RELATIONSHIP BETWEEN THE EFFECTIVENESS OF INORGANIC IODINE AND THE SEVERITY OF GRAVES THYROTOXICOSIS: A RETROSPECTIVE STUDY

OBJECTIVE

Inorganic iodine is often used to treat patients with Graves thyrotoxicosis who do not tolerate thionamides due to adverse effects. However, predictors of continued inorganic iodine efficacy have not been fully elucidated. This study aimed to investigate the factors affecting the continued efficacy of potassium iodide (KI) in patients with Graves thyrotoxicosis.

METHODS

In this study, among 1,197 patients with Graves disease who were initially treated with thionamides, we retrospectively studied 24 consecutive Japanese patients whose treatment was changed to KI alone due to the adverse effects of thionamides. We divided these patients into 2 groups: patients who had maintained euthyroid function for at least 180 days (nonrecurrence group, n = 11), and patients who had not maintained euthyroid function for 180 days (recurrence group, n = 13).

RESULTS

Free triiodothyronine (FT3) and free thyroxine (FT4) levels on the day of changing from thionamides to KI were statistically higher in the recurrence group than in the nonrecurrence group (FT3, 9.3 [range, 5.2-11.6] vs. 3.7 [3.3-4.8] pg/mL, P = .02 and FT4, 3.6 [1.8-4.5] vs. 1.4 [1.2-1.9] ng/dL, P = .02). FT4 levels on the day of drug change were significantly higher in the recurrence group, even after adjusting for thionamide or KI dose. In the recurrence group, the duration of KI effect was inversed correlated with FT3 and FT4 levels on the day of drug change.

CONCLUSION

Continued efficacy of KI after thionamides might be inversely correlated with thyrotoxicosis severity on the day of drug change.

ABBREVIATIONS

ANOVA = analysis of variance eTV = estimated thyroid volume FT3 = free triiodothyronine FT4 = free thyroxine IQR = interquartile range KI = potassium iodide MMI = thiamazole PTU = propylthiouracil RAIT = radioactive iodine therapy TRAb = TSH receptor antibody TSH = thyroid stimulating hormone.

No Effect of Levothyroxine and Levothyroxine-Induced Subclinical Thyrotoxicosis on the Pharmacokinetics of Sorafenib in Healthy Male Subjects

BACKGROUND

Patients receiving the multikinase inhibitor sorafenib for locally recurrent or metastatic, progressive, differentiated thyroid carcinoma (DTC) refractory to radioactive iodine often receive concomitant levothyroxine for thyrotropin (TSH) suppression. In the Phase 3 DTC trial (DECISION), sorafenib exposure was approximately twofold higher than that observed in other cancers. This study assessed sorafenib pharmacokinetics without and with concomitant levothyroxine to examine whether a levothyroxine interaction or levothyroxine-induced subclinical thyrotoxicosis results in increased sorafenib exposure in patients with DTC.

METHODS

This was an open-label, two-period sequential treatment study in healthy male subjects. In period 1, day 1, subjects received a single oral dose of sorafenib 400 mg, followed by a minimal 10-day washout. In period 2, day 1, levothyroxine 300 μg was administered orally once daily (q.d.) for 14 days. After 10 days, a single oral concomitant dose of sorafenib 400 mg was given. Blood samples for sorafenib pharmacokinetic analyses were obtained pre-dose and at time points up to 96 hours after sorafenib dosing. Samples for thyroid tests were collected before and after levothyroxine dosing.

RESULTS

Twenty-five subjects completed the study and were evaluable for pharmacokinetic analysis. Levothyroxine 300 μg q.d. was well tolerated and induced subclinical thyrotoxicosis, producing full suppression of TSH (M ± SD = 0.032 ± 0.027 mIU/L) and increased free thyroxine (from 0.94 ± 0.09 to 1.77 ± 0.33 ng/dL) and free triiodothyronine (from 2.87 ± 0.28 to 4.24 ± 0.66 pg/mL) levels by day 11 of period 2. The geometric mean (%CV) sorafenib maximum concentration (C_max) without and with levothyroxine was 2.09 (68.1) and 1.78 (63.9) mg/L, respectively, with a corresponding geometric mean area under the curve of 68.1 (68.2) and 64.3 (66.3) mg·h/L. Median (range) time to C_max was 4.00 (2.98-16.0) and 4.02 (1.98-36.0) hours, respectively. Mean (%CV) half-life was 24.0 (25.3) and 25.7 (21.0) hours. All study drug-related adverse events were mild and included headache and fatigue for sorafenib, and headache, increased alanine aminotransferase and glutamate dehydrogenase, fatigue, and nervousness for levothyroxine.

