Heart failure from thyrotoxicosis due to Graves' disease

A 30-year-old female patient with a past medical history of pernicious anaemia presented with pleuritic chest pain, palpitations, fatigue, coryzal symptoms and a high temperature. She was hypoxic and tachycardic and was extensively investigated as well as aggressively treated. A type 1 'gut feeling' assessment by the admitting medical registrar made the diagnosis possible as thyroid function tests were grossly deranged and pointed to Graves' disease causing heart failure, complicated by pneumonia. The patient was discharged on carbimazole, antibiotics and beta blockers. Due to a resultant thrombocytopaenia, she has now been swapped onto propylthiouracil and is under active follow up.

Hyperthyroxinemia with a non-suppressed TSH: how to confidently reach a diagnosis in this clinical conundrum

Disorders of thyroid function are among the commonest referrals to endocrinology. While interpretation of thyroid function testing is usually straightforward, accurate interpretation becomes significantly more challenging when the parameters do not behave as would be expected in normal negative feedback. In such cases, uncertainty regarding further investigation and management arises. An important abnormal pattern encountered in clinical practice is that of high normal or raised free thyroxine (fT4) with inappropriately non-suppressed or elevated thyroid-stimulating hormone (TSH). In this short review using two clinical vignettes, we examine the diagnostic approach in such cases. A diagnostic algorithm is proposed to ensure that a definitive diagnosis is reached in these challenging cases.

A remarkable case of thyrotoxicosis initially caused by graves' disease followed by a probable TSHoma - a case report

BACKGROUND

Graves' disease is the commonest cause of thyrotoxicosis whilst thyrotropin (TSH)-producing pituitary adenomas (thyrotropinomas, TSHomas) are very rare and account for just 1-2% of all pituitary adenomas. Coexistence of a TSHoma and Graves' disease has been very rarely reported. Here, we report a case of a patient whose initial presentation with primary thyrotoxicosis due to Graves' disease, was subsequently followed by a relapse of thyrotoxicosis due to a probable TSHoma.

CASE

A sixty-eight year old woman was referred to our department with classical features of thyrotoxicosis. Initial biochemistry confirmed hyperthyroxinaemia [free thyroxine (fT4) 20.4 pmol/L (reference range 7.0-16.0)] and a suppressed TSH [< 0.02mIU/L (0.50-4.20)]. A technetium pertechnetate uptake scan was consistent with Graves' Disease. She was treated with carbimazole for 18 months and remained clinically and biochemically euthyroid. After stopping carbimazole her fT4 started to rise but TSH remained normal. Laboratory assay interference was excluded. A TRH stimulation test demonstrated a flat TSH response and pituitary MRI revealed a microadenoma. Remaining pituitary hormones were in the normal range other than a slightly raised IGF-1. An ¹¹C-methionine PET/CT scan coregistered with volumetric MRI (Met-PET-MRI^CR) demonstrated high tracer uptake in the left lateral sella region suggestive of a functioning adenoma. The patient declined surgery and was unable to tolerate cabergoline or octreotide. Thereafter, she has elected to pursue a conservative approach with periodic surveillance.

CONCLUSION

This is a very unusual case of thyrotoxicosis caused by two different processes occurring in the same patient. It highlights the importance of considering dual pathology when previously concordant thyroid function tests become discordant. It also highlights a potential role of Met-PET-MRI^CR in the localisation of functioning pituitary tumours.

Approach to the Patient With Thyrotoxicosis Using Telemedicine

CONTEXT

The potential for endocrine care via telemedicine has been recognized since the early 2000s when clinical outcome data demonstrated improvements in glycemic control with telemedicine. The widespread use of telemedicine during the COVID-19 pandemic has pushed telemedicine beyond diabetes care and into clinical areas with a paucity of published data. The evaluation and treatment of thyrotoxicosis heavily relies on laboratory assessment and imaging with physical exam playing a role to help differentiate the etiology and assess the severity of thyrotoxicosis.

