Comparison of pathophysiology in subclinical hyperthyroidism with different etiologies.

Subclinical hyperthyroidism (SHyper) is defined as normal levels of free thyroxine (fT4) and free triiodothyronine (fT3) with suppressed levels of TSH. Previous studies have reported the individual pathophysiology of endogenous SHyper patients and athyreotic patients receiving TSH suppression therapy with levothyroxine; however, apparently no studies have compared the two conditions. Five-hundred-forty untreated endogenous SHyper patients and 1,024 patients receiving TSH suppression therapy who underwent total thyroidectomy for papillary thyroid carcinoma were sampled. Thyroid hormone profiles and peripheral indices related to thyrotoxicosis were investigated in endogenous SHyper patients, athyreotic patients receiving TSH suppression therapy, and healthy participants. Endogenous SHyper patients showed significantly higher thyroid hormone levels (fT4 [p < 0.001] and fT3 [p < 0.001]), and peripheral indices showed a significant tendency towards thyrotoxicosis (strong TSH suppression: alkaline phosphatase [ALP, p < 0.001], creatinine [Cre, p < 0.001], pulse rate [p < 0.05]; and mild TSH suppression: Cre [p < 0.05]) than healthy participants. In contrast, athyreotic patients receiving TSH suppression therapy showed a significant tendency towards thyrotoxicosis than healthy participants only when TSH was strongly suppressed (fT3 [p < 0.001] and Cre [p < 0.001]). Endogenous SHyper patients showed significantly higher fT3 levels (p < 0.001) than athyreotic patients receiving TSH suppression therapy; however, there was a significant tendency towards thyrotoxicosis only when TSH was strongly suppressed (ALP [p < 0.05] and pulse rate [p < 0.05]). The effects of endogenous SHyper and TSH suppression therapy on target organ function are different. Although the serum thyroid hormone profile is similar to that of the thyrotoxic state, athyreotic patients receiving TSH suppression therapy with mildly suppressed serum TSH levels are not thyrotoxic.

Therapeutic plasmapheresis for the treatment of thyrotoxicosis: A retrospective multi-center study.

BACKGROUND AND AIMS: Thyroid storm and severe thyrotoxicosis remain among the most frequent endocrine emergencies, and first-line hyperthyroidism treatment is not always an option. Since the first report in 1970, plasmapheresis is a second-line treatment for severe or otherwise untreatable thyrotoxicosis when rapid euthyroidism is desired. METHODS: We present a retrospective study of the experience in treating thyrotoxicosis with plasmapheresis between 2012 and 2020 in two specialized centers in Colombia. We register the demographic and clinical characteristic and compare the thyroid hormones and other biochemical measurements before and after treatment. RESULTS: Data from 19 patients was obtained, 58% female with a median age of 35 years (IQR 23.5), and most of them with Graves' disease. The most frequent indication for plasmapheresis was thyroid storm. A median of 4 (IQR 2) sessions lead to a significant reduction in FT4 (P .0001) and TT3 (P < .0003) with a nonsignificant decrease in beta-blocker (P .7353) dose, no change in hepatic enzymes, and no adverse events. After plasmapheresis, thyroidectomy was performed in 10 patients. CONCLUSIONS: Plasmapheresis is an effective and safe treatment option for reducing circulating thyroid hormones in severe thyrotoxicosis when other forms of treatment are contraindicated or in case of urgent thyroid and non-thyroid surgery. It is limited by its cost and the need for highly specialized resources.

A Case Report on Type 2 Amiodarone Induced Thyrotoxicosis and Hypercalcemia.

Amiodarone, the most commonly used antiarrhythmic drug, can cause either hypothyroidism by inhibiting iodide transport into the thyroid gland or hyperthyroidism. We present a rare case of type 2 amiodarone-induced thyrotoxicosis with hypercalcemia. A 64-year-old man with systolic heart failure, hypertension, and hyperthyroidism presented with complaints of dyspnea on exertion, orthopnea, and vomiting for several days. Laboratory tests showed low thyroid stimulating hormone <0.01 mIU/L, high free triiodothyronine (FT3) of 24.8 ng/dL, free thyroxine (FT4) of >5.0 ng/dL, and hypercalcemia of 12.9 mg/dL. Hypercalcemia, a rare presentation of AIT, was treated with calcitonin and intravenous fluids. The patient was taken off methimazole and started on propylthiouracil for the persistent elevation of thyroid hormones, especially FT3, and to reduce the conversion of T4 to T3. The patient was not completely responding to treatment with propylthiouracil alone, so prednisone was added to the regimen on day 12, effectively returning the patient to the euthyroid state.