CONCLUSIONS

Levothyroxine 300 μg q.d. for 14 days was well tolerated, induced subclinical thyrotoxicosis, and did not affect sorafenib pharmacokinetics. The findings suggest that concomitant use of levothyroxine with sorafenib is not likely responsible for the previously reported increase in sorafenib exposure in patients with DTC. However, the possible effects of long-term levothyroxine dosing were not assessed.

Clinical Features of Nivolumab-Induced Thyroiditis: A Case Series Study

BACKGROUND

The programmed cell death-1 (PD-1) pathway is a novel therapeutic target in immune checkpoint therapy for cancer. It consists of the PD-1 receptor and its two ligands, programmed death-ligand 1 (PD-L1) and programmed death-ligand 2 (PD-L2). Nivolumab is an anti-PD-1 monoclonal antibody approved for malignant melanoma, advanced non-small cell lung cancer, and advanced renal cell carcinoma in Japan. Thyrotoxicosis and hypothyroidism have both been reported in international Phase 3 studies and national post-marketing surveillance of nivolumab in Japan.

METHODS

This study analyzed five consecutive cases with thyroid dysfunction associated with nivolumab therapy. Second, it examined the mRNA and protein expressions of PD-L1 and PD-L2 by reverse transcription polymerase chain reaction and Western blotting.

RESULTS

All patients were diagnosed with painless thyroiditis. Thyrotoxicosis developed within four weeks from the first administration of nivolumab and normalized within four weeks of onset in three of the five patients. Hypothyroidism after transient thyrotoxicosis developed in two patients, and preexisting hypothyroidism persisted in one patient. The other two patients were treated with glucocorticoids and discontinued nivolumab therapy for comorbid adverse events. One did not develop hypothyroidism, and the other developed mild, transient hypothyroidism. In addition, it was verified that normal thyroid tissue expresses PD-L1 and PD-L2 mRNA and those proteins.

CONCLUSIONS

In the present cases, nivolumab-induced thyrotoxicosis seemed to be associated with painless thyroiditis, while no patient with Graves' disease was observed. A transient and rapid course with subsequent hypothyroidism was observed in nivolumab-induced thyroiditis. In addition, it was verified that PD-L1 and PD-L2 are expressed in normal thyroid tissue. This suggests that nivolumab therapy reduces immune tolerance, even in normal thyroid tissue, and leads to the development of thyroiditis. Treating thyrotoxicosis with only supportive care and considering levothyroxine replacement therapy once subsequent hypothyroidism occurs is proposed. Further investigations are required to confirm whether glucocorticoid therapy and discontinuation of nivolumab therapy prevent subsequent hypothyroidism.

Incidence of abnormal liver biochemical tests in hyperthyroidism

OBJECTIVE

Abnormal serum liver function tests are common in patients with untreated thyrotoxicosis, even prior to the initiation of antithyroidal medications that may worsen the severity of the abnormal serum liver biochemistries. There is a wide range of the incidence of these abnormalities in the published literature. The aim of this study was to assess the risks factors and threshold of thyrotoxicosis severity for developing an abnormal liver biochemical test upon the diagnosis of new thyrotoxicosis.

DESIGN

Single-institution retrospective cohort study.

PATIENTS

Patients of ≥18 years old receiving medical care at a large, academic, urban US medical centre between 2002-2016.

MEASUREMENTS

Inclusion criteria were a serum thyroid stimulating hormone (TSH) concentration of <0·3 mIU/l or ICD-9 code for thyrotoxicosis, with thyrotoxicosis confirmed by either a concurrent elevated serum triiodothyronine (T3) or thyroxine (T4) concentration ([total or free] within 3 months), and an available liver biochemical test(s) within 6 months of thyrotoxicosis. The biochemical liver tests assessed were serum aspartate transaminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AP), gamma-glutamyltransferase (GGT), total bilirubin, and conjugated bilirubin concentrations.

RESULTS

In this cohort of 1514 subjects, the overall incidence of any biochemical liver test abnormality within 6 months of thyrotoxicosis was 39%. An initial serum TSH concentration <0·02 mIU/l, male gender, and African-American race were significant predictors of an abnormal serum liver biochemical test within 6 months of the diagnosis of new-onset untreated thyrotoxicosis.

CONCLUSIONS

This study identifies risk factors for patients who develop an abnormal serum liver biochemical test result within 6 months of a diagnosis of untreated thyrotoxicosis.

Plasma proteome and metabolome characterization of an experimental human thyrotoxicosis model

BACKGROUND

Determinations of thyrotropin (TSH) and free thyroxine (FT4) represent the gold standard in evaluation of thyroid function. To screen for novel peripheral biomarkers of thyroid function and to characterize FT4-associated physiological signatures in human plasma we used an untargeted OMICS approach in a thyrotoxicosis model.

