Levothyroxine Monotherapy: What Works Better for the Individual With Hypothyroidism?

OBJECTIVE

I explore objective data not supporting the addition of liothyronine (medication) (LT3) to levothyroxine (medication) (LT4) in patients with hypothyroidism. Accurate identification of patients with symptomatic (almost exclusively overt) hypothyroidism is important in evaluating clinical outcomes of therapies. Recent studies have documented that nearly a third of individuals who are offered thyroid hormone are euthyroid at the time of initiation. Additionally, others are clinically diagnosed without biochemical confirmation, so a sizable proportion of those started on LT4 are not hypothyroid. The assumption that nonhypothyroid symptoms will resolve with LT4 is problematic. The true underlying cause of these symptoms remains unidentified and untreated.

METHODS

In a narrative fashion I will review the positive predictive value of and correlation of symptoms consistent with hypothyroidism and confirmed hypothyroidism likely to favorably respond to thyroid hormone replacement.

RESULTS

Following a review of the reliability of thyroid-stimulating hormone (TSH) in predicting a euthyroid state, the correlation of circulating triiodothyronine (serum measurement) (T3) levels with symptoms and predictive value of T3 to forecast the outcome of adding LT3 to LT4 will be reviewed. The utility of striving for high, middle, or low TSH set points within the expected range to predict changes in clinical quality of life and the ability of blinded patients to sense subtle differences along this spectrum will be documented. In addition, the clinical impact of single nucleotide polymorphisms in the type 2 deiodinase gene will be reviewed. Finally, the overall satisfaction of selected patients with their thyroid hormone treatments will be outlined and preferences for T3-containing treatments from blinded studies will be summarized.

CONCLUSION

Basing thyroid hormone treatment decisions on patient symptoms likely results in missed diagnoses We should encourage primary care physicians to assess a differential diagnosis, exclude other diagnoses, and not assume a thyroid etiology when TSH is normal. Modifying treatment to a particular TSH target or adjusting based on a low T3 level does not seem to enhance patient outcomes. Finally, pending further trials of "symptomatic" participants, using sustained release LT3 to mimic normal physiology, and including monocarboxylate 10 transporter and Type 2 deiodinase polymorphisms and objective outcomes, I will continue to depend on therapy with LT4 monotherapy and seek alternative explanations for my patients' nonspecific symptoms.

Comparative Effectiveness of Persistent Use of a Name-Brand Levothyroxine (Synthroid®) vs. Persistent Use of Generic Levothyroxine on TSH Goal Achievement: A Retrospective Study Among Patients with Hypothyroidism in a Managed Care Setting

Introduction

Levothyroxine monotherapy (Synthroid® or multiple generic levothyroxine [GL] formulations) is standard treatment for hypothyroidism. Our objective was to compare effectiveness (as measured by achievement of thyroid-stimulating hormone [TSH] levels) and economic outcomes of Synthroid vs. any one of multiple GLs in patients with hypothyroidism.

Methods

Data for this retrospective cohort study were obtained from the HealthCore Integrated Research Database®. All study patients had ≥ 2 claims between 1 January 2006 and 31 December 2017 with ICD-9/10-CM diagnosis codes for hypothyroidism; were persistent users of Synthroid vs. any GL; and had ≥ 1 TSH laboratory result during 12-month follow-up. Patients were divided into one of two cohorts based on index medication and were 1:1 matched using propensity scores. The primary outcome was the proportion of patients with last TSH laboratory result during follow-up within the reference range (0.3–4.12 mIU/L). Secondary outcomes included all-cause and hypothyroidism-related healthcare resource utilization (HCRU) and costs.

Results

After propensity score matching, the Synthroid and GL cohorts each contained 18,382 patients. At follow-up, significantly more patients receiving Synthroid were in the TSH reference range vs. GL (78.5% vs. 77.2%, respectively, p =  0.002). HCRU and costs were broadly similar between the cohorts in terms of all-cause inpatient hospitalizations, emergency department visits, outpatient services, and pharmacy fills. Irrespective of index medication, patients with TSH within the reference range had significantly lower hypothyroidism-related medical and total costs compared to those outside the range.

Conclusions

This real-world data study showed Synthroid was associated with better TSH target achievement vs. GL in a US managed care population. Achieving TSH goals may provide substantial economic value by reducing hypothyroidism-related HCRU and costs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01969-3.

Thyroid testing paradigm switch from thyrotropin to thyroid hormones-Future directions and opportunities in clinical medicine and research

PURPOSE

Recently published papers have demonstrated that particularly in untreated individuals, clinical parameters more often associate with thyroid hormone, particularly free thyroxine (FT4), levels than with thyrotropin (TSH) levels. Clinical and research assessments of the thyroid state of peripheral tissues would therefore be more precise if they were based on FT4 levels rather than on TSH levels. In this paper we describe implications of, and opportunities provided by, this discovery.

CONCLUSIONS

The FT4 level may be the best single test of thyroid function. The addition of free triiodothyronine (FT3) and TSH levels would further enhance test sensitivity and distinguish primary from secondary thyroid dysfunction respectively. There are opportunities to reconsider testing algorithms. Additional potential thyroidology research subjects include the peripheral differences between circulating FT4 and FT3 action, and outcomes in patients on thyroid replacement therapy in terms of thyroid hormone levels. Previously performed negative studies of therapy for subclinical thyroid dysfunction could be repeated using thyroid hormone levels rather than TSH levels for subject selection and the monitoring of treatment. Studies of outcomes in older individuals with treatment of high normal FT4 levels, and pregnant women with borderline high or low FT4 levels would appear to be the most likely to show positive results. There are fresh indications to critically re-analyse the physiological rationale for the current preference for TSH levels in the assessment of the thyroid state of the peripheral tissues. There may be opportunities to apply these research principles to analogous parameters in other endocrine systems.

