Interventions to improve symptomatology in patients with hypothyroidism and persistent symptoms: A systematic review

BACKGROUND

Levothyroxine (LT4) monotherapy is the standard treatment for hypothyroidism; however, 10-15% of patients have persistent hypothyroid symptoms despite normalizing thyroid hormone levels with LT4. This study aims to summarize the best available evidence on interventions to improve symptomatology in patients with hypothyroidism and persistent symptoms.

METHODS

A systematic search was conducted in March 2022 for randomized controlled trials and observational studies on interventions for adult patients with persistent hypothyroid symptoms despite biochemical euthyroidism on thyroid hormone replacement.

RESULTS

A total of 277 articles were reviewed and seven fulfilled the inclusion criteria. 455 participants were included. Most intervention participants were female (78.6%) with a mean age of 47.5 (±2.8) years. Five clinical trials evaluating ginger (vs. starch), L-carnitine (vs. placebo), combination LT4 and liothyronine (LT3) (vs. LT4 or placebo), and surgery for patients with serum antithyroid peroxidase (TPO Ab) titers greater than 1000 IU/ml (vs. LT4) found inconsistent improvement in hypothyroidism related symptoms and general health. The two clinical trials with the largest improvement in fatigue scores were the use of ginger and surgery. One observational study comparing thyroidectomy vs observation found no significant difference on general health. Lastly, another observational study evaluating combination LT4/LT3 (vs. LT4 monotherapy) found improvement in fatigue and quality of life. There were 31 (12%) adverse events in the intervention group and 18 (10.8%) in the comparator group.

CONCLUSIONS

There is no high-quality evidence supporting any intervention for persistent symptoms in hypothyroidism. Available evidence, limited by the risk of bias, inconsistency, and heterogeneity, suggests that some persistent symptoms, particularly fatigue, could improve with ginger and thyroidectomy.

Development of hypothyroidism following hemithyroidectomy: A population-based study

PURPOSE

Hypothyroidism is a known possibility after hemithyroidectomy, with a highly variable incidence in the literature ranging from 8 to 60 %. Incidence of hypothyroidism after hemithyroidectomy was evaluated with a secondary aim to assess incidence in patients with Hashimoto's disease.

MATERIALS & METHODS

A retrospective study using the TriNetX global federated research network was performed. We included patients within the last 15 years that were ≥18 years of age and had Current Procedural Terminology codes for hemithyroidectomy. Patients were excluded if they had a total or completion thyroidectomy at any time, a history of thyroid cancer, were preoperatively either on levothyroxine, diagnosed with hypothyroidism, or had a Thyroid Stimulating Hormone ≥ 4 m[IU]/L. We assessed the 3 month incidence of hypothyroidism postoperatively based on the International Classification of Diseases code, TSH ≥ 4 m[IU]/L, or taking levothyroxine after surgery.

RESULTS

6845 patients met the inclusion criteria. Most of the cohort was female (67 %) and white (63 %). The mean age at surgery for this population was 54 ± 14.8 years. During the 15 years of data, we found the 3-month incidence of hypothyroidism following hemithyroidectomy to be 23.58 %. The median time to develop the disease was 41.8 months. A subgroup analysis of those with Hashimoto's revealed a 3-month incidence of 31.1 % of patients developing hypothyroidism after surgery.

CONCLUSIONS

This population-based study gives additional insight into the incidence of hypothyroidism after hemithyroidectomy. This will help improve perioperative patient counseling and management.

SNP rs11185644 in RXRA gene and SNP rs2235544 in DIO1 gene predict dosage requirements in a cross-sectional sample of hypothyroid patients

BACKGROUND AND PURPOSE

Primary hypothyroidism due to abnormality in the thyroid gland is the most common endocrine disease The recommended starting dose of levothyroxine replacement therapy is 1.6 µg/kg. This dose however is not optimal for every patient and dose adjustments are frequently done. Genetic polymorphisms in the absorption and metabolism pathway of levothyroxine are likely to influence its dose requirements. This study aimed to study the influence of genetic polymorphisms on levothyroxine replacement requirements.

METHODS

This was a cross-sectional study. Participants were recruited through a private nutrition clinic and through announcements distributed in the University of Petra in Amman, Jordan between September 2020 and February 2021. Hypothyroid patients had already been on stable doses of levothyroxine for the previous 3 months. A questionnaire was distributed to collect demographic and clinical information and a blood sample was taken for DNA extraction and clinical biochemistry analysis. rs11249460, rs2235544, rs225014, rs225015, rs3806596, rs11185644, rs4588, rs602662 were analyzed using Applied Biosystems TaqMan™ SNP Genotyping Assays on Rotor-Gene® Q and rs3064744 by direct sequencing. SPSS and Excel were used to perform analysis.

RESULTS

76 patients were studied. The equation we calculated to find predicted daily dose of levothyroxine (mcg/kg) is 3.22+ (0.348 for CT genotype of rs11185644, 0 for other genotypes) + 0.027*disease duration (years) - 0.014*age (years) - 0.434*T3 (pmol/L) levels+ (0.296 for CC genotype of rs2235544, 0 for other genotypes).

CONCLUSION

SNP rs11185644 in RXRA gene and SNP rs2235544 in DIO1 affect dose requirement in hypothyroid patients and if confirmed in larger trials they can be used to individualize thyroxine starting doses.

Clinical phenotypes of euthyroid, hyperthyroid, and hypothyroid thyroid-associated ophthalmopathy

OBJECTIVE

To compare the demographic and clinical phenotypes of thyroid-associated ophthalmopathy (TAO) with euthyroidism (Eu-TAO), hyperthyroidism (Hr-TAO), and hypothyroidism (Ho-TAO).

METHODS

We enrolled 2158 TAO patients in this retrospective study and assessed their demographics, clinical manifestations, activity, and severity.

RESULTS

Among the enrolled patients, 526 (24.37%) had Eu-TAO, 1544 (71.55%) had Hr-TAO, and 88 (4.08%) had Ho-TAO. Compared to Hr-TAO (2.02) and Ho-TAO (2.52) patients, Eu-TAO (1.57) patients had the lowest female-to-male ratio (p = 0.026). The mean ages of Eu-TAO, Hr-TAO, and Ho-TAO patients were 43.11 ± 12.05, 42.23 ± 13.63, and 47.39 ± 13.28 years, respectively (p = 0.001). Patients with Eu-TAO had more unilateral involvement (50% vs. 14.38% vs. 21.59%, p < 0.001) than Hr-TAO or Ho-TAO patients. Clinically active TAO patients presented 8.56% in euthyroid vs. 13.86% in hyperthyroid vs. 11.36% in hypothyroid (p = 0.006). Regarding the severity of the European Group on Graves' Orbitopathy (EUGOGO) classification among euthyroid, hyperthyroid, and hypothyroid patients, mild TAO was present in 67.68, 54.27, and 72.72% of participants, moderate-to-severe TAO in 31.18, 42.49, and 26.14%, and sight-threatening TAO in 1.14, 3.24, and 1.14%, respectively. Eu-TAO was positively correlated with unilateral involvement (OR = 5.671, p < 0.001) and age (OR = 1.013, p = 0.003) and negatively correlated with the female-to-male ratio (OR = 0.656, p < 0.001) and TAO severity (OR = 0.742, p < 0.01).

