Interpretation Of Thyroid Function Tests Research Articles

Should we depend on reference intervals from manufacturer package inserts? Comparing TSH and FT4 reference intervals from four manufacturers with results from modern indirect methods and the direct method.

Correct interpretation of thyroid function tests relies on correct reference intervals (RIs) for thyroid-stimulating hormone (TSH) and free thyroxine (FT4). ISO15189 mandates periodic verification of RIs, but laboratories struggle with cost-effective approaches. We investigated whether indirect methods (utilizing historical laboratory data) could replace the direct approach (utilizing healthy reference individuals) and compared results with manufacturer-provided RIs for TSH and FT4. We collected historical data (2008-2022) from 13 Dutch laboratories to re-establish RIs by employing indirect methods, TMC (for TSH) and refineR (for FT4). Laboratories used common automated platforms (Roche, Abbott, Beckman or Siemens). Indirect RIs (IRIs) were determined perlaboratory per year and clustered per manufacturer (>1.000.000 data points per manufacturer). Direct RIs (DRIs) were established in 125 healthy individuals per platform. TSH IRIs remained robust over the years for all manufacturers. FT4 IRIs proved robust for three manufacturers (Roche, Beckman and Siemens), but the IRI upper reference limit (URL) of Abbott showed a decrease of 2 pmol/L from 2015. Comparison of the IRIs and DRIs for TSH and FT4 showed close agreement using adequate age-stratification. Manufacturer-provided RIs, notably Abbott, Roche and Beckman exhibited inappropriate URLs (overall difference of 0.5-1.0 µIU/mL) for TSH. For FT4, the URLs provided by Roche, Abbott and Siemens were overestimated by 1.5-3.5 pmol/L. These results underscore the importance of RI verification as manufacturer-provided RIs are often incorrect and RIs may not be robust. Indirect methods offercost-effective alternatives for laboratory-specific or platform-specific verification of RIs.

Diagnosis and Management of Congenital Hypothyroidism: An Updated Overview

Context: Hypothyroidism describes an endocrine disorder that occurs when the thyroid gland cannot secrete adequate thyroid hormones. Congenital hypothyroidism refers to a lack of thyroid hormone among newborns. Evidence Acquisition: The ISI Web of Sciences, Scopus, PubMed, and Google Scholar databases were reviewed for relevant articles published from 2000 to 2022. Results: Congenital hypothyroidism, occurring in approximately one in 2,000 to one in 4,000 newborns, ranks among the most frequent causes of intellectual disability that can be prevented. The screening of newborns, confirmation assessments, interpretation of thyroid function tests accurately, prompt and therapeutic treatment, and regular follow-up contribute to a very good neurocognitive outcome later in life. Since the timely diagnosis of congenital hypothyroidism is critical in preventing mental retardation, clinicians must be kept abreast of this disorder and educate nursing and medical students regarding accurate interpretations of diagnostic testing and the recognition of associated symptoms. Most newborns with congenital hypothyroidism present no symptoms, even though their TSH or T4 levels are likely to have fluctuated significantly. As a result, congenital hypothyroidism was rarely detected in newborns before the introduction of neonatal screenings. Conclusions: We provide an overview of the etiology, epidemiology, manifestation, diagnosis, and treatment of congenital hypothyroidism based on the latest studies.

Neonatal reference intervals for thyroid stimulating hormone and free thyroxine assayed on a Siemens Atellica® IM analyzer: a cross sectional study

