5: Diagnosis and management of hyperthyroidism and hypothyroidism

Exposure to iodine, essential and non-essential trace element through seaweed consumption in humans

Seaweed consumption has gained popularity due to its nutritional value and potential health benefits. However, concerns regarding the bioaccumulation of several trace elements highlight the need for comprehensive studies on exposure associated with seaweed consumption. To address this gap in knowledge, we carried out a feeding intervention study of three common edible seaweeds (Nori, Kombu, and Wakame) in 11 volunteers, aiming to elucidate the extent of both beneficial and harmful trace element exposure through seaweed consumption in humans. Concentrations of total arsenic, cobalt, copper, cadmium, iodine, molybdenum, selenium, and zinc were measured in urine samples before and following seaweed consumption. Elements concentrations were also measured in the seaweeds provided for the study. Descriptive analysis for each element were conducted and we used quantile g-computation approach to assess the association between the 8-element mixture and seaweed consumption. Differences in urine element concentrations and seaweed consumption were analyzed using generalized estimating equations (GEE). Urinary concentrations of iodine and total arsenic increased after seaweed consumption. When we analyze the 8-element mixture, the largest weight was observed for iodine after Kombu consumption while for total arsenic was observed after Wakame consumption. Similar results were observed when we compared the mean differences between the elements before and after seaweed consumption through the GEE. Seaweed consumption relates with increased urinary iodine and total arsenic concentrations, particularly after Kombu and Wakame consumption.

Clinical pharmacology of thyroid and antithyroid drugs

Autoimmune diseases accompanied by the development of hypothyroidism (Hashimoto's thyroiditis) and hyperthyroidism (Graves' disease) are one of the most common disorders of the thyroid gland. Hypothyroidism is a clinical syndrome that occurs as a result of thyroid hormone deficiency. Hyperthyroidism is excessive activity of the thyroid gland accompanied by hypersecretion of thyroid hormones. In simple terms, to achieve a euthyroid state in both clinical syndromes, two drugs are (most commonly) used - levothyroxine (hypothyroidism) and thioamide (hyperthyroidism). While it may seem simple, during the treatment, which is life-long in the case of hypothyroidism, patients should actually be carefully monitored, with the adjustment of the drug dose and the inclusion of other drugs for the treatment of comorbidities.

Risk assessment of iodine intake from the consumption of red seaweeds (Palmaria palmata and Chondrus crispus)

Seaweeds are a basic food in the Asian diet. The search for functional and healthy foods has increased the seaweed consumption in Europe and the USA. Seaweeds are a source of essential elements such as iodine. However, high intake levels of iodine can cause damages to human health. Red seaweeds like dulse (Palmaria palmata) and Irish moss (Chondrus crispus) are common in shops and large stores. The iodine level in 30 samples of red seaweeds (dulse and Irish moss) has been determined by redox volumetry with sodium thiosulfate to determine the iodine content of both species and to assess the iodine dietary exposure from dulse and Irish moss consumption. Irish moss (3.86 ± 1.49 mg/kg dry weight) has the highest average iodine content. Four grams per day of dehydrated Irish moss seaweeds contributes greatly to the iodine recommended daily intake (DRI) for children (25.7%). The consumption of analyzed seaweeds (4 g/day) does not pose a health risk. However, the consumption of 286 g/day of Irish moss would lead to exceeding the UL for the adult population set at 1100 μg/day. It is necessary that the consumer respects the consumption guidelines of the seaweed packers.

Elevated levels of circulating thyroid hormone do not cause the medical sequelae of hyperthyroidism

BACKGROUND

Clinicians have been reluctant to use high dose thyroid (HDT) to treat affective disorders because high circulating levels of thyroid hormone have traditionally been equated with hyperthyroidism, and understood as the cause of the medical sequelae of hyperthyroidism, such as osteoporosis and cardiac abnormalities. This conclusion is not supported by (HDT) research.

METHODS

A literature review of research related to the morbidity and mortality of HDT treatment was performed.

RESULTS

There exists a large body of research involving the use of HDT treatment to prevent the recurrence of differentiated thyroid cancer and to treat affective disorders. A review of this literature finds a lack of support for HDT as a cause of osteoporosis, nor is there support for an increase in morbidity or mortality associated with HDT. This finding contrasts with the well-established morbidity and mortality associated with Graves' disease, thyroiditis, and other endogenous forms of hyperthyroidism.