CONCLUSIONS

Eu-TAO patients are older and less likely to be female, and show more unilateral and milder clinical phenotypes than hyper/hypothyroid TAO patients.

Association of hypothyroidism with acute COVID-19: a systematic review

OBJECTIVE

There is an increasing body of literature on the impact of COVID-19 on the pituitary-thyroid axis. Therefore, we conducted a systematic review to assess the prevalence of hypothyroidism in patients with COVID-19.

METHODS

A literature review was conducted using LitCOVID for study selection in PubMed and MEDLINE till May 2021. All relevant original articles evaluating thyroid dysfunction were included and information regarding the prevalence of hypothyroid disease in COVID-19 was retrieved from the eligible articles.

RESULTS

Out of 32 articles, six articles qualified for the final analysis which included 1160 patients. There was significant heterogeneity among the included articles. Most of the patients had lower mean triiodothyronine (T3) and normal or low thyroid-stimulating hormone (TSH). Increased TSH ranged from 5.1% to 8% while low T3 was present in up to 28% of the patients. In these studies, the prevalence of altered thyroid hormones was significantly more in COVID-19 patients as compared to control groups. A positive correlation between low mean T3 and clinical severity of COVID-19 was reported.

CONCLUSION

This systematic review reveals a significant proportion of hypothyroidism associated with COVID-19. Therefore, routine assessment of thyroid function is warranted in hospitalized COVID-19 patients.

Comparison of Dosing Schemes for Thyroid Hormone Replacement Therapy After Thyroidectomy

BACKGROUND

Current thyroid hormone replacement therapy (THRT) is built on weight-based standard calculation of dose. A novel Poisson regression model, which accounts for seven clinical variables, was recently proposed to improve accuracy of THRT. We aimed to compare the accuracy of estimated THRT dose to reach euthyroid and the difference in predicted dose between the Poisson (scheme A) and the weight-based standard (scheme B) in patients following total thyroidectomy for benign disease.

METHODS

We retrospectively reviewed medical record of patients who underwent total or completion thyroidectomy for benign disease at a single institution between 2011 and 2019. The THRT dose was calculated using both schemes. We compared the difference between calculated THRT and prediction rates for optimal THRT dosing needed to achieve a euthyroid state between dosing schemes. Patients were evaluated for achieving euthyroid state, defined as TSH 0.45-4.5 mIU/L. We also compared dosing error rates (> 25 mcg over- and underdosing) between schemes. Prediction rates were compared by BMI tertiles to account for the effect of BMI extremes in achieving euthyroid state. The difference in predicted dose between schemes was calculated in both the total sample size and patients that met euthyroid. A measure of agreement, Kappa, was used to estimate agreement between dosing schemes.

RESULTS

A total of 406 patients underwent total thyroidectomy for benign disease, with 184 having sufficient follow up data confirming euthyroid state. Of the 184 patients, 85.9% (n = 158) were women, 81% (n = 149) were Hispanic, and 56.5% (n = 104) were obese with a median BMI of 30.8 kg/m2. Scheme A resulted in a higher, but not statistically significant, accuracy rate (A: 60.3%, n = 111 versus B: 53.8%, n = 99; P = 0.21). Overdosing errors were lower with Scheme A (A:17.9% versus B: 32.1%; P = 0.0025) and less extreme > 25 µg (A: 17.9% versus B: 26.1%; P = 0.08). A trend in improved accuracy in patients with a BMI > 35 kg/m2 was noted (A: 46.9% versus B: 34.4%; P = 0.20). Scheme A also resulted in less overdosing errors in obese patients compared to Scheme B (A: 19.2% versus 45.2%; P = 0.0006). The average difference in predicted dose between schemes was an entire dose difference, mean of 16.0 µg and 15.8 µg for the total and euthyroid samples respectively. Furthermore, for the majority of patients the predicted dose did not match between the two dosing schemes for total and euthyroid samples, 76% (n = 311) and 76% (n = 141) respectively. In patients that achieved euthyroid, agreement between dosing schemes was low to moderate (Kappa = 0.360).

CONCLUSIONS

Lower rates of overdosing were found for scheme A, particularly with obese patients. No statistically significant differences in predicted THRT dose was observed between schemes. The difference in predicted dose between schemes was on average 15 ug, correlating with an entire dose. The consideration of clinical variables other than weight (scheme A) when determining optimal THRT dosing may be of importance to prevent overdoses, with particular clinical relevance in patients with higher BMIs.

Effect of thiamazole on kainic acid-induced seizures in mice

Kainic acid (KA) induced epileptic seizures in mice is a commonly used experimental model of epilepsy. Previous studies have suggested the roles of various neurotransmitters and oxidative stress in KA-induced seizures. An important role of hypothyroidism has also been suggested in epilepsy. Thiamazole (TZ) is an anti-hyperthyroid drug with antioxidant property. This study reports the effect of TZ on KA-induced epileptic seizures in mice, produced by intraperitoneal (IP) injection of KA (18 mg/kg). Prior to KA injection, the animals were treated with TZ (12.5, 25 and 50 mg/kg IP). Our results showed that in KA alone group, about half of the animals developed seizures. Pre-treatment of mice with TZ significantly increased the frequency of seizures in dose-dependent manner. Administration of TZ significantly reduced the latency time and aggravated the severity of seizures. TZ also increased the mortality in KA-treated mice. Striatal dopamine and serotonin levels were markedly increased in KA alone treated mice, which were not significantly affected by TZ treatment. Among the indices of oxidative stress, we observed a significant reduction in cerebral vitamin E whereas the levels of cerebral malondialdehyde and conjugated dienes were significantly increased in animals with high severity of seizures. In conclusion, TZ potentiated the frequency and severity of experimental seizure in mice. There is a possibility of altered metabolism of KA in presence of TZ that might have potentiated the toxicity of KA. These findings suggest a caution while administering anti-hyperthyroid drugs in epileptic seizures.

Standard hypothyroid treatment did not restore proper metabolic response to carbohydrate

PURPOSE

Hypothyroidism is associated with a lower metabolic rate, impaired glucose tolerance, and increased responsiveness of sympathetic nervous system to glucose ingestion. The Levothyroxine (LT4) monotherapy is the standard treatment for hypothyroidism; however to what extent this treatment restores the patients' metabolism has not been verified. The aim of this study was to test the hypothesis that standard LT4 therapy may not restore proper metabolic response to carbohydrate ingestion.