BackgroundDeriving population specific reference intervals (RIs) or at the very least verifying any RI before adoption is good laboratory practice. Siemens has provided RIs for thyroid stimulating hormone (TSH) and free thyroxine (FT4) determined on their Atellica® IM analyzer for all age groups except the neonatal age group which provides a challenge for laboratories that intend to use it to screen for congenital hypothyroidism (CH) and other thyroid disorders in neonates. We set out to determine RIs for TSH and FT4 using data obtained from neonates undergoing routine screening for CH at the Aga Khan University Hospital, Nairobi, Kenya.MethodologyTSH and FT4 data for neonates aged 30 days and below were extracted from the hospital management information system for the period March 2020 to June 2021. A single episode of testing for the same neonate was included provided both TSH and FT4 were done on the same sample. RI determination was performed using a non-parametric approach.ResultsA total of 1243 testing episodes from 1218 neonates had both TSH and FT4 results. A single set of test results from each neonate was used to derive RIs. Both TSH and FT4 declined with increase in age with a more marked decline seen in the first 7 days of life. There was a positive correlation between logFT4 and logTSH (rs (1216) = 0.189, p = < 0.001). We derived TSH RIs for the age groups 2–4 days (0.403–7.942 µIU/mL) and 5–7 days (0.418–6.319 µIU/mL), and sex specific RIs for males (0.609–7.557 µIU/mL) and females (0.420–6.189 µIU/mL) aged 8–30 days. For FT4, separate RIs were derived for the age groups 2–4 days (1.19–2.59 ng/dL), 5–7 days (1.21–2.29 ng/dL) and 8–30 days (1.02–2.01 ng/dL).ConclusionOur neonatal RIs for TSH and FT4 are different from those published or recommended by Siemens. The RIs will serve as a guide for the interpretation of thyroid function tests in neonates from sub-Saharan Africa where routine screening for congenital hypothyroidism using serum samples is done on the Siemens Atellica® IM analyzer.

Bangladesh endocrine society guidelines for the diagnosis and management of thyroid disease during pregnancy and the postpartum

Background: In Bangladesh, patients with thyroid disorders are managed in accordance with the recognized guidelines and based on expert experience, as comprehensive national guidelines are currently lacking. The Bangladesh Endocrine Society (BES), as a professional body, has been working to develop guidelines for the last couple of years. Most recently, BES formulated practical recommendations for the management of thyroid disorders during pregnancy, which will be termed the “Guideline on Thyroid Disorders in Pregnancy in Bangladesh 2022,” Methods: The BES formed a task force comprising experts in this field to formulate the practical recommendations for the management of thyroid disorders during pregnancy under several sections. The members of this task force comprehensively reviewed the available evidence for the specific conditions. Three well-known databases (Google Scholar, PubMed, and Scopus) were searched to determine the evidence. The task force members were well trained on reviewing the documents and methods of evidence synthesis. Each section of the recommendation was drafted by one member and subsequently reviewed. There was no barrier to the date or type of article published in the aforementioned databases except for articles published other than English. Due to the scarcity of intervention studies, ideas and findings of observational studies, case studies and expert recommendations were considered during the formulation of the guidelines. All members and affiliated persons declared no competing interest, and it was managed and communicated by the President of the BES. Results: The current guidelines for the management of thyroid disease in pregnancy include recommendations about the screening of thyroid function in pregnancy, planning pregnancy in women with thyroid disorders, interpretation of thyroid function tests, management of hypothyroidism and hyperthyroidism in pregnancy, management of thyroid nodules and thyroid emergencies throughout pregnancy, postpartum care, and directions of future research. Conclusions: Our utmost efforts were centered on developing evidence-based recommendations to inform all the levels of clinicians of Bangladesh for the easy understanding and decision-making processes in the management of thyroid disorders in pregnancy and afterward. While we care most to prepare the guideline, all recommendations are the opinion of society and admit the scope of making individualized decisions for the optimal care of patients.

Interpretation of TSH and T4 for diagnosing minor alterations in thyroid function: a comparative analysis of two separate longitudinal cohorts