CASE DESCRIPTION

We describe a patient presenting for evaluation of new thyrotoxicosis via telemedicine, and describe modifications to consider for thorough, safe evaluation via telemedicine.

CONCLUSION

Telemedicine may be an ideal way to assess and treat patients with thyrotoxicosis who are not able to physically attend a visit with an endocrinologist but still have access to a laboratory for blood draws. Potential challenges include access to imaging and high-volume surgeons if needed. Clinical and economic outcomes of telemedicine care of thyrotoxicosis should be studied so that standards of care for endocrine telemedicine can be established.

Pitfalls in the assessment of gestational transient thyrotoxicosis

Gestational transient thyrotoxicosis (GTT) is associated with direct stimulation of the maternal thyroid gland by human chorionic gonadotropin (hCG). It is characterized by slightly higher thyroid hormone and lower thyroid-stimulating hormone (TSH) levels in early pregnancy and mild or no symptoms. While GTT must be distinguished from Graves' disease (GD), which is associated with maternal and fetal complications, treated GD and new-onset GD in pregnancy are occasionally challenging to distinguish. Evaluating serum hCG levels and TSH receptor antibody (TRAb) titers can help, but the results are not irrefutable due to pregnancy-related immunosuppression. Moreover, GTT can follow unusual clinical courses in relation to some pregnancy complications. Excessive hCG production can cause severe GTT symptoms in patients with hyperemesis gravidarum, trophoblastic disease, or multiple pregnancies. Thyrotoxicosis can emerge beyond the second trimester in patients with gestational diabetes mellitus and mirror syndrome, because of delayed elevations in the hCG levels. Detailed knowledge about GTT is necessary for correct diagnoses and its appropriate management. This review focuses on the diagnosis of GTT, and, particularly, its differentiation from GD, and unusual clinical conditions associated with GTT that require comprehensive management.

Immunoassay Interference on Thyroid Function Tests During Treatment with Nivolumab

Background: Immune checkpoint inhibitors (ICIs) are associated with several endocrine side effects. In particular, the use of programmed cell death protein-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) inhibitors is related to a higher incidence of thyroid dysfunction. Patient Findings: An 85 years-old patient, diagnosed with a metastatic melanoma treated with nivolumab, presented to our hospital with severe ICI-related thyrotoxicosis. Diagnosis was complicated by a biochemical interference on thyroid hormones assay, probably induced by nivolumab. Summary: Baseline laboratory examination conducted before onset of anticancer therapy showed normal thyroid function test (TFTs). A few days after receiving the second nivolumab administration, the patient developed a severe thyrotoxicosis. According to destructive thyroiditis, in a short period thyrotropin (TSH) levels normalized and rapidly increased, but free thyroxine (fT4) levels were inappropriately elevated and did not decrease as expected. The sample was processed by using a Siemens Centaur^® immunoassay. We reanalyzed the same sample at another laboratory and with a different immunoassay method (Roche Elecsys^®). The results obtained from this assay confirmed severe hypothyroidism with appropriately low fT4 levels. We suspected a possible nivolumab-associated interference on the fT4 assay. Therefore, we subjected the same sample to a polyethylene glycol (PEG) 6000 precipitation, a simple method for the removal of macromolecules, before assaying for fT4 levels. Evaluation of the post-PEG-precipitation sample (Siemens Centaur immunoassay) revealed appropriately low fT4 levels. The patient was started on levothyroxine (LT4) therapy, with monthly TFT monitoring using the Roche immunoassay. Approximately 9 months after starting nivolumab therapy, the patient was advised treatment cessation. A month later, the TFTs were retested on a Siemens Centaur immunoassay, and appropriate fT4 levels were observed in accordance with normal TSH levels on adequate LT4 replacement therapy. Conclusions: We report a possible novel nivolumab-induced biochemical interference on assays of fT4 levels. The hypothesis of a biochemical drug-induced interference is further supported by the disappearance of the interference after the withdrawal of nivolumab. Further studies are needed to prove the biochemical mechanisms of this interference.