METHODS

Energy expenditure, glucose tolerance, and catecholamine response to glucose ingestion were compared in 18 subjects with pharmacologically compensated hypothyroidism (PCH) and controls, at baseline and during oral glucose tolerance test conditions.

RESULTS

Metabolic rate was significantly lower in PCH (P < 0.0001). Glucose tolerance was decreased in this group with no differences in insulin resistance indicators between both groups. Adrenergic activity (P < 0.05) as well as adrenergic reaction to glucose ingestion (P < 0.001) were stronger in PCH.

CONCLUSIONS

Standard treatment for hypothyroidism does not restore the normal metabolic reaction to carbohydrate which is observed in healthy people.

Prospective role of thyroid disorders in monitoring COVID-19 pandemic

COVID-19 pandemic has affected more than 200 countries and 1.3 million individuals have deceased within eleven months. Intense research on COVID-19 occurrence and prevalence enable us to understand that comorbidities play a crucial role in spread and severity of SARS-CoV-2 infection. Chronic kidney disease, diabetes, respiratory diseases and hypertension are among the various morbidities that are prevalent in symptomatic COVID-19 patients. However, the effect of altered thyroid-driven disorders cannot be ignored. Since thyroid hormone critically coordinate and regulate the major metabolism and biochemical pathways, this review is on the potential role of prevailing thyroid disorders in SARS-CoV-2 infection. Direct link of thyroid hormone with several disorders such as diabetes, vitamin D deficiency, obesity, kidney and liver disorders etc. suggests that the prevailing thyroid conditions may affect SARS-CoV-2 infection. Further, we discuss the oxidative stress-induced aging is associated with the degree of SARS-CoV-2 infection. Importantly, ACE2 protein which facilitates the host-cell entry of SARS-CoV-2 using the spike protein, are highly expressed in individuals with abnormal level of thyroid hormone. Altogether, we report that the malfunction of thyroid hormone synthesis may aggravate SARS-CoV-2 infection and thus monitoring the thyroid hormone may help in understanding the pathogenesis of COVID-19.

Ketogenic diet as a potential intervention for lipedema

Lipedema (LI) is a common yet misdiagnosed condition, often misconstrued with obesity. LI affects women almost exclusively, and its painful and life-changing symptoms have long been thought to be resistant to the lifestyle interventions such as diet and exercise. In this paper, we discuss possible mechanisms by which patients adopting a ketogenic diet (KD) can alleviate many of the unwanted clinical features of LI. This paper is also an effort to provide evidence for the hypothesis of the potency of this dietary intervention for addressing the symptoms of LI. Specifically, we examine the scientific evidence of effectiveness of adopting a KD by patients to alleviate clinical features associated with LI, including excessive and disproportionate lower body adipose tissue (AT) deposition, pain, and reduction in quality of life (QoL). We also explore several clinical features of LI currently under debate, including the potential existence and nature of edema, metabolic and hormonal dysfunction, inflammation, and fibrosis. The effectiveness of a KD on addressing clinical features of LI has been demonstrated in human studies, and shows promise as an intervention for LI. We hope this paper leads to an improved understanding of optimal nutritional management for patients with LI and stimulates future research in this area of study.

Should cardiac surgery be delayed in patients with uncorrected hypothyroidism?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: 'should cardiac surgery be delayed in patients with uncorrected hypothyroidism?' A total of 1412 papers were found using the reported search, of which 7 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. There was limited high-quality evidence with the majority of the studies being retrospective. One propensity-matched analysis and 6 cohort studies provided the evidence that there was no significant difference in the rate of major adverse cardiac events including mortality based on thyroid status. However, hypothyroidism and subclinical hypothyroidism were associated with higher rates of postoperative atrial fibrillation. Based on the available evidence, we conclude that cardiac surgery should not be delayed to allow achievement of euthyroid status.

Decompensated hypothyroidism: A review for the emergency clinician

BACKGROUND

Decompensated hypothyroidism, formerly known as myxedema coma, is an endocrine emergency that commonly presents with altered mental status, as well as hypothermia and depressed vital signs. The condition is often caused by an inciting event, which may lead to significant delays in the diagnosis and management of this disease. Although the incidence is low, this disease is associated with significant morbidity and mortality. Therefore, it is important for emergency clinicians to be aware of this condition.

OBJECTIVE

This narrative review evaluates the emergency medicine diagnosis and management of adult patients with decompensated hypothyroidism.

DISCUSSION

Decompensated hypothyroidism is a severe hypothyroid state associated with multiple organ failure. The diagnosis can be challenging due to similarities with more common diseases and lack of consideration of the diagnosis. Many patients may present with altered sensorium or depressed vital signs. Clinicians should obtain a thyroid stimulating hormone and free thyroxine level when considering the diagnosis. Management involves resuscitation, early steroid supplementation, thyroid hormone replacement, and treatment of the inciting event.

CONCLUSIONS

Decompensated hypothyroidism should be considered in the evaluation of patients with altered sensorium and depressed vital signs so as to not miss this critical diagnosis.

A novel thyroid hormone receptor alpha gene mutation, clinic characteristics, and follow-up findings in a patient with thyroid hormone resistance

Thyroid hormone receptor alpha (THRA) gene mutation is a thyroid hormone resistance syndrome characterized by near-normal thyroid function tests and tissue-specific hypothyroidism. In this case study, we report a novel de novo p.G291S heterozygous mutation in the THRA gene was detected at mutation analysis. A 4-year-old male patient was admitted due to short stature, motor-mental retardation, and constipation. At physical examination, coarse facial appearance, eyelid edema, pallor, and umbilical hernia were observed. Primary thyroid hormone resistance should be considered in patients with phenotypically hypothyroid features. Laboratory analysis found moderate elevation in free triiodothyronine (T3) levels, normochromic normocytic anemia, and elevated creatine kinase levels. In conclusion, THRA gene mutation should be considered in patients with clinical hypothyroid findings and increased/moderately elevated free T3, decreased/ normal free thyroxine, normal thyroid-stimulating hormone levels, and increased muscle enzymes.

Interactive Effects of Exercise, Sex Hormones, and Transient Congenital Hypothyroidism on Long-Term Potentiation in Hippocampal Slices of Rat Offspring

Introduction:

The long-term adverse effects of transient thyroid function abnormalities at birth on intellectual development are proven. The effect of exercise increases in the presence of sex hormones. The current study aimed at investigating the possibility that a combination of sex hormones and exercise has synergistic effects on neural plasticity in Transient Congenital Hypothyroidism (TCH) rats.

Methods:

To induce hypothyroidism in the mothers, Propylthiouracil (PTU) was added to drinking water (100 mg/L) on the 6th day of gestation and continued until the 21^st Postnatal Day. From Postnatal Day (PND) 28 to 47, the female and male pups received 17β-estradiol and testosterone, respectively. The mild treadmill exercise began 30 minutes after the sex hormones or vehicle administration. On PND 48, electrophysiological experiments were performed on brain slices.