METHODS

A sample of 16 healthy young men were treated with levothyroxine for 8 weeks and plasma was sampled before the intake was started as well as at two points during treatment and after its completion, respectively. Mass spectrometry-derived metabolite and protein levels were related to FT4 serum concentrations using mixed-effect linear regression models in a robust setting. To compile a molecular signature discriminating between thyrotoxicosis and euthyroidism, a random forest was trained and validated in a two-stage cross-validation procedure.

RESULTS

Despite the absence of obvious clinical symptoms, mass spectrometry analyses detected 65 metabolites and 63 proteins exhibiting significant associations with serum FT4. A subset of 15 molecules allowed a robust and good prediction of thyroid hormone function (AUC = 0.86) without prior information on TSH or FT4. Main FT4-associated signatures indicated increased resting energy expenditure, augmented defense against systemic oxidative stress, decreased lipoprotein particle levels, and increased levels of complement system proteins and coagulation factors. Further association findings question the reliability of kidney function assessment under hyperthyroid conditions and suggest a link between hyperthyroidism and cardiovascular diseases via increased dimethylarginine levels.

CONCLUSION

Our results emphasize the power of untargeted OMICs approaches to detect novel pathways of thyroid hormone action. Furthermore, beyond TSH and FT4, we demonstrated the potential of such analyses to identify new molecular signatures for diagnosis and treatment of thyroid disorders. This study was registered at the German Clinical Trials Register (DRKS) [DRKS00011275] on the 16th of November 2016.

Mild Thyrotoxicosis Leads to Brain Perfusion Changes: An Arterial Spin Labelling Study

Hypo- and hyperthyroidism have effects on brain structure and function, as well as cognitive processes, including memory. However, little is known about the influence of thyroid hormones on brain perfusion and the relationship of such perfusion changes with cognition. The present study aimed to demonstrate the effect of short-term experimental hyperthyroidism on brain perfusion in healthy volunteers and to assess whether perfusion changes, if present, are related to cognitive performance. It is known that an interaction exists between brain perfusion and cerebral oxygen consumption rate and it is considered that neural activation increases cerebral regional perfusion rate in brain areas associated with memory. Measuring cerebral blood flow may therefore represent a proxy for neural activity. Therefore, arterial spin labelling (ASL) measurements were conducted and later analysed to evaluate brain perfusion in 29 healthy men before and after ingesting thyroid hormones for 8 weeks. Psychological tests concerning memory were performed at the same time-points and the results were correlated with the imaging results. In the hyperthyroid condition, perfusion was increased in the posterior cerebellum in regions connected with cerebral networks associated with cognitive control and the visual cortex compared to the euthyroid condition. In addition, these perfusion changes were positively correlated with changes of performance in the German version of the Auditory Verbal Learning Task [AVLT, Verbaler Lern-und-Merkfähigkeits-Test (VLMT)]. Cerebellar perfusion and function therefore appears to be modulated by thyroid hormones, likely because the cerebellum hosts a high number of thyroid hormone receptors.

Incidence of Thyroid-Related Adverse Events in Melanoma Patients Treated With Pembrolizumab

CONTEXT

Immune checkpoint blockade is associated with endocrine-related adverse events. Thyroid dysfunction during pembrolizumab therapy, an anti-programmed cell death 1 (PD-1) receptor monoclonal antibody, remains to be fully characterized.

OBJECTIVE

To assess the incidence and characteristics of pembrolizumab-associated thyroid dysfunction.

DESIGN AND SETTING

Thyroid function was monitored prospectively in melanoma patients who initiated pembrolizumab within an expanded access program at a referral oncology center. 18Fluorodeoxyglucose uptake on positron emission tomography/computed tomography (18FDG-PET/CT) was reviewed in cases compatible with inflammatory thyroiditis.

PATIENTS

Ninety-nine patients with advanced melanoma (age, 26.3-93.6 years; 63.6% females) who received at least one administration of pembrolizumab.

MAIN OUTCOME MEASURES

Patient characteristics, thyroid function (TSH, free T4), thyroid autoantibodies, and 18FDG-PET/CT.

RESULTS

Eighteen adverse events of thyroid dysfunction were observed in 17 patients. Thyrotoxicosis occurred in 12 patients, of which nine evolved to hypothyroidism. Isolated hypothyroidism was present in six patients. Levothyroxine therapy was required in 10 of 15 hypothyroid patients. Thyroid autoantibodies were elevated during thyroid dysfunction in four of 10 cases. Diffuse increased 18FDG uptake by the thyroid gland was observed in all seven thyrotoxic patients who progressed to hypothyroidism.

