue or residual thyroid cancer, were enrolled. Patients who were proven to have distant metastasis to lung or bone were excluded. Low- to high-risk patients based on 2015 American thyroid association management guidelines who underwent first HD-RIT in our department were included. The period from total thyroidectomy to HD-RIT was limited within 12 months. The following parameters were collected and evaluated: age, gender, histology type and TNM stage of thyroid cancer, glomerular filtration rate on the admission day for total thyroidectomy (baseline GFR), GFR on the day of HD-RIT (follow-up GFR), thyroglobulin (Tg) and TSH levels on the day of HD-RIT, and EDR on the discharge day after HD-RIT.

RESULTS

There were 386 patients using the THW method and 281 patients choosing the rh-TSH method. The baseline GFR of the THW group (106±16 mL/min/1.73 m2) and that of the rh-TSH group (104±17 mL/min/1.73 m2) were within normal limits and there was no significant difference. However, follow-up GFR of the THW group (84±17 mL/min/1.73 m2) was much lower than that of the rh-TSH group (104±16 mL/min/1.73 m2) (P=0.000). In the THW group, the follow-up GFR decreased significantly (P=0.000), yet the follow-up GFR of the rh-TSH group was not statistically different when compared with its baseline GFR (P=0.142). EDRs were lower in all rh-TSH subgroups compared to those of THW subgroups with statistical significance. Tg and TSH levels were not different between the two groups, excluding a few small-sized subgroups analyses.

CONCLUSIONS

In this retrospective analysis of renal function and EDR, the use of rh-TSH appears to help maintain renal function and finally decrease EDR in contrast to the THW method when undergoing HD-RIT.

Transcriptional regulators of Na,K-ATPase subunits

The Na,K-ATPase classically serves as an ion pump creating an electrochemical gradient across the plasma membrane that is essential for transepithelial transport, nutrient uptake and membrane potential. In addition, Na,K-ATPase also functions as a receptor, a signal transducer and a cell adhesion molecule. With such diverse roles, it is understandable that the Na,K-ATPase subunits, the catalytic α-subunit, the β-subunit and the FXYD proteins, are controlled extensively during development and to accommodate physiological needs. The spatial and temporal expression of Na,K-ATPase is partially regulated at the transcriptional level. Numerous transcription factors, hormones, growth factors, lipids, and extracellular stimuli modulate the transcription of the Na,K-ATPase subunits. Moreover, epigenetic mechanisms also contribute to the regulation of Na,K-ATPase expression. With the ever growing knowledge about diseases associated with the malfunction of Na,K-ATPase, this review aims at summarizing the best-characterized transcription regulators that modulate Na,K-ATPase subunit levels. As abnormal expression of Na,K-ATPase subunits has been observed in many carcinoma, we will also discuss transcription factors that are associated with epithelial-mesenchymal transition, a crucial step in the progression of many tumors to malignant disease.

Hypokalaemia in a hyperthyroid domestic shorthair cat with adrenal hyperplasia

A 13-year-old female domestic shorthair cat presented with polyphagia and weight loss. Marked systolic hypertension was found on examination. Elevated total thyroxine levels confirmed hyperthyroidism, and hypokalaemia was also documented. A euthyroid state and normotension were achieved following 4 weeks of treatment with carbimazole and amlodipine. Despite potassium supplementation, the hypokalaemia worsened. Abdominal ultrasonography revealed left adrenomegaly. Plasma aldosterone concentrations were initially in the lower half of the reference interval and, when repeated 2 months later, were undetectable. Urea and creatinine remained in the lower half of the reference interval throughout treatment, and urine specific gravity suggested good urine concentrating ability. The fractional excretion of potassium confirmed a renal source of potassium loss. Blood gas analysis was unremarkable. It was theorised that an aldosterone precursor was causing signs of mineralocorticoid excess and undetectable plasma aldosterone levels. Treatment with an aldosterone receptor antagonist successfully increased the serum potassium concentration. Owing to difficulties administering medication and associated effects on life quality the cat was euthanased. Adrenal hyperplasia was apparent on post-mortem histopathology.

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.

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.

V2 vasopressin receptor deficiency causes changes in expression and function of renal and hypothalamic components involved in electrolyte and water homeostasis

Polyuria, hypernatremia, and hypovolemia are the major clinical signs of inherited nephrogenic diabetes insipidus (NDI). Hypernatremia is commonly considered a secondary sign caused by the net loss of water due to insufficient insertion of aquaporin-2 water channels into the apical membrane of the collecting duct cells. In the present study, we employed transcriptome-wide expression analysis to study gene expression in V2 vasopressin receptor (Avpr2)-deficient mice, an animal model for X-linked NDI. Gene expression changes in NDI mice indicate increased proximal tubular sodium reabsorption. Expression of several key genes including Na+-K+-ATPase and carbonic anhydrases was increased at the mRNA levels and accompanied by enhanced enzyme activities. In addition, altered expression was also observed for components of the eicosanoid and thyroid hormone pathways, including cyclooxygenases and deiodinases, in both kidney and hypothalamus. These effects are likely to contribute to the clinical NDI phenotype. Finally, our data highlight the involvement of the renin-angiotensin-aldosterone system in NDI pathophysiology and provide clues to explain the effectiveness of diuretics and indomethacin in the treatment of NDI.