Repeat Fine Needle Aspiration Cytology Refines the Selection of Thyroid Nodules for Afirma Gene Expression Classifier Testing

Background: Molecular testing (MT) refines risk stratification for thyroid nodules that are indeterminate for cancer by fine needle aspiration (FNA) cytology. Criteria for selecting nodules for MT vary and remain largely untested, raising questions about the best strategy for maximizing the usefulness of MT while minimizing the harms of overtesting. We used a unique data set to examine the effects of repeat FNA cytology-based criteria for MT on management decisions and nodule outcomes. Methods: This was a study of adults (age 25-90 years; 281 women and 72 men) with cytologically indeterminate (Bethesda III/IV) thyroid nodules who underwent repeat FNA biopsy and Afirma Gene Expression Classifier (GEC) testing (N = 363 nodules from 353 patients) between June 2013 and October 2017 at a single institution, with follow-up data collected until December 2019. Subgroup analysis was performed based on classification of repeat FNA cytology. Outcomes of GEC testing, clinical/sonographic surveillance of unresected nodules, and histopathologic diagnoses of thyroidectomies were compared between three testing approaches: (i) Reflex (MT sent on the basis of the initial Bethesda III/IV FNA), (ii) SemiRestrictive (MT sent if repeat FNA is Bethesda I-IV), and (iii) Restrictive (MT sent only if repeat FNA is Bethesda III/IV) testing approaches. Results: Restricting MT to nodules that remain Bethesda III/IV on repeat FNA would have missed 4 low-risk cancers and 3 noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP) (collectively 2% of the test population) but would have avoided diagnostic surgery for 42 benign nodules (12% of the test population). The Restrictive testing strategy was more specific (delta 0.126 confidence interval [CI 0.093 to 0.159] and 0.129 [CI 0.097 to 0.161], respectively) but less sensitive (delta -0.339 [CI -0.424 to -0.253] and -0.340 [CI -0.425 to -0.255], respectively) than the Reflex and SemiRestrictive approaches for detecting NIFTP or cancer. Conclusions: Repeat FNA cytology can guide the selection of cytologically indeterminate thyroid nodules that warrant MT. The Restrictive model of performing Afirma GEC only on nodules with two separate biopsies showing Bethesda III/IV cytology would reduce the rate of diagnostic surgery for histologically benign nodules while missing only rare low-risk tumors. Given the low but nontrivial risks of thyroidectomy, the higher specificity of the Restrictive testing approach disproportionately outweighs the potential harms.

Combined molecular and histologic end points inform cancer risk estimates for thyroid nodules classified as atypia of undetermined significance

BACKGROUND

Thyroid nodules classified as atypia of uncertain significance (AUS) on fine-needle aspiration cytology are heterogeneous. Prior studies reported a higher risk of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP)/cancer among AUS nodules that had cytologic (AUS-C) versus architectural (AUS-A) atypia; however, such studies were generally confined to resected cohorts, introducing bias into risk calculations. The authors hypothesized that combined histologic and molecular end points would permit clinically meaningful calculations of NIFTP/malignancy risk among AUS nodules.

METHODS

The study consisted of 279 thyroid nodules classified as AUS on initial fine-needle aspiration and tested by the Afirma Gene Expression Classifier (GEC) between June 2013 and October 2017. Results of GEC testing and histopathologic diagnoses were stratified by AUS classifiers. The AUS-A category was further subclassified as 1) hypocellular microfollicular or 2) cellular with mixed but predominantly microfollicular architecture. NIFTP/cancer risk was calculated for each subgroup, with the inclusion of unresected nodules that had benign GEC results as low-risk end points comparable to histologically benign nodules.

RESULTS

When only histologic end points were considered, there was no difference in NIFTP/cancer risk (25% vs 23%; P = .82). By using molecular and histologic end points, AUS cases with cytologic atypia trended toward higher NIFTP/cancer risk than AUS-A cases (14% vs 6%; P = .06). Furthermore, AUS-A cases showed a trend toward lower NIFTP/cancer risk for hypocellular microfollicular aspirates (3%) compared with cellular samples that had mixed/predominantly microfollicular architecture (13%; P = .18).

CONCLUSIONS

The inclusion of unresected benign GEC nodules in risk-of-malignancy calculations provides more accurate results, which may be helpful for informing patient management as well as quality improvement in the cytopathology laboratory.

USE OF THE FREE THYROXINE INDEX TO REFINE THE LOWER LIMIT OF A FREE THYROXINE IMMUNOASSAY FOR DETECTION OF SECONDARY HYPOTHYROIDISM

OBJECTIVE

To determine the utility of measuring free T₄ index (FT₄I) in patients with low free T₄ (FT₄) levels using immunoassay and normal thyroid-stimulating hormone for the evaluation of secondary hypothyroidism.

METHODS

We performed a retrospective medical chart review of patients seen at a single institution as outpatients who had a simultaneously normal thyroid-stimulating hormone level, low FT₄ level, and any FT₄I measured between June 2014 and October 2016. Demographic, laboratory, and imaging data were collected. Using FT₄I as the reference for diagnosis of hypothyroidism, the sensitivity and specificity of the FT₄ immunoassay's lower-limit thresholds were determined. Within each threshold group, available brain imaging and biochemical evaluation were categorized according to the presence or absence of pituitary disease.

RESULTS

A total of 155 sets of result pairs (FT₄ and FT₄I) performed on 118 subjects were analyzed. The lower limit of a normal FT₄ level by immunoassay at this institution was 0.93 ng/dL, though all pairs with FT₄ ≥0.89 ng/dL had a normal FT₄I. All pairs with FT₄ ≤0.67 ng/dL had a low FT₄I. No pituitary macroadenomas were identified in any subject, though the rates of pituitary imaging in this patient sample were low.

CONCLUSION

Patients with a borderline low FT₄ level by immunoassay often have normal FT₄I. In such patients at our center, significant structural and biochemical pituitary pathology was uncommon.

Alternative routes of levothyroxine administration for hypothyroidism

PURPOSE OF REVIEW

The aim of the article is to present the basics of oral levothyroxine (LT4) absorption, reasons why patients may have persistently elevated serum thyroid stimulation hormone (TSH) levels, and alternative strategies for LT4 dosing.

RECENT FINDINGS

Although oral LT4 tablets are most commonly used for thyroid hormone replacement in patients with hypothyroidism, case studies report that liquid oral LT4, intravenous, intramuscular, and rectal administration of LT4 can successfully treat refractory hypothyroidism.

SUMMARY

Hypothyroidism is one of the most common endocrine disorders encountered by primary care physicians and endocrinologists. LT4 is one of the most widely prescribed medications in the world and it is the standard of care treatment for hypothyroidism. Generally, hypothyroid patients will be treated with LT4 tablets to be taken orally, and monitoring will occur with routine serum thyroid tests, including TSH concentrations. However, many patients fail to maintain serum TSH levels in the target range while managed on oral LT4 tablets. A subset of these patients would be considered to have poorly controlled hypothyroidism, sometimes termed refractory hypothyroidism. For these patients, optimization of ingestion routines and alternative formulations and routes of administration of LT4 can be considered, including oral liquid, intravenous, intramuscular, and even rectal formulations.