CONCLUSIONS

Thyroid dysfunction is common in melanoma patients treated with pembrolizumab. Hypothyroidism and thyrotoxicosis related to inflammatory thyroiditis are the most frequent presentations. Serial measurements of thyroid function tests are indicated during anti-PD-1 monoclonal antibody therapy. Thyrotoxicosis compatible with inflammatory thyroiditis was associated with diffuse increased 18FDG uptake by the thyroid gland. The prospective role of thyroid autoantibodies should be further investigated, together with the histopathological correlates.

Partial prediction of postpartum Graves' thyrotoxicosis by sensitive bioassay for thyroid-stimulating antibody measured in early pregnancy

Graves' disease often occurs after delivery. However, it has been difficult to predict who will develop Graves' hyperthyroidism. We attempted to predict postpartum onset of Graves' disease by measuring anti-TSH receptor antibodies (TRAb) and thyroid-stimulating antibodies (TSAb) in early pregnancy. TRAb was measured by a third generation assay and TSAb was measured by a newly developed sensitive bioassay. In 690 early pregnant women, 2 showed borderline TRAb positive reactions. However, none of them developed Graves' disease after delivery. Thirty-eight of 690 pregnant women were positive for anti-thyroid peroxidase antibodies (TPOAb) and 4 were positive for TSAb. Two of these 4 women developed postpartum Graves' hyperthyroidism. These findings indicate that the third generation TRAb assay was not useful, but that the sensitive TSAb bioassay was moderately useful for predicting the postpartum onset of Graves' hyperthyroidism.

Testicular germ cell tumour presenting as thyrotoxicosis

A case is reported of a patient who presented to his family doctor with a short history of cough with signs and symptoms of thyrotoxicosis. Carbimazole treatment had little effect and his symptoms worsened to include severe shortness of breath. He was investigated further and found to have multiple lung and liver metastases from an unknown primary site. Biopsy and subsequent post-mortem investigations revealed a testicular tumour and a grossly elevated serum human chorionic gonadotrophin (hCG) concentration.

The biochemical and clinical thyrotoxicosis is presumed to be due to the thyrotrophic activity of excess hCG secretion, in a situation analogous to that seen in hydatidiform mole or in hyperemesis gravidarum.

Maternal First Trimester TSH Concentrations: Do They Affect Perinatal and Endocrine Outcomes?

We aimed to examine the distribution of 1(st) trimester TSH and evaluate its association with perinatal outcomes and future development of maternal thyrotoxicosis. This retrospective cohort study included data of all women without prior thyroid disease who delivered a singleton at our medical center from 1/2001 to 12/2011 and had a 1(st) trimester TSH<4.0 mU/l. Women were divided according to 1(st) trimester TSH concentrations into quartiles and by predefined TSH values (mU/l): 1) TSH<0.1; 2) TSH 0.11-0.2; 3) TSH 0.21-0.4; and 4) TSH 0.4-4. Obstetrical outcomes, hCG concentrations, and future thyroid status were collected from electronic medical records. A total of 13 841 women fulfilled the inclusion criteria. Mean maternal TSH concentration at 5 weeks of gestation was 2.09±0.83 mU/l and decreased to 1.29±0.87 mU/l in weeks 8-9 with an increase towards the end of the 1(st) trimester. Odds ratio for future thyrotoxicosis was 3.64 in the lowest compared to the highest TSH quartile and 10.03 in those with TSH<0.1 compared to TSH 0.41-4 mU/l. Rates of female fetuses were higher in the low TSH quartiles and in the lower TSH groups, however baby gender was not associated with increased risk of future thyrotoxicosis. Low maternal 1(st) trimester TSH quartiles or concentrations were not associated with adverse pregnancy outcome. Only a minor fraction of pregnant women with a low first tirmester TSH subsequently developed future thyrotoxicosis.

The presence of anti-thyroglobulin (TgAb) and/or anti-thyroperoxidase antibodies (TPOAb) does not exclude the diagnosis of type 2 amiodarone-induced thyrotoxicosis

PURPOSE

It is widely accepted that type 2 amiodarone-induced thyrotoxicosis (AIT) generally occurs in patients with a normal thyroid gland without signs of thyroid autoimmunity. However, it is currently unknown if the presence of anti-thyroglobulin (TgAb) and/or anti-thyroperoxidase antibodies (TPOAb) in AIT patients without other signs of an underlying thyroid disease may impair the response to glucocorticoid therapy.

METHODS

We performed a pilot retrospective cohort study with matched-subject design and an equivalence hypothesis, comparing the response to glucocorticoid therapy between 20 AIT patients with a normal thyroid gland, low radioiodine uptake, undetectable TSH receptor antibodies and positive TgAb and/or TPOAb (Ab+ group), and 40 patients with the same features and absent thyroid antibodies (Ab- group).

RESULTS

The mean cure time was 54 ± 68 days in the Ab+ group and 55 ± 49 days in the Ab- group (p = 0.63). The equivalence test revealed an equivalent cure rate after 60, 90 and 180 days (p = 0.67, 0.88 and 0.278, respectively). The occurrence of permanent hypothyroidism was higher in the Ab+ group than in the Ab- group (26.3 vs 5.13 %, p = 0.032).