Results:

Increase of Long-Term Potentiation (LTP) was observed in sedentary-non-hormone female rats of TCH group, compared with that of the control. The exercise enhanced LTP in control rats, but the hormones showed no significant effect. The effect of exercise and sex hormone was not significant in the TCH group. The combination of exercise and testosterone enhanced LTP in TCH male rats, while the combination of exercise and estradiol or each of them individually did not produce such an effect on LTP in TCH female rats.

Conclusion:

The study findings showed an increase in excitatory transmission despite the returning of thyroid hormone levels to normal range in TCH female rats. Also a combination treatment including exercise and testosterone enhanced LTP in male rats of TCH group, which was a gender-specific event.

Assessment of hair cortisol in euthyroid, hypothyroid, and subclinical hypothyroid subjects

PURPOSE

Hypothyroidism is associated with an increase in serum cortisol level while the long-term activity of hypothalamic-pituitary-adrenal (HPA) axis in hypothyroid, and subclinical hypothyroid (SCH) subjects has not been studied. This study aimed to assess the hair cortisol levels as a long-term activity of HPA axis in hypothyroid, SCH and a group of healthy adult subjects. Also, it aimed to examine the correlation of hair cortisol levels with hypothalamic-pituitary-thyroid (HPT) axis and anthropometric measures.

METHODS

We prospectively evaluated a group of normal, SCH and hypothyroid subjects. Serum TSH, FT4, and FT3 were measured as a component of the HPT axis. Hair samples were collected, prepared, followed by extraction of hair cortisol and measurement in pg/mg of hair. Hair cortisol levels were compared in normal, SCH and hypothyroid groups and correlated with HPT axis and anthropometric data.

RESULTS

A total of 65 healthy volunteers were analyzed, and the mean hair cortisol level was reported to be 17.38 pg/mg of hair. Hair cortisol level was slightly higher in the SCH subjects, 18.19 pg/mg of hair; however the difference was not significant. Compared to the euthyroid subject, a significantly higher hair cortisol level was recorded in the hypothyroid subjects, 24.17 pg/mg hair, p < .05. Hair cortisol was significantly and positively associated with each of the serum TSH, age, weight and BMI (p < .05).

CONCLUSIONS

Overt hypothyroidism but not SCH is significantly associated with higher hair cortisol levels compared to normal subjects, and a significant relation between hair cortisol with HPT axis was found. Also, weight and BMI were positively correlated with hair cortisol level.

Effect of Thyroid Hormone Derangements on Sexual Function in Men and Women

INTRODUCTION

Sexual dysfunction affects many people, with 33‒60% of women reporting sexual dysfunction and 8‒52% of men with erectile dysfunction or premature ejaculation. In an effort to determine the constellation of factors responsible for sexual dysfunction, the effect of thyroid hormone derangements has been of recent interest.

AIM

To investigate the associations between thyroid hormones and sexual dysfunction in women and men.

METHODS

Literature was reviewed to examine the effects of hypo- and hyperthyroidism on sexual function.

MAIN OUTCOME MEASURE

We present a summary of the effects of thyroid dysfunction on domains of sexual functioning.

RESULTS

Most studies demonstrate that men with hypo- and hyperthyroidism have increased rates of sexual dysfunction, including erectile dysfunction in men with hypothyroidism. However, studies vary on the strength of correlation between hormonal derangement and level of sexual dysfunction. In both men with hyper- and hypothyroidism, treating the thyroid disorder at least partially reverses sexual dysfunction. In contrast, the current literature provides no consensus on the effect of hypothyroidism, hyperthyroidism, or Hashimoto's thyroiditis on female sexual function. In studies that observed increased rates of sexual dysfunction in women with thyroid disorders, correction of the thyroid derangement resulted in resolution of some sexual dysfunction. Studies are also conflicted on whether there is a relationship between the degree of sexual dysfunction and the degree of hormone derangement in women. However, prior work has demonstrated a relationship between thyroid autoantibodies and sexual dysfunction in women.

CONCLUSION

Thyroid dysfunction is an important factor in the pathogenesis of sexual dysfunction in men and possibly women. Evidence suggests a reversibility of sexual dysfunction with correction of thyroid dysfunction, although the exact pathophysiology of thyroid-mediated sexual dysfunction remains unknown. However, current evidence supports thyroid derangements rather than autoantibodies as the causative factor in men, whereas autoantibodies appear to play a more prominent role in women. Bates JN, Kohn TP, Pastuszak AW. Effect of Thyroid Hormone Derangements on Sexual Function in Men and Women. Sex Med Rev 2020;8:217-230.

The Effects of Vitamin D Supplementation on Thyroid Function in Hypothyroid Patients: A Randomized, Double-blind, Placebo-controlled Trial

BACKGROUND

Data on the effects of vitamin D supplementation on thyroid function in hypothyroid patients are scarce.

OBJECTIVE

This study was done to evaluate the effects of vitamin D supplementation on thyroid function in hypothyroid patients.

MATERIAL AND METHODS

This randomized double-blind, placebo-controlled trial was conducted on 201 hypothyroid patients aged 20-60 years old. Subjects were randomly assigned into two groups to intake either 50,000 IU vitamin D supplements (n = 102) or placebo (n = 99) weekly for 12 weeks. Markers of related with thyroid function were assessed at first and 12 weeks after the intervention.

RESULTS

After 12 weeks of intervention, compared to the placebo, vitamin D supplementation resulted in significant increases in serum 25-hydroxyvitamin D (+26.5 ± 11.6 vs. 0.0 ± 0.0 ng/mL, P < 0.001) and calcium (+0.4 ± 0.7 vs. 0.1 ± 0.6 mg/dL, P = 0.002), and a significant decrease in serum thyroid-stimulating hormone (TSH) levels (-0.4 ± 0.6 vs. +0.1 ± 2.0 μIU/mL, P = 0.02). A trend towards a greater decrease in serum parathyroid hormone (PTH) levels was observed in vitamin D group compared to placebo group (-3.8 vs. +1.9, P = 0.07). We did not observe any significant changes in serum T3, T4, alkaline phosphatase (ALP) and albumin levels following supplementation of vitamin D compared with the placebo.

CONCLUSION

Overall, the current study demonstrated that vitamin D supplementation among hypothyroid patients for 12 weeks improved serum TSH and calcium concentrations compared with the placebo, but it did not alter serum T3, T4, ALP, PTH, and albumin levels.

