Subclinical Hypothyroidism

Cognitive Function in Children With Idiopathic Subclinical Hypothyroidism: Effects of 2 Years of Levothyroxine Therapy

BACKGROUND

Long-term consequences of mild subclinical hypothyroidism (SH) in children are still unclear, and the need for levothyroxine (L-T4) supplementation remains controversial. We designed a 2-year, case-control, prospective study of a cohort of children with SH to evaluate the effects of L-T4 therapy on neurocognitive outcome.

METHODS

Thirty-four children, age 9.1 ± 2.6 years, with long-lasting, idiopathic, and mild SH, and 34 healthy matched controls, were enrolled. Twenty SH children underwent a 2-year L-T4 treatment (group A), whereas 14 refused treatment and were reevaluated after a 2-year-follow-up (group B). IQ and specific cognitive domains were evaluated in all children at study entry and after 2 years of therapy (group A) or observation (group B) in SH individuals.

RESULTS

In SH children baseline IQ scores were normal and comparable to controls (full-scale IQ [FSIQ] 100.4 ± 11.3 vs 101.8 ± 14.2, verbal IQ [VIQ] 99.7 ± 13.7 vs 98.3 ± 14.9 and performance IQ [PIQ] 101.2 ± 10.4 vs 105 ± 10.4).In group A, L-T4 treatment was associated with normalization of thyrotropin (6.3 ± 1.0 mIU/L at baseline vs 2.8 ± 1.4 mIU/L at 2 years, P < .001). However, 2-year L-T4 therapy was not associated with a change in IQ scores (FSIQ 104.4 ± 13.8 vs 102.7 ± 11.0; VIQ 101.8 ± 14.9 vs 102.3 ± 11.9; and PIQ 106.5 ± 13.9 vs 102.7 ± 10.7) or in verbal or performance subtest scores. No significant differences were found in IQ scores after 2 years of treatment in group A compared to group B after a 2-year follow-up.

CONCLUSIONS

Our data suggest neurocognitive function in children is not impaired by persistent, mild, untreated SH and is not significantly modified by 2-year L-T4 supplementation.

Subclinical hypothyroidism and anxiety may contribute to metabolic syndrome in Sichuan of China: a hospital-based population study

The prevalence of Metabolic syndrome (MetS) in Sichuan of China has not yet been estimated. Meanwhile the association among anxiety, subclinical hypothyroidism (SCH) and MetS was less well-studied. The data was retrieved retrospectively from Health Promotion Center of West China Hospital database between 2014 and 2017. Internal validation by randomizing into training and testing panel by 9:1 and external validation with National Health and Nutrition Examination Survey (NHNES) were conducted. 19006 subjects were included into analysis, and 3530 (18.6%) of them were diagnosed with MetS. In training panel, age, sex (male), SCH (presence), SAS score, alcohol (Sometimes & Usual) and smoking (Active) were identified as independent risk factors for MetS, which was confirmed in testing panel internally. NHNES data validated externally the association between free thyroxine (fT4) and MetS components. The C-indices of predicting MetS nomogram were 0.705 (95% CI: 0.696–0.714) and 0.728 (95% CI: 0.701–0.754) in training and testing panel respectively. In conclusion, MetS prevalence was 18.6% in Sichuan. SCH and anxiety may be associated with MetS independently. A risk scale-based nomogram with accurate and objective prediction ability was provided for check-up practice, but more cohort validation was needed.

Association of Subclinical Hypothyroidism and Cardiovascular Disease With Mortality

IMPORTANCE

Subclinical hypothyroidism is a common clinical entity among US adults associated in some studies with an increase in the risk of cardiovascular disease (CVD) and mortality. However, the extent to which CVD mediates the association between elevated serum thyrotropin (TSH) and mortality has not yet been well established or sufficiently quantified.

OBJECTIVE

To elucidate the extent to which subclinical hypothyroidism, elevated serum TSH and normal serum free thyroxine, or high-normal TSH concentrations (ie, upper normative-range TSH concentrations) are associated with mortality through CVD among US adults.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study relied on representative samples of US adults enrolled in the National Health and Nutrition Examination Survey in 2001 to 2002, 2007 to 2008, 2009 to 2010, and 2011 to 2012 and their mortality data through 2015. Data were analyzed from January to August 2019.

MAIN OUTCOMES AND MEASURES

Cox proportional hazards regression models were used to investigate associations between the TSH concentration category (subclinical hypothyroidism or tertiles of serum TSH concentrations within the reference range; low-normal TSH, 0.34-1.19 mIU/L; middle-normal TSH, 1.20-1.95 mIU/L; and high-normal TSH, 1.96-5.60 mIU/L) and all-cause mortality. Mediation analysis was used within the counterfactual framework to estimate natural direct associations (not through CVD) and indirect associations (through CVD).

RESULTS

Of 9020 participants, 4658 (51.6%) were men; the mean (SD) age was 49.4 (17.8) years. Throughout follow-up (median [interquartile range], 7.3 [5.4-8.3] years), serum thyroid function test results consistent with subclinical hypothyroidism and high-normal TSH concentrations were both associated with increased all-cause mortality (subclinical hypothyroidism: hazard ratio, 1.90; 95% CI, 1.14-3.19; high-normal TSH: hazard ratio, 1.36; 95% CI, 1.07-1.73) compared with the middle-normal TSH group. Cardiovascular disease mediated 14.3% and 5.9% of the associations of subclinical hypothyroidism and high-normal TSH with all-cause mortality, respectively, with the CVD mediation being most pronounced in women (7.5%-13.7% of the association) and participants aged 60 years and older (6.0%-14.8% of the association).

CONCLUSIONS AND RELEVANCE

In this study, CVD mediated the associations of subclinical hypothyroidism and high-normal TSH concentrations with all-cause mortality in the US general population. Further studies are needed to examine the clinical benefit of thyroid hormone replacement therapy targeted to a middle-normal TSH concentration or active CVD screening for people with elevated TSH concentrations.

gp91phox, a Novel Biomarker Evaluating Oxidative Stress, Is Elevated in Subclinical Hypothyroidism

BACKGROUND

gp91^phox, the catalytic core of NADPH oxidase (NOX) and biomarker of NOX activation, has been recently recognized as a parameter of systemic oxidative stress in several studies. Subclinical hypothyroidism (SH) is characteristic of elevated level of serum thyroid stimulating hormone (TSH) and is frequently accompanied with cholesterolemia. In this study, the levels of serum soluble gp91^phox were measured to assess the oxidative stress in patients with SH. And the relationship among gp91^phox, low-density lipoprotein-C (LDL-C), and TSH was also investigated.

METHODS

A total of 51 subjects were enrolled and categorized into four groups: the healthy controls subjects (n = 13), controls with high level of LDL-C alone (n = 12), SH with normal level of LDL-C (n = 11), and SH with high level of LDL-C (n = 15). The related clinical and laboratory data were collected for statistical analysis. All the patients were newly diagnosed and did not take any medication. The information of lipid profile and thyroid function was extracted, and the concentrations of gp91phox were obtained with ELISA.