CONCLUSIONS

The presence of TgAb and/or TPOAb does not affect the response to glucocorticoid therapy, suggesting that the patients with features of destructive form of AIT should be considered as having a type 2 AIT irrespective of the presence of TGAb or TPOAb. These patients have a higher risk of developing hypothyroidism after the resolution of thyrotoxicosis and should be monitored accordingly.

Lack of α2C-Adrenoceptor Results in Contrasting Phenotypes of Long Bones and Vertebra and Prevents the Thyrotoxicosis-Induced Osteopenia

A series of studies have demonstrated that activation of the sympathetic nervous system (SNS) causes osteopenia via β₂-adrenoceptor (β₂-AR) signaling. However, in a recent study, we found an unexpected and generalized phenotype of high bone mass in female mice with chronic sympathetic hyperactivity, due to double gene inactivation of adrenoceptors that negatively regulate norepinephrine release, α_2A-and α_2C-AR (α_2A/2C-AR^-/-). These findings suggest that β₂-AR is not the single adrenoceptor involved in bone turnover regulation and show that α₂-AR signaling may also mediate the SNS actions in the skeleton. In addition, we found that α_2A/2C-AR^-/- animals are resistant to the thyrotoxicosis-induced osteopenia, suggesting that thyroid hormone (TH), when in supraphysiological levels, interacts with the SNS to control bone mass and structure, and that this interaction may also involve α₂-AR signaling. In the present study, to further investigate these hypotheses and to discriminate the roles of α₂-AR subtypes, we have evaluated the bone phenotype of mice with the single gene inactivation of α_2C-AR subtype, which mRNA expression was previously shown to be down regulated by triiodothyronine (T3). A cohort of 30 day-old female α_2CAR^-/- mice and their wild-type (WT) controls were treated with a supraphysiological dose of T3 for 30 or 90 days, which induced a thyrotoxic state in both mouse lineages. The micro-computed tomographic (μCT) analysis showed that α_2C-AR^-/- mice present lower trabecular bone volume (BV/TV) and number (Tb.N), and increased trabecular separation (Tb.Sp) in the femur compared with WT mice; which was accompanied by decreased bone strength (determined by the three-point bending test) in the femur and tibia. The opposite was observed in the vertebra, where α_2C-AR^-/- mice show increased BV/TV, Tb.N and trabecular thickness (Tb.Th), and decreased Tb.Sp, compared with WT animals. In spite of the contrasting bone phenotypes of the femur and L5, thyrotoxicosis negatively regulated most of the micro architectural features of the trabecular bone in both skeletal sites of WT, but not of α_2C-AR^-/- mice. T3 treatment also decreased biomechanical properties (maximum load and ultimate load) in the femur and tibia of WT, but not of knockout mice. The mRNA expression of osteocalcin, a marker of mature osteoblasts, and tartrate-resistant acid phosphatase, which is expressed by osteoclasts and is involved in collagen degradation, was increased by T3 treatment only in WT, and not in α_2C-AR^-/- mice. Altogether, these findings suggest that α_2C-AR subtype mediates the effects of the SNS in the bone in a skeletal site-dependent manner, and that thyrotoxicosis depends on α_2C-AR signaling to promote bone loss, which sustains the hypothesis of a TH-SNS interaction to modulate bone remodeling and structure.

Postpartum thyroid dysfunction in women with autoimmune thyroiditis

INTRODUCTION

Autoimmune thyroiditis (AIT) is a predisposing factor for developing postpartum thyroid dysfunction (PPTD).

AIM

To study the characteristics of PPTD in women with AIT.

METHODS

Thirty-eight women with pre-existing AIT were included in the study. Thyroid-stimulating hormone, free triiodthyronine, free thyroxine, thyroid peroxidase antibodies, thyroglobulin antibodies were measured and ultrasound evaluation of the thyroid gland was performed in the first trimester of pregnancy and during the first year following delivery.

RESULTS

Thyroid dysfunction was recognized in 68.4% of the patients - 28.9% presented with hypothyroidism and 39.5 % with thyrotoxicosis. The immunological and morphological parameters did not differ between euthyroid women and those with thyroid dysfunction. At the end of the postpartum period restoration of euthyroid state (being on the treatment before pregnancy) was observed in 15.4% of patients with PPTD, while 84.6% required increase of the levothyroxine dose. The analysis found a significantly lower volume of the thyroid gland, shorter duration of the disease, a lower dose of levothyroxine before and during gestation in patients with impaired thyroid function at the end of the postpartum period.