Thyrotoxic Periodic Paralysis and Complicated Thyrotoxicosis, Two Presentations of Hyperthyroidism with Notable Differences in their Clinical Manifestations: An Experience from a Tertiary Care Hospital in the United States

OBJECTIVE

Thyrotoxic periodic paralysis (TPP) is a muscular disorder characterized by sudden episodes of muscle weakness and hypokalemia in the setting of thyrotoxicosis. We aimed to report our experience with TPP in West Texas and compare its clinical presentation to that of patients admitted for complicated thyrotoxicosis.

METHODS

Retrospective review of records of adult patients with admission diagnosis of hyperthyroidism, thyrotoxicosis, and/or discharge diagnosis of periodic paralysis seen at our institution in a 6-year period.

RESULTS

Patients admitted for complicated thyrotoxicosis were more commonly females of a mean age of 44 years. Patients with TPP were more commonly Hispanic males of a mean age of 27 years. Despite no significantly different thyroid hormone levels, patients with TPP presented with less-severe signs and symptoms of hyperthyroidism, as reflected by lower Burch-Wartofsky score on admission (19 vs. 35; P<.001) and lower occurrence of atrial fibrillation in the TPP group (0% vs. 36%; P<.001). Finally, 89% of TPP patients presented with corrected QT (QTc) prolongation, whereas only 19% of thyrotoxic patient presented with a prolonged QTc.

CONCLUSION

Hispanic patients with TTP seems to have relative resistance to the actions of thyroid hormones and commonly present with QTc prolongation, a risk factor for cardiac arrhythmias.

ABBREVIATIONS

BWS = Burch-Wartofsky point scale; EKG = electrocardiogram; FT3 = free triiodothyronine; FT4 = free thyroxine; ICD = International Classification of Diseases; QTc = corrected QT; TPP = thyrotoxic periodic paralysis.

Diagnostic testing for Graves' or non-Graves' hyperthyroidism: A comparison of two thyrotropin receptor antibody immunoassays with thyroid scintigraphy and ultrasonography

OBJECTIVE

Graves' disease (GD) is the most common cause of hyperthyroidism. In many cases, when the aetiological diagnosis of GD is not evident based on the clinical evaluation and thyroid function testing, it may become challenging to distinguish Graves' hyperthyroidism from other forms of thyrotoxicosis. The current study was primarly carried out to compare the diagnostic effectiveness of two TSH receptor antibody immunoassays (IMAs), ultrasonography and thyroid scintigraphy in hyperthyroidism scenario.

METHODS

We retrospectively analysed consecutive patients with newly diagnosed and untreated thyrotoxicosis who underwent thyroid functional tests, both TRAb and TSI measurements, thyroid scintigraphy and ultrasonography. TRAb assessment was carried out by Kryptor^® compact PLUS, while TSI by Immulite^® . Echo pattern 3 corresponded to 'thyroid inferno', and the final diagnosis of GD vs non-Graves' hyperthyroidism was made according to the thyroid scan (qualitative scintigraphy). Receiver operating characteristic (ROC) curves were drawn using the final diagnosis as reference. Clinical sensitivity and specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated for all the tests.

RESULTS

A total of 124 untreated hyperthyroid patients were included in our study (GD, n = 86 vs non-Graves' hyperthyroidism, n = 38). ROC curves showed that the optimal cut-off values associated with the highest diagnostic sensitivity and specificity was 0.7 IU/L for TRAb Kryptor^® (93 [85.4-97.4] and 86.8 [71.9-95.5]) and 0.1 IU/L for TSI Immulite^® (94.2 [86.9-98.1] and 84.2 [68.7-93.9]), respectively. For the echo pattern 3, we found a good sensitivity (92.1%) and a high PPV (95.2%) but a quite low specificity value (69.8%) and a relative low NPV (57.5%). For thyroid scintigraphy, the TcTU cut-off value of 1.3% corresponded to the best limit for sensitivity and specificity in our patients (95.3 [88.5-98.7] and 96.4 [81.6-99.4]). The Passing-Bablok regression equation and the Bland-Altman test showed a great degree of correlation and agreement existed between TRAb Kryptor^® and Immulite^® TSI results.