BackgroundMinor alterations in thyroid function are frequent, and interpretation of thyroid function tests in the individual patient can be challenging. Furthermore, the choice of thyroid function test is debatable. To inform the debate, we performed a comparative evaluation of the variation in thyrotropin (TSH) and thyroxine (T4) in two different cohorts to illustrate the precision of TSH and T4 in the diagnosis and monitoring of thyroid dysfunction.MethodsA comparative analysis of two separate longitudinal studies previously surveyed with monthly blood sampling for one year among 35 subjects. Participants were included based on T4 within the reference range and TSH either within (euthyroid; n = 15) or above (subclinical hypothyroidism; n = 20) the laboratory reference range on two independent blood samplings before inclusion. Exclusion criteria were known thyroid disease or use of thyroid interfering medication. TSH and T4 in individual samples were measured in a single batch to prevent between-batch variation. The distributions TSH and T4 were compared among euthyroid and subclinical hypothyroid individuals, and bootstrap estimates were used to calculate area under the curve (AUC).ResultsCollection of twelve, monthly blood samples in the 35 participants provided 420 samples, and data completeness was 100%. The mean TSH was 1.27/7.19 mIU/L and the mean total T4 was 106/85 nmol/L in euthyroid/subclinical hypothyroid participants. The subclinical hypothyroidism state deviated from the euthyroid by 20% for total T4 and by 466% for TSH. The overlap between the euthyroid and subclinical hypothyroid groups was 92.6% (389/420) for total T4 and 9.0% (38/420) of test results for TSH. The estimated AUC was 0.999 (95%-CI: 0.995; 1.00) for TSH and 0.853 (0.736; 0.935) for total T4. There was no confidence interval overlap between participant groups for TSH while there was a considerable overlap for total T4 (p < 0.001).ConclusionThe distributions of thyroid function tests illustrated how TSH outperforms T4 for detecting delicate differences in thyroid function in an individual. Thus, TSH was markedly better than T4 to discriminate between the subtle differences in thyroid function corroborating that TSH is the more sensitive and accurate index of thyroid function status in the individual patient.

CHANGES IN THE PHYSIOLOGY OF THE THYROID GLAND IN PREGNANCY AND THE NEED FOR TRIMESTER-SPECIFIC REFERENCE VALUES IN THYROID STATUS: A REVIEW

Pregnancy is a unique state of the female organism in which occur physiological changes that arenecessary to maintain the pregnancy. To be able to respond to the increased metabolic needs of pregnancy and tomaintain an adequate level of thyroid hormones in the blood, the thyroid gland responds with changes in its functionand anatomy as well. Changes in thyroid function are mainly associated with increased levels of thyroxine-bindingglobulins in the blood. Their level increases as a result of estrogen stimulation in pregnancy and they are synthesizedin the liver. Changes in the physiology of the thyroid gland during pregnancy also occur as a result of stimulation ofthe TSH receptors of the gland by the human chorionic gonadotropin hormone (hCG) which is secreted by theplacental trophoblast.Due to the difference in the physiology of the thyroid gland in and outside of pregnancy, a special interpretation ofthe results of functional thyroid tests is required. Changes in hormone values are transitory, especially expressed inthe first trimester of pregnancy. A healthy pregnant patient without thyroid pathology or disease compensates forthose changes and a sufficient amount of thyroid hormones is produced. The presence of thyroid hormones in anoptimal concentration in the blood maintains a successful pregnancy and secures normal neurological developmentof the fetus. Diseases of the thyroid gland lead to a decrease its compensatory ability during pregnancy and thecontributes to the inability to respond to the increased metabolic needs that follow.The motive for this paper are the pregnant patients with undiagnosed or unrecognized thyroid gland diseases beforepregnancy, where we encounter conditions when the thyroid gland cannot respond to the physiological changes thatoccur. One of the negative outcomes of this condition can be spontaneous pregnancy loss in the first trimester.Therefore, a special interpretation of the thyroid status in pregnancy is needed and the introduction of constantreference values that will apply only to pregnancy.World recommendations designate reference values for TSH and thyroid hormones respectively for each trimester ofpregnancy, the so-called trimester-specific reference values. In case of absence of trimester-specific referencevalues, there are recommendations regarding the special interpretation of thyroid function tests and reference values;as well as recommendations for using adjusted values according to demographic characteristics that will apply to alltrimesters. This review of literature recommendations would help in the management of patients in order to achievean optimal serum level of thyroid-stimulating hormone and achieve a successful pregnancy, thus imposing the needto introduce recommendations in our laboratories for thyroid analysis values specific to pregnancy, which will differfrom those for the non-pregnant population

Thyroid Disorders.

Thyroid Disorders.

Postpartum Thyroid Abnormalities and Systemic Lupus Erythematosus: Is There a Link?