RESULTS

The levels of serum soluble gp91phox evidently increased in the patients with SH with a high level of LDL-C (81.52 ± 37.00 ug/mL) as compared to the healthy controls (54.98 ± 1.83ug/mL, p < 0.001), controls with high level of LDL-C (61.21 ± 4.48 ug/mL, p=0.038) and SH with a normal level of LDL-C (62.82 ± 11.67ug/mL, p=0.027). Additionally, the levels of gp91^phox showed a significant positive correlation with both the levels of LDL-C (r = 0.595, p < 0.001) and TSH (r = 0.346, p=0.013) by the Spearman correlation analyses. The correlation remained significant even when the effect of another factor was controlled (TSH: when the effect of LDL-C was controlled, r = 0.453, p=0.001; LDL-C: when the effect of TSH was controlled, r = 0.291, p=0.040). The main effect analysis showed an independent main effect of either LDL-C (p = 0.041) or TSH (p=0.022) on gp91^phox without interaction (p=0.299).

CONCLUSIONS

Our work demonstrated that the levels of gp91^phox, a novel biomarker for measuring the oxidative stress, were significantly elevated in the patients with SH. And LDL-C and TSH were both independent predictors of gp91^phox. Abbreviations. BMI : Body mass index; TC : Total cholesterol; LDL-C : Low-density lipoprotein cholesterol; HDL-C : High-density lipoprotein cholesterol; TG : Triglyceride; FBG : Fasting blood glucose; FT3 : Free triiodothyronine; FT4 : Free thyroxine; TSH: Thyroid stimulating hormone; SBP : Systolic blood pressure; DBP : Diastolic blood pressure; SD : Standard deviation; LSD: Least significant difference.

Assessment of subclinical hypothyroidism for a clinical score and thyroid peroxidase antibody: a comparison with euthyroidism grouped by different thyroid-stimulating hormone levels

Background

Subclinical hypothyroidism (SCH) might have many symptoms of hypothyroidism. The controversy appears to lower the level of thyroid-stimulating hormone (TSH) and group subjects with TSH of more than 3 or even 2.5 mIU/L as SCH subjects.

Objectives

To assess SCH subjects both clinically using Zulewski clinical score and biochemically and to evaluate whether the euthyroid subjects with high-normal TSH (HNT) have any clinical symptom or subnormal biochemical finding.

Methods

A prospective cross-sectional study of 233 subjects, 67 with SCH and 166 euthyroidism, was conducted. Euthyroid subjects were divided according to the level of TSH as HNT (>2.5 mIU/L) and low-normal TSH (0.5–2.5 mIU/L). The subjects were examined for clinical feature including Zulewski clinical score and biochemical evaluations including thyroid peroxidase antibody (TPO-Ab) titer. The comparisons between groups were assessed using independent sample t test, and correlations between variables were evaluated using Pearson correlation.

Results

A significantly higher clinical score and higher frequencies of symptoms were found in the SCH group compared to the euthyroid group. The most frequent symptom was fatigue. Euthyroid subjects with HNT were found to have higher TPO-Ab titers than those with low-normal TSH, P < 0.05. The Zulewski clinical score was positively correlated with TSH and TPO-Ab titer but negatively correlated with the FT4 level, P < 0.05.

Conclusions

Zulewski clinical score is higher in SCH subjects compared to euthyroid subjects and can aid in assessing SCH subjects. A significant correlation exists between Zulewski clinical score and each of the TSH, FT4, and TPO-Ab titer levels. The frequency of TPO-Ab positivity is high in SCH. Additionally, euthyroid with higher TSH levels has higher level of TPO-Ab titer but not higher clinical score.

The Association Between Subclinical Hypothyroidism and Sleep Quality: A Population-Based Study

Background and Aim

The relationship between subclinical hypothyroidism (SHYPO) and sleep quality is still unclear. Our objective was to compare the sleep quality between SHYPO patients and a control group with normal thyroid function.

Methods

A total of 2224 patients with SHYPO and 12,622 euthyroid (EUTH) control group patients were included in the present study. The Pittsburgh Sleep Quality Index (PSQI) was used to assess sleep quality. The sleep outcomes were compared to explore the association between SHYPO and sleep quality. Furthermore, we tried to identify the risk factors of poor sleep in SHYPO patients.

Results

Compared to the EUTH control patients, SHYPO patients had a higher PSQI score (6.83 ± 2.67 vs 6.64 ± 2.63, p =0.004) and a higher proportion of poor sleepers (67.09% vs 64.75%, p =0.033). Moreover, subjects with SHYPO were associated with poorer sleep (Odd Ratio (OR) 1.120, 95% Confidence Intervals (CI) 1.016 to 1.235, p =0.023), longer sleep latency (OR 1.162, 95% CI 1.053 to 1.282, p =0.003), and shorter sleep duration (OR 1.148, 95% CI 1.019 to 1.293, p =0.023) after adjusting for potential confounders. Furthermore, we found that lower age, lower body mass index, and women were risk factors for poor sleep quality in SHYPO patients.

Conclusion

Our findings suggest a relationship between SHYPO and poor sleep quality in a large Chinese population.

Thyroid function before and after Roux-en-Y gastric bypass: an observational study

BACKGROUND

Population studies have shown a positive association between thyroid-stimulating hormone (TSH) and body mass index. Recent studies have shown a significant increase in the prevalence of subclinical hypothyroidism (SCH) in obesity. Weight reduction after Roux-en-Y gastric bypass (RYGB) seems to significantly decrease TSH levels.

OBJECTIVES

The purpose of this study was to evaluate the prevalence of SCH in obese patients (class II and III) and to observe the behavior of thyroid hormones (TSH, hormone triiodothyronine, thyroxine, free thyroxine) with significant weight loss after RYGB.

SETTING

Hospital Nossa Senhora das Graças, Curitiba, Paraná, Brazil.

METHODS

We retrospectively reviewed the medical records of 215 obese patients who underwent RYGB between 2005 and 2012 with a follow-up of at least 2 years. The study was observational and descriptive. The selected times for clinical and laboratory evaluations were preoperative, 3, 6, 12, and 24 months after the procedure. Association, correlation, and variance analyses were performed.

RESULTS

The prevalence of SCH preoperatively was 9.3%. SCH was corrected in 89.5% of patients 12 months after RYGB. We did not find an association between TSH and BMI (r = .002, P = .971). There was a positive impact of bariatric surgery on all metabolic variables. We showed that serum TSH level had no positive correlation with the presence or absence of metabolic syndrome.

CONCLUSIONS

Weight loss after bariatric surgery leads to normalization of TSH levels in most patients and none developed overt hypothyroidism. Obese patients with SCH should not be treated with thyroid hormone replacement. Serial monitoring of thyroid function after obesity therapy seems to be a reasonable approach.

Effect of metformin on thyroid function tests in patients with subclinical hypothyroidism: an open-label randomised controlled trial

PURPOSE

Though most of the observational studies have shown that metformin can reduce serum thyroid stimulating hormone (TSH) level in patients of hypothyroidism with diabetes or polycystic ovarian disease, randomised controlled trials are sparse. The primary objective of this study was to evaluate the effect of metformin on thyroid function tests (TSH, free T4, and free T3) in patients with subclinical hypothyroidism (SCH).

METHODOLOGY

In this open label, parallel arm, randomised controlled trial, 60 patients of SCH (TSH 5.5-10 mIU/L) were randomised to either metformin group (1500 mg/day) or control group.