Effect of thyroid hormone on the postnatal renal expression of NHE8

We previously demonstrated that there are developmental changes in proximal tubule Na(+)/H(+) exchanger (NHE) activity. There is a maturational increase in postnatal brush-border membrane (BBM) vesicle NHE3 protein abundance and decrease in NHE8 protein abundance. The purpose of this study was to determine whether thyroid hormone plays a role in the rat renal maturational isoform switch from NHE8 to NHE3 and whether thyroid hormone regulates NHE8. Administration of thyroid hormone to neonatal rats, before the normal postnatal increase in serum thyroid hormone levels at 3 wk of age, resulted in a premature increase in NHE3/beta-actin BBM protein abundance and mRNA abundance. Thyroid hormone also caused a premature decrease in BBM NHE8/beta-actin protein abundance, whereas there was no change in mRNA expression (standardized to 28s). Rats made hypothyroid from birth were studied at 28 days, after the normal maturational increase in thyroid hormone. In these hypothyroid adult rats, the maturational increase in BBM NHE3 protein abundance and NHE3 mRNA expression was prevented. In contrast, the developmental decrease in BBM NHE8 protein abundance was prevented in hypothyroid adults, but mRNA expression was unchanged in hypothyroid rats. To determine whether the effect of thyroid hormone was due to a direct epithelial effect, we studied normal rat kidney cells in culture. We recently showed that this cell line expresses NHE8, but does not express NHE3. Thyroid hormone caused a decrease in surface expression of NHE8, determined by biotinylation, but total cellular abundance remained unchanged. NHE8 activity, measured as the sodium-dependent rate of intracellular pH recovery from an acid load, was less with thyroid treatment than control. In conclusion, thyroid hormone plays a potential role in the developmental isoform change from NHE8 to NHE3 and decreases NHE8 activity.

Effect of experimentally induced hypothyroidism on sulfate renal transport in rats

Decreased serum sulfate concentrations are observed in hypothyroid patients. However, the mechanism involved in thyroid hormone-induced alterations of renal sulfate homeostasis is unknown. The objectives of this investigation were to determine the effect of 6-propyl-2-thiouracil (PTU)-induced hypothyroidism in rats on 1) the in vivo serum concentrations, renal clearance, and renal reabsorption of sulfate, 2) the in vitro renal transport in brush-border membrane (BBM) and basolateral membrane (BLM) vesicles, and 3) the cellular mechanism of the hypothyroid-induced alteration in sulfate renal transport. Serum sulfate concentrations, renal fractional reabsorption of sulfate, and creatinine clearance were decreased significantly in the hypothyroid group. The Vmax values for sodium-sulfate cotransport in BBM were significantly decreased in the kidney cortex from the hypothyroid animals (0.90 +/- 0.31 vs. 0.49 +/- 0.08 nmol. mg-1. 10 s-1, n = 5-6, P < 0.05) without changes in Km. There were no significant differences in Vmax and Km for sulfate/anion exchange transport in BLM. Sodium-dependent sulfate transporter (NaSi-1) mRNA and protein levels were significantly lower in the kidney cortex from hypothyroid rats. Hypothyroidism did not alter the membrane motional order (fluidity) in BBM and BLM, which indicates that the changes in the membrane fluidity do not represent the mechanism for the altered renal transport. These results demonstrate that PTU-induced hypothyroidism decreases sodium-sulfate cotransport by downregulation of the NaSi-1 gene.

Effects of thyroid hormone on the neonatal renal cortical Na+/H+ antiporter

The neonatal proximal tubule has a lower rate of bicarbonate absorption than that of adults. This is due, in part, to a lower rate of apical membrane Na+/H+ antiporter activity. The purpose of these studies was to examine if thyroid hormone could be a factor in the maturational increase in Na+/H+ antiporter activity. Hypothyroid (0.01% propylthiouracil in drinking water starting at day 14 gestation and throughout the postnatal period), euthyroid, and hyperthyroid (intraperitoneal triiodothyronine, 10 micrograms/100 g body wt, once daily on days 17 to 20 of postnatal life) rats were all studied at 21 days of life. Renal cortical brush border Na+/H+ antiporter activity was 453 +/- 24, 527 +/- 30 and 608 +/- 25 pmol/mg protein in the hypothyroid, euthyroid and hyperthyroid groups, respectively (P < 0.001). Hyperthyroid neonates had approximately twofold greater renal cortical NHE-3 mRNA abundance than euthyroid and hypothyroid neonates (P < 0.05). Brush border membrane NHE-3 protein abundance in hypothyroid and hyperthyroid neonates was one-third and twofold that of euthyroid 21-day-old rats, respectively (P < 0.001). These data are consistent with a potential role of thyroid hormone in the postnatal increase in Na+/H+ antiporter activity.