DISCUSSION

The lack of evidence that exogenous HDT causes osteoporosis, cardiac abnormalities or increases mortality compared with the significant morbidity and mortality of hyperthyroidism requires an alternative cause for the medical sequelae of hyperthyroidism. One possibility is an autoimmune mechanism.

CONCLUSION

High circulating levels of thyroid hormone is not the cause of the sequela of hyperthyroidism. The reluctance to using high dose thyroid is unwarranted.

Identifying a Small Molecule Blocking Antigen Presentation in Autoimmune Thyroiditis

We previously showed that an HLA-DR variant containing arginine at position 74 of the DRβ1 chain (DRβ1-Arg74) is the specific HLA class II variant conferring risk for autoimmune thyroid diseases (AITD). We also identified 5 thyroglobulin (Tg) peptides that bound to DRβ1-Arg74. We hypothesized that blocking the binding of these peptides to DRβ1-Arg74 could block the continuous T-cell activation in thyroiditis needed to maintain the autoimmune response to the thyroid. The aim of the current study was to identify small molecules that can block T-cell activation by Tg peptides presented within DRβ1-Arg74 pockets. We screened a large and diverse library of compounds and identified one compound, cepharanthine that was able to block peptide binding to DRβ1-Arg74. We then showed that Tg.2098 is the dominant peptide when inducing experimental autoimmune thyroiditis (EAT) in NOD mice expressing human DRβ1-Arg74. Furthermore, cepharanthine blocked T-cell activation by thyroglobulin peptides, in particular Tg.2098 in mice that were induced with EAT. For the first time we identified a small molecule that can block Tg peptide binding and presentation to T-cells in autoimmune thyroiditis. If confirmed cepharanthine could potentially have a role in treating human AITD.

THE ABSENCE OF THYROID DISEASE IN AN AUSTRALIAN HEPATITIS C COHORT TREATED WITH TRIPLE COMBINATION THERAPY: A PARADIGM SHIFT

OBJECTIVE

To assess the prevalence of thyroid disease in triple combination therapy with interferon (IFN)-α, ribavirin (RBV), and protease inhibitors (boceprevir and telaprevir) for the treatment of chronic hepatitis C virus (HCV) infection in an Australian hepatitis C cohort. Also, to compare with those who received dual RBV and IFN in the past.

METHODS

A preliminary, retrospective, and nested case control study of thyroid disease in patients who underwent triple combination therapy for chronic HCV infection compared with dual therapy at a major tertiary referral hospital center. Fifty-nine patients were treated with such therapy at the Hunter New England Area Hepatitis C Treatment Center. Of these, 38 were treated with boceprevir and 21 with telaprevir. All had genotype 1 HCV infection. The main outcome measures included (1) the prevalence of thyroid disease (TD), including hyperthyroidism and hypothyroidism, and (2) thyroid outcome comparison with patients who had received dual therapy.

RESULTS

There was no case of TD detected for the entire duration of therapy with triple anti-HCV therapy. There was a significant absence of TD in the protease inhibitor-treated group.

CONCLUSION

No case of TD was detected during the treatment of HCV patients with protease inhibitor-based triple therapy. The reasons for this are unclear. Larger studies are necessary to confirm this finding.

An examination of myth: a favorable cardiovascular risk-benefit analysis of high-dose thyroid for affective disorders

INTRODUCTION

High dose thyroid (HDT) is included in major treatment guidelines for the treatment of bipolar disorders. Yet it is seldom used partly based on perceived cardiovascular risks. The cardiovascular risks of HDT are examined.

METHODS

A literature search was conducted for the cardiovascular risks of HDT and for comparisons sake psychiatric medications. Case reports of atrial fibrillation (afib) associated with HDT are reported.