RESULT

A total of 46 patients (23 in each group) completed the study and no significant difference in serum TSH, free T4 or free T3 was found in between the 2 groups. Neither there was any significant change in serum TSH, free T4 or free T3 (pre and post 6 months) within the individual groups. However, the rate of normalisation of serum TSH in patients with negative thyroid antibody was significantly higher than patients with positive thyroid antibody (71.4% vs. 18.8%; P = 0.026) in metformin group in post hoc analysis. Fasting plasma glucose, serum high-density lipoprotein and indices of insulin sensitivity significantly improved in metformin group. Four patients (17%) had mild gastrointestinal adverse effects in the metformin group.

CONCLUSION

We did not find any significant change in thyroid function test in patients with SCH with metformin therapy.

Screening for thyroid dysfunction and treatment of screen-detected thyroid dysfunction in asymptomatic, community-dwelling adults: a systematic review

BACKGROUND

This systematic review was conducted to inform the Canadian Task Force on Preventive Health Care recommendations on screening for thyroid dysfunction (TD). The review sought to answer key questions on the benefits and harms of screening for TD, patients' values and preferences for screening, and the benefits and harms of treating screen-detected TD.

METHODS

This review followed Canadian Task Force on Preventive Health Care methods, which include the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. The search strategy used for benefits and harms of screening and treatment was an update to the 2014 review by the US Preventive Services Task Force and searched MEDLINE and the Cochrane Library. MEDLINE, Embase, ProQuest Public Health, and SCOPUS were searched for patients' values and preferences for screening. Outcomes of interest included all-cause mortality, deaths due to cardiovascular diseases, fatal and non-fatal cardiovascular events, atrial fibrillation, fractures, quality of life, cognitive function, and harms due to TD treatment. Two reviewers independently screened abstracts and full texts according to pre-determined inclusion criteria and assessed the risk of bias for each study included. Strength and quality of the evidence was assessed for each outcome. A narrative synthesis was conducted due to heterogeneity of the included studies.

RESULTS

No studies were found on screening for TD, treatment of subclinical hyperthyroidism, or patients' values and preferences for screening for TD. Twenty-two studies (from 24 publications) on the treatment of TD in patients with screen-detected subclinical hypothyroidism were included. Results from the included randomized controlled trials suggested no benefit of treatment for subclinical hypothyroidism for the large majority of outcomes. We found very low-quality evidence (from two cohort studies) for a small reduction in all-cause mortality among adults < 65 or 40-70 years who were treated for TD compared to those who were not.

CONCLUSIONS

This review found moderate to very low-quality evidence on the benefits and harms of treatment for subclinical hypothyroidism, with most of the evidence showing no benefit of treatment.

Thyroid hormone therapy for subclinical hypothyroidism

Subclinical Hypothyroidism (SCH) is defined as a raised level of serum TSH level in the presence of normal circulating free thyroid hormones. SCH is a highly prevalent condition displaying some peculiarities, both in terms of the diagnostic and therapeutic approach, when specific population and/or concomitant diseases are taken into account. The debate upon whether LT4 therapy should be initiated or not in patients with SCH is a long lasting one and still it remains controversial. Current evidence supports the concept that the clinical consequences of SCH may be profoundly different in relation to several patient-specific characteristics. Aim of the present review is to provide updated indications for SCH treatment in specific clinical settings. These will include the management of SCH in obese and diabetic patients, in pregnant women, and in specific age groups. Treatment modalities, including LT4 doses and recommended follow-up strategy will also be discussed. In the era of "precision medicine" the decision to-treat-not-to-treat SCH should be individualized taking into account risks and beneficial outcomes of LT4 therapy. With this in mind, we reviewed the most relevant studies in the recent literature in order to provide evidence for or against LT4 replacement therapy for SCH in specific clinical settings.

T4 + T3 combination therapy: any progress?

Guidelines on T4 + T3 combination therapy were published in 2012. This review investigates whether the issue is better understood 7 years later. Dissatisfaction with the outcome of T4 monotherapy remains high. Persistent symptoms consist mostly of fatigue, weight gain, problems with memory and thinking and mood disturbances. T4 monotherapy is associated with low serum T3 levels, which often require TSH-suppressive doses of L-T4 for normalization. Peripheral tissue thyroid function tests during T4 treatment indicate mild hyperthyroidism at TSH < 0.03 mU/L and mild hypothyroidism at TSH 0.3-5.0 mU/L; tissues are closest to euthyroidism at TSH 0.03-0.3 mU/L. This is explained by the finding that whereas T4 is usually ubiquinated and targeted for proteasomal degradation, hypothalamic T4 is rather stable and less sensitive to ubiquination. A normal serum TSH consequently does not necessarily indicate a euthyroid state. Persistent symptoms in L-T4 treated patients despite a normal serum TSH remain incompletely understood. One hypothesis is that a SNP (Thr92Ala) in DIO2 (required for local production of T3 out of T4) interferes with its kinetics and/or action, resulting in a local hypothyroid state in the brain. Effective treatment of persistent symptoms has not yet realized. One may try T4 + T3 combination treatment in selected patients as an experimental n = 1 study. The 2012 ETA guidelines are still valid for this purpose. More well-designed randomized clinical trials in selected patients are key in order to make progress. In the meantime the whole issue has become rather complicated by commercial and political overtones, as evident from skyrocketing prices of T3 tablets, aggressive pressure groups and motions in the House of Lords.

Endocrine function and gland volume after endoscopic transsphenoidal surgery for nonfunctional pituitary macroadenomas

OBJECTIVE

Loss of pituitary function due to nonfunctional pituitary adenoma (NFPA) may be due to compression of the pituitary gland. It has been proposed that the size of the gland and relative perioperative gland expansion may relate to recovery of pituitary function, but the extent of this is unclear. This study aims to assess temporal changes in hormonal function after transsphenoidal resection of NFPA and the relationship between gland reexpansion and endocrine recovery.

METHODS

Patients who underwent endoscopic transsphenoidal surgery by a single surgeon for resection of a nonfunctional macroadenoma were selected for inclusion. Patients with prior pituitary surgery or radiosurgery were excluded. Patient characteristics and endocrine function were extracted by chart review. Volumetric segmentation of the pre- and postoperative (≥ 6 months) pituitary gland was performed using preoperative and long-term postoperative MR images. The relationship between endocrine function over time and clinical attributes, including gland volume, were examined.

RESULTS

One hundred sixty eligible patients were identified, of whom 47.5% were female; 56.9% of patients had anterior pituitary hormone deficits preoperatively. The median tumor diameter and gland volume preoperatively were 22.5 mm (interquartile range [IQR] 18.0-28.8 mm) and 0.18 cm3 (IQR 0.13-0.28 cm3), respectively. In 55% of patients, endocrine function normalized or improved in their affected axes by median last clinical follow-up of 24.4 months (IQR 3.2-51.2 months). Older age, male sex, and larger tumor size were associated with likelihood of endocrine recovery. Median time to recovery of any axis was 12.2 months (IQR 2.5-23.9 months); hypothyroidism was the slowest axis to recover. Although the gland significantly reexpanded from preoperatively (0.18 cm3, IQR 0.13-0.28 cm3) to postoperatively (0.33 cm3, IQR 0.23-0.48 cm3; p < 0.001), there was no consistent association with improved endocrine function.