CONCLUSION

The risk of PPTD in women with AIT predating pregnancy is higher among women with preserved thyroid functional capacity motivating a thorough assessment of thyroid hormone levels and close follow-up of those women during the postpartum period.

Prospective population-based study of the association between vitamin D status and incidence of autoimmune disease

Beside its traditional role in skeletal health, vitamin D is believed to have multiple immunosuppressant properties, and low vitamin D status has been suggested to be a risk factor in the development of autoimmune disease. We investigated the association between vitamin D status and development of autoimmune disease. We included a total of 12,555 individuals from three population-based studies with measurements of vitamin D status (25-hydroxy vitamin D). We followed the participants by linkage to the Danish National Patient Register (median follow-up time 10.8 years). Relative risks of autoimmune disease were estimated by Cox regression and expressed as hazard ratios, HRs (95 % confidence intervals CIs). There were 525 cases of incident autoimmune disease. The risk for a 10 nmol/l higher vitamin D was: for any autoimmune disease (HR = 0.94 % CI 0.90, 0.98); thyrotoxicosis (HR = 0.83, 95 % CI 0.72, 0.96); type 1 diabetes (HR = 0.95, 95 % CI 0.88, 1.02), multiple sclerosis (HR = 0.89, 95 % CI 0.74, 1.07), iridocyclitis (HR = 1.00, 95 % CI 0.86, 1.17); Crohn's disease (HR = 0.95, 95 % CI 0.80, 1.13), ulcerative colitis (HR = 0.88, 95 % CI 0.75, 1.04); psoriasis vulgaris (HR = 0.99, 95 % CI 0.86, 1.13); seropositive rheumatoid arthritis (HR = 0.97, 95 % CI 0.89, 1.07), and polymyalgia rheumatica (HR = 0.94, 95 % CI 0.83, 1.06). We found statistically significant inverse associations between vitamin D status and development of any autoimmune disease and thyrotoxicosis in particular. Our findings suggest a possible protective role of a higher vitamin D status on autoimmune disease but warrant further studies to clarify causality.

Race/Ethnicity and the prevalence of thyrotoxicosis in young Americans

BACKGROUND

Race/ethnicity may be a newly recognized risk factor for Graves' disease.

OBJECTIVE

The aim of this study was to examine the prevalence of thyrotoxicosis by race/ethnicity in Americans aged 12-49 years using three National Health and Nutritional Examination Surveys (NHANES).

METHODS

Data were analyzed from 17,939 participants in NHANES III (1988-1994), NHANES 1999-2002, and NHANES 2007-2010 with available thyroid function test results. Thyrotoxicosis was defined as a serum thyrotropin (TSH) of ≤0.1 mIU/L or subjects taking methimazole or propylthiouracil, and overt thyrotoxicosis was defined as high serum thyroxine and a serum TSH of ≤0.1 mIU/L. Logistic regression was performed accounting for the complex sampling design of NHANES, and the results from all three NHANES surveys were combined using a random-effects model.

RESULTS

There were 75 study participants with point prevalent thyrotoxicosis, representing a pooled prevalence of 0.4% for Americans aged 12-49 years. Prevalent thyrotoxicosis was nearly three times more likely in non-Hispanic black subjects compared with non-Hispanic whites (OR=2.9 [CI 1.5-5.7]), while there was no difference between the prevalence of thyrotoxicosis in Mexican Americans compared to non-Hispanic whites (OR=1.2 [CI 0.6-2.4]; I2 for heterogeneity=0% for both). Among 27 patients with overt thyrotoxicosis, the odds ratio was 8.7 [CI 0.7-112.6] for non-Hispanic blacks and 4.6 [CI 0.4-59.3] for Mexican Americans compared with non-Hispanic whites.

CONCLUSIONS

The results suggest there are race/ethnicity differences in the prevalence of thyrotoxicosis. Future studies should address whether these differences are due to heritable factors, environmental exposures, or a combination of both.

Serum human chorionic gonadotropin levels and thyroid hormone levels in gestational transient thyrotoxicosis: Is the serum hCG level useful for differentiating between active Graves' disease and GTT?

Gestational transient thyrotoxicosis (GTT) is defined as transient thyrotoxicosis caused by the stimulating effect of human chorionic gonadotropin (hCG) during pregnancy. We attempted to identify the serum hCG level that causes GTT, and we compared the serum hCG levels and thyroid hormone levels of GTT patients according to whether they had a background of thyroid disease. We also evaluated serum hCG as a parameter for differentiating between active Graves' disease (GD) and GTT. We reviewed the 135 cases of pregnant women who came to our hospital to be evaluated for thyrotoxicosis during their 7th to 14th week of pregnancy, and their serum hCG level was measured at that time. Among the 135 pregnant women with thyrotoxicosis; 103 of the women had GTT, and the other 32 women had active GD. There were no correlations between their serum hCG levels and free thyroid hormone levels. There were no significant differences in thyroid hormone levels or hCG levels among the GTT groups with different thyroid disease backgrounds; i.e., the GTT group without thyroid disease, GTT group with chronic thyroiditis, GTT group with non-functioning thyroid nodules, and GTT group with GD in remission. The serum hCG level of the GTT group was significantly higher than in the active GD group, but it was not a good parameter for differentiating between the two groups. The FT3/FT4 ratio of the active GD was significantly higher than in GTT group, and was a better parameter for differentiation.