Abstract Introduction: Postpartum Thyroiditis (PPT) is an autoimmune disorder characterized by destruction of the thyroid gland within the first year after delivery. Systemic Lupus Erythematosus (SLE), another autoimmune disease, has been associated with a spectrum of thyroid disorders. While the prevalence of thyroid diseases in patients with SLE is increased, the association between SLE and PPT is not well known. The infrequency of encountering SLE and PPT makes abnormal thyroid tests in the postpartum period a diagnostic challenge. Clinical Case: A 27-year-old G1P1001 who was five months postpartum and not breast feeding was referred to Endocrinology clinic for evaluation of abnormal thyroid function tests. Past medical history was significant for SLE with renal and pericardial involvement. SLE was well controlled, treated with hydroxychloroquine. Family history was significant for hypothyroidism in her mother. She was asymptomatic and appeared clinically euthyroid. Vitals were stable and physical exam was negative for goiter, nodule or orbitopathy. Lab results at two months postpartum showed an elevated TSH of 3.87 UIU/mL (Normal 0.40-3.8 UIU/mL) and at four months postpartum TSH was low at 0.012 UIU/mL. Repeat labs at five months postpartum continued to show a low TSH at 0.007 UIU/mL with mildly elevated Free T4 at 1.7 ng/dL (Normal 0.6-1.6 ng/dL) and elevated Free T3 of 6.0 pg/mL (Normal 2.1-3.8 pg/mL). Anti-thyroid peroxidase antibodies (TPO), thyroid stimulating antibodies (TSI) and TSH receptor antibodies (TRAb) were negative. Thyroid Ultrasound with Doppler was within normal limits. Radioactive Iodine Uptake and Scan, obtained at 6 months postpartum, showed high normal uptake (17% and 32% at 4 hours and 24 hours respectively), suggestive of recovery phase of PPT. The most recent TSH was elevated at 8.5 UIU/mL and Free T4 was low at 0.7 ng/dL. Disease course was consistent with PPT. Conclusion: The Th1 (T-helper) lymphocyte immune predominance in autoimmune thyroid disease and SLE is the immune-pathogenetic base of the association between both diseases. Postpartum thyroiditis is a variant of chronic autoimmune thyroiditis. Serum anti-TPO antibodies vary during pregnancy and tend to increase early and may decline later. Immunologic tolerance increases during pregnancy, fades in the postpartum period and makes interpretation of thyroid function tests and disease process challenging. Pregnant and postpartum patients who have SLE have increased prevalence of thyroid disease. Causes are multifactorial with a higher prevalence of hypothyroidism and thyroid autoantibodies. Hyperthyroidism is much less likely. One comparable study found 6 of 43 (14%) women with SLE developed PPT and only one of these patients had positive thyroid antibodies. These reports and our patient illustrate the variability of thyroid function tests in patients with SLE.

Biological variation and analytical goals of four thyroid function biomarkers in healthy European volunteers.

Interpretation of thyroid function tests by means of biological variation (BV) data is essential to identify significant changes between serial measurements at an individual level. Data on thyroid parameters in adults are limited. We aimed at determining the BV of four thyroid function test (thyroid-stimulating hormone (TSH), free thyroxin (FT4), free triiodothyronine (FT3) and thyroglobulin (Tg)) by applying recent recommendations to acquire BV data on a latest generation of immunoassay. Nineteen healthy volunteers (8 males and 11 females) were drawn every week during 5 consecutive weeks. Samples were analysed in duplicate on the Cobas 602 analyzer (Roche Diagnostics). After normality assessment, outlier exclusion and homogeneity of variance analysis, analytical variation (CVA ), within-subject biological variation (CVI ) and between-subject biological variation (CVG ) were determined using nested ANOVA. CVA , CVI and CVG were 0.9%, 19.7% and 37.6% for TSH; 3.6%, 4.6% and 10.8% for FT4; 2.2%, 6.0% and 8.6% for FT3; and 0.9%, 15.4% and 84.9% for Tg. Index of individuality (II) for all parameters was between 0.2 and 0.7. The percentage above which the change between two measures is truly significant (reference change value) was 54.7% for TSH, 16.2% for FT4, 17.7% for FT3 and 42.8% for Tg. Based on recent international recommendations, our study provides updated BV data for four thyroid function tests in European healthy volunteers. Reliable BV characteristics, and especially RCV, can facilitate the interpretation of consecutive thyroid function tests in an individual and therefore have the potential to efficiently support clinical decisions regarding thyroid diseases.