Thyroid Hemiagenesis in a Thyroiditis Prone Mouse Strain

BACKGROUND

Thyroid hemiagenesis, a rare congenital condition detected by ultrasound screening of the neck, is usually not manifested clinically in humans. This condition has been reported in mice with hypothyroidism associated with induced deficiency in paired box 8 and NK2 homeobox 1, sonic hedgehog, or T-box 1. Unexpectedly, we observed thyroid hemiagenesis in NOD.H2^h4 mice, an unusual strain that spontaneously develops iodide enhanced thyroid autoimmunity but remains euthyroid.

OBJECTIVES AND METHODS

First, to compare mice with thyroid hemiagenesis versus bilobed littermates for serum T4, autoantibodies to thyroglobulin (ELISA) and thyroid peroxidase (TPO; flow cytometry with eukaryotic cells expressing mouse TPO), gross anatomy, and thyroid histology; second, to estimate the percentage of mice with thyroid hemiagenesis in the NOD.H2^h4 mice we have studied over 6 years.

RESULTS

Thyroid hemiagenesis was observed in 3 of 1,025 NOD.H2^h4 mice (2 females, 1 male; 0.3$). Two instances of hemiagenesis were in wild-type females and one in a transgenic male expressing the human TSHR A-subunit in the thyroid. Two mice had very large unilobed glands, as in some human cases with this condition. Thyroid lymphocytic infiltration, serum T4, and the levels of thyroid autoantibodies were similar in mice with thyroid hemiagenesis and bilobed littermates.

CONCLUSIONS

Unlike hypothyroidism associated with hemiagenesis in transcription factor knockout mice, hemiagenesis in euthyroid NOD.H2^h4 mice occurs spontaneously and is phenotypically similar to that occasionally observed in humans.

Free triiodothyronine level correlates with statin responsiveness in acute myocardial infarction

BACKGROUND

Although thyroid hormone (TH) has important effects on lipid metabolism, the relationship between TH and statin responsiveness has never been investigated. We hypothesize that TH plays an important role in statin responsiveness in patients with acute myocardial infarction (AMI).

METHODS

Consecutive 1091 hospitalized AMI patients in Fuwai hospital (Beijing, China) were enrolled into this current study. The study population was divided into three groups based on the intensity of statin treatment: low-intensity (n = 221), moderate-intensity (n = 712) and high-intensity (n = 158). Lipid levels were measured after statin therapy lasting for 10-14 days. The association between TH, lipid profile levels and achievement of low-density lipoprotein cholesterol (LDL-C) lowering goals was explored in patients with AMI on statin therapy.

RESULTS

By general linear analysis, a significant linear trend between free triiodothyronine (FT3) and LDL-C level (linear coefficient r = -0.082, P = 0.001) and FT3 and total cholesterol (TC) level (r = -0.105, P = 0.031) was observed in the moderate-intensity statin group. A more apparent linear trend was detected in the high-intensity statin group (for LDL-C: r = -0.113, P = 0.005; for TC: r = -0.172, P = 0.029, respectively). However, no significant correlation was observed in the low-intensity statin group. Compared with the low-FT3 group (defined as FT3 < 1.79 pg/mL), the OR (95% CI) for attaining a LDL-C < 3.0mmol/L was found to be 2.217 (1.001-4.839) in the higher FT3 group (> 2.95 pg/mL). The OR (95% CI) for attaining the more intensive goal (LDL-C < 1.8mmol/L) was 2.836 (1.014-5.182).

CONCLUSIONS

Our study reveals that variation in FT3 levels is related to the cholesterol-lowering responsiveness of statins in AMI patients. These findings suggest that low FT3 may be a factor responsible for lack of LDL-C goal attainment and patients' poor responsiveness to statin treatment.

Association between genetic polymorphism and levothyroxine bioavailability in hypothyroid patients

Thyroid hormones play a vital role in the human body for growth and differentiation, regulation of energy metabolism, and physiological function. Hypothyroidism is a common endocrine disorder, which generally results from diminished normal circulating concentrations of serum thyroxine (fT4) and triiodothyronine (fT3). The primary choice in hypothyroidism treatment is oral administration of levothyroxine (L-T4), a synthetic T4 hormone, as approximately 100-125 μg/day. Generally, dose adjustment is made by trial and error approach. However, there are several factors which might influence bioavailability of L-T4 treatment. Genetic background could be an important factor in hypothyroid patients as well as age, gender, concurrent medications and patient compliance. The concentration of thyroid hormones in tissue is regulated by both deiodinases enzyme and thyroid hormone transporters. In the present study, it was aimed to evaluate the effects of genetic differences in the proteins and enzymes (DIO1, DIO2, TSHR, THR and UGT) which are efficient in thyroid hormone metabolism and bioavailability of L-T4 in Turkish population. According to our findings, rs225014 and rs225015 variants in DIO2, which catalyses the conversion of thyroxine (pro-hormone) to the active thyroid hormone, were associated with TSH levels. It should be given lower dose to the patients with rs225014 TT and rs225015 GG genotypes in order to provide proper treatment with higher effectivity and lower toxicity.

Influence of thyroid function on glomerular filtration rate and other estimates of kidney function in two pediatric patients

To determine the optimal method of evaluating kidney function in patients with thyroid dysfunction, this study compared the estimated glomerular filtration rate derived from serum creatinine, cystatin C, or β2-microglobulin with inulin or creatinine clearance in two pediatric patients, one with hypothyroidism and the other with hyperthyroidism. It was observed that the kidney function decreased in a hypothyroid child and enhanced in a hyperthyroid child, with their kidney function becoming normalized by treatment with drugs, which normalized their thyroid function. Kidney function cannot be accurately evaluated using cystatin C-based or β2-microglobulin-based estimated glomerular filtration rate in patients with thyroid dysfunction, as these tests overestimated glomerular filtration rate in a patient with hypothyroidism and underestimated glomerular filtration rate in a patient with hyperthyroidism, perhaps through a metabolic rate-mediated mechanism. In both our patients, 24-h urinary creatinine secretion was identical before and after treatment, suggesting that creatinine production is not altered in patients with thyroid dysfunction. Therefore, kidney function in patients with thyroid dysfunction should be evaluated using creatinine-based estimated glomerular filtration rate.

The Effects of Hydroalcoholic Extract of Nigella sativa Seeds on Serum Estradiol and Prolactin Levels and obstetric Criteria due to Hypothyroidism in Rat

Background:

The aim of this study was investigation of the effects of Nigella sativa (NS) seeds on hypothyroid pregnant rats and their progenies.

Materials and Methods:

Hypothyroidism was induced by propylthiouracil (PTU) 0.03% in drinking water. Female rats were divided into seven groups: control, PTU, PTU-NS (100, 200, and 400 mg/kg), and NS (100 and 400 mg/kg). All treatments were done 20 days before mating and during pregnancy. The weight of rat dams and progenies, number of progenies and serum T4, estradiol and prolactin (PRL) levels in rat dams were measured for all groups.