Nondiagnostic Fine-Needle Aspiration Biopsy of Thyroid Nodules: Outcomes and Determinants

Background: Nondiagnostic results are common following fine-needle aspiration biopsy (FNAB) of thyroid nodules, but recommendations for the management of these patients vary. We sought to determine the outcomes and predictors of nondiagnostic FNABs in a single-center cohort of patients undergoing thyroid nodule evaluation. Methodology: We identified all first time ultrasound-guided FNABs performed between May 2007 and June 2013 at the Beth Israel Deaconess Medical Center Thyroid Nodule Clinic and examined demographic data, follow-up ultrasounds, repeated FNABs, and histopathologic findings. We examined the likelihood of diagnostic findings and of cancer with increasing numbers of nondiagnostic evaluations with their exact binomial confidence intervals [CIs] and potential predictors of nondiagnostic status using generalized estimating equations. Results: During the six-year period, 2234 unique individuals underwent ultrasound-guided FNAB of a thyroid nodule. The probability of obtaining a diagnostic biopsy declined from 84.4% [95% CI 82.8-85.8%] for initial FNABs to 57.6% [CI 50.8-64.2%] for the first re-FNAB and further to 42.4% [CI 25.5-60.8%] for second re-FNABs. Adjusted risk of nondiagnostic FNAB strongly increased with increasing numbers of previous biopsies and was also higher among whites. The overall rate of diagnosis of malignancy after a nondiagnostic FNAB was 8.1% [CI 4.2-13.7%] and was similar regardless of the number of previous nondiagnostic aspirations. Conclusion: Following an initial nondiagnostic FNAB, the probability of yielding a diagnostic result declines with each sequential repeat FNAB. Nonetheless, a tangible possibility of malignancy remains even after repeated nondiagnostic FNABs.

Thyrotoxicosis after massive triiodothyronine (LT3) overdose: a coast-to-coast case series and review

Excessive exogenous thyroid hormone ingestion may lead to severe thyrotoxicosis and cause potential harm. We have reviewed the literature and suggested that thyroid hormone supplementation should not be used to alleviate nonspecific complaints in patients with normal endogenous thyroid function. Failure to do so may cause serious harm, as demonstrated in one of the cases described here. In addition, treatment based on symptom relief only without biochemical measure may lead to overmedication - as reported from academic hospitals both in Canada and the United States. Given the risk of severe thyrotoxicosis from potential compounding errors, pharmacies providing a compounding service should be subject to more rigorous monitoring by the food and drug administration. Clinicians should also use local biochemical markers when titrating thyroid hormone supplements even though the normal thyroid function reference range has its limitation, failure to do so may result in iatrogenic thyrotoxicosis.

Thyroxine and treatment of hypothyroidism: seven decades of experience

Hypothyroidism is one of the most common endocrine disorders, affecting as much as 10% of the global population. There is a rich cultural milieu of treatment history and interventions dating as far back as 2 millennia. Chinese cretins were treated with sheep thyroid in the 6th century. In 1890, transplanted animal thyroid tissue resulted in a prompt clinical response in a myxedematous patient, and in 1891 injections of sheep thyroid were reported. One year later, the oral administration of fresh sheep thyroid glands was noted to be effective. Within a few years, the danger of over-dosage with extracts was recognized and dosing guidance indicated a low dose start and gradual increase as required based on symptoms. Orally ingested extracts became widespread and by 1914 thyroxine had been crystallized. In 1927, thyroxine, was synthesized as an acid, limiting oral absorption. Finally a sodium salt of thyroxine was introduced in 1949. These synthetic preparations were then made available for clinical use. Prior to 1970, extracts and combination therapy with synthetic LT4 and LT3 were standard replacement until the peripheral deiodinase-mediated T4 to T3 conversion documented the endogenous generation of T3 from LT4 in athyreotic subjects. This resulted in advocacy for patients previously treated with combinations and desiccated thyroid be transitioned to L-thyroxine monotherapy. The determination of the optimal dose has evolved such that now a general recommendation for replacement dosage of LT4 is 1.6-1.7 mcg/kg/day. Thyroid hormone extracts were established prior to the FDA's establishment in 1906, and when the Food, Drug, and Cosmetic act of 1938 enhanced the FDA's regulatory authority. In 1997, FDA declared LT4 products to be new drugs subject to regulation and quickly a pharmacokinetic process to determine interchangeability among approved LT4 products ensued. Differences in bioavailability of 12.5% or more may be considered therapeutically equivalent and therefore such products interchangeable. To assure refill to refill consistency, all levothyroxine sodium products now meet a 95-105% potency specification throughout their labeled shelf-lives. Seventy years after Kendall's great achievement in isolating thyroxine, we have thyroxine products with precise amounts of synthetic hormone that meet demanding regulations to assure high product quality, predictable bioavailability given its narrow therapeutic range, and now are left with potential variance in the therapeutic efficacy among different preparations.

Systematic Review and Meta-analysis of the Impact of Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP) on Cytological Diagnosis and Thyroid Cancer Prevalence

A re-named diagnosis of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) likely impacts the prevalence of thyroid cancer and risk of malignancy in populations based on the established Bethesda System of Reporting Thyroid Cytopathology (TBSRTC). This study was done to investigate the prevalence and cytological distribution of NIFTP. PRISMA guided systematic review was done from a database search of Pubmed, EMBASE, and Medline using the search terms "non-invasive follicular thyroid neoplasm with papillary-like nuclear features", "non-invasive follicular variant of papillary carcinoma", "niftp", and "Bethesda" until November 2018. Original articles with surgically proven diagnoses of NIFTP using strict NIFTP criteria were included. Twenty-nine studies with 1563 cases of NIFTP were included. The pooled prevalence of NIFTP in cases which would be classified previously as the follicular variant of papillary thyroid cancer (FVPTC) and papillary thyroid cancer (PTC) were 43.5% (95% CI 33.5-54.0%) and 4.4% (95% CI 2.0-9.0%) respectively. The pooled TBSRTC distribution of cases diagnosed as NIFTP was: from the non-diagnostic category 3.6% (95% CI 2.4-5.3%), benign 10.0% (95% CI 7.2-13.6%), AUS/FLUS 34.2% (95% CI 28.2-40.8%), FN/SFN 22.7% (95% CI 17.2-29.4%), suspicious for malignancy 22.4% (95% CI 17.7-27.9%), and malignant 7.5% (95% CI 4.2-12.9%). While a significant reduction in FVPTC prevalence is anticipated, a modest reduction of PTC prevalence is also expected with adoption of the NIFTP terminology that would be distributed mainly among lesions classified as indeterminate thyroid nodules. Further studies are needed to identify unique clinical characteristics of these lesions preoperatively.