Interplay Between Thyroid Hormone Status and Pulmonary Hypertension in Graves' Disease: Relevance of the Assessment in Thyrotoxic and Euthyroid Patients.

Background: Graves' disease (GD) is the most common cause of hyperthyroidism and can cause cardiac changes, such as pulmonary hypertension. Methods: This is a prospective study in which we obtained demographic, clinical, laboratory data and characteristics of the GD, in addition to investigating cardiorespiratory function, focusing on the detection of pulmonary hypertension. Patients were separated into two groups: thyrotoxicosis and euthyroidism. Ninety patients with GD of both sexes, over 18 years of age, were included. The cardiorespiratory assessment included an echocardiographic evaluation, a questionnaire of specific symptoms, spirometry and a six-minute walk test. Results: The hyperthyroid group included 42 patients (47.73%) and the euthyroid group 46 patients (52.27%); 78 were women (86.67%). The prevalence of pulmonary hypertension between the hyperthyroidism (48.57%) and the euthyroidism (29.41%) groups was not different. Free thyroxine levels (FT4) (OR 1.266), higher left atrium volume (OR 1.113) and right ventricle diameter were associated with pulmonary hypertension. A direct correlation between FT4 with forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1), as also an inverse correlation between initial oxygen saturation (SpO2) with diagnostic time and drop SpO2 with the ratio between the diastolic velocity E of the mitral flow and the diastolic velocity of the mitral ring (E/e') were observed in the euthyroid group. An inverse correlation between FT4 levels with walked distance as % of predicted value, and a direct correlation between E/e' ratio and walked distance as % of predicted value were observed in the hyperthyroid group. Conclusion: We emphasize the importance of a cardiorespiratory reassessment in GD, even after a long-term control of the thyrotoxic state, as we demonstrate that about 30% of these patients remain with PH and are subject to specific treatment.

Serum thyroid stimulating hormone level for predicting utility of thyroid uptake and scan.

BACKGROUND: Thyroid uptake and scan (TUS) is a clinical tool used for differentiation of thyrotoxicosis etiologies. Although guidelines recommend ordering a TUS for evaluation of low TSH levels, no specific value is defined. This study aimed to determine a TSH cutoff at which TUSs yield a greater likelihood of successful determination of etiology to avoid unnecessary testing. METHODS: This was a retrospective study on 137 patients seen by an endocrinologist who underwent TUS for evaluation of low TSH (<0.4 µU/mL). A receiver operating curve analysis was performed to determine the TSH cutoff with maximal sensitivity and specificity for prediction of diagnostic utility. RESULTS: Ninety percent of TUSs (n = 123) led to a diagnosis, while 10% (n = 14) were inconclusive or normal. Diagnoses included Graves' diseases (52%), toxic multinodular goiter (19%), thyroiditis (12%), and solitary toxic adenoma (7%). The median TSH value was 0.008 µU/mL (IQR 0.005, 0.011), and the median free T4 value was 1.7 µU/mL (IQR 1.3, 2.8). The ROC analysis produced an area under the curve of 0.86. The optimal TSH cutoff value was 0.02 µU/mL (sensitivity 80%, specificity 93%) for prediction of diagnostic yield. CONCLUSION: This study demonstrates that TSH is a useful predictor of the utility of TUS in yielding an etiology of thyrotoxicosis. Our analysis showed that TUS had a greater likelihood of determining an etiology when TSH was ≤0.02 µU/mL. This information can help clinicians avoid unnecessary cost and patient time burden when TUS is unlikely to aid in determining the etiology of thyrotoxicosis.

Randomised trial of block and replace vs dose titration thionamide in young people with thyrotoxicosis.