CONCLUSIONS

Thyroid scintigraphy remains the most accurate method to differentiate causes of thyrotoxicosis. However, TRAb assays can be alternatively adopted in this setting, limiting the use of thyroid scintigraphy (TcTU evaluation) to TRAb-negative patients. Thyoid US is less accurate than both TRAb/TSI and thyroid scintigraphy, but the 'thyroid inferno' pattern provides a high PPV for GD.

Shorter Recall Period for the Thyroid-Related Patient-Reported Outcome Measure ThyPRO Did Not Change the Accuracy as Evaluated by Repeated Momentary Measurements

Background: The thyroid-related patient-reported outcome measure ThyPRO has become the gold standard for measuring thyroid-related quality of life and uses a 4-week recall period. The impact of the length of recall is unresolved. To minimize recall bias, the US Food and Drug Administration has argued in favor of short recall periods or measures describing current states. We investigated whether a 1-week recall version of ThyPRO was less prone to recall bias than the original ThyPRO, using averaged momentary ThyPRO measurements as the hypothesized true mean of patients' symptoms. Methods: Patients newly diagnosed with thyrotoxicosis were included (N = 122). During a 28-day study period, participants answered momentary questions three times daily via a smartphone, weekly retrospective surveys with a 1-week recall period, and the original survey with a 4-week recall period on day 28. Twelve ThyPRO items from four multi-item scales were used. Mean momentary ratings for each scale were compared with recall ratings of 1- and 4-week periods, respectively. Results: The mean momentary ratings were highly correlated with retrospective ratings and remained rather constant when altering the reporting period from four weeks to one week. We found consistently lower scores (i.e., better thyroid-related quality of life) on momentary ratings compared with retrospective ratings. The mean differences between momentary ratings and retrospective ratings were similar for both recall periods. The original 4-week ThyPRO accurately summarized the mean of all 1-week ThyPROs. Conclusions: Shortening the recall period of ThyPRO from four weeks to one week was not associated with less recall bias within this subset of items. Nor did 1-week recall seem to compromise the accuracy of ThyPRO. Thus, either version of ThyPRO can be used in future studies.

[Thyrotoxic hypokalemic periodic paralysis in two African black women]

Thyrotoxic hypokalemic periodic paralysis is a rare complication of hyperthyroidism. It has been most often reported in Asian subjects while it has been little described in the black population. Its mechanism has been little elucidated, but it would be caused by hyperactivity of the Na+/K+pump. We here report two cases of thyrotoxic hypokalemic periodic paralysis in black African subjects. The clinical manifestation was identical in both patients: proximal muscle paralysis of the lower limbs. Paralysis was associated with severe hypokalemia and occurred in female patients treated for Graves' disease without any other associated disease. Outcome was immediately favorable under potassium supplementation. Treatment of hyperthyroidism prevented recurrences. This study highlights the importance of suspecting the diagnosis of thyrotoxic hypokalemic periodic paralysis despite its rarity in the black African population.

Neutrophil-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, and platelet-tolymphocyte ratio in different etiological causes of thyrotoxicosis

Background/aim

The most common causes of thyrotoxicosis include Graves’ disease (GD), toxic multinodular goiter (TMNG), toxic adenoma (TA), and subacute granulomatous thyroiditis (SAT). In our study, we aimed to see whether neutrophil‐to‐lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet‐to‐lymphocyte ratio (PLR), and mean platelet volume (MPV) may be helpful in the differential diagnosis of these diseases.

Materials and methods

We retrospectively analyzed the hospital records of the Endocrinology Clinic of our hospital between 2016 and 2019. We included data from 66 GD, 37 TA, and 35 SAT patients. We compared the data with those of 35 healthy subjects as controls.