CONCLUSIONS

Recovery of endocrine function can occur several months and even years after surgery, with more than 50% of patients showing improved or normalized function. Tumor size, and not gland volume, was associated with preserved or recovered endocrine function.

Hypothyroidism in Context: Where We've Been and Where We're Going

Hypothyroidism affects up to 5% of the general population, with a further estimated 5% being undiagnosed. Over 99% of affected patients suffer from primary hypothyroidism. Worldwide, environmental iodine deficiency is the most common cause of all thyroid disorders, including hypothyroidism, but in areas of iodine sufficiency, Hashimoto’s disease (chronic autoimmune thyroiditis) is the most common cause of thyroid failure. Hypothyroidism is diagnosed biochemically, being overt primary hypothyroidism defined as serum thyroid-stimulating hormone (TSH) concentrations above and thyroxine concentrations below the normal reference range. Symptoms of hypothyroidism are non-specific and include mild to moderate weight gain, fatigue, poor concentration, depression, and menstrual irregularities, while the consequences of untreated or under-treated hypothyroidism include cardiovascular disease and increased mortality. Levothyroxine has long been the main tool for treating hypothyroidism and is one of the world’s most widely prescribed medicines. In adults with overt hypothyroidism, levothyroxine is usually prescribed at a starting dose of 1.6 µg/kg/day, which is then titrated to achieve optimal TSH levels (0.4–4.0 mIU/L), according to the therapeutic target. We here summarise the history of levothyroxine and discuss future issues regarding the optimal treatment of hypothyroidism. Because nearly one-third of patients with treated hypothyroidism still exhibit symptoms, it is important that levothyroxine is used more appropriately to achieve maximum benefit for patients. In order to ensure this, further research should include more accurate assessments of the true prevalence of hypothyroidism in the community, optimisation of the levothyroxine substitution dose, proper duration of treatment, and identification of patients who may benefit from combination therapy with levothyroxine plus levotriiodothyronine.

Funding: Merck.

Plain Language Summary: Plain language summary available for this article.

Hypothyroidism is one of the most common diseases worldwide, and levothyroxine is the usual medication prescribed to manage it. Hypothyroidism occurs when the thyroid gland, located in the neck, does not produce enough thyroid hormone for the body’s requirements. This can result in heart disease, infertility, and poor brain development in children. People with hypothyroidism may have changes in body weight, and feel tired, weak or unhappy, all of which can reduce their quality of life. In underdeveloped parts of the world, the main reason why people develop hypothyroidism is that they not getting enough iodine from food. Thus, many countries try to increase iodine intake by adding iodine to salt. In areas of the world where people ingest enough iodine, the most common cause of hypothyroidism is Hashimoto’s disease. This is an autoimmune disease in which the person’s immune system produces cells and antibodies that attack the thyroid gland. Most people with hypothyroidism will need to take levothyroxine for a long time, perhaps even for the rest of their lives. Levothyroxine replaces the person’s levels of thyroid hormone and makes them feel better, but the dose often needs to be adjusted for the best effect. In addition, many people with hypothyroidism do not know they have it. Research is ongoing to ensure that more people with hypothyroidism are diagnosed and are given effective treatment, and to work out the best way to use levothyroxine so that patients get the best results.

[Post-treatment follow-up of head and neck cancer patients]

Post-therapeutic follow-up of patients with head and neck cancer involves numerous professionals. The radiation oncologist should play an active role in this process. His oncological knowledge and technical expertise position him as a cornerstone for the detection of recurrences from the treated tumor, the research of second primary cancers and the screening of potential side-effects induced by the different treatments administered. To improve the benefits/costs ratio and allow good patient-compliance, follow-up programs should be built through close collaboration between the different contributors and planned according to a feasible schedule. Paraclinical exams must be arranged to respond to accurate objectives. Patient-education is essential to ensure the patient's full understanding and active participation. Finally, the transfer of the long-term follow-up of cancer survivors from specialists to primary care physicians is relevant but would require a prospective evaluation of its efficiency for this specific population.

Subclinical Hypothyroidism: A Review

IMPORTANCE

Subclinical hypothyroidism, defined as an elevated serum thyrotropin (often referred to as thyroid-stimulating hormone, or TSH) level with normal levels of free thyroxine (FT4) affects up to 10% of the adult population.

OBSERVATIONS

Subclinical hypothyroidism is most often caused by autoimmune (Hashimoto) thyroiditis. However, serum thyrotropin levels rise as people without thyroid disease age; serum thyrotropin concentrations may surpass the upper limit of the traditional reference range of 4 to 5 mU/L among elderly patients. This phenomenon has likely led to an overestimation of the true prevalence of subclinical hypothyroidism in persons older than 70 years. In patients who have circulating thyroid peroxidase antibodies, there is a greater risk of progression from subclinical to overt hypothyroidism. Subclinical hypothyroidism may be associated with an increased risk of heart failure, coronary artery disease events, and mortality from coronary heart disease. In addition, middle-aged patients with subclinical hypothyroidism may have cognitive impairment, nonspecific symptoms such as fatigue, and altered mood. In the absence of large randomized trials showing benefit from levothyroxine therapy, the rationale for treatment is based on the potential for decreasing the risk of adverse cardiovascular events and the possibility of preventing progression to overt hypothyroidism. However, levothyroxine therapy may be associated with iatrogenic thyrotoxicosis, especially in elderly patients, and there is no evidence that it is beneficial in persons aged 65 years or older.

CONCLUSIONS AND RELEVANCE

Subclinical hypothyroidism is common and most individuals can be observed without treatment. Treatment might be indicated for patients with subclinical hypothyroidism and serum thyrotropin levels of 10 mU/L or higher or for young and middle-aged individuals with subclinical hypothyroidism and symptoms consistent with mild hypothyroidism.

Thyroid blood flow in inferior thyroid artery as predictor for increase in levothyroxine dosage during pregnancy in women with Hashimoto's thyroiditis - a retrospective study

Background

We examined whether inferior thyroid artery peak systolic velocity (ITA-PSV) predicts an increase in levothyroxine (LT4) dosage in pregnant women with Hashimoto’s thyroiditis.

Methods

Twenty-two women with Hashimoto’s thyroiditis who were planning and later achieved pregnancy or confirmed as pregnant were enrolled in this retrospective longitudinal observational study. ITA-PSV and thyroid volume were measured using ultrasonography. Serum concentrations of free thyroxine (F-T4), free triiodothyronine (F-T3), and thyroid stimulating hormone (TSH) were simultaneously determined. We adjusted LT4 dosage to maintain serum TSH at < 2.5 μIU/mL (1st trimester) and later at < 3 μIU/mL (2nd, 3rd trimester).

Results

Eighteen patients (81.8%) required an increase in LT4 dosage during pregnancy, of whom 7 (31.8%) required an increase ≥50 μg. Multivariable regression analysis showed that TSH (β = 0.507, p = 0.008) and ITA-PSV (β = − 0.362, p = 0.047), but not thyroid volume, F-T4, or F-T3, were independently associated with increased LT4 dosage. Receiver-operating characteristic analysis for predicting an increase in LT4 ≥ 50 μg/day showed that the area under the curve (0.905) for ITA-PSV with TSH was not significantly increased (p = 0.123) as compared to that (0.743) for TSH alone, whereas integrated discrimination improvement was significantly increased (27.9%, p = 0.009).