OBJECTIVE: First-line treatment of thyrotoxicosis in young people is thionamide anti-thyroid drug (ATD) in a blocking dose with levothyroxine replacement (block and replace, BR) or in a smaller dose tailored to render the patient euthyroid (dose titration, DT). Our objective was to determine which regimen provides more stable biochemical control. DESIGN: A multi-centre phase III, open-label randomised trial comparing BR with DT in patients aged 2-17 years with newly diagnosed thyrotoxicosis at 15 UK centres. METHODS: Patients were randomised shortly after diagnosis and treated for 3 years. The primary outcome was the percentage of serum thyroid-stimulating hormone (TSH) levels in the reference range between 6 months and 3 years. Secondary outcomes included the proportion of Free thyroxine (FT4) levels in the reference range, adverse event frequency and 4 years outcome (remission/relapse). RESULTS: Eighty-two patients were randomised, with details on clinical course in 81 (62 Female); 40 were allocated to BR (41 DT). Three withdrew with one ineligible. The mean percentage of serum TSH within reference range was 60.2% in BR and 63.8% in DT patients; adjusted difference 4.3%, 95% CI (-7.8 to 16.4); P = 0.48. Proportions for FT4 were 79.2% in BR and 85.7% in DT patients; adjusted difference 6.8%, (-0.2 to 15.6); P = 0.13. Three patients developed neutropenia - all on BR. 6 BR and 10 DT patients were in remission at 4y. CONCLUSION: This randomised trial has shown no evidence to suggest that BR, when managing the young patient with thyrotoxicosis, is associated with improved biochemical stability when compared to DT.

Thyroid disorders and SARS-CoV-2 infection: From pathophysiological mechanism to patient management.

The World Health Organization (WHO) declared the COVID-19 epidemic to be a global pandemic in March 2020. COVID-19 is an infection caused by SARS-CoV-2, a coronavirus that utilizes the angiotensin-2 converting enzyme to penetrate thyroid and pituitary cells, and may result in a "cytokine storm". Based on the pathophysiological involvement of the pituitary-thyroid axis, the current review discusses the diagnosis of abnormal thyroid function test, and the management of patients presenting with thyrotoxicosis, thyroid-associated orbitopathy and hypothyroidism in the context of SARS-CoV-2 infection.

Identification of Resistance to Exogenous Thyroxine in Humans.

Background: Thyroxine (T4) to triiodothyronine (T3) deiodination in the hypothalamus/pituitary is mediated by deiodinase type-2 (D2) activity. Dio2(-/-) mice show central resistance to exogenous T4. Patients with resistance to exogenous thyroxine (RETH) have not been described. The aim of this study was to identify hypothyroid patients with thyrotropin (TSH) unresponsiveness to levothyroxine (LT4) and to characterize the clinical, hormonal, and genetic features of human RETH. Methods: We investigated hypothyroid patients with elevated TSH under LT4 treatment at doses leading to clinical and/or biochemical hyperthyroidism. TSH and free T4 (fT4) were determined by chemiluminescence, and total T4, T3, and reverse T3 (rT3) by radioimmunoassay. TSH/fT4 ratio at inclusion and T3/T4, rT3/T4, and T3/rT3 ratios at follow-up were compared with those from patients with resistance to thyroid hormone (RTH) due to thyroid hormone receptor-ß (THRB) mutations. DIO2, including the Ala92-D2 polymorphism, selenocysteine binding protein 2 (SECISBP2), and THRB were fully sequenced. Results: Eighteen hypothyroid patients (nine of each sex, 3-59 years) treated with LT4 showed elevated TSH (15.5 ± 4.7 mU/L; reference range [RR]: 0.4-4.5), fT4 (20.8 ± 2.4 pM; RR: 9-20.6), and TSH/fT4 ratio (0.74 ± 0.25; RR: 0.03-0.13). Despite increasing LT4 doses from 1.7 ± 1.0 to 2.4 ± 1.7 µg/kg/day, TSH remained elevated (6.9 ± 2.7 mU/L). Due to hyperthyroid symptoms, LT4 doses were reduced, and TSH increased again to 7.9 ± 3.2 mU/L. In the euthyroid/hyperthyrotropinemic state, T3/T4 and T3/rT3 ratios were decreased (9.2 ± 2.4, RR: 11.3-15.3 and 2.5 ± 1.4, RR: 7.5-8.5, respectively) whereas rT3/T4 was increased (0.6 ± 0.2; RR: 0.43-0.49), suggesting reduced T4 to T3 and increased T4 to rT3 conversion. These ratios were serum T4-independent and were not observed in RTH patients. Genetic testing was normal. The Ala92-D2 polymorphism was present in 7 of 18 patients, but the allele dose did not correlate with RETH. Conclusions: Human RETH is characterized by iatrogenic thyrotoxicosis and elevated TSH/fT4 ratio. In the euthyroid/hyperthyrotropinemic state, it is confirmed by decreased T3/T4 and T3/rT3 ratios, and elevated rT3/T4 ratio. This phenotype may guide clinicians to consider combined T4+T3 therapy in a targeted fashion. The absence of germline DIO2 mutations suggests that aberrant post-translational D2 modifications in pituitary/hypothalamus or defects in other genes regulating the T4 to T3 conversion pathway could be involved in RETH.