MON-462 Rebel Nodule or Reluctant Gland? the Challenge Presented by Heterophile Antibodies

Introduction:Interpretation of thyroid function tests (TFTs) in background of non-specific symptoms concerning for hypothyroidism, has become challenging with assay interference. Heterophile antibody interferences are both test and laboratory platform dependent. We present a case of a toxic nodule erroneously diagnosed as isolated central hypothyroidism due to heterophile antibody interference.Case:A 38 year old lady was referred to Endocrinology for possible central hypothyroidism with symptoms of progressive fatigue, 40lb unintentional weight loss, poor appetite, nausea, intermittent diarrhea/constipation, occasional cold intolerance and intermittent lightheadedness. TFTs suggested low TSH 0.175 mcIU/ml (N 0.35-3.8 mcIU/ml) and low FT4 0.74 ng/dl (N 0.8-1.8 ng/dl). Pituitary hormone evaluation revealed normal ACTH, AM cortisol, IGF-1, prolactin and FSH. A pituitary MRI was normal.Two months later, she had worsening fatigue, anxiety with palpitations and tremors, and 14lb weight gain. TFTs again confirmed low TSH (0.575 mcIU/ml) and lower FT4 (0.70 ng/dl). Empirical weight-based levothyroxine (LT4) supplementation was initiated for central hypothyroidism. Six weeks later, TFTs showed hyperthyroidism (TSH <0.005 mcIU/ml, FT4 1.57 ng/dl). The patient endorsed worsening lightheadedness and palpitations on LT4, which resolved on LT4 discontinuation. One month later, TFTs were abnormal again (TSH 0.047 mcIU/ml, FT4 0.74 ng/dl).Due to persistent discordance in symptoms and biochemical tests, TFTs were evaluated for heterophile antibody interference. While HAMA-treated TSH remained low (0.04 mIU/l), FT4 by equilibrium dialysis (FT4 ED) was normal (1.1 ng/dl, regular assay 0.74 ng/dl), suggesting subclinical hyperthyroidism. A thyroid uptake scan confirmed an autonomous toxic right thyroid nodule with suppressed remaining gland. Patient ultimately underwent 15 mCi RAI ablation of the nodule. TFTs done 1 month post-RAI suggested normal TSH (1.2 mcIU/ml) and normal FT4 ED (1 ng/dl). Previous symptoms have since resolved.Conclusion:Current methods of TFTs are generally reliable in diagnosing and monitoring thyroid disease. Rarely, medications, supplements, and endogenous antibodies can bind to TSH, T4 or lab reagent, resulting in inaccurate values. This has become increasingly common with use of high dose biotin. TSH with HAMA/heterophile antibodies and FT4 ED are more accurate forms of diagnostic testing.When approaching patients with symptoms not consistent with typical hypo- or hyperthyroidism and are not responding as expected to therapy, it is important to consider more accurate testing to rule out assay errors.

Interpretación de las pruebas de función tiroidea

&#x0D; &#x0D; &#x0D; &#x0D; Los desórdenes de la glándula tiroides son comunes y pueden afectar hasta el 10% de la población en general. En muchas ocasiones los síntomas pueden ser inespecíficos, por lo que el médico en busca de un trastorno tiroideo debe llegar a un diagnóstico funcional y anatómico. Las mediciones séricas de las hormonas tiroideas confirman si hay un exceso, un déficit o si las concentraciones son normales. Para ello, se requiere un rango de referencia de la población local, y específicamente por grupos de edad, para una correcta interpretación de las pruebas de función tiroidea. Las hormonas tiroideas juegan un papel fundamental en el sistema endocrino, controlan el metabolismo general del cuerpo, el desarrollo neural, el crecimiento normal y la maduración de los huesos, así como funciones cardiovasculares y renales, entre otras. En esta revisión se pretende dar una aproximación a las pruebas tiroideas más relevantes, partiendo de la biosíntesis y secreción de las hormonas tiroideas, hasta llegar al abordaje para un diagnóstico inicial del paciente con trastorno tiroideo, mencionando los aspectos más importantes de los diferentes patrones tiroideos. El tratamiento detallado de cada uno de ellos, supera las expectativas de esta revisión.&#x0D; &#x0D; &#x0D; &#x0D;