Results

NLR, MLR, and PLR were found to be higher in the SAT group when compared to other groups. The post hoc analysis of comparison of NLR, MLR, and PLR in each group showed that NLR and PLR were significantly different in the SAT group when compared to the GD, TA, and controls groups (P < 0.001, P = 0.003, and P < 0.001 for NLR respectively and P < 0.001 for PLR in all groups). MPV levels were different between groups (P = 0.007). However, the intergroup analysis (Tukey’s test) failed to show a statistically significant difference for any of the groups. In patients with SAT, PLR and NLR were significantly higher than in the GD, TA, and control groups. MLR was also higher in SAT when compared to other groups, but the difference was not statistically significant.

Conclusion

High PLR and NLR may be helpful to differentiate SAT from GD and TA, the other common causes of thyrotoxicosis.

The Delayed Diagnosis of Thyroid Storm in Patients with Psychosis

We herein report two cases of patients with thyroid storm with a delayed diagnosis due to psychosis. The patients were a 63-year-old woman with bipolar II disorder and a 37-year-old man with major depressive disorder. The psychoses in both patients were well controlled with medication. Although they both showed symptoms of thyrotoxicosis, the symptoms were ignored, presumably because the psychological manifestations of worsening of psychosis and thyroid storm are similar. When the mental or physical state of patients with psychosis changes, thyroid hormone levels should be measured for early treatment.

Thyrotoxicosis with concomitant thyroid cancer

Thyrotoxicosis with concomitant thyroid cancer is rare and poorly recognized, which may result in delayed diagnosis, inappropriate treatment and even poor prognosis. To provide a comprehensive guidance for clinicians, the etiology, pathogenesis, diagnosis and treatment of this challenging setting were systematically reviewed. According to literatures available, the etiologies of thyrotoxicosis with concomitant thyroid cancer were categorized into Graves' disease with concurrent differentiated thyroid cancer (DTC) or medullary thyroid cancer, Marine-Lenhart Syndrome with coexisting DTC, Plummer's disease with concomitant DTC, amiodarone-induced thyrotoxicosis with concomitant DTC, central hyperthyroidism with coexisting DTC, hyperfunctioning metastases of DTC and others. The underlying causal mechanisms linking thyrotoxicosis and thyroid cancer were elucidated. Medical history, biochemical assessments, radioiodine uptake, anatomic and metabolic imaging and ultrasonography-guided fine-needle aspiration combined with pathological examinations were found to be critical for precise diagnosis. Surgery remains a mainstay in both tumor elimination and control of thyrotoxicosis, while anti-thyroid drugs, beta-blockers, 131I, glucocorticoids, plasmapheresis, somatostatin analogs, dopamine agonists, radiation therapy, chemotherapy and tyrosine kinase inhibitors should also be appropriately utilized as needed.

Mean peak systolic velocity of superior thyroid artery for the differential diagnosis of thyrotoxicosis: a diagnostic meta-analysis

BACKGROUND

Thyrotoxicosis is often caused by destructive thyroiditis (DT) or Graves' disease (GD), and a prompt and accurate differential diagnosis for thyrotoxicosis is needed as management strategy differs. A meta-analysis of published literature was performed to evaluate the diagnostic accuracy for differentiating GD from DT patients by the measurement of mean peak systolic velocity of superior thyroid artery (STA-PSV) using ultrasonography.

METHODS

The databases of Embase, Pubmed, Cochrane, Web of Science, Wanfang, and CNKI were retrieved without time limit to identify eligible studies. The statistical information and scientific quality were assessed and classified. The data were analyzed using Stata12.0 software.

RESULTS

A total of 11 studies with 1052 cases only from Asia were included. Meta-analysis results showed the pooled sensitivity and pooled specificity of STA-PSV by ultrasonography were 0.86 (95% CI, 0.80-0.90) and 0.93 (95% CI, 0.86-0.97) in distinguishing GD from DT, respectively, with the AUC of 0.94 (95% CI, 0.92-0.96) .

CONCLUSION

STA-PSV by ultrasonography is a useful diagnostic method in differentiating GD from DT. More studies from other countries are needed to further evaluate the accuracy of STA-PSV for the differential diagnosis of thyrotoxicosis.