Serum Adiponectin Levels and Changes in Glucose Metabolism before and after Treatment for Thyroid Dysfunction

OBJECTIVE

Adiponectin is an adipokine which is known to decrease in individuals associated with obesity and insulin resistance. In this study, we aimed to investigate the serum adiponectin levels and glucose metabolism in patients with thyroid dysfunction before and after treatment.

METHODS

Newly diagnosed overt hypothyroid (n=20) and thyrotoxic (n=23) patients and healthy controls (n=20) with a body mass index of <30 kg/m(2) were evaluated prospectively. Patients with a known state of insulin resistance, including prediabetes and overt diabetes, and individuals with chronic diseases were excluded. Thyroid function and fasting plasma glucose (FPG), insulin, homeostatic model assessment (HOMA) insulin resistance (HOMA-IR) and HOMA-beta cell function (HOMA-beta), lipid and adiponectin levels were investigated in the basal state and after the restoration of euthyroidism.

RESULTS

The basal fasting FPG levels were lower in the hypothyroid patients than the control subjects (p=0.02) and similar between the thyrotoxic patients and control subjects (p=0.127). The basal HOMA-beta levels were higher in the patients with hypothyroidism than in those with thyrotoxicosis (p=0.015). Following the restoration of euthyroidism, the FPG levels significantly increased in the hypothyroid patients (p=0.002) and decreased in the thyrotoxic (p=0.001) patients. The basal plasma adiponectin levels were 14.55±8.4 mcg/mL, 13.79±9.13 mcg/mL and 11.68±6.0 mcg/mL in the hypothyroid and thyrotoxic patients and healthy controls, respectively (p=0.503). The adiponectin levels decreased significantly in the patients with hypothyroidism (p=0.047), whereas they did not change in the patients with thyrotoxicosis (p=0.770) after achieving euthyroidism.

CONCLUSION

In this study, following the restoration of euthyroidism, the FPG levels increased in the hypothyroidism patients and decreased in the thyrotoxicosis patients, despite the lack of changes in the HOMA-IR and HOMA-beta levels. Meanwhile, the hypothyroid, thyrotoxic and euthyroid subjects had similar basal adiponectin levels, and a significant decrease in the adiponectin levels was observed after treatment for hypothyroidism, despite the absence of changes after treatment for thyrotoxicosis, indicating the need for further studies with a larger sample size.

Therapeutic particularities in amiodarone induced thyroid disorder in patients with underlying cardiac condition

AIM

the analysis of therapeutic approach in patients with basic heart condition and amiodarone induced thyroid dysfunction--correlations with the evolution and prognosis.

MATERIAL AND METHODS

The study included 215 patients, 90 men and 125 women aged between 35 and 87, with different cardiac pathologies hospitalized in the Cardiology Clinic between 2004-2014, who received amiodarone treatment, in most cases for prophylaxis of various arrhythmias, both supraventricular and ventricular. During the evolution, these patients have developed amiodarone-induced thyroid dysfunction (hypo- or hyper function).

RESULTS AND DISCUSSION

The evaluation of thyroid function after starting treatment was performed in 187 patients (86.97%). Diagnosis of amiodarone-induced thyroid dysfunction was based on hormonal dosages of TSH, FT4 and FT3, endocrinological examination and thyroid ultrasound. Thyroid dysfunction treatment was initiated, depending on the situation, in all patients during the hospitalization. Treatment included anti thyroid drugs or hormones substitution and in some cases a minimal dose of prednisone.

CONCLUSIONS

Thyroid dysfunction regardless of the type (with hypo- or hyper function) requires continuous changes of the cardiovascular treatment, and association, where appropriate, with thyroid dysfunction medication. In some cases the latter determines cardiovascular side effects, for instance corticotheraphy may become a factor of imbalance for the hemodynamic status of the patient (by fluid retention, increased blood pressure, hyper glycemia).

[Distribution of IgG subclasses of TgAb and TPOAb in sera from patients with Graves' disease, Graves' disease plus Hashimoto's thyroiditis and Hashimoto's thyrotoxicosis]

OBJECTIVE

To evaluate the distribution of IgG subclasses of TgAb and TPOAb in sera from patients with Graves' disease (GD), Graves' disease plus Hashimoto's thyroiditis (GH) and Hashimoto's thyrotoxicosis.