Cytomorphology of Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features and the Impact of New Nomenclature on Molecular Testing

The re-naming of noninvasive follicular variant papillary thyroid cancer to the apparently non-malignant, noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) impacts the prevalence of malignancy rates, thereby affecting mutation frequency in papillary thyroid cancer. Preoperative assessment of such nodules could affect management in the future. The original publications following the designation of the new nomenclature have been extensively reviewed. With the adoption of NIFTP terminology, a reduction in the follicular variant of papillary thyroid cancer (FVPTC) prevalence is anticipated, as is a modest reduction of papillary thyroid cancer (PTC) prevalence that would be distributed mainly across indeterminate thyroid nodules. Identifying NIFTP preoperatively remains challenging. RAS mutations are predominant but the presence of BRAF V600E mutation has been observed and could indicate inclusion of the classical PTC. The histological diagnosis of NIFTP to designate low-risk encapsulated follicular variant papillary thyroid cancers (EFVPTCs) would impact malignancy rates, thereby altering the mutation prevalence. The histopathologic criteria have recently been refined with an exclusion of well-formed papillae. The preoperative identification of NIFTP using cytomorphology and gene testing remains challenging.

An Online Survey of Hypothyroid Patients Demonstrates Prominent Dissatisfaction

BACKGROUND

Approximately 15% more patients taking levothyroxine (LT4) report impaired quality of life compared to controls. This could be explained by additional diagnoses independently affecting quality of life and complicating assignment of causation. This study sought to investigate the underpinnings of reduced quality of life in hypothyroid patients and to provide data for discussion at a symposium addressing hypothyroidism.

METHODS

An online survey for hypothyroid patients was posted on the American Thyroid Association Web site and forwarded to multiple groups. Respondents were asked to rank satisfaction with their treatment for hypothyroidism and their treating physician. They also ranked their perception regarding physician knowledge about hypothyroidism treatments, need for new treatments, and life impact of hypothyroidism on a scale of 1-10. Respondents reported the therapy they were taking, categorized as LT4, LT4 and liothyronine (LT4 + LT3), or desiccated thyroid extract (DTE). They also reported sex, age, cause of hypothyroidism, duration of treatment, additional diagnoses, and prevalence of symptoms.

RESULTS

A total of 12,146 individuals completed the survey. The overall degree of satisfaction was 5 (interquartile range [IQR] = 3-8). Among respondents without self-reported depression, stressors, or medical conditions (n = 3670), individuals taking DTE reported a higher median treatment satisfaction of 7 (IQR = 5-9) compared to other treatments. At the same time, the LT4 treatment group exhibited the lowest satisfaction of 5 (IQR = 3-7), and for the LT4 + LT3 treatment group, satisfaction was 6 (IQR = 3-8). Respondents taking DTE were also less likely to report problems with weight management, fatigue/energy levels, mood, and memory compared to those taking LT4 or LT4 + LT3.

CONCLUSIONS

A subset of patients with hypothyroidism are not satisfied with their current therapy or their physicians. Higher satisfaction with both treatment and physicians is reported by those patients on DTE. While the study design does not provide a mechanistic explanation for this observation, future studies should investigate whether preference for DTE is related to triiodothyronine levels or other unidentified causes.

American Thyroid Association Guidelines and Statements: Past, Present, and Future

BACKGROUND

The American Thyroid Association (ATA) is continually striving to improve the quality of its publications. The ATA Guidelines Policies and Procedures Task Force was active during 2017. It recently recommended convening a formal standing committee to review and update policies and procedures for the development of clinical practice guidelines (CPGs) and Statements on an ongoing basis.

OBJECTIVE

This statement reviews the history of official ATA publications and discusses the challenges and findings identified by the Task Force. We also wish to present our "work in progress" and propose future directions for the new ATA Guidelines and Statements Committee (ATA GSC).

METHODS

Our Task Force reviewed the publication record of the ATA with respect to CPGs. We also reviewed existing ATA policies for CPGs and other official statements, examined policies of other organizations, solicited input from external experts and organizations, and convened five conference calls and two in-person meetings.

RESULTS

The ATA has a rich history of developing official publications that have been influential based on download and citation records as well as changes in practice trends. Key future issues to be further addressed by the ATA GSC include the following: (i) striving to improve the methodologic rigor of development of CPGs while balancing considerations of feasibility and timeliness and the role of transparently communicated expert opinion; (ii) formalizing a framework and process for development of new Statements; (iii) increasing stringency and transparency of management of competing interests of individuals being considered for CPG/Statement panel membership; (iv) encouraging consideration of equity and diversity in CPG/Statement development group composition; (v) increasing relevant stakeholder representation (including patient representatives) in development of CPGs/Statements; and (vi) expanding future guideline implementation strategies.

CONCLUSIONS

As shown by the completed literature search, the ATA has a long history of producing CPGs and Statements with global impact on informing clinical management, education, and research in thyroid diseases. The ATA remains committed to a process of continual improvement of its publications and to meeting stakeholder information needs. Based on the work of our Task Force, we have identified many elements that are needed to achieve this goal and areas of challenge for our new committee.

Current evidence for the treatment of hypothyroidism with levothyroxine/levotriiodothyronine combination therapy versus levothyroxine monotherapy

OBJECTIVE

Hypothyroidism is relatively common, occurring in approximately 5% of the general US population aged ≥12 years. Levothyroxine (LT4) monotherapy is the standard of care. Approximately, 5%-10% of patients who normalise thyroid-stimulating hormone levels with LT4 monotherapy may have persistent symptoms that patients and clinicians may attribute to hypothyroidism. A long-standing debate in the literature is whether addition of levotriiodothyronine (LT3) to LT4 will ameliorate lingering symptoms. Here, we explore the evidence for and against LT4/LT3 combination therapy as the optimal approach to treat euthyroid patients with persistent complaints.

METHODS

Recent literature indexed on PubMed was searched in March 2017 using the terms "hypothyroid" or "hypothyroidism" and "triiodothyronine combination" or "T3 combination." Relevant non-review articles published in English during the past 10 years were included and supplemented with articles already known to the authors.

FINDINGS

Current clinical evidence is not sufficiently strong to support LT4/LT3 combination therapy in patients with hypothyroidism. Polymorphisms in deiodinase genes that encode the enzymes that convert T4 to T3 in the periphery may provide potential mechanisms underlying unsatisfactory treatment results with LT4 monotherapy. However, results of studies on the effect of LT4/LT3 therapy on clinical symptoms and thyroid-responsive genes have thus far not been conclusive.

CONCLUSIONS

Persistent symptoms in patients who are biochemically euthyroid with LT4 monotherapy may be caused by several other conditions unrelated to thyroid function, and their cause should be aggressively investigated by the clinician.

Invasive follicular variant of papillary thyroid cancer harboring the NRAS mutation Q61K and presenting with bone metastasis-A case report

•

A patient with invasive follicular variant of papillary thyroid cancer presented with bone metastasis.

•

The thyroid tumor harbored an isolated RAS mutation.