Thyrotoxicosis: Diagnosis and Management

Thyrotoxicosis is the clinical manifestation of excess thyroid hormone action at the tissue level due to inappropriately high circulating thyroid hormone concentrations. Hyperthyroidism, a subset of thyrotoxicosis, refers specifically to excess thyroid hormone synthesis and secretion by the thyroid gland. We performed a review of the literature on these topics utilizing published data in PubMed and MEDLINE. In this review, we discuss the more common etiologies of thyrotoxicosis, focusing on the current approach to diagnosis and management, new trends in those directions, and potential upcoming changes in the field.

Predicting outcomes and complications following radioiodine therapy in Graves' thyrotoxicosis

OBJECTIVE

Radioiodine (RAI) is an effective treatment for Graves' thyrotoxicosis but is associated with a failure rate of 15% and may be a risk factor for thyroid eye disease (TED) and weight gain. We sought to examine predictors of RAI failure, weight gain, TED and patient satisfaction.

DESIGN

Retrospective cohort study.

PATIENTS

A total of 655 episodes of RAI in Graves' thyrotoxicosis patients (2006-2015).

MEASUREMENTS

Biochemical assessment, including TFTs and thyrotropin receptor antibodies (TRAb), clinical features (eg, TED, weight and thionamide use) and patient questionnaire.

RESULTS

The treatment failure rate was 17%. Failure was greater with higher fT4 (P = 0.002) and higher TRAb (P = 0.004). Failure rate was 42.2% when TRAb >40 U/L. Median weight gain was 3.2 kg in those with normal fT4 prior to RAI and 5.8 kg when fT4 was elevated (P < 0.001). New TED developed in 7.6% but was not associated with post-RAI dysthyroidism. Treatment satisfaction was generally high (median response 8/10).

CONCLUSIONS

Treatment failure after RAI occurs in predictable groups and this should be reflected in the information provided to patients. Weight gain is common and may not entirely be explained by a return to pre-thyrotoxic baseline. We were unable to detect any significant impact of post-RAI dysthyroidism on weight gain, TED or thyroid symptoms in this large cohort.

Amiodarone-Induced Thyroid Dysfunction: A Clinical Update

Amiodarone is one of the most commonly prescribed antiarrhythmic agents in clinical practice owing to its efficacy, even with high toxicity profile. The high iodine content and the prolonged biological half-life of the drug can result in thyroid dysfunction in a high proportion of patients treated with amiodarone even after cessation of amiodarone. Both hypothyroidism and hyperthyroidism are common side effects that mandate regular monitoring of patients with thyroid function tests. Amiodarone-induced hypothyroidism (AIH) is diagnosed and managed in the same way as a usual case of hypothyroidism. However, differential diagnosis and clinical management of amiodarone-induced thyrotoxicosis (AIT) subtypes can be challenging. With the aid of a case snippet, we update the current evidence for the diagnostic work up and management of patients with amiodarone-induced thyroid dysfunction in this article.

More, less or both?

A 67-year-old Caucasian woman with no prior medical history was admitted to our hospital with complaints of generalised weakness, nausea, diarrhoea and weight loss. The patient suffered from tachycardia and hypotension. Blood tests revealed Graves' thyrotoxicosis and the patient was treated accordingly. However, patient's health continued to decline rapidly and further tests revealed a concomitant Addisonian crisis. Additional treatment with corticosteroids led to a full recovery. It is well known that autoimmune endocrine disorders tend to cluster. However, the presentation is usually sequential in time. This case reports the highly rare simultaneous presentation of Addison's disease and Graves' thyrotoxicosis. It also provides several suggestions to help establish the diagnoses.

[Apparent thyrotoxicosis in a patient with multiple sclerosis: biochemical assay interference due to high dose biotin use]

BACKGROUND

Supraphysiological doses of biotin are being tested in patients with multiple sclerosis. Biotin can cause interference with laboratory assessment of thyroid function, and therefore give a false suggestion of thyrotoxicosis.