Thyroid disease in peri‑ and postmenopause period (literature review)

The interpretation of thyroid function tests should be cautiously made during the perimenopause and postmenopause period bearing in mind that physiologic changes do exist in this group of women in terms of secretion and metabolism of thyrotropin and thyroid hormones. Moreover the incidence of thyroid disorders increases in postmenopausal and elderly women. There is no consensus for screening postmenopausal women even though there is well‑known evidence about the effect of thyroid status on cognitive function, cardiovascular risk, bone turnover, and longevity. The diagnosis of any thyroid disorder is challenging in these patients because the symptoms are more subtle and attributed to menopausal symptoms. Management requires more attention in this population than that of younger groups, because high doses of L‑thyroxine can lead to cardiac complications and increased bone turnover. Furthermore radio‑iodine is preferred in treatment of hyperthyroidism in older patients. The risk of nodular thyroid disease and thyroid cancers increases in this group. Although the diagnostic approach is the same as for young patients, the risk of surgery is high and disease prognosis is worse. Decision for menopausal hormonal therapy should be individualized regardless of the concomitant presence of thyroid disorders.

Trimester-Specific Reference Intervals for Thyroid Function Parameters in Indian Pregnant Women during Final Phase of Transition to Iodine Sufficiency.

Background:Interpretation of thyroid function tests during pregnancy depends on gestational age, method, and population-specific reference intervals. Therefore, there is a worldwide trend to establish trimester-specific levels for different populations. The aim of this study was to establish a trimester-specific reference range for thyroid function parameters during pregnancy in Indian women.Materials and Methods:Thyroid function tests (TSH, FT4, TT4, TT3) of 80, 76, and 73 women at 1st, 2nd, and 3rd trimester, respectively, and 168 nonpregnant women were analyzed after exclusion of low UIC(<150 μg/L) and anti-TPO positivity(>35 IU/ml). Urinary iodine excretion (UIC) was assessed in all. The 2.5th and 97.5th percentile values were used to determine the reference ranges for thyrotropin (TSH), free thyroxine (FT4), total thyroxine (TT4), and total triiodothyronine (TT3) for each trimester of pregnancy.Results:The reference range for TSH for first trimester was 0.19–4.34 μIU/ml, for second trimester 0.46–4.57 μIU/ml, and for third trimester 0.61–4.62 μIU/ml. The reference range during three trimesters for FT4 (ng/dl) was 0.88–1.32, 0.89–1.60, and 0.87–1.54, for total T4 (μg/dl) was 5.9–12.9, 7.4–15.2, and 7.9–14.9. In nonpregnant women, FT4 was 0.83–1.34, total T4 was 5.3–11.8, and TSH was 0.79–4.29. The mean UIC in nonpregnant women was 176 ± 15.7 μg/L suggesting iodine-sufficiency in the cohort.Conclusion:The trimester-specific TSH range in pregnant women in this study is not significantly different from nonpregnant reference range in the final phase of transition to iodine sufficiency in India.

Thyroid disorders during pregnancy and anesthetic considerations

Our knowledge about thyroid function during pregnancy has made rapid strides in the recent past. However, there are not much published reports in anesthesia literature regarding these newer developments. Even though an anesthesiologist is not the primary care physician, he/she may occasionally encounter pregnant patients with thyroid dysfunction in routine practice of anesthesia. This article aims to update anesthesiologists about recent developments in understanding of thyroid physiology during pregnancy, effects of thyroid dysfunction on mother and fetus, interpretation of thyroid function tests as well as treatment and anesthetic considerations.