Postpartum Follow-Up of Patients with Subclinical Hypothyroidism During Pregnancy.

Background: Subclinical hypothyroidism (SCH) in pregnancy is associated with adverse pregnancy and perinatal outcomes. However, few studies have investigated the evolution of postpartum thyroid function in these women. This study aimed to determine the postpartum outcomes of SCH during pregnancy and the clinical and biochemical factors related to the evolution of long-term hypothyroidism. Methods: A total of 393 women diagnosed with SCH during pregnancy (defined as thyrotropin [TSH] >4.0 µIU/mL with normal free thyroxine levels according to the 2017 American Thyroid Association guidelines) were prospectively followed up after delivery. Among them, 216 underwent long-term follow-up [median (interquartile range) follow-up time: 11 (7-19) months] postpartum. The clinical and biochemical characteristics of the women with long-term postpartum hypothyroidism and euthyroidism were compared. Linear mixed model (LMM) was used to explore the risk factors for longitudinal changes of TSH, and logistic regression analysis was employed to identify the independent predictors of long-term postpartum hypothyroidism. Results: The probability of long-term hypothyroidism after delivery in SCH during pregnancy was 38.9%. Among the subjects with normal thyroid function 6-week postpartum, 28.2% developed hypothyroidism during long-term follow-up. The LMM showed that gestational age at the time of SCH diagnosis (estimate: -0.018, p = 0.004) and thyroid peroxidase antibodies (TPOAb) (estimate: 0.001, p = 0.020) were significantly associated with longitudinal changes of TSH. The logistic regression model showed that TPOAb positive both during pregnancy and six-week postpartum was a risk factor for long-term hypothyroidism after delivery (odds ratio = 4.686 [95% confidence interval 1.242 to 17.680], p = 0.023). Conclusions: More than one-third of patients with SCH during pregnancy had persistent hypothyroidism after delivery. We recommend that patients with TPOAb positive both during pregnancy and six-week postpartum undergo close follow-up to detect persistent hypothyroidism, especially before the next pregnancy.

Effect of high-dose intravenous glucocorticoid therapy on serum thyroid hormone concentrations in type 2 amiodarone-induced thyrotoxicosis: an exploratory study.

PURPOSE: Type 2 amiodarone-induced thyrotoxicosis (AIT2) is a form of drug-induced destructive thyroiditis, usually treated with oral glucocorticoids (oGCs). Our objective was to investigate the short-term effects of intravenous glucocorticoids (ivGCs) on serum thyroid hormone concentrations in patients with AIT2. METHODS: Exploratory study of three naive AIT2 patients treated with iv methylprednisolone (two pulses of 400 mg with no interpulse oGCs), followed by oGCs, matched 1:3 with AIT2 patients treated with oGCs alone. Changes in serum thyroid hormone concentrations were evaluated in the short-term period (24 h and 7 days) and after a cumulative dosage of 400 and 800 mg equivalents of methylprednisolone; in addition, healing time and duration of exposure to GCs were calculated. RESULTS: During the first 24 h of treatment, serum FT4 concentrations increased in ivGCs patients, and decreased in oGCs patients (+ 3.3% vs - 10.7%, respectively, p = 0.025). After 7 days, serum FT4 and FT3 concentrations decreased significantly in both groups, with no statistical difference between them (p = 0.439 for FT4 and p = 0.071 for FT3), even though the cumulative GCs dose was higher in ivGCs than in oGCs patients (800 mg vs 280 mg, p = 0.008). Furthermore, the iv administration of single 400 mg pulses of methylprednisolone resulted in a less significant decrease in serum thyroid hormone concentrations when compared to equivalent GCs doses fractionated in several consecutive days (p = 0.021 for FT4 and p = 0.052 for FT3). There were no significant differences in the healing time (p = 0.239) and duration of exposure to GCs (p = 0.099). CONCLUSIONS: High-dose ivGCs therapy does not offer advantages over standard oGCs therapy in the rapid, short-term control of AIT2.

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.