RESULTS

While hyperthyroidism is a significant cardiovascular risk factor causing a 20% premature death rate, HDT treatment does not appear to be of significant cardiovascular risk. HDT differs from hyperthyroidism in significant ways. The sequela of hyperthyroidism are increasingly tied to autoimmune complications which are absent with HDT. Equating hyperthyroidism with HDT is incorrect. The five case reports of HDT treatment associated with afib were potentially caused by other factors. If HDT increases the risks of afib, monitoring for afib would minimizes the risk. Even in overt hyperthyroidism the risk of other arrhythmias are minimal. When compared to many psychiatric medications HDT is as safe or safer.

LIMITATIONS

There are no direct studies of cardiovascular risks of HDT for affective patients. High tolerance of a medication does not necessarily imply lack of risk. The five case reports were spontaneous, other cases may not have been reported.

CONCLUSION

The cardiovascular risks of HDT appear to be low. HDT is at least as safe as or safer than many psychiatric medications. It is effective and well tolerated.

A longitudinal study of thyroid autoantibodies in pregnancy: the importance of test timing

OBJECTIVE

Thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TGAb) are frequently measured to investigate thyroid dysfunction in pregnancy. Despite the recognized fall of these autoantibodies in pregnancy, there is limited guidance on the timing of such testing. We assessed optimal test timing of TPOAb/TGAb for the detection of Hashimoto's thyroiditis and post-partum thyroid dysfunction (PPTD).

DESIGN

Prospective longitudinal study with recruitment in Trimester 1.

PATIENTS

Healthy women ≤13 weeks' gestation from Mercy Hospital for Women, a tertiary obstetric hospital in Melbourne.

MEASUREMENTS

Serum TPOAb, TGAb, TSH and fT4 were measured at Trimester 1 (T1), Trimester 2(T2), Trimester 3(T3) and postpartum (PP) in each participant. Post-partum thyroid dysfunction (PPTD) was defined if TSH deviated from the assay's nonpregnant reference interval. Longitudinal random-effect logistic regression was used to investigate the association between time and positive/negative thyroid autoantibody status.

RESULTS

Samples from 140 women at T1 (12·0: 10·3-13·0) (median: IQR weeks' gestation); 95 at T2 (24·3: 23·0-25·9), 79 at T3 (35·9: 34·8-36·7) and 83 at PP (12·4: 10·8-14·6 weeks post-partum) were attained. At T1, 13 (9%) and 15 (11%) women had positive TPOAb and TGAb, respectively. The odds of having a positive TPOAb were 96% lower at T2 [OR = 0·04 (95% CI: 0·02-0·8; P = 0·03)] and 97% lower at T3 [OR = 0·03 (95% CI: 0·001-0·6; P = 0·02)] than at T1. Similarly, the odds of having a positive TGAb were 99·4% lower [OR = 0·006 (95% CI: 0-0·3; P = 0·01)] at T2, and 99·5% lower [OR = 0·005 (95% CI: 0-0·4; P = 0·02)] at T3 than at T1. The ROC analysis diagnostic ORs for a positive TPOAb and/or TGAb to predict PPTD were 7·8 (95% CI: 2·2-27·6), 1·2 (95% CI: 0-8·9), 2·0 (95% CI: 0-16·8), and 12·2 (95% CI: 3·3-44·9) at T1, T2, T3 and post-partum, respectively.

CONCLUSIONS

A significant proportion of pregnant women lose their thyroid autoantibody positivity after T1. The gestation-dependent loss of TPOAb/TGAb positivity and reduction in diagnostic accuracy for predicting PPTD limits the value of testing at T2 and T3.

A favorable risk-benefit analysis of high dose thyroid for treatment of bipolar disorders with regard to osteoporosis

High dose thyroid hormone has been in use since the 1930s for the treatment of affective disorders. Despite numerous papers showing benefit, the lack of negative trials and its inclusion in multiple treatment guidelines, high dose thyroid has yet to find wide spread use. The major objection to the use of high dose thyroid is the myth that it causes osteoporosis. This paper reviews the literature surrounding the use of high dose thyroid, both in endocrinology and in psychiatry. High dose thyroid does not appear to be a significant risk factor for osteoporosis while other widely employed psychiatric medications do pose a risk. Psychiatrists are uniquely qualified to do the risk-benefit analyses of high dose thyroid for the treatment of the bipolar I, bipolar II and bipolar NOS. Other specialties do not have the requisite knowledge of the risks of alterative medications or of the mortality and morbidity of the bipolar disorders to do a full risk benefit analysis.