•

The report challenges recent views that thyroid tumors with isolated RAS mutations may have a non-aggressive clinical course and may be candidates for conservative management.

Introduction

The follicular variant of papillary thyroid cancer (FVPTC) can be noninvasive or invasive. The invasive form of FVPTC commonly harbors BRAF mutations whereas RAS mutations are more often associated with noninvasive FVPTC and a favorable clinical outcome.

Case report

A 47-year-old man presented with a metastasis to his right iliac bone as the initial manifestation of a 1.6 cm invasive FVPTC. After total thyroidectomy, the patient underwent additional treatment, including thyroid hormone suppressive treatment to non-detectable TSH levels, repeated courses of radioiodine treatment, external beam radiation, and treatment with the tyrosine kinase inhibitor sorafenib. Despite these therapeutic efforts, the disease progressed with growth of the iliac mass and additional metastatic spread to cervical and lumbar vertebrae causing increasing pain and disability. The patient succumbed to the disease four years after presentation. Retrospective next-generation sequencing of the primary tumor using a pan-cancer targeted mutation and gene fusion panel revealed NRAS Q61K mutation and no other oncogenic alterations.

Discussion

The study challenges the concept that thyroid neoplasms with isolated RAS mutations are often associated with favorable clinical behavior and may be candidates for conservative management.

Conclusion

An isolated RAS mutation in invasive FVPTC may be associated with an aggressive clinical behavior.

American Thyroid Association Scientific Statement on the Use of Potassium Iodide Ingestion in a Nuclear Emergency

This document serves to summarize the issues and the American Thyroid Association (ATA) position regarding the use of potassium iodide as a thyroid blocking agent in the event of a nuclear accident. The purpose is to provide a review and updated position statement regarding the advanced distribution, stockpiling, and availability of potassium iodide in the event of nuclear radiation emergencies in the United States.

ADVERSE EVENT REPORTING IN PATIENTS TREATED WITH THYROID HORMONE EXTRACT

OBJECTIVE

Thyroid hormone extract is used for the treatment of thyroid disorders, but limited data exist on adverse events commonly noted by the physicians associated with this use. The purpose of this survey was to report adverse events observed by expert physicians managing patients treated for thyroid disease with thyroid hormones.

METHODS

Members of the American Thyroid Association, The Endocrine Society, and the American Association of Clinical Endocrinologists developed a survey instrument modeled on the U.S. Food and Drug Administration (FDA)'s reported adverse events for levothyroxine that would effectively assess the clinical experience of frequent prescribers of thyroid hormone. Survey links were emailed to physicians, and the websites of each society provided links to the data collection form.

RESULTS

A total of 174 reports of adverse events occurring in patients on thyroid hormone extract were received. Ninety-one of these reports were accompanied by alterations in thyrotropin values and were further analyzed. Of these, 62 (68%) subjects had developed new symptoms associated with altered thyroid-stimulating hormone (TSH). A majority of TSH changes and symptoms described were consistent with thyrotoxicosis (65%), and 2 patients had developed arrhythmias. Reporters noted difficulty in dose adjustment by primary care providers due to confusion in interpreting thyroid function test results while on thyroid extract, which often necessitated subspecialty referrals.

CONCLUSION

These adverse event reports should stimulate consideration by the FDA to regulate and monitor thyroid hormone extract use and consider standardizing these extracts to meet current standards of manufacture, hormone content, availability, and shelf-life, like the rigor with which preparations such as levothyroxine are monitored.

ABBREVIATIONS

AE = adverse event ATA = American Thyroid Association FDA = Food and Drug Administration LT3 = liothyronine LT4 = levothyroxine PTF = Pharmacovigilance Task Force T3 = triiodothyronine TSH = thyroid-stimulating hormone.

Variable Cold-Induced Brown Adipose Tissue Response to Thyroid Hormone Status

BACKGROUND

In addition to its role in adaptive thermogenesis, brown adipose tissue (BAT) may protect from weight gain, insulin resistance/diabetes, and metabolic syndrome. Prior studies have shown contradictory results regarding the influence of thyroid hormone (TH) levels on BAT volume and activity. The aim of this pilot study was to gain further insights regarding the effect of TH treatment on BAT function in adult humans by evaluating the BAT mass and activity prospectively in six patients, first in the hypothyroid and then in the thyrotoxic phase.

METHODS

The study subjects underwent 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scanning after cold exposure to measure BAT mass and activity while undergoing treatment for differentiated thyroid cancer, first while hypothyroid following TH withdrawal at the time of the radioactive iodine treatment and then three to six months after starting TH suppressive treatment when they were iatrogenically thyrotoxic. Thermogenic and metabolic parameters were measured in both phases.

RESULTS

All study subjects had detectable BAT under cold stimulation in both the hypothyroid and thyrotoxic state. The majority but not all (4/6) subjects showed an increase in detectable BAT volume and activity under cold stimulation between the hypothyroid and thyrotoxic phase (total BAT volume: 72.0 ± 21.0 vs. 87.7 ± 16.5 mL, p = 0.25; total BAT activity 158.1 ± 72.8 vs. 189.0 ± 55.5 SUV*g/mL, p = 0.34). Importantly, circulating triiodothyronine was a stronger predictor of energy expenditure changes compared with cold-induced BAT activity.

CONCLUSIONS

Iatrogenic hypothyroidism lasting two to four weeks does not prevent cold-induced BAT activation, while the use of TH to induce thyrotoxicosis does not consistently increase cold-induced BAT activity. It remains to be determined which physiological factors besides TH play a role in regulating BAT function.

The emergence of levothyroxine as a treatment for hypothyroidism

OBJECTIVE

To describe the historical refinements, understanding of physiology and clinical outcomes observed with thyroid hormone replacement strategies.

METHODS

A Medline search was initiated using the search terms, levothyroxine, thyroid hormone history, levothyroxine mono therapy, thyroid hormone replacement, combination LT4 therapy, levothyroxine Bioequivalence. Pertinent articles of interest were identified by title and where available abstract for further review. Additional references were identified in the course of review of the literature identified.

RESULTS

Physicians have intervened in cases of thyroid dysfunction for more than two millennia. Ingestion of animal thyroid derived preparations has been long described but only scientifically documented for the last 130 years. Refinements in hormone preparation, pharmaceutical production and regulation continue to this day. The literature provides documentation of physiologic, pathologic and clinical outcomes which have been reported and continuously updated. Recommendations for effective and safe use of these hormones for reversal of patho-physiology associated with hypothyroidism and the relief of symptoms of hypothyroidism has documented a progressive refinement in our understanding of thyroid hormone use. Studies of thyroid hormone metabolism, action and pharmacokinetics have allowed evermore focused recommendations for use in clinical practice. Levothyroxine mono-therapy has emerged as the therapy of choice of all recent major guidelines.