Conclusions

In pregnant patients with Hashimoto’s thyroiditis, ITA-PSV was a significant predictor of increase in LT4 dosage independent of TSH level, while ITA-PSV plus TSH showed significantly improved predictability as compared to TSH alone. These results suggest that ITA-PSV reflects residual thyroid function and is useful for evaluating the need for increased thyroid hormone production in pregnant patients with Hashimoto’s thyroiditis.

EMPATHY: A New Tool for Identifying the Most Suitable Thyroxine Formulation in Hypothyroid Patients

Background: Therapy of hypothyroidism is based on the administration of appropriate doses of levothyroxine (LT4). A failure to achieve the thyrotropin (TSH) target may be due to poor compliance with the LT4 therapy in about 60% of cases or to malabsorption in about 40% of cases. No tools are available for detecting malabsorption disorders before the choice of the most appropriate therapy. The aim of this study was to validate the Evaluation of Malabsorption in PATients with HYpothyroidism (EMPATHY) questionnaire and to demonstrate its usefulness in indicating the most appropriate therapy. Methods: EMPATHY consists of seven questions that allow the evaluation of several intolerances and allergies. Three hundred (100 males) newly diagnosed hypothyroid patients were enrolled and randomly assigned to complete an EMPATHY questionnaire (150 patients; group 1) or to a control group (150 patients; group 2). The choice of thyroxine formulation and dose for each group was made on the basis of the questionnaire answers or based on the history. Thyroid hormones and TSH were evaluated at enrollment and then every two months for six months; the number of the dose adjustments in the six months for each patient was recorded. Results: Of the 150 patients in each group, 21 (14%) in group 1 and 42 (28%) in group 2 (p = 0.005) needed more than two dose adjustments within six months. After six months of replacement therapy, six (4%) patients in group 1 and 17 (11%) in group 2 (p = 0.03) did not have appropriately controlled hypothyroidism (TSH ≥2.5 mIU/L). A significantly higher LT4 final dose was found in group 2 (148 ± 33 μg/day) than in group 1 (136 ± 28 μg/day; p = 0.003). Conclusions: Validation of EMPATHY provides endocrinologists with a useful tool in clinical practice, permitting a better personalization of LT4 replacement therapy, a more rapid attainment of the target TSH levels, and a decreased need for dose adjustments after initiating therapy.

Early menarche is independently associated with subclinical hypothyroidism: a cross-sectional study

Background Subclinical hypothyroidism (SH) is more frequent in females than males, with a female to male ratio ranging from 1.5 to 5 in the general population. The aim of this study was to evaluate for the first time the association of reproductive factors, particularly age at menarche, with SH risk. Materials and methods In a cross-sectional study, reproductive factors such as age at menarche, at menopause and at first birth, lactation, parity, full-term pregnancies, reproductive years, use of oral contraceptives and hormonal replacement therapy, somatometric data and insulin resistance parameters were recorded in 72 consecutive female patients with SH and 72 healthy female controls matched on age (±5 years) and date of diagnosis (±1 month). Results SH cases exhibited significantly younger age at menarche than controls (12.6 ± 1.2 vs. 13.3 ± 0.8 years, respectively, p < 0.001). Cases presented later age at first pregnancy with a lower number of full-term pregnancies (p = 0.04). Early age at menarche was independently associated with SH risk, above and beyond thyroid autoimmunity, body mass index (BMI), hip circumference (HC), homeostatic model assessment of insulin resistance and alcohol consumption [odds ratio (OR): 0.22, 95% confidence interval (CI): 0.11-0.44; p < 0.001]. Conclusions It is possible that an interplay of early exposure to estrogens, as expressed by early menarche, and induction of thyroid autoimmunity may be associated with SH risk. More prospective studies shedding light on the role of estrogens in SH are required to confirm these findings.

Direct correlation between serum homocysteine level and insulin resistance index in patients with subclinical hypothyroidism: Does subclinical hypothyroidism increase the risk of diabetes and cardio vascular disease together?

BACKGROUND

Subclinical hypothyroidism known as mild thyroid disorder without significant sign and symptoms. The correlation between subclinical hypothyroidism and some of cardiovascular disease risk factors such as serum lipids, homocysteine levels and also insulin resistance index is not well established and the current study was conducted to clarify this issue.

METHODS AND MATERIALS

Seventy four patients with mild elevation in levels of thyroid stimulating hormone (TSH) along with normal levels of T3 and T4 were selected as patients group and 74 age and sex matched individuals were selected as healthy control group. Serum insulin, triglyceride, glucose, total cholesterol, LDL-cholesterol, HDL-cholesterol and homocysteine levels were measured. Obtained data compared between groups with independent sample t-test. For evaluation of the correlation between mentioned parameters Pearson correlation coefficient method was used.

RESULTS

Serum levels of LDL-C and total cholesterol significantly increased in SCH group compared to healthy control group. Homeostatic Model Assessment of Insulin Resistance (HOM-IR) and serum homocysteine level significantly elevated in patients with SCH compared to control group. There was a significant direct correlation between HOM-IR and serum homocysteine levels in SCH patients.

CONCLUSION

Subclinical hypothyroidism likely have significant effect on insulin resistance as major diabetes risk factors and also cardiovascular disease risk factors such as homocysteine. The direct correlation between HOM-IR with serum homocysteine level indicate the possible role of insulin resistance in elevation of serum homocysteine in SCH patient group.

Spontaneous primary hypothyroidism in 7 adult cats

BACKGROUND

Naturally occurring hypothyroidism in adult cats is rare, with only 4 cases reported.

OBJECTIVES

To describe the historical, clinical, laboratory, and scintigraphic features of adult cats with spontaneous hypothyroidism.

ANIMALS

Seven adult cats referred for suspected hypothyroidism.

METHODS

Prospective case series. We collected data on cats' signalment, clinical signs, results of physical examination, routine laboratory and thyroid hormone testing, and thyroid imaging (thyroid scintigraphy or ultrasound). We subsequently treated cats with levothyroxine and evaluated their response to treatment.

RESULTS

Cats ranged from 3.5 to 11 years, with no apparent breed predilection; 6/7 cats were male. Only 2/7 cats were initially tested because of signs of hypothyroidism (hair-coat changes, lethargy, obesity); others were tested for routine thyroid monitoring or palpable thyroid nodules. Four were azotemic (serum creatinine, 2.2-3.4 mg/dL). Six of the cats had low serum thyroxine (T4 ) and free T4 (fT4 ) concentrations, whereas all 7 cats had high thyroid-stimulating hormone (TSH) concentrations. In 6/7 cats, thyroid scintigraphy revealed bilateral goiter with intense radionuclide uptake; imaging showed no visible thyroid tissue in the other. After levothyroxine treatment, serum concentrations of T4 and fT4 increased and TSH fell; high serum creatinine normalized in azotemic cats; and repeat imaging showed reduction in goiter size.