Hypothyroidism in clinical practice

Background:

Hypothyroidism is the most common endocrine disease that was seen in the clinical practice especially for family physicians.

Methods:

This review article covered the important practical clinical issues for managing overt hypothyroidism, subclinical hypothyroidism and hypothyroidism during pregnancy.

Conclusions:

The clinical issues were addressed by clinical scenario followed by questions and stressed on the important clinical points.

Impact of thyroid dysfunction on erythropoietin dosage in hemodialysis patients

BACKGROUND

Although thyroid diseases exist in patients with renal failure, thyroid function tests are not routine tests in patients on chronic hemodialysis (HD). Therefore, the impact of thyroid diseases on erythropoietin (EPO) dosage in HD patients is not well defined. This study evaluated the relationship between the dose of EPO and the presence or absence of thyroid dysfunction in HD patients.

METHODS

This study included 1013 adult patients on HD who did not have a malignancy, liver cirrhosis, thalassemia, iron deficiency, gastrointestinal bleeding, or a major operation within 6 months. Patients were characterized as being euthyroid, or having the sick euthyroid syndrome, primary hypothyroidism, subclinical hypothyroidism, hyperthyroidism, or subclinical hyperthyroidism based on thyroid function tests. Routine biochemistry profiles including an index of the efficiency of HD, along with clinical data over the previous 6-month period, were collected and analyzed. Multiple regression models were employed to assess the relationship between the dose of EPO and the presence or absence of thyroid status.

RESULTS

The mean monthly EPO dosages were 77.7±37.0, 70.2±40.6, 90.8±68.4, 78.5±46.7, and 82.3±41.2 μg, respectively, in the sick euthyroid syndrome, euthyroid patients, hypothyroidism, subclinical hypothyroidism, and subclinical hyperthyroidism groups (p<0.05). After adjustment of all other variables in multiple regression, the mean monthly EPO dosage was 19.00±8.59 μg more in hypothyroid patients compared with euthyroid patients (p=0.027). Further, considering an interaction with the presence of diabetes, the mean monthly EPO dosage in patients with either hypothyroidism or subclinical hypothyroidism and diabetes was 54.66±17.12 μg (p=0.001) and 31.51±10.38 μg more than that of euthyroid patients, respectively (p=0.002).

CONCLUSIONS

In HD patients, the EPO dosage required to maintain the target hemoglobin level is significantly higher in patients having both hypothyroidism or subclinical hypothyroidism and diabetes than in euthyroid patients.

An observational study of the initial management of hypothyroidism in France: the ORCHIDÉE study

OBJECTIVE

To document the initial management of hypothyroidism in France with respect to diagnostic setting, investigations, and therapeutic approach.

DESIGN

Observational study of the management by primary care practitioners (PCPs) and endocrinologists of patients diagnosed with, and treated for, hypothyroidism during the enrollment period or the previous 6 months.

METHODS

A representative sample of PCPs and endocrinologists enrolled up to five consecutive patients and reported sociodemographic, clinical, therapeutic, and laboratory data. Data were submitted at baseline and at the first measurement of TSH after starting the treatment.

RESULTS

The analysis population comprised 1255 patients (mean (s.d.) age 52.8 (16.3) years; 84% female). Hypothyroidism was suspected on clinical grounds in 77% of patients, with goiter in 16%. Autoimmune thyroiditis, supported by positive anti-thyroid antibodies, was the most frequent diagnosis (59%), followed by iatrogenic causes (28%), of which thyroidectomy was the most common. The median baseline TSH was 8.6 mIU/l, suggesting a high incidence of subclinical hypothyroidism. Imaging studies were requested in over 75% of patients, with ultrasound performed in 98% and scintigraphy performed in 19% of these patients. Both groups of physicians treated their patients almost exclusively with levothyroxine. Endocrinologists were more likely than PCPs to provide counseling on how to take medication correctly.

CONCLUSIONS

This observational study of a large cohort of patients with newly diagnosed hypothyroidism in France illustrates current practice and indicates some areas where physician education may be required to optimize adherence to guidelines and cost-effectiveness.