Results:

Serum T4 in all PTU-NS groups before mating was significantly increased versus PTU group. Body weight of rat dams before mating in all groups of PTU-NS was increased versus PTU group by P < 0.001, P < 0.05, and P < 0.001, respectively and in NS 100 and NS 400 was increased versus control group (P < 0.001). The number of offspring was significantly decreased in PTU and PTU-NS versus control group. The weight of progenies in NS 400 was higher than control group (P < 0.001) and was increased in PTU-NS 200 and PTU-NS 400 versus PTU group by P < 0.001 and P < 0.05, respectively. Serum PRL level in rat dams in control, PTU, and PTU-NS groups were not statistically different between groups but significantly increased in NS 400 group when compared to control group. Estradiol levels were not significantly different in rat dams at 5 days after delivery.

Conclusion:

These results demonstrated that feeding of rat dams with NS extract before mating has positive protective effects on progenies. These effects may be due to antioxidant properties of NS in reducing oxidative stress and thyroid damages induced by PTU.

Association between thyroid hormone parameters and dyslipidemia among type 2 diabetes mellitus patients: Comparative cross-sectional study

BACKGROUND

The relationship between thyroid function and lipid profile has been documented in T2DM and healthy subjects. The aim of the current study was to assess the association between thyroid hormone parameters and dyslipidemia in T2DM and non-diabetic study participants.

METHOD AND MATERIALS

In this comparative cross-sectional study, 214 type 2 diabetic and 214 non-diabetic study participants were enrolled. Clinical and anthropometric data were collected from all study participants. After overnight fasting, 10ml of whole blood samples were drawn for the measurement of serum TSH, free thyroxine (fT4), free triiodothyronine (fT3), serum reactive C-protein levels, as well as for lipid profile test and glucose.

RESULT

The burden of hypothyroidism and subclinical hypothyroidism among T2DM study participants were 73 (17.05%) and 13 (3.04%) respectively. Comparatively, T2DM study participants had significantly higher serum lipid level than non-diabetics. Stratified by TSH, hypothyroid T2DM study participants had increased lipid level than euthyroid subjects. T2DM serum TSH have shown a positive significant correlation with all lipid profile parameters except HDL-C. In the final model (multivariate linear regression), diabetics serum TSH significantly and positively associated with TG and BMI. Diabetic serum fT3 and fT4 negatively associated with body mass index. In addition, diabetics serum fT3 negatively and serum fT4 positively associated with TC and HDL-C respectively.

CONCLUSION

T2DM study subjects had significantly higher lipid level than nondiabetic and We identified that TSH was positively associated with serum TG and BMI among T2DM study participants.

TSH cut off point based on depression in hypothyroid patients

BACKGROUND

The prevalence of depressive symptoms in hypothyroidism is high. Considering that hypothyroidism and depression share some clinical features, some researchers use the "brain hypothyroidism" hypothesis to explain the pathogenesis of depression. We aimed to detect a new TSH cut-off value in hypothyroidism based on depression symptoms.

METHODS

A cross-sectional study was conducted on hypothyroid patients referred to endocrine clinics. Individuals who had developed euthyroid state under treatment with levothyroxine with TSH levels of 0.5-5 MIU/L with no need for dosage change were included in the study. After comprehensive history taking, laboratory tests including TSH, T4 and T3 were performed. Beck depression questionnaire was completed for all patients by trained interviewers. TSH cut-off values based on depression was determined by Roc Curve analysis.

RESULTS

The participants were 174 hypothyroid patients (Female; 116: 66.7%, Male; 58: 33.3%) with mean age 45.5 ± 11.7 (19-68) years old. Based on Beck depression test, scores less than 10 was considered healthy and more than 10 were considered depressed. According to Roc curve analysis, the optimal cut- off value of TSH was 2.5 MIU/L with 89.66% sensitivity. The optimal TSH cut- off based on severe depression was 4 MIU/L.

CONCLUSION

The present study suggests that a clinically helpful TSH cut-off value for hypothyroidism should be based on associated symptoms, not just in population studies. Based on the assessment of depression, our study concludes that a TSH cutofff value of 2.5 MIU/L is optimal.

Childhood adversities and chronic conditions: examination of mediators, recall bias and age at diagnosis

OBJECTIVES

The aim of this study was to (1) identify the influence of childhood socioeconomic status (CSES) on five chronic conditions: asthma, bronchitis, hypothyroid, migraine, and psychiatric disorders in later life; (2) determine the mediating role of childhood abuse (CA) in these associations, and (3) quantify recall bias due to respondent's mental health in these associations.

METHODS

10,325 men and women from the Tromsø Study were followed for 13 years, and Poisson regression models were used.

RESULTS

Low CSES was associated with a 16-23% higher risk of chronic conditions, and CA was associated with a 16-58% higher risk of chronic conditions (p < 0.05). A minor proportion of the association between CSES and CA (3.98%, p < 0.05); CSES and chronic conditions (5.54-8.71%, p < 0.05); and CA and chronic conditions (9.51-19.52%, p < 0.05), were driven by recall bias due to the respondent's mental health. CA mediated the association between CSES and chronic conditions (9.58-25.06%, p < 0.05).

CONCLUSIONS

Low CSES and CA are associated with higher risk of chronic conditions in later life. A minor proportion of these associations are driven by recall bias.

Effects of aerobic and anaerobic exercise on spatial learning ability in hypothyroid rats: a pilot study

[Purpose] This pilot study analyzed the degradation of spatial learning ability caused by hypothyroidism using aerobic and anaerobic exercise. [Subjects and Methods] The experiments were performed on 11, four-week-old male Sprague-Dawley rats. Hypothyroidism-induced rats receiving propylthiouracil (PTU) treatment were divided into aerobic exercise, anaerobic exercise, and control groups. Each group performed exercise and rest for four weeks. Changes in lethargy, memory deterioration, and thyroid function were measured in each group by blood analysis and open field and Morris water maze tests. [Results] After four weeks, blood analysis revealed that the thyroid hormone levels had returned to normal in the aerobic exercise, anaerobic exercise, and control groups, whereas the open field and Morris water maze tests showed that the aerobic and anaerobic exercise groups had faster recovery compared to that of the control group. In addition, comparison of aerobic and anaerobic groups showed that the anaerobic exercise group had faster recovery compared to that of the aerobic group. [Conclusion] The findings of this study suggest that exercise helped to improve lethargy and deteriorated spatial learning ability caused by hypothyroidism and to recover function in rats. Anaerobic exercise was more beneficial than aerobic exercise in alleviating symptoms.

Myopathy in Pediatric Thyroid States: A Review of the Literature

This review highlights the presentations of myopathy in children in both hypothyroid and hyperthyroid states with an emphasis on the pathophysiology, diagnosis and treatment. Based on our review of the literature data, myopathy should be considered in all children presenting with muscular weakness or altered muscle enzymes in the context of thyroid disease.