CONCLUSIONS AND CLINICAL IMPORTANCE

Primary hypothyroidism develops in adult cats, with a higher prevalence than previously thought. Most cats appear to develop a goitrous form of hypothyroidism associated with thyroid hyperplasia, whereas thyroid atrophy appears to be less common. With levothyroxine replacement, clinical and laboratory abnormalities improve or resolve.

Association of Thyroid Hormone Therapy With Quality of Life and Thyroid-Related Symptoms in Patients With Subclinical Hypothyroidism: A Systematic Review and Meta-analysis

IMPORTANCE

The benefit of thyroid hormone therapy for subclinical hypothyroidism is uncertain. New evidence from recent large randomized clinical trials warrants an update of previous meta-analyses.

OBJECTIVE

To conduct a meta-analysis of the association of thyroid hormone therapy with quality of life and thyroid-related symptoms in adults with subclinical hypothyroidism.

DATA SOURCES

PubMed, EMBASE, ClinicalTrials.gov, Web of Science, Cochrane Library, CENTRAL, Emcare, and Academic Search Premier from inception until July 4, 2018.

STUDY SELECTION

Randomized clinical trials that compared thyroid hormone therapy with placebo or no therapy in nonpregnant adults with subclinical hypothyroidism were eligible. Two reviewers independently evaluated eligibility based on titles and abstracts of all retrieved studies. Studies not excluded in this first step were independently assessed for inclusion after full-text evaluation by 2 reviewers.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted data, assessed risk of bias (Cochrane risk-of-bias tool), and evaluated the quality of evidence (GRADE tool). For synthesis, differences in clinical scores were transformed (eg, quality of life) into standardized mean differences (SMDs; positive values indicate benefit of thyroid hormone therapy; 0.2, 0.5, and 0.8 correspond to small, moderate, and large effects, respectively). Random-effects models for meta-analyses were applied.

MAIN OUTCOMES AND MEASURES

General quality of life and thyroid-related symptoms after a minimum follow-up of 3 months.

RESULTS

Overall, 21 of 3088 initially identified publications met the inclusion criteria, with 2192 adults randomized. After treatment (range, 3-18 months), thyroid hormone therapy was associated with lowering the mean thyrotropin value into the normal reference range compared with placebo (range, 0.5-3.7 mIU/L vs 4.6 to 14.7 mIU/L) but was not associated with benefit regarding general quality of life (n = 796; SMD, -0.11; 95% CI, -0.25 to 0.03; I2=66.7%) or thyroid-related symptoms (n = 858; SMD, 0.01; 95% CI, -0.12 to 0.14; I2=0.0%). Overall, risk of bias was low and the quality of evidence assessed with the GRADE tool was judged moderate to high.

CONCLUSIONS AND RELEVANCE

Among nonpregnant adults with subclinical hypothyroidism, the use of thyroid hormone therapy was not associated with improvements in general quality of life or thyroid-related symptoms. These findings do not support the routine use of thyroid hormone therapy in adults with subclinical hypothyroidism.

Cognitive functioning and quality of life in patients with Hashimoto thyroiditis on long-term levothyroxine replacement

OBJECTIVE

Intrinsic imperfections of thyroid hormone replacement therapy may affect long-term general well-being. In patients with Hashimoto thyroiditis (HT), cognitive functioning may be affected via altered thyroid hormones action as well as by the autoimmune process. The aim of this study was to evaluate cognitive function and quality of life (QoL) in patients on long-term levothyroxine replacement for HT in relation to thyroid function tests and TPO (thyroid-peroxidase) antibody (TPOAb) status.

DESIGN

Retrospective cross-sectional study.

PATIENTS AND MEASUREMENTS

One-hundred-and thirty patients with HT on long-term levothyroxine replacement and 111 euthyroid control subjects. Both groups were divided into two age subgroups, 20-49 years (N = 59 vs N = 79) and > 50 years (N = 71 vs N = 32). Evaluation included biochemical and neuropsychological tests, evaluating attention, global cognitive status, verbal and working memory, executive function, depression and anxiety, and quality of life. We used ANOVA and partial correlations to test for significant associations.

RESULTS

FT4 (free-thyroxine), FT3 (free-triiodothyronine) levels and FT3/FT4 ratio were not different between patients and controls. Mean TSH (thyroid-stimulating hormone) was normal in all subjects but significantly higher in the patients (20-49 yrs:3.64 ± 2.74 vs 1.93 ± 1.10, >50 yrs:3.93 ± 2.84 vs 1.91 ± 0.90). Antibodies (TgAb,TPOAb) were higher in patients. Global cognitive function (MMSE-Mini mental state examination), conceptual tracking (TMT-Trail Making Test:A/B), verbal divergent thinking (like Phonemic fluency test), and anxiety and depression scores were significantly worse in patients vs controls. QoL was impaired in patients. there was a significant negative correlation between antibodies (TPOAb, TgAb) and quality in life (total SF36 score).

CONCLUSION

Patients on long-term levothyroxine replacement show persistent impairments in both cognitive functioning and general well-being.

Meconium microbiome associates with the development of neonatal jaundice

OBJECTIVE

Neonatal jaundice is a common disease that affects up to 60% of newborns. Gut microbiota mediated the excretion of bilirubin from the human body. However, the relationship between early gut microbiome and development of neonatal jaundice is not fully understood. Here we sought to characterize meconium microbiome of newborns and to clarify its association with risk of neonatal jaundice.

METHODS

We conducted a nested case-control study with 301 newborns providing meconium samples from 2014 to 2015. The main outcome was the development of neonatal jaundice at 42 day follow-up. 16S rRNA gene sequencing was performed to profile the meconium microbiome. LEfSe was employed to identify different features between control and case groups. Logistic regression was used to estimate the risk effect of early gut microbiome on neonatal jaundice.

RESULTS

Logistic regression models suggested that higher ɑ-diversity was significantly associated with lower risk of jaundice in cesarean infants (OR 0.72, 95% CI 0.52-0.98), but not in infants born naturally. Higher relative abundance of Bifidobacterium pseudolongum in newborn meconium was significantly associated with lower risk of jaundice both in cesarean-born infants and in the total subjects (OR 0.24, 95% CI 0.07-0.68; OR 0.55, 95% CI 0.31-0.95, respectively). Spearman's correlations showed that relative abundance of B. pseudolongum was significantly correlated with ɑ-diversity (P < 0.01).

CONCLUSION

Preventive and treatment methods implying early gut microbiome intervention could be promising for the management of neonatal jaundice.

Mild Hypothyroidism in Childhood: Who, When, and How Should Be Treated?

Mild hypothyroidism, also known as subclinical hypothyroidism (SH), is biochemically defined as serum TSH levels above the upper limit of the reference range, in the presence of normal serum concentrations of total T4 and free T4 (FT4). In the neonatal period, mild hypothyroidism can be defined by the presence of a TSH value between 6 and 20 mIU/L and normal FT4 levels. After the neonatal period, SH can be defined mild if TSH ranges between 4.5 and 10 mIU/L. The management of mild hypothyroidism in childhood is challenging. The major concern is to establish whether this condition should always be considered an expression of mild thyroid dysfunction. Indeed, the effects of untreated mild hypothyroidism are still not completely defined. In the neonatal period, concern exists about neurocognitive outcome; in children, although there is no clear evidence of alterations in growth or neurocognitive development, subtle cardiovascular abnormalities have been documented. Therefore, there is still uncertainty about the need of treatment across all ages, and the management should be based on the age of the child, the etiology, and the degree of TSH elevation, as well as on other patient factors. This review updates current evidences on diagnosis and management of mild hypothyroidism in childhood.