Resistant thyrotoxicosis in a patient with graves disease: a case report

Background. Conventional management of thyrotoxicosis includes antithyroid drugs, radioactive iodine, and surgery while adjunctive treatment includes beta-blockers, corticosteroids, inorganic iodide and iopanoic acid. Very rarely, patients may be resistant to these modalities and require additional management. Case Presentation. A 50-year-old lady presented with weight loss and palpitations diagnosed as atrial fibrillation. Her past history was significant for right thyroid lobectomy for thyrotoxicosis. Thyroid functions tests at this presentation showed free T4 of 6.63 ng/dl (normal range: 0.93–1.7) and TSH of <0.005 μIU/mL (normal range: 0.4–4.0). She was given aspirin, propranolol, heparin and carbimazole; however free T4 failed to normalize. Switching to propylthiouracil (PTU) did not prove successful. She was then given high doses of prednisolone (1 mg/kg/day) and lithium (400 mg twice daily) which prepared the patient for radioactive iodine treatment by reducing free T4 levels (2.82 ng/dl). Two doses of radioactive iodine were then administered 6 months apart. Subsequently she became hypothyroid and was started on thyroid replacement therapy. Conclusion. This case highlights management options in patients with resistant thyrotoxicosis. Radioactive iodine and surgery are definitive modes of treatment in such complex cases while steroids and lithium play an important role in preparing patients for more definitive treatment.

Current concepts in graves' disease

Graves' disease is the most common cause of hyperthyroidism in the developed world. It is caused by an immune defect in genetically susceptible individuals in whom the production of unique antibodies results in thyroid hormone excess and glandular hyperplasia. When unrecognized, Graves' disease impacts negatively on quality of life and poses serious risks of psychosis, tachyarrhythmia and cardiac failure. Beyond the thyroid, Graves' disease has diverse soft-tissue effects that reflect its systemic autoimmune nature. Thyroid eye disease is the most common of these manifestations and is important to recognise given its risk to vision and potential to deteriorate in response to radioactive iodine ablation. In this review we discuss the investigation and management of Graves' disease, the recent controversy regarding the hepatotoxicity of propylthiouracil and the emergence of novel small-molecule thyroid-stimulating hormone (TSH) receptor ligands as potential targets in the treatment of Graves' disease.

The case of thyroid hormones: how to learn physiology by solving a detective case

Thyroid diseases are prevalent among endocrine disorders, and careful evaluation of patients' symptoms is a very important part in their diagnosis. Developing new pedagogical strategies, such as problem-based learning (PBL), is extremely important to stimulate and encourage medical and biomedical students to learn thyroid physiology and identify the signs and symptoms of thyroid dysfunction. The present study aimed to create a new pedagogical approach to build deep knowledge about hypo-/hyperthyroidism by proposing a hands-on activity based on a detective case, using alternative materials in place of laboratory animals. After receiving a description of a criminal story involving changes in thyroid hormone economy, students collected data from clues, such as body weight, mesenteric vascularization, visceral fat, heart and thyroid size, heart rate, and thyroid-stimulating hormone serum concentration to solve the case. Nevertheless, there was one missing clue for each panel of data. Four different materials were proposed to perform the same practical lesson. Animals, pictures, small stuffed toy rats, and illustrations were all effective to promote learning, and the detective case context was considered by students as inviting and stimulating. The activity can be easily performed independently of the institution's purchasing power. The practical lesson stimulated the scientific method of data collection and organization, discussion, and review of thyroid hormone actions to solve the case. Hence, this activity provides a new strategy and alternative materials to teach without animal euthanization.

Optimization of thyroxine replacement therapy after total or near-total thyroidectomy for benign thyroid disease

BACKGROUND

Total or near-total thyroidectomy is increasingly used to treat benign thyroid conditions. Lifelong treatment with thyroxine (T4) is then required, but the optimal dose is difficult to predict. This study investigated factors that might predict the ideal T4 dose, with the aim of reducing delays in achieving normal thyroid function after surgery.

METHODS

Data on 98 patients who underwent total or near-total thyroidectomy for benign disease were reviewed retrospectively. Patient and operative variables that might predict time to achieve normal thyroid function and optimal T4 replacement dose were examined. These data were then used to formulate an algorithm for T4 dosage, based on patient weight, that was subsequently applied prospectively to a comparable group of 27 patients.