Exogenous apelin changes alpha and beta myosin heavy chain mRNA expression and improves cardiac function in PTU-induced hypothyroid rats

The most important conditions associated with hypothyroidism is the cardiac dysfunction. Apelin is an endogenous ligand, involved in energy storage and metabolism which improves cardiac contractility. This study was done to evaluate the effects of apelin, l-Thyroxin (T4) or a combination of both, on cardiac function and mRNA expression of two contractile proteins, α and β myosin heavy chain (α-MHC and β-MHC), in 6-propyl-2-thiouracil (PTU)-induced hypothyroid rats. Forty male Wistar rats were randomly assigned into five groups: Ctrl (Control), and 4 hypothyroid groups (H, HA, HT, and HAT). The Hypothyroid (H) group received 0.05% PTU in the drinking water for six weeks; the next 3 groups, along with PTU, received apelin (HA, 200μg/kg/day, ip), T4 (HT, 20μg/kg/day, gavage), or a combination of both drugs (HAT) for the last 2weeks (weeks 5 and 6). TSH and T4 were measured using ELISA kit. Isolated hearts of animals were perfused in Langendorff apparatus and left ventricular developed pressure, cardiac contractility, heart rate, rate pressure product and perfusion pressure were assessed using PowerLab ADInstruments. In addition α-MHC and β-MHC mRNA expression were evaluated by RT-PCR method in heart tissue. Apelin alone or accompanied by T4 significantly increased cardiac contractility and performance as compared to hypothyroid group. Apelin also significantly increased the alpha-MHC mRNA expression and in the presence of T4 significantly decreased beta-MHC mRNA expression. It seems that apelin alone may improve cardiac function in hypothyroid rats via genomic pathways.

Effect of l-Thyroxine on Micronuclei Frequency in Peripheral Blood Lymphocytes in Clinical and Experimental Conditions

The aim was to study the genotoxic effect of high concentration of thyroxine (T4) in vivo in peripheral blood lymphocytes (PBL) of the patients suffering from thyroid disorders. The effect was compared by performing in vitro experiments with addition of increasing concentration of T4 (0.125-1 µM) in whole blood samples from healthy donors. Cytokinesis-blocked micronuclei (CBMN) assay method was used to assess the DNA damage in the PBL. The study included 104 patients which were grouped as control (n = 49), hyperthyroid (n = 31) and hypothyroid (n = 24). A significant increase in micronuclei (MN) frequency was observed in hyperthyroid patients when compared with the hypothyroid and euthyroid group thereby suggesting increased genotoxicity in hyperthyroidism (p < 0.001). A significant increase in MN frequency was observed at T4 concentration of 0.5 µM and above when compared to lower T4 concentrations (0.125 and 0.25 µM) and basal in in vitro experiments (p = 0.000). The results indicate that the T4 in normal concentration does not exhibit the genotoxic effect, as observed in both the in vivo and in vitro experiments. The toxicity of T4 increases at and above 0.5 μM concentration in vitro. Therefore acute T4 overdose should be handled promptly and effectively so as to avoid the possible genotoxic effect of high concentration of T4 in vivo.

Involvement of inducible nitric oxide synthase in the loss of cardioprotection by ischemic postconditioning in hypothyroid rats

Cardioprotection by ischemic postconditioning (IPost) is negated in hypothyroidism; the underlying mechanisms however are unknown. This study aimed at determining whether changes in Bax, Bcl-2, eNOS, and iNOS gene expressions are involved in the negating effects of IPost against ischemia-reperfusion (IR) injury in hypothyroidism. The hearts from control and hypothyroid rats were perfused in Langendorff apparatus and exposed to 30 min ischemia, followed by 120 min reperfusion and IPost. In a subgroup of hypothyroid rats, ischemia duration was extended to 40 min. Hemodynamic parameters, infarct size, and gene expressions were measured. Compared to controls, hypothyroid rats with 30 min ischemia had higher recovery of post-ischemic LVDP and ± dp/dt, confirmed by decreased CK and LDH levels (187 ± 16 vs. 485 ± 41 and 191 ± 9 vs. 702 ± 48 U/L, respectively; p<0.05), decreased infarct size (6.7 ± 1.1 vs. 46.1 ± 1.7%; p<0.05), and a reduced DNA laddering pattern. Recovery of post-ischemic LVDP and ± dp/dt decreased and infarct size increased following extension of ischemia period in hypothyroid rats. IPost increased eNOS and Bcl-2 expression by 3.2-fold and 3.7-fold and decreased Bax and iNOS expression by 79% and 38%, respectively; it also reduced IR-induced DNA laddering pattern in controls, whereas no change was observed in hypothyroid rats, regardless of the ischemia period. In conclusion, hearts from hypothyroid rats were resistant to IR injury, partly due to the lower expression of iNOS and subsequent reduction in apoptosis after IR. In hypothyroid rats, IPost was not associated with further reduction in iNOS expression and failed to provide additional cardioprotection against ischemia.

Evaluation of calcium and lead interaction, in addition to their impact on thyroid functions in hyper and hypothyroid patients

There is compelling evidence in support of interaction between calcium (Ca) and lead (Pb) in thyroid disorders. The aim of present study was to compare the level of Ca and Pb with thyroid hormones such as thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxin (FT4) in serum samples of hyperthyroid (HPRT) and hypothyroid (HPOT) patients of both genders. For comparative purpose, age-matched (25-50 years) subjects having no thyroid disorders were selected as referents/controls. The serum samples were acid-digested prior to analysis by atomic absorption spectrometry. The validity and accuracy of the methodology were checked by certified reference materials. The resulted data indicates that the mean values of Ca in serum samples of HPRT patients were significantly higher than those of referent subjects (p < 0.01), while reverse pattern was observed in the case of HPOT patients. The level of Pb was higher in the serum samples of both types of thyroid patients, but difference was significant in case of HPOT patients as compare to referent subjects (p < 0.01). A negative correlation was observed between serum Ca levels and TSH of HPRT patients (-r = 0.37-0.39, p < 0.01), while FT3 and FT4 have positive correlation (r = 0.49-0.52 and r = 0.46-0.47), p values <0.01. The Pb in serum had positive correlation with TSH (r = 0.48-0.51, p < 0.005), while negative correlation was observed for FT3 and FT4 (-r = 0.55-0.56, 0.5-0.54, p < 0.05) in HPRT patients. On the other hand, a reverse pattern was observed, for correlation of Ca and Pb with thyroid functions in HPOT patients.