CONCLUSIONS

The evolution of thyroid hormone therapies has been significant over an extended period of time. Thyroid hormone replacement is very useful in the treatment of those with hypothyroidism. All of the most recent guidelines of major endocrine societies recommend levothyroxine mono-therapy for first line use in hypothyroidism.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY POSITION STATEMENT ON THYROID DYSFUNCTION CASE FINDING

Hypothyroidism and hyperthyroidism can be readily diagnosed and can be treated in a safe, cost-effective manner. Professional organizations have given guidance on how and when to employ thyroid-stimulating hormone testing for the detection of thyroid dysfunction. Most recently, the United States Preventive Services Task Force did not endorse screening for thyroid dysfunction based on a lack of proven benefit and potential harm of treating those with thyroid dysfunction, which is mostly subclinical disease. The American Association of Clinical Endocrinologists (AACE) is concerned that this may discourage physicians from testing for thyroid dysfunction when clinically appropriate. Given the lack of specificity of thyroid-associated symptoms, the appropriate diagnosis of thyroid disease requires biochemical confirmation. The Thyroid Scientific Committee of the AACE has produced this White Paper to highlight the important difference between screening and case-based testing in the practice of clinical medicine. We recommend that thyroid dysfunction should be frequently considered as a potential etiology for many of the nonspecific complaints that physicians face daily. The application and success of safe and effective interventions are dependent on an accurate diagnosis. We, therefore, advocate for an aggressive case-finding approach, based on identifying those persons most likely to have thyroid disease that will benefit from its treatment.

A 2015 Survey of Clinical Practice Patterns in the Management of Thyroid Nodules

CONTEXT

The management of thyroid nodules has changed dramatically over the past two decades. In the interim, technological advances including high-resolution ultrasound and molecular testing of thyroid nodules have been introduced.

OBJECTIVE

We sought to document current practices in the management thyroid nodules and assess the extent to which technological advances have been incorporated into current practice. We further sought to compare current practice to recommendations made in a recently updated American Thyroid Association (ATA) clinical practice guideline (CPG) and examine differences in thyroid nodule management among international members of U.S.-based endocrine societies.

METHODS

Members of The Endocrine Society, ATA, and American Association of Clinical Endocrinologists were invited to participate in a Web-based survey dealing with testing, treatment preference, and modulating factors in patients with thyroid nodules.

RESULTS

A total of 897 respondents participated in the survey, including 661 members of The Endocrine Society, 454 American Association of Clinical Endocrinologists members, and 365 ATA members. Thyroid fine-needle aspiration (FNA) in 2015 is generally performed by endocrinologists (56.6%) and radiologists (31.9%), most frequently using ultrasound guidance (83.3%). Respondents in general have a lower threshold for FNA of thyroid nodules than that recommended in the updated ATA CPG. Management depends on the FNA result, with follicular lesion of undetermined significance/atypia of undetermined significance resulting in molecular testing (38.8% of respondents), repeat FNA cytology (31.5%), or immediate referral for thyroid surgery (24.4%). Nodules showing follicular neoplasm by FNA are referred for thyroid surgery by 61.2% of respondents (46.6 % lobectomy, 14.6 % total thyroidectomy) or molecular testing (29.0 %). Nodules found suspicious but not conclusive for malignancy (Bethesda category V), are referred for thyroid surgery (86.0%) and rarely undergo molecular testing (9.5%). During pregnancy, only 47.6% of respondents would perform FNA in the absence of nodular growth, with most respondents deferring FNA until after pregnancy. Endocrinologists are 64.2% less likely to perform FNA in an octogenarian than a younger patient with a comparable thyroid nodule. Striking international differences were identified in the routine measurement of calcitonin and in the use of molecular testing of thyroid nodules.

CONCLUSIONS

In summary, our survey of clinical endocrinologists on the management of thyroid nodules documents current practice patterns and demonstrates both concordance and focal discordance with recently updated CPGs. Both international differences and a change in practice patterns during the past two decades are demonstrated.

Building a Quality Management System for a Thyroid Nodule Clinic

BACKGROUND

There are few published quality metrics relevant to fine-needle aspirations (FNA) of the thyroid and endocrinology. With the development of a Thyroid Nodule Clinic within an academic practice, the Division of Endocrinology, in collaboration with the Department of Medicine Quality Improvement Team, established a system to monitor the results and follow-up of thyroid biopsies to ensure patient safety and to prevent adverse clinical outcomes attributable to delayed or incomplete follow-up.

METHODS

All FNA performed are identified using billing data from the Thyroid Nodule Clinic. Results were followed using the Beth Israel Deaconess Online Medical Record (OMR) system, and information is collected on documented follow-up plan and actions taken. Missing data are flagged for review. Over the reporting period, the monitoring process and categories were modified to account for adoption of the Bethesda reporting criteria and implementation of gene expression classifier testing. Specific workflow plans were developed for each cytopathologic classification.

RESULTS

Between July 2007 and June 2014, 3895 FNAs were performed. The quality improvement tracking process found that 3856/3895 (99%) biopsy cases had documented follow-up since initiation of the project.

CONCLUSION

This monitoring process has ensured quality patient care, with confidence that patients having FNAs are receiving documented necessary follow-up for treatment of their nodular conditions. This system serves as a potential model for others to use in their endocrine practice in managing the results of thyroid nodule biopsies.

Low iodine diet in differentiated thyroid cancer: a review

Radioactive iodine (RAI) ablation is a beneficial, adjuvant therapy for the management of differentiated thyroid cancer (DTC) after thyroidectomy. The goal of RAI is to destroy remnant thyroid and microscopic cancerous tissue. Radioactive iodine uptake is enhanced by elevating TSH levels and initiating a low iodine diet (LID) prior to ablation. An ideal LID should preferably not exceed 50 mcg/day of dietary iodine for 1-2 weeks, although the duration may be shortened to a week with a structured patient education programme. A pre-ablation spot urinary iodine concentration (UIC) of <100 mcg/l and/or a urinary iodine to creatinine ratio (UICR) of <100 mcg/gCr would support an adequate LID preparation. Hyponatraemia, most likely due to iatrogenic hypothyroidism, is a potential side effect associated with LID and occurs during and a few days after the LID. Although the overall incidence of hyponatraemia is low, patients at high risk (older age, female sex, use of thiazide diuretics) may benefit from serum sodium monitoring. The existing evidence on the impact of LID on RAI ablation has been largely inconsistent due to retrospective study designs and the lack of an objective measurement of urinary iodine levels. Future large prospective randomized control trials are needed to elucidate and confirm the crucial role of LID in achieving successful RAI ablation and greater disease-free survival in DTC.