RESULTS

The median time to achieve normal thyroid function was 14.5 (range 2-120) weeks before introduction of the algorithm, and was greater in patients needing large changes in T4 dose. In multivariate analysis, the best predictors of optimal T4 dose were bodyweight (r = 0.46, P < 0.001) and age (r = -0.32, P = 0.002). Subsequent use of a weight-related algorithm improved time to achieve normal thyroid function.

CONCLUSION

The T4 replacement dosage after total or near-total thyroidectomy is largely influenced by bodyweight. Use of a weight-related algorithm improves patient care compared with use of standard T4 dose-titration methods.

The spectrum of thyroid dysfunction in an Australian hepatitis C population treated with combination Interferon-alpha2beta and Ribavirin

BACKGROUND

The study aims to assess the pattern of thyroid response to combination Interferon-alpha2beta (IFN-alpha) and Ribavirin (RBV) anti-viral therapy in an Australian hepatitis C cohort. These include the prevalence of thyroid dysfunction (TD) including hyperthyroidism and hypothyroidism and their possible predictors, the common overall pattern of thyroid function tests whilst receiving therapy and TD outcomes, and the correlation with HCV status outcome.

METHODS

A retrospective analysis of all medical records was performed to assess thyroid function in Hepatitis C Virus (HCV) patients who were treated at the Hunter Area hepatitis C treatment center between 1995 and March 2004. The centre is part of the John Hunter hospital, a major tertiary referral centre in New South Wales, Australia.

RESULTS

There were 272 cases available for review. The prevalence of TD is 6.7 percent and is made up predominantly of females (80 percent). There were 3 (1.1 percent) cases of hyperthyroidism with 2 (67 percent) females. Thirteen out of fifteen (80 percent) cases of hypothyroidism were females with the overall prevalence of 5.5 percent. The majority of hypothyroid patients still required Thyroxine supplement at the end of follow up.

CONCLUSION

Ninety three percent of HCV treated patients have intact thyroid function at the end of treatment. The predominant TD is hypothyroidism. The predominant pattern of thyrotoxicosis (TTX) is that of thyroiditis although the number is small. Graves' like disease was not observed. People with pre-existing thyroid auto-antibodies should be closely monitored for thyroid dysfunction, particularly hypothyroidism.

The role of autoimmunity at diagnosis of type 1 diabetes in the development of thyroid and celiac disease and microvascular complications

OBJECTIVE

The purpose of this study was to explore whether the presence of thyroid and endomysial autoantibodies at diagnosis of type 1 diabetes in children predicts development of thyroid and celiac disease, respectively, and whether diabetes-associated autoantibodies at diagnosis predict development of microvascular complications up to 13 years later.

RESEARCH DESIGN AND METHODS

Autoantibodies were measured at diagnosis of type 1 diabetes in 173 children aged 0-15 years and included thyroperoxidase antibody (TPOA), endomysial antibody (EMA), islet cell autoantibody, GAD antibody (GADA), and insulin autoantibody. Thyroid disease was defined as thyroid stimulating hormone level > or = 5 microU/ml. Celiac disease was confirmed by small-bowel biopsy. Assessment of microvascular complications included stereoscopic fundal photography, pupillometry, thermal threshold, and albumin excretion rate (AER).

RESULTS

The incidence rates for thyroid and celiac disease were 0.9 and 0.7 per 100 patient-years, respectively. Within 13 years, 6 of 13 children with positive TPOA tests at diagnosis developed thyroid disease compared with 5 of 139 children with negative TPOA tests (P < 0.001). All four patients with positive EMA titers at diagnosis had biopsy-proven celiac disease. Five of 11 patients who developed thyroid disease and 4 of 8 who developed celiac disease had negative TPOA and EMA tests at diagnosis, respectively. Retinopathy was detected in 39% and elevated AER in 36%. The presence of diabetes-associated autoantibodies at diagnosis did not predict microvascular complications though GADA titer levels predicted pupillary abnormality.

CONCLUSIONS

Elevated TPOA and EMA levels at diagnosis of type 1 diabetes predict the development of thyroid and celiac disease, respectively. In children with negative antibody titers at diagnosis, screening at 2-year intervals is recommended.