Association between free thyroid hormones values and the lipid profile in middle-aged women with chronic symptoms

AIMS

To determine the association between the thyroid hormones(FT3, FT4 and TSH) and the lipid profile markers(HDL-c, LDL-c and triglycerides) values in middle-aged women with no metabolic disorders and recurrent chronic symptomatology.

MATERIALS AND METHODS

We carried out an analytical cross-sectional study in euthyroid women with recurrent chronic symptoms of at least six months with no apparent diagnosis who attended the endocrinological gynaecology outpatient service of a private clinic in Lima-Peru during 2012-2014. Participants who met the eligibility criteria were evaluated according to their thyroid hormones(FT3, FT4 and TSH) and lipid profile markers(HDL-c, LDL-c and triglycerides) values. We elaborated univariate/multivariate linear regression models to evaluate the association between the thyroid markers and the lipid profile levels. The reported association measure was the beta coefficient(β) with its respective p-value.

RESULTS

We analyzed 211 participants, the average age was 44.9 ± 14.0(SD) years, the FT3 and FT4 mean levels were 3.2 ± 0.4 pg/mL and 1.2 ± 0.2 ng/dL respectively, while the TSH median was 2.8(IQR:1.9-4.0) μU/mL. The mean or median levels of LDL-c, HDL-c and triglycerides were of 137.5 ± 37.9 mg/dL, 54.0 ± 15.0 mg/dL and 118.5(IQR:79.5-169.5) mg/dL respectively. In the multivariate linear regression model between the FT3 and LDL-c levels, we found that for each increase in a FT3 unit, the LDL-c values decreased on average 30.85 mg/dL(p < 0.01). We found no statistically significant associations in the other multivariate models of linear regression, among the other thyroid hormones and lipid markers.

CONCLUSION

We found an inverse association between the FT3 and LDL-c values in women with chronic gynaecological symptoms.

Impact of Thyroid Autoimmunity on Thyroid Function in 12-year-old Children With Celiac Disease

OBJECTIVES

Celiac disease (CD) is associated with thyroid autoimmunity and other autoimmune diseases. Data are, however, lacking regarding the relationship between thyroid autoimmunity and thyroid function, especially in regard to CD. Our aim was to investigate the impact of thyroid autoimmunity on thyroid function in 12-year-old children with CD compared to their healthy peers.

METHODS

A case-referent study was conducted as part of a CD screening of 12-year-olds. Our study included 335 children with CD and 1695 randomly selected referents. Thyroid autoimmunity was assessed with antibodies against thyroid peroxidase (TPOAb). Thyroid function was assessed with thyroid-stimulating hormone and free thyroxine.

RESULTS

TPOAb positivity significantly increased the risk of developing hypothyroidism in all children. The odds ratios (with 95% confidence intervals) were 5.3 (2.7-11) in healthy 12-year-olds, 10 (3.2-32) in screening-detected CD cases, 19 (2.6-135) in previously diagnosed CD cases, and 12 (4.4-32) in all CD cases together. Among children with TPOAb positivity, hypothyroidism was significantly more common (odds ratio 3.1; 95% CI 1.03-9.6) in children with CD (10/19) than in children without CD (12/46).

CONCLUSIONS

The risk of thyroid dysfunction due to thyroid autoimmunity is larger for those with CD than their healthy peers. Our study indicates that a gluten-free diet does not reduce the risk of thyroid dysfunction. Further studies are required for improved understanding of the role of the gluten-free diet for the risk of autoimmune diseases in children with CD.

Does Subclinical Hypothyroidism Affect Hospitalization Outcomes and Mortality in Congestive Cardiac Failure Patients?

Objective

This study aimed to determine the differences in hospitalization outcomes among patients admitted for congestive cardiac failure (CCF) with underlying subclinical hypothyroidism (SCH).

Methods

This retrospective case-control study used data from the nationwide inpatient sample (NIS) for the years 2012–2014. We identified cases with CCF as the primary diagnosis and SCH as the secondary diagnosis using validated ICD-9-CM codes and controls with CCF only. The differences in hospitalization outcomes and hospital characteristics were quantified using the multinomial logistic regression model (adjusted odds ratio (aOR)).

Results

A total of 143,735 CCF patients were enrolled in this study, and 73,440 cases had IH. About 31.8% of SCH patients were hospitalized for more than four days (median) compared to 44.7% patients without SCH (P < .001). The median hospitalization charges per admission for CCF was $20,312. CCF patients with SCH had lower odds of longer hospitalization (aOR = .709, 95% CI .660-.762, P < .001) and higher hospitalization charges (aOR = .783, 95% CI .728-.841, P < .001) compared to CCF patients without SCH. CCF patients with SCH had two times higher odds of minor morbidity (aOR = 2.276; 95% CI 2.105-2.462; P < .001) but lower odds of major morbidity (aOR = .783; 95% CI .728-.841; P < .001). Inpatient mortality with SCH patients (2%) compared to 3.6% patients without SCH (P < .001). CCF patients with SCH had lower odds of in-hospital mortality (aOR = .547; 95% CI .496-.604; P < .001). CCF patients with SCH had higher odds of being seen in rural non-teaching hospitals (aOR = 1.696; 95% CI 1.572-1.831; P < .001). Also, CCF patients with SCH had the highest likelihood of presence in the western region of the United States (aOR = 149.924; 95% CI 110.497-203.419; P < .001) followed by the southern region (aOR = 31.431; 95% CI 26.066-37.900; P < .001).

Conclusions

Among CCF with SCH patients during hospitalization, we observed a variation in hospitalization outcomes, including inpatient length of stay and cost, morbidity, and in-hospital mortality. We found no significant increase in mortality and major morbidity in CCF patients with SCH. There were differences in the hospital characteristics between CCF patients with and without SCH. Thus, hospital bed size, location, and teaching status act as predictors for a co-diagnosis of SCH in CCF. Further research is needed to guide the development of clinical care models for targeting early diagnosis and treatment to determine whether thyroid hormone replacement would be beneficial for CCF patients with SCH and improve quality of care in these patients.

MANAGEMENT OF ENDOCRINE DISEASE: Pitfalls on the replacement therapy for primary and central hypothyroidism in adults

Hypothyroidism is one of the most common hormone deficiencies in adults. Most of the cases, particularly those of overt hypothyroidism, are easily diagnosed and managed, with excellent outcomes if treated adequately. However, minor alterations of thyroid function determine nonspecific manifestations. Primary hypothyroidism due to chronic autoimmune thyroiditis is largely the most common cause of thyroid hormone deficiency. Central hypothyroidism is a rare and heterogeneous disorder characterized by decreased thyroid hormone secretion by an otherwise normal thyroid gland, due to lack of TSH. The standard treatment of primary and central hypothyroidism is hormone replacement therapy with levothyroxine sodium (LT4). Treatment guidelines of hypothyroidism recommend monotherapy with LT4 due to its efficacy, long-term experience, favorable side effect profile, ease of administration, good intestinal absorption, long serum half-life and low cost. Despite being easily treatable with a daily dose of LT4, many patients remain hypothyroid due to malabsorption syndromes, autoimmune gastritis, pancreatic and liver disorders, drug interactions, polymorphisms in DIO2 (iodothyronine deiodinase 2), high fiber diet, and more frequently, non-compliance to LT4 therapy. Compliance to levothyroxine treatment in hypothyroidism is compromised by daily and fasting schedule. Many adult patients remain hypothyroid due to all the above mentioned and many attempts to improve levothyroxine therapy compliance and absorption have been made.