Subclinical hypothyroidism: a historical view and shifting prevalence

BACKGROUND AND AIMS

Accurate diagnosis and treatment of subclinical hypothyroidism (SCH) is challenging in clinical practice because of differing upper limits of normal (ULN) for thyroid-stimulating hormone (TSH). This review summarises the various definitions of SCH and their impact on reported SCH prevalence.

METHODOLOGY

Articles reporting the prevalence of SCH in relation to the ULN of TSH in human studies were identified through an English-language PubMed search for 'subclinical hypothyroidism,' 'prevalence,' and 'TSH' within the title and/or abstract. Relevant articles and related literature were selected for inclusion.

RESULTS

Estimates for the prevalence of SCH varied by sex, age, race/ethnicity, and geographic location (range, 0.4-16.9%). Higher rates of SCH were consistently reported in women (0.9-16.9%) and older individuals (2.7-16.9%). However, the ULN of TSH in those considered free of thyroid disease and not at risk increased progressively with age, suggesting that reports of SCH prevalence in elderly people may be overestimated. Multiple studies reported an increased risk of progression to overt hypothyroidism among individuals with elevated TSH and antithyroid antibodies.

CONCLUSIONS

Given the variable definition of SCH based on an inconsistent ULN for TSH, it is currently difficult to ascertain the true prevalence of SCH and to correctly label and treat patients with SCH; use of age-adjusted definitions may be considered when assessing prevalence. A diagnosis of SCH does not necessarily merit treatment, especially if TSH elevations are transient (i.e. not persistent for > 3-6 months) and the patient lacks other risk factors for developing overt hypothyroidism.

Performance of the Afirma Gene Expression Classifier in Hürthle Cell Thyroid Nodules Differs from Other Indeterminate Thyroid Nodules

BACKGROUND

The recently introduced Afirma gene expression classifier (AGEC) provides binary results (benign or suspicious) to guide management of cytologically indeterminate thyroid nodules. The AGEC is intended to reduce unnecessary surgeries for benign nodules, and management algorithms favor surgery for suspicious results. Limited data are available on the performance of this test for Hürthle cell nodules (HCNs). This study hypothesized that a predominance of Hürthle cells leads to an increased rate of suspicious AGEC results with a potential for overtreatment, despite a relatively low risk of malignancy.

METHODS

The pathology databases from three tertiary care facilities were queried from 2010 to 2014 for fine-needle aspirates (FNAs) diagnosed as suspicious for Hürthle cell neoplasm (SHCN) or atypia of undetermined significance/follicular lesion of undetermined significance concerning for Hürthle cell neoplasm (AFHCN). Cytology diagnoses were rendered internally prior to AGEC testing. The patient demographics, FNA diagnosis, AGEC result, surgical procedure, and pathologic outcomes were recorded.

RESULTS

The cohort consisted of 134 patients with HCNs. Prior to AGEC availability, 62 patients underwent surgery: 81% (50/62) of patients had surgery, and 34% (17/50) of the resected index nodules were malignant. After introduction of the AGEC, 72 patients underwent AGEC testing: 65% (47/72) of patients had surgery, and 13% (6/46) of the resected nodules were malignant. Thirty-two percent (23/72) of patients had a benign AGEC result and did not undergo surgery, and 4% (3/72) had surgery despite a benign AGEC result with benign final pathology, whereas 63% (45/72) of patients had suspicious AGEC results, with 96% of these patients (43/45) undergoing surgery, and 14% (6/43) of these index nodules were malignant.

CONCLUSIONS

While 32% of tested patients declined surgery based on a benign AGEC, 86% of patients with suspicious AGEC findings had unnecessary surgery, reflecting a substantially lower rate of malignancy from what was previously reported for all indeterminate nodules. Given the approximate pretest malignancy risk of 25-35% for an FNA diagnosis of SHCN or AFHCN, a suspicious AGEC diagnosis does not increase the probability of malignancy in an HCN, and patients should be counseled accordingly.

Reversible morbidity markers in subclinical hypothyroidism

IMPORTANCE

Subclinical hypothyroidism (SCH) is a common clinical entity with a putative role in a wide range of disorders. The impact of SCH on mortality and markers of morbidity has been demonstrated, but studies have shown inconsistent results. Evidence regarding the effect of levothyroxine treatment on reversing morbidity markers is emerging, but the value of treatment is still unclear.

OBJECTIVE

The objectives of this review were to assess recent, high-quality studies evaluating the role of SCH in cardiovascular health, cognition, mood, pregnancy, anemia, and renal disease; to examine the effects of levothyroxine on reducing mortality or reversing markers of morbidity in these conditions; and to consider how new research insights may help guide clinical practice.

EVIDENCE REVIEW

A PubMed search was conducted (using 'subclinical hypothyroidism' [Title/Abstract] AND morbidity [MeSH Subheading] as search criteria) and was restricted to human studies published in the English language between 1990 and 2013. Subsequent searches of retrieved articles yielded further studies, which were included based on quality. Emphasis was given to large observational studies, well-conducted meta-analyses, and randomized controlled trials.

FINDINGS

The difficulty of diagnosing SCH, particularly in the elderly, may underlie many of the conflicting results seen in the literature. Increased understanding of the at-risk patient population will result in better selection of study subjects and, likely, unequivocal results. Regardless of the current confusion, emerging evidence suggests that certain markers of morbidity are reversed by levothyroxine therapy across the disorders examined here.

CONCLUSION AND RELEVANCE

Future large, well-controlled studies will not only clarify the role of SCH but also help identify patients for whom levothyroxine treatment will provide the most benefit.

A 2013 survey of clinical practice patterns in the management of primary hypothyroidism

CONTEXT

In 2012, comprehensive clinical practice guidelines (CPGs) were published regarding the management of hypothyroidism.

OBJECTIVE

We sought to document current practices in the management of primary hypothyroidism and compare these results with recommendations made in the 2012 American Thyroid Association (ATA)/American Association of Clinical Endocrinologists (AACE) hypothyroidism CPGs. In addition, we sought to examine differences in management among international members of U.S.-based endocrine societies and to compare survey results with those obtained from a survey of ATA members performed 12 years earlier.

METHODS

Clinical members of The Endocrine Society (TES), the ATA, and the AACE were asked to take a web-based survey consisting of 30 questions dealing with testing, treatment, and modulating factors in the management of primary hypothyroidism.