Review of American Thyroid Association guidelines for the diagnosis and management of thyroid disease during pregnancy and the postpartum

Thyroid disease in pregnancy is a common clinical problem. Since the guidelines for the management of these disorders by the American Thyroid Association (ATA) were first published in 2011, significant clinical and scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid disease in women during pregnancy, preconception, and the postpartum period. The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations. The guideline task force had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members. The revised guidelines for the management of thyroid disease in pregnancy include recommendations regarding the interpretation of thyroid function tests in pregnancy, iodine nutrition, thyroid autoantibodies and pregnancy complications, thyroid considerations in infertile women, hypothyroidism in pregnancy, thyrotoxicosis in pregnancy, thyroid nodules and cancer in pregnant women, fetal and neonatal considerations, thyroid disease and lactation, screening for thyroid dysfunction in pregnancy, and directions for future research.&#x0D; We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid disease in pregnant and postpartum women. While all care must be individualized, such recommendations provide, in our opinion, optimal care paradigms for patients with these disorders.

Onemocnění štítné žlázy v seniorském věku

The incidence of most thyroid diseases are prevalent in women in ratio 8 : 1 to men, and especially hypothyroidism arises with age. Unrecognized thyroid dysfunction leads to increased: cardiovascular risk, bone fractures, cognitive impairment, depression, and mortality. The symptoms of thyroid diseases can be nonspecific or common in seniors with ageing complaints. The interpretation of thyroid function tests, the physiological changes in secretion and metabolism of thyrotropin (TSH) and thyroid hormones must be considered, as well as the influence of comorbidities, certain drugs, and individual set point of pituitary gland. According to many observations the serum TSH, thyroxine (T4), concentrations depend on age, comorbidities, and medical treatment - these together sometimes make the diagnosis of thyroid dysfunction complicated in older population. The observational data may suggest a diminished pituitary sensitivity to T4 in the ageing population. According to several studies, serum TSH concentration is probably age-dependant and the upper limit of TSH could be 5.28-5.9 mIU/l in those who are > 70 years old. Therapy of thyroid dysfunction is different in elderly persons than in young people; hypothyroidism should be treated with caution, because high doses of thyroxine can lead to cardiac arrhythmias and increased bone turnover. Hyperthyroidism could be treated either with surgery or preferable with radioiodin. Especially the diagnosis of subclinical hypothyroidism should be made with caution after concerning different important circumstances. Nevertheless there are certain conditions, when subclinical hypothyroidism must be treated. Key words: ageing - hyperthyroidism - hypothyroidism - thyroid diseases.

Hypothyroidism in hospitalized elderly patients: a sign of worse prognosis.

Overt hypothyroidism has adverse clinical consequences and might worsen prognosis in critically ill elderly patients. However, the difficult interpretation of thyroid function tests (TFT) due to non-thyroidal illness (NTI) has led to discouragement of screening for thyroid dysfunction. Our aim was to determine the prevalence of TFT compatible with hypothyroidism and to study its influence on mortality among hospitalized elderly patients. In this prospective study we consecutively included all patients ≥60years admitted by the Internal Medicine Department to the hospital ward (n=451) of the Cesar Milstein Hospital in Buenos Aires, Argentina. TFT were done on day 1 and 8. Thyroid function categories were defined as overt and subclinical hypothyroidism, overt and subclinical hyperthyroidism, euthyroidism and NTI. Stage of chronic kidney disease (CKD), Adult Comorbidity Evaluation (ACE)-27, and intra-hospital mortality were recorded. The association between mortality and TFT categories was studied by Cox regression. Out of 451 patients (77.0±7.9years, 54% females) 76% were categorized as NTI, 4% as overt hypothyroid, 10% as subclinical hypothyroid, 1% as subclinical hyperthyroid and 9% as euthyroid. Overt hypothyroid patients showed significantly higher mortality than the rest of the groups (25%, p<0.05) while ACE-27 was similar among all of them (p=0.658). In addition, patients within the overt hypothyroid category showed a higher mortality rate than NTI in a model adjusted by Stage 5-CKD, ACE-27, sex and age [HR 3.1 (1.14-8.41), p<0.026]. Overt hypothyroidism during hospitalization was associated with elevated mortality. Further studies would reveal if TFT alterations compatible with hypothyroidism should be diagnosed/treated in hospitalized elderly patients.