Economic Evaluation of Recombinant Human Thyroid Stimulating Hormone Stimulation vs. Thyroid Hormone Withdrawal Prior to Radioiodine Ablation for Thyroid Cancer: The Korean Perspective

BACKGROUND

Previous studies have suggested that recombinant human thyroid stimulating hormone (rhTSH) stimulation is an acceptable alternative to thyroid hormone withdrawal (THW) when radioiodine remnant ablation is planned for thyroid cancer treatment, based on superior short-term quality of life with non-inferior remnant ablation efficacy. This study evaluated the cost-effectiveness of radioiodine remnant ablation using rhTSH, compared with the traditional preparation method which renders patients hypothyroid by THW, in Korean perspective.

METHODS

This economic evaluation considered the costs and benefits to the Korean public healthcare system. Clinical experts were surveyed regarding the current practice of radioiodine ablation in Korea and their responses helped inform assumptions used in a cost effectiveness model. Markov modelling with 17 weekly cycles was used to assess the incremental costs per quality-adjusted life year (QALY) associated with rhTSH. Clinical inputs were based on a multi-center, randomized controlled trial comparing remnant ablation success after rhTSH preparation with THW. The additional costs associated with rhTSH were considered relative to the clinical benefits and cost offsets.

RESULTS

The additional benefits of rhTSH (0.036 QALY) are achieved with an additional cost of Korean won W961,105, equating to cost per QALY of W26,697,361. Sensitivity analyses had only a modest impact upon cost-effectiveness, with one-way sensitivity results of approximately W33,000,000/QALY.

CONCLUSION

The use of rhTSH is a cost-effective alternative to endogenous hypothyroid stimulation prior to radioiodine ablation for patients who have undergone thyroidectomy in Korea.

Sex-Dependent Claudin-1 Expression in the Liver of Euthyroid and Hypothyroid Mice

BACKGROUND

In the liver the tight junction protein claudin-1 plays an important role in bile secretion by maintaining the paracellular barrier of bile canaliculi and the bile duct. A diminished bile excretion has been found in hypothyroid patients, and the prevalence of gallstones is increased in hypothyroidism. This association, however, only applies for men and is in contrast to the well-established female preponderance of biliary disease in the general population.

OBJECTIVES

We hypothesized that hypothyroidism could lead to altered claudin-1 expression in the liver, and that this effect may be sex specific.

METHODS

We characterized claudin-1 expression and localization in livers of euthyroid and hypothyroid male and female C57BL/6NTac mice by real-time PCR, Western blot and immunofluorescence.

RESULTS

Claudin-1 is expressed in canalicular regions and the bile ducts of the murine liver. Livers of female mice showed lower claudin-1 expression than male livers. In hypothyroid livers, female animals showed an elevated claudin-1 expression, whereas reduced claudin-1 expression was found in male animals compared to the euthyroid controls.

CONCLUSION

We demonstrate a correlation between claudin-1 expression and hypothyroidism in the murine liver. Furthermore, a sex-dependent alteration of claudin-1 expression was found.

Circulating irisin concentrations in rat models of thyroid dysfunction -- effect of exercise

OBJECTIVES

The speculation that the myokine irisin could regulate whole body energy expenditure led to the anticipation that irisin may have therapeutic potential in metabolic diseases. Regulation of irisin under conditions of metabolic derangements in altered thyroid status, and the changes in irisin response to exercise remain to be investigated.

METHODS

Serum irisin concentration was measured in sixty male Wistar rats subjected to either sedentary life or 8-week chronic swimming exercise after induction of hyper- or hypothyroidism (10 rats/group). The effect of acute exercise on serum irisin was assessed in 10 additional rats subjected once to forced swimming against a load (5% of body weight) and compared to sedentary rats.

RESULTS

Serum irisin was significantly higher in both sedentary hyper- and hypothyroid rats (by 45%, p<0.001, and 30%, p<0.001, respectively) versus euthyroid controls. Serum irisin also increased after acute exercise (p<0.001 versus sedentary control). Chronic training episodes failed to significantly alter serum irisin in all thyroid hormone profiles. Serum irisin correlated positively with serum creatine kinase (r=0.45, p<0.001) and with muscle and liver concentrations of malondialdehyde (r=0.50 and r=0.47 respectively, p<0.001 for both), and negatively with muscle and liver content of reduced glutathione (r=-0.34, p=0.003 and r=-0.28, p=0.018 respectively) in pooled groups. However, significance of these associations was waived when analyzing each group separately. Serum irisin was not associated with skeletal muscle mass, insulin resistance, blood glucose, lipids or TSH.

CONCLUSIONS

Both hyper- and hypothyroidism are associated with up-regulation of serum irisin in male rats, possibly as a response to oxidative damage and/or myopathy observed in both conditions. Acute exercise, which is also associated with oxidative stress, increases serum irisin. No obvious association was detected linking serum irisin to metabolic abnormalities in thyroid dysfunction.

Amelioration of improper differentiation of somatostatin-positive interneurons by triiodothyronine in a growth-retarded hypothyroid mouse strain

Thyroid hormone (TH) plays an important role in brain development, and TH deficiency during pregnancy or early postnatal periods leads to neurological disorders such as cretinism. Hypothyroidism reduces the number of parvalbumin (PV)-positive interneurons in the neocortex and hippocampus. Here we used a mouse strain (growth-retarded; grt) that shows growth retardation and hypothyroidism to examine whether somatostatin (Sst)-positive interneurons that are generated from the same pool of neural progenitor cells as PV-positive cells are also altered by TH deficiency. The number of PV-positive interneurons was significantly decreased in the neocortex and hippocampus of grt mice as compared with normal control mice. In contrast to the decrease in the number of PV neurons, the number of Sst-positive interneurons in grt mice was increased in the stratum oriens of the hippocampus and the hilus of the dentate gyrus, although their number was unchanged in the neocortex. These changes were reversed by triiodothyronine administration from postnatal day (PD) 0 to 20. TH supplementation that was initiated after PD21 did not, however, affect the number of PV- or Sst-positive cells. These results suggest that during the first three postnatal weeks, TH may be critical for the generation of subpopulations of interneurons.

TSH - Clinical Aspects of its Use in Determining Thyroid Disease in the Elderly. How Does it Impact the Practice of Medicine in Aging?

The last four decades have seen enormous growth in the efficacy of serum thyroid stimulating hormone (thyrotropin, TSH) assay methodology, establishing TSH as the hallmark of thyroid testing. At the center of the considerations is the strong inverse correlation between serum thyrotropin and free thyroxine concentrations. While it is widely accepted that elevated serum TSH concentrations are consistent with thyroid dysfunction, a vast multitude of additional factors must be considered before an accurate clinical diagnosis can be made followed by an appropriate treatment. Epidemiological studies have demonstrated slightly elevated serum TSH concentrations among the elderly population. There is, however, a debate whether these elevated TSH levels reflect an increased prevalence of hypothyroidism among the elderly or a normal aspect of healthy aging. A comprehensive analysis of the many variables associated with this debate and TSH measurement as a diagnostic tool in aging should provide insight into the clinical efforts to diagnose and treat thyroid disease, particularly in the elderly population.