RESULTS

In total, 880 respondents completed the survey, including 618 members of TES, 582 AACE members, and 208 ATA members. North American respondents accounted for 67.6%, Latin American 9.7%, European 9.2%, Asia and Oceania 8.1%, and Africa and Middle East 5.5%. Overt hypothyroidism would be treated using l-T4 alone by 99.2% of respondents; 0.8% would use combination l-T4 and liothyronine (l-T3) therapy. Generic l-T4 would be used by 49.3% and a brand name by 49.9%. The rate of replacement would be gradual (38.5%); an empiric dose, adjusted to achieve target (33.6%); or a calculated full replacement dose (27.8%). A target TSH of 1.0 to 1.9 mU/L was favored in the index case, but 3.0 to 3.9 mU/L was the most commonly selected TSH target for an octogenarian. Persistent hypothyroid symptoms despite achieving a target TSH would prompt testing for other causes by 84.3% of respondents, a referral to primary care by 11.3%, and a change to l-T4 plus l-T3 therapy by 3.6%. Evaluation of persistent symptoms would include measurement of T3 levels by 21.9% of respondents. Subclinical disease with a TSH 5.0 to 10.0 mU/L would be treated without further justification by 21.3% of respondents, or in the presence of positive thyroid peroxidase antibodies (62.3%), hypothyroid symptoms (60.9%), high low-density lipoprotein (52.9%), or goiter (46.6%). The TSH target for a newly pregnant patient was <2.5 mU/L for 96.1% of respondents, with 63.5% preferring a TSH target <1.5 mU/L. Thyroid hormone levels would be checked every 4 weeks during pregnancy by 67.7% and every 8 weeks by an additional 21.4%. A hypothyroid patient with TSH of 0.5 mU/L who becomes pregnant would receive an immediate l-T4 dose increase by only 36.9% of respondents.

CONCLUSION

The current survey of clinical endocrinologists catalogs current practice patterns in the management of hypothyroidism and demonstrates 1) a nearly exclusive preference for l-T4 alone as initial therapy, 2) the widespread use of age-specific TSH targets for replacement therapy, 3) a low threshold for treating mild thyroid failure, 4) meticulous attention to TSH targets in the pregnant and prepregnant woman, and 5) a highly variable approach to both the rate and means of restoring euthyroidism for overt disease. Both alignment and focal divergence from recent CPGs are demonstrated.

Neuropsychiatric manifestations of thyroid disease

The interface between thyroid hormone action and neuropsychiatric function is intricate, and several mechanisms of thyroid hormone uptake into brain tissues, hormone activation, and influences on neurotransmitter generation have been identified. Symptoms of hypothyroidism are nonspecific, whereas those attributed to thyrotoxicosis may be more characteristic. Neuropsychiatric manifestations triggered by thyroid dysfunction likely respond well to reestablishment of the euthyroid state, although some patients have persistent complaints. The addition of LT3 to ongoing LT4 replacement has yet to be definitively shown to be advantageous. Treatment of euthyroid depression with LT3 in addition to antidepressant therapy lacks convincing evidence of superior outcomes.

Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association

OBJECTIVE

Hypothyroidism has multiple etiologies and manifestations. Appropriate treatment requires an accurate diagnosis and is influenced by coexisting medical conditions. This paper describes evidence-based clinical guidelines for the clinical management of hypothyroidism in ambulatory patients.

METHODS

The development of these guidelines was commissioned by the American Association of Clinical Endocrinologists (AACE) in association with American Thyroid Association (ATA). AACE and the ATA assembled a task force of expert clinicians who authored this article. The authors examined relevant literature and took an evidence-based medicine approach that incorporated their knowledge and experience to develop a series of specific recommendations and the rationale for these recommendations. The strength of the recommendations and the quality of evidence supporting each was rated according to the approach outlined in the American Association of Clinical Endocrinologists Protocol for Standardized Production of Clinical Guidelines-2010 update.

RESULTS

Topics addressed include the etiology, epidemiology, clinical and laboratory evaluation, management, and consequences of hypothyroidism. Screening, treatment of subclinical hypothyroidism, pregnancy, and areas for future research are also covered.

CONCLUSIONS

Fifty-two evidence-based recommendations and subrecommendations were developed to aid in the care of patients with hypothyroidism and to share what the authors believe is current, rational, and optimal medical practice for the diagnosis and care of hypothyroidism. A serum thyrotropin is the single best screening test for primary thyroid dysfunction for the vast majority of outpatient clinical situations. The standard treatment is replacement with L-thyroxine. The decision to treat subclinical hypothyroidism when the serum thyrotropin is less than 10 mIU/L should be tailored to the individual patient.

Subclinical hypothyroidism, mood, and cognition in older adults: a review

OBJECTIVES

To perform a critical review of the literature on the mood and cognitive changes associated with subclinical hypothyroidism (SCH), with an emphasis on older adults. To evaluate these data against the Consensus Statement on the management of SCH from the American Association of Clinical Endocrinologists, the American Thyroid Association, and The Endocrine Society.

METHOD

A comprehensive literature review.

RESULTS

Subclinical hypothyroidism may be associated with an increased risk of mood and cognitive dysfunction, although the strength of this association and the efficacy of replacement hormone therapy require further investigation.

CONCLUSION

It remains unclear whether SCH leads to significant mood and cognitive impairments in most older patients. More research is required to determine the nature and extent of this association and whether thyroid hormone replacement therapy is appropriate and effective in treating SCH-associated neurobehavioral impairments.

Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association

BACKGROUND

Hypothyroidism has multiple etiologies and manifestations. Appropriate treatment requires an accurate diagnosis and is influenced by coexisting medical conditions. This paper describes evidence-based clinical guidelines for the clinical management of hypothyroidism in ambulatory patients.

METHODS

The development of these guidelines was commissioned by the American Association of Clinical Endocrinologists (AACE) in association with American Thyroid Association (ATA). AACE and the ATA assembled a task force of expert clinicians who authored this article. The authors examined relevant literature and took an evidence-based medicine approach that incorporated their knowledge and experience to develop a series of specific recommendations and the rationale for these recommendations. The strength of the recommendations and the quality of evidence supporting each was rated according to the approach outlined in the American Association of Clinical Endocrinologists Protocol for Standardized Production of Clinical Guidelines-2010 update.

RESULTS

Topics addressed include the etiology, epidemiology, clinical and laboratory evaluation, management, and consequences of hypothyroidism. Screening, treatment of subclinical hypothyroidism, pregnancy, and areas for future research are also covered.

CONCLUSIONS

Fifty-two evidence-based recommendations and subrecommendations were developed to aid in the care of patients with hypothyroidism and to share what the authors believe is current, rational, and optimal medical practice for the diagnosis and care of hypothyroidism. A serum thyrotropin is the single best screening test for primary thyroid dysfunction for the vast majority of outpatient clinical situations. The standard treatment is replacement with L-thyroxine. The decision to treat subclinical hypothyroidism when the serum thyrotropin is less than 10 mIU/L should be tailored to the individual patient.