2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum.

Thyroid disease in pregnancy is a common clinical problem. Since the guidelines for the management of these disorders by the American Thyroid Association (ATA) were first published in 2011, significant clinical and scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid disease in women during pregnancy, preconception, and the postpartum period. The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations. The guideline task force had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members. The revised guidelines for the management of thyroid disease in pregnancy include recommendations regarding the interpretation of thyroid function tests in pregnancy, iodine nutrition, thyroid autoantibodies and pregnancy complications, thyroid considerations in infertile women, hypothyroidism in pregnancy, thyrotoxicosis in pregnancy, thyroid nodules and cancer in pregnant women, fetal and neonatal considerations, thyroid disease and lactation, screening for thyroid dysfunction in pregnancy, and directions for future research. We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid disease in pregnant and postpartum women. While all care must be individualized, such recommendations provide, in our opinion, optimal care paradigms for patients with these disorders.

Impacto del empleo de umbrales específicos de referencia en el diagnóstico de las alteraciones funcionales tiroideas en la mujer gestante

ObjectiveTo determine trimester- and assay-specific reference intervals for thyroid hormones during pregnancy, and the impact of using non-specific intervals on the diagnosis of functional disorders in the first trimester. MethodsA total of 759 healthy pregnant women older than 18 years with uncomplicated single intrauterine gestations and attending Primary Care Centres were consecutively recruited from January 2014 to September 2014. After excluding women who did not complete the follow-up during pregnancy, and those with functional thyroid disorders or with thyroid-specific autoantibodies, a total of 411 pregnant women were selected as the reference population. TSH, FT4, and FT3 were measured in each trimester using electrochemiluminescence immunoassay, and urinary iodine concentration was measured in the first and in the third trimester using high performance liquid chromatography. ResultsThe TSH reference intervals expressed as median and 2.5-97.5 percentiles were: 1.53μIU/ml (0.26-3.95), 1.90μIU/ml (0.78-3.85) and 1.89μIU/ml (0.71-3.61) in first, second and third trimesters, respectively. The median urinary iodine concentration (UIC) was 171.31μg/l (90.7-274.9) in the first trimester and 190.37μg/l (96.44-360.38) in the third. Interpretation of thyroid function tests using non-local-pregnant reference intervals would result in misclassification of the thyroid function in a significant percentage of pregnant women (19.8% with the proposed international specific reference intervals, and 8.52% with the non-specific reference intervals of our assay). ConclusionsThe use of non-local reference intervals for the diagnosis of thyroid disorders during pregnancy could lead to a large number of misclassified results, contributing to sub-optimal patient care.

A Review of the Phenomenon of Hysteresis in the Hypothalamus-Pituitary-Thyroid Axis.

The existence of a phase of prolonged suppression of TSH despite normalization of serum thyroid hormones over a variable period of time during the recovery of thyrotoxicosis has been documented in literature. Conversely, a temporary elevation of TSH despite attainment of euthyroid levels of serum thyroid hormones following extreme hypothyroidism has also been observed. This rate-independent lag time in TSH recovery is an evidence of a “persistent memory” of the history of dysthyroid states the hypothalamus–pituitary–thyroid (HPT) axis has encountered after the thyroid hormone perturbations have faded out, a phenomenon termed “hysteresis.” Notwithstanding its perplexing nature, hysteresis impacts upon the interpretation of thyroid function tests with sufficient regularity that clinicians risk misdiagnosing and implementing erroneous treatment out of ignorance of this aspect of thyrotropic biology. Mathematical modeling of this phenomenon is complicated but may allow the euthyroid set point to be predicted from thyroid function data exhibiting strong hysteresis effects. Such model predictions are potentially useful for clinical management. Although the molecular mechanisms mediating hysteresis remain elusive, epigenetics, such as histone modifications, are probably involved. However, attempts to reverse the process to hasten the resolution of the hysteretic process may not necessarily translate into improved physiology or optimal health benefits. This is not unexpected from teleological considerations, since hysteresis probably represents an adaptive endocrinological response with survival advantages evolutionarily conserved among vertebrates with a HPT system.