CASE DESCRIPTION

A 64-year-old patient was referred for assessment of thyrotoxicosis, due to Graves' disease. Antithyroid medication was started, but there was no effect on laboratory results. In addition, he developed symptoms which subsequently could be attributed to iatrogenic hypothyroidism. Biotin interference, when assaying TSH and thyroxin, was suspected. Upon further investigation, the patient revealed to use high doses of biotin. After discontinuation of the biotin treatment, the thyroid function test normalized.

CONCLUSION

It is expected that in the future, patients with multiple sclerosis will use biotin more often. Therefore, it is important for healthcare professionals to be aware that biotin can interfere with immunoassays for thyroid hormones, to avoid misdiagnosis and unnecessary treatment for hyperthyroidism.

Maternal Thyrotropin Receptor Antibody Concentration and the Risk of Fetal and Neonatal Thyrotoxicosis: A Systematic Review

BACKGROUND

In pregnant women with Graves' disease, maternal thyrotropin receptor antibodies (TRAb) can cross the placenta and induce fetal or neonatal thyrotoxicosis. Symptoms of fetal thyrotoxicosis are tachycardia, intrauterine growth restriction, and intra-uterine death. Recommendations on an upper limit of TRAb concentrations below which intensive fetal monitoring can be safely omitted vary between different guidelines. The objective of this study was to define an evidence-based cutoff level for maternal TRAb necessitating additional fetal monitoring during pregnancy.

METHODS

A literature search was performed to identify studies on pregnant women with Graves' disease and fetal and/or neonatal thyrotoxicosis. Only studies that reported TRAb were included.

RESULTS

From a total of 229 identified titles, 20 articles could be included in the analysis. A total of 53 cases of fetal and/or neonatal thyrotoxicosis were described. The lowest level of maternal TRAb leading to neonatal thyrotoxicosis was 4.4 U/L, which corresponds to 3.7 times the upper limit of normal. The level of evidence for this threshold is moderate to low.

CONCLUSION

In women with Graves' disease, intensive fetal monitoring is recommended when maternal TRAb concentrations are >3.7 times the upper limit of normal. This cutoff level should be interpreted with caution, since evidence is limited.

Managing thyrotoxicosis in the acute medical setting

Thyrotoxicosis is common and can present in numerous ways with patients exhibiting a myriad of symptoms and signs. It affects around 1 in 2000 people annually in Europe1. The thyroid gland produces two thyroid hormones - thyroxine (T4) and triiodothyronine (T3). Thyroxine is inactive and is converted by the tissues and organs that need it into tri-iodothyronine. In health, the production of these thyroid hormones is tightly regulated by the secretion of thyroid stimulating hormone (TSH; thyrotropin) from the pituitary gland. The term 'thyrotoxicosis' refers to the clinical manifestations of hyperthyroidism.

[CME: Thyrotoxicosis and Thyroiditis]

Hyperthyroidism is caused by an increased synthesis of thyroid hormones or release of preformed thyroid hormones due to destruction of thyroid tissue, or there is an exogenous extrathyroidal source. The term thyroiditis describes a heterogeneous group of disorders, which result in destruction of thyroid tissue and release of preformed thyroid hormones. Although a less common condition, a thyroiditis remains an important differential diagnosis for thyrotoxicosis, and a symptomatic therapy is the cornerstone of treatment. Because of the classical triphasic clinical course a 'wait and see strategy' is reasonable, especially during the first and self-limited hyperthyroid phase. Usually a transient hypothyroid phase follows, before the euthyroid function is restored within a year. However, as permanent hypothyroidism may result, regular follow-up and in that case treatment with levothyroxine is mandatory.

Thyrotoxic Channelopathies

Thyrotoxic periodic paralysis (TPP), a disorder most commonly seen in Asian men, is characterized by abrupt onset of hypokalemia and paralysis. The condition primarily affects the lower extremities and is secondary to thyrotoxicosis. Early recognition of TPP is vital to initiating appropriate treatment and to avoiding the risk of rebound hyperkalemia that may occur if high-dose potassium replacement is given. Here we present a case of 31 year old male with thyrotoxic periodic paralysis with diagnostic and therapeutic approach.