Subclinical hypothyroidism: new trials, old caveats

The indications for levothyroxine replacement therapy for subclinical hypothyroidism (SH) remain a subject of debate, especially when prescribed for older adults. The results of the recent TRUST trial indicate that levothyroxine does not improve clinical symptom scores among elderly patients with SH. While there is much concern regarding the dilemma of introducing or withholding levothyroxine, less attention may be paid to the differential diagnosis of an elevated TSH level, which is the prerequisite for diagnosing SH. Herein, we review these issues facing endocrinologists and internists/generalists either in practice or in training. When a patient presents abnormal thyroid test results compatible with SH, a series of issues need to be addressed before the implementation of replacement therapy is considered: first, an isolated TSH elevation not linked to a primary thyroid pathology should be excluded; second, the persistent nature of the patient's TSH elevation and SH profile should be verified; third, SH symptoms and potential complications relevant for the specific patient should be documented; fourth, expectations from levothyroxine substitution therapy for SH in the specific patient should be clarified. Only then can the decision be made whether levothyroxine substitution should be introduced or not.

Prevalence and Annual Incidence of Thyroid Disease in Korea from 2006 to 2015: A Nationwide Population-Based Cohort Study

BACKGROUND

The incidence of thyroid nodules has increased worldwide in recent years. Thyroid dysfunction is a potential risk factor for hypercholesterolemia, cardiovascular disease, osteoporosis, arrhythmia, and neuropsychiatric disease. This study investigated the prevalence and annual incidence of thyroid nodules, hypothyroidism, and hyperthyroidism in Koreans.

METHODS

In this nationwide population-based cohort study, 51,834,660 subjects were included using the National Health Information database from 2006 to 2015, after the exclusion of subjects with thyroid cancer.

RESULTS

The prevalence in Korea in 2015 of thyroid nodules, hypothyroidism in patients taking thyroid hormone, and hyperthyroidism in patients undergoing treatment was 15.82/1,000 population, 15.94/1,000 population, and 2.76/1,000 population, respectively. All these diseases were more prevalent among women than among men. The number of incident cases of these three thyroid diseases steadily increased from 2006 to 2012, and then decreased through 2015. The incidence of thyroid nodules, hypothyroidism treated with thyroid hormone, and treated hyperthyroidism was 6.79/1,000 population, 1.76/1,000 population, and 0.55/1,000 population, respectively, in Korea in 2015. The use of methimazole continuously increased, from 33% of total antithyroid drug prescriptions in 2006 to 74.4% in 2015, and it became the most frequently prescribed antithyroid drug in Korea. In contrast, the use of propylthiouracil continuously decreased.

CONCLUSION

This was the first nationwide study of the prevalence and annual incidence of thyroid nodules, hypothyroidism, and hyperthyroidism to take into account recent changes and to include the current status of patients receiving treatment.

THYROID HORMONE REPLACEMENT REDUCES THE RISK OF CARDIOVASCULAR DISEASES IN DIABETIC NEPHROPATHY PATIENTS WITH SUBCLINICAL HYPOTHYROIDISM

OBJECTIVE

Patients with diabetic nephropathy (DMN) have an increased risk of cardiovascular disease (CVD). However, strategies to reduce this risk are limited. Thyroid hormone replacement therapy (THRT) in patients with hypothyroidism has been shown to reduce several surrogate markers of CVD. Therefore, we performed a study to determine if THRT would reduce CVD risk in patients with subclinical hypothyroidism (SCH) and DMN.

METHODS

This was a retrospective, nonrandomized study of patients with type 2 diabetes, DMN, and SCH. Those with known thyroid dysfunction or taking THRT at baseline were excluded. Patients receiving THRT for at least 180 days were included in the THRT group, while the remaining patients were assigned to the non-THRT group. The primary outcome was CVD events, which included coronary syndrome, cerebrovascular events, and peripheral artery diseases.

RESULTS

Among the 257 patients, 83 (32.3%) were in the THRT group. The mean ages were 62.7 ± 12.3 and 66.8 ± 12.4 years in the THRT and non-THRT groups, respectively. The corresponding numbers of male patients were 32 (40.0%) and 94 (53.1%). During a mean follow-up of 38.0 ± 29.2 months, 98 CVD events were observed. Acute coronary syndrome and cerebrovascular event prevalence rates were lower in the THRT group than the non-THRT group, but there was no difference for peripheral artery diseases. Multivariate Cox analysis revealed that THRT was independently associated with a decreased CVD event risk.

CONCLUSION

THRT may decrease the risk of CVD in DMN patients with SCH. Randomized trials are needed to verify this finding.

ABBREVIATIONS

CV = cardiovascular DMN = diabetic nephropathy eGFR = estimated glomerular filtration rate fT4 = free thyroxine HbA1c = glycosylated hemoglobin HR = hazard ratio hs-CRP = high-sensitivity C-reactive protein LDL-C = low-density lipoprotein cholesterol SCH = subclinical hypothyroidism T2DM = type 2 diabetes THRT = thyroid hormone replacement therapy TSH = thyroid-stimulating hormone.

Effect of Levothyroxine on Blood Pressure in Patients With Subclinical Hypothyroidism: A Systematic Review and Meta-Analysis

Background: Patients with subclinical hypothyroidism (SCH) have elevated blood pressure, but the effect of levothyroxine (LT4) therapy on blood pressure among those patients is still unclear. This study aimed to assess whether LT4 therapy could reduce blood pressure in SCH patients through a systematic review and meta-analysis. Methods: PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science were searched. Randomized controlled trials (RCTs) assessing the effect of LT4 therapy on blood pressure or prospective follow-up studies comparing the blood pressure level before and after LT4 treatment were included, and the mean difference of systolic blood pressure (SBP) or diastolic blood pressure (DBP) was pooled using random-effect meta-analysis. Results: Twenty-nine studies including 10 RCTs and 19 prospective follow-up studies were eligible for the analysis. Meta-analysis of 10 RCTs suggested that LT4 therapy could significantly reduce SBP in SCH patients by 2.48 mmHg (95% CI -4.63 to -0.33, P = 0.024). No heterogeneity was observed among these 10 RCTs (I² = 0%). Meta-analysis of the 19 prospective follow-up studies found that LT4 therapy significantly decreased SBP and DBP by 4.80 mmHg (95%CI -6.50 to -3.09, P < 0.001) and 2.74 mmHg (95%CI -4.06 to -1.43, P < 0.001), respectively. Conclusion: The findings suggest that LT4 replacement therapy can reduce blood pressure in SCH patients, which needs to be validated in more clinical trials with larger samples.