Thyroid hormone action in chronic kidney disease

Temporary hypothyroidism in severe crush syndrome: a potential novel entity

BACKGROUND

Thyroid hormone synthesis is a complex process in the human body. Although the thyroid gland is essential for thyroid hormone synthesis, skeletal muscles also have crucial roles in thyroid hormone metabolism due to the deiodinase activities of the muscle cells. Hypothyroidism-related myopathy is a well-known entity. However, systemic effects of acute myopathies, such as rhabdomyolysis, on thyroid hormone metabolism have not to date been fully clarified.

METHODS

Fifty-three earthquake victims were evaluated retrospectively. We investigated the thyroid function tests (TFTs) among patients with creatine kinase (CK) levels higher than 10.000 U/L at admission. Fifteen patients had CK levels higher than 10.000 U/L and 12 of them had data of TFTs, including thyroid stimulating hormone (TSH), free T4 (FT4), and free T3 (FT3) during hospitalization. These patients were evaluated.

RESULTS

TSH levels were increased in all seven patients who required HD due to severe crush syndrome. Decreased FT4 levels were detected in 71.4% of them. None of the five non-HD patients had increased TSH levels or reduced FT4 levels. During follow-up, all patients survived. Renal and thyroid functions were normalized during follow-up without thyroxin replacement in patients with no prior history of hypothyroidism. Moreover, TFTs were normalized in two patients with history of hypothyroidism under thyroxine treatment without dose adjustments.

CONCLUSIONS

In severe forms of crush syndrome, temporary hypothyroidism might be seen. The exact mechanism underlying this entity is not well-known. Further clinical and experimental trials should be conducted to illuminate the mechanism of disrupted thyroid hormonogenesis in crush syndrome victims.

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.

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.

Association of Triiodothyronine Levels with Left Ventricular Function, Cardiovascular Events, and Mortality in Hemodialysis Patients

Background

Hemodialysis (HD) patients have altered free triiodothyronine (fT3) levels. A low fT3 level is a strong and inverse mortality predictor in HD patients. However, little is known about the relationship between fT3 and left ventricular function in HD patients.

Methods

A total of 128 maintenance HD patients were enrolled in this study. A thyroid function test with blood sampling and echocardiography was conducted. Low-T3 syndrome was defined as fT3 level <3.62 pmol/L and normal thyroid stimulating hormone (TSH). Overall mortality and rate of cardiovascular (CV) events were assessed during 48 months of follow-up.

Results

Low-T3 syndrome was detected in 57 (44.5%) of the 128 patients. Patients with low-T3 syndrome had a shorter duration of HD (49.1 vs. 73.3, p = 0.01), and lower serum albumin (35.1 vs. 40.4 g/L, p<0.001), left ventricular ejection fraction (LVEF; 54.7% vs. 63.9%, p<0.001), and fractional shortening at endocardial levels (endoFS; 29.3% vs. 34.8%, p = 0.001) compared to those with normal fT3 levels. In multivariate linear regression, LVEF, albumin, and duration of HD were independently correlated with fT3 levels. In addition, fT3 was also correlated with LVEF. During the study period, 13 (10.1%) patients died, CV events occurred in 15 (11.7%) patients. In Cox regression analysis, low fT3 level and elevated high-sensitivity C-reactive protein (hs-CRP) were associated with mortality and CV events.

Conclusions

In HD patients, fT3 level is positively correlated with LVEF. Low fT3 level and elevated hs-CRP predicted all-cause mortality and CV events.

Prevalence and clinical characteristics of hypothyroidism in a population undergoing maintenance hemodialysis

BACKGROUND

The prevalence of hypothyroidism in persons with chronic kidney disease is documented to be higher, compared to the normal population. However, no data is available about the prevalence rate of hypothyroidism among hemodialysis patients in Nepal.

METHODS

A cross-sectional analysis was done on consecutive patients enrolled for maintenance hemodialysis in the Hemodialysis Unit of Gandaki Medical College Teaching Hospital, Pokhara, Nepal, during the period of one year (1(st) January 2011 to 31(st) December 2011). Total 64 subjects with end stage renal disease were recruited for the study. Thyroid function tests were performed at the time of starting regular hemodialysis. Classical symptoms and signs of hypothyroidism were assessed in all patients.

RESULTS

Among the study subjects 17 (26.6%) had serum thyroid stimulating hormone levels above the laboratory reference range (>6.16 μIU/ml). Among them 12 (18.7%) patients had clinically significant symptoms or signs requiring thyroxin replacement. Cold intolerance, constipation, tingling sensation, dry skin, periorbital odema, pericardial effusion, pleural effusion and ascites were found at significantly higher rate in the hypothyroid patient group (p<0.05).

CONCLUSION

The diagnosis of hypothyroidism can be easily missed in the end-stage kidney disease population, because the symptoms of chronic kidney disease and hypothyroidism overlap. In our study we have found high prevalence of hypothyroidism. Clinicians should pay attention on this factor and screen routinely for thyroid disorders in the chronic kidney disease population.