Reconhecimento da paralisia periódica hipocalêmica tireotóxica na emergência: relato de caso e revisão da literatura / Recognizing thyrotoxic hypokalemic periodic paralysis on emergency settings: a case report and literature revie

A paralisia periódica hipocalêmica tireotóxica é uma complicação inusitada do hipertireoidismo, porém é considerada urgência endocrinológica e ainda frequentemente subdiagnosticada. Sua apresentação clínica consiste na tríade de défice de potássio, tireotoxicose e fraqueza muscular ­ sendo esse último sintoma comum em diversas patologias. Realizamos uma revisão bibliográfica e destacamos, por meio do relato de caso, a importância do diagnóstico precoce dessa doença, possibilitando uma evolução favorável ao paciente, independente de sua etnia, sexo ou região geográfica. Atentamos ainda ao tratamento da doença, que, apesar de sua simplicidade, acarreta muitos equívocos.

The thyrotoxic hypokalemic periodic paralysis is a rare complication of hyperthyroidism, but is considered an endocrinological urgency, and yet frequently underdiagnosed. Its clinical presentation consists of potassium deficit, thyrotoxicosis, and muscular weakness, with the latter symptom being very common in several pathologies. We performed a bibliographic review and highlight, through a case report, the importance of the early diagnosis of this disease to allow favorable progression to the patient, regardless of ethnicity, sex, or geographical region. We also reinforce the importance of the disease treatment which, despite its simplicity, leads to many mistakes.

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.

Management of thyrotoxicosis during pregnancy.

Thyrotoxicosis during pregnancy should be adequately managed and controlled to prevent maternal and fetal complications. The evaluation of thyroid function in pregnant women is challenged by the physiological adaptations associated with pregnancy, and the treatment with antithyroid drugs (ATD) raises concerns for the pregnant woman and the fetus. Thyrotoxicosis in pregnant women is mainly of autoimmune origin, and the measurement of thyroid stimulating hormone-receptor antibodies (TRAb) plays a key role. TRAb helps to distinguish the hyperthyroidism of Graves' disease from gestational hyperthyroidism in early pregnancy, and to evaluate the risk of fetal and neonatal hyperthyroidism in late pregnancy. Furthermore, the measurement of TRAb in early pregnancy is recommended to evaluate the need for ATD during the teratogenic period of pregnancy. Observational studies have raised concern about the risk of birth defects associated with the use of ATD in early pregnancy and challenged the clinical management and choice of treatment.

Influence of thyroid dysfunction on brain natriuretic peptide level in health examination participants.

The tissue-specific circulating markers of thyroid hormone action on cardiac function have not been established. Although the relationship between thyroid function and plasma brain natriuretic peptide (BNP) levels has been evaluated in patients with thyroid disorders, the relationship between these parameters in the general population has not been yet studied. We conducted retrospective cohort study by health examination with concurrent measurements of TSH, free T4, body mass index, systolic blood pressure, hemoglobin, and estimated glomerular filtration rate from participants who visited the Department of Health Checkup, Enshu Hospital between July 2008 and March 2017. After participants with abnormal electrocardiogram and/or any history of cardiac disease were excluded, 2,807 individuals were subjected. Multivariate analyses demonstrated that, when compared to euthyroidism (n = 2,629), the increase in BNP levels was significant in overt thyrotoxicosis (n = 21) but not in subclinical thyrotoxicosis (n = 53) or subclinical hypothyroidism (n = 97). Interestingly, the standardized partial regression coefficient was the smallest for thyroid function category (overt thyrotoxicosis compared to euthyroidisim; ß = 0.048, p = 0.006) among the independent variables including age, body mass index, systolic blood pressure, and hemoglobin. In longitudinal comparison, we identified 986 participants who had sequential data on the measurements and were stable as euthyroidism and subclinical hypothyroidism. Their annual percent change in BNP demonstrated no significant differences. In conclusion, a direct stimulatory effect of thyroid hormone on the secretion (or production) of BNP was confirmed even in a large number of health examination participants.

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.

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 neutrophil­to­lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet­to­lymphocyte 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.

Serotonin syndrome unmasking thyrotoxicosis.

A 26-year-old cachectic man presented with an altered mental status. He was agitated, tremulous, hyperthermic and diaphoretic with largely dilated pupils. Collateral history revealed acute ingestion of 3,4-methylenedioxymethamphetamine on a background of chronic drug abuse. His condition deteriorated requiring sedation and intubation with transfer to the intensive care unit. A diagnosis of serotonin syndrome was made, based on his findings in keeping with the Hunter criteria, and he was treated with supportive management during a resultant and briefly sustained delirium. With gradual resolution of his agitated state, further questioning and blood work a concurrent, and potentially contributory, thyrotoxicosis was revealed. The patient was commenced on treatment for this with urgent outpatient follow-up with both a local otolaryngologist and endocrinologist for consideration of further treatment.