METHODS

Patients with GD (n = 33), GH (n = 31) or Hashimoto's thyrotoxicosis (n = 18) diagnosed by fine needle aspiration cytology at Department of Endocrinology of Peking University First Hospital, Beijing Haidian Hospital, China-Japan Friendship Hospital and Civil Aviation General Hospital during the period from January 2010 to May 2013 were enrolled. All of them had TgAb and TPOAb. The total serum IgG and IgG subclasses of TgAb and TPOAb were detected by antigen-specific enzyme-linked immunosorbent assay (ELISA). The prevalence and relative amount of IgG subclasses were calculated and compared among three groups.

RESULTS

The levels of TRAb in GD group (21.80(7.53, 40) U/L) were significantly higher than those in GH (7.30(3.10, 25.40) U/L) (P = 0.000) and Hashimoto's thyrotoxicosis groups (4.90(1.69, 16.43) U/L) (P = 0.003). And no significant differences were found in the levels of TgAb and TPOAb. The prevalence of TgAb IgG3 subclass in Hashimoto's thyrotoxicosis group (66.7%) was higher than GD group (35.5%) and GH group (36.4%) and the difference was close to significance (P = 0.066). There were significant differences of relative amount of TgAb IgG2 and TgAb IgG4 among three groups (P = 0.039 and 0.013), and GD patients had higher relative amounts of TgAb IgG2 (0.59(0.34, 0.94)) and TgAb IgG4 (0.57(0.28, 0.97)) than GH patients (TgAb IgG2, 0.31(0.23, 0.34); TgAb IgG4, 0.26(0.09, 0.48)) or patients with Hashimoto's thyrotoxicosis (TgAb IgG2, 0.32(0.24, 0.83); TgAb IgG4, 0.33(0.10, 0.65)) (for TgAb IgG2, P = 0.009 and 0.167; for TgAb IgG4, P = 0.005 and 0.041 respectively). No significant difference was found in the prevalence of each TPOAb IgG subclass. The difference of relative amount of TPOAb IgG2 among three groups was close to significance (P = 0.069). And the relative amount was higher in sera from GD patients (0.39 ± 0.04) than that in GH patients (0.29 ± 0.13) or patients with Hashimoto's thyrotoxicosis (0.26 ± 0.02) (P = 0.104 and 0.002 respectively).

CONCLUSION

The patients with high levels of TgAb IgG2, TgAb IgG4 and TPOAb IgG2 subclasses have a greater risk of GD. The IgG subclass distribution of TgAb and TPOAb might help to differentiate the causes of thyrotoxicosis in autoimmune thyroid diseases.

An unusual case of hypopituitarism and transient thyrotoxicosis following asymptomatic pituitary apoplexy

Although pituitary function is often impaired in pituitary apoplexy, the development of thyrotoxicosis is rare. We describe an unusual case of hypopituitarism due to pituitary apoplexy coexisting with transient hyperthyroidism. A 74-year-old woman presented with severe fatigue, palpitation, appetite loss, hypotension, and hyponatremia. Endocrine studies showed hyperthyroidism and anterior pituitary hormone deficiencies. A magnetic resonance imaging suggested recent-onset pituitary apoplexy in a pituitary tumor, although the patient had no apoplectic symptoms such as headache and visual disturbance. Thyrotoxicosis and adrenal insufficiency worsened her general condition. Glucocorticoid supplementation improved her clinical symptoms and hyponatremia. Serum anti-thyrotropin receptor and thyroid-stimulating antibody titers were negative, and her thyroid function was spontaneously normalized without antithyroid medication, suggesting painless thyroiditis. Thereafter, her thyroid function decreased because of central hypothyroidism and 75 µg of levothyroxine was needed to maintain thyroid function at the euthyroid stage. The pituitary mass was surgically removed and an old hematoma was detected in the specimen. Considering that painless thyroiditis develops as a result of an autoimmune process, an immune rebound mechanism due to adrenal insufficiency probably caused painless thyroiditis. Although the most common type of thyroid disorder in pituitary apoplexy is central hypothyroidism, thyrotoxicosis caused by painless thyroiditis should be considered even if the patient has pituitary deficiencies. Because thyrotoxicosis with adrenal insufficiency poses a high risk for a life-threatening adrenal crisis, prompt diagnosis and treatment are critical.

Determinants of serum T4 and T3 at the time of diagnosis in nosological types of thyrotoxicosis: a population-based study

OBJECTIVE

To characterize thyroid hormone levels at the time of diagnosis in the nosological types of thyrotoxicosis diagnosed in the population and to analyze determinants for serum thyroxine (T4) and tri-iodothyronine (T3).

DESIGN

Population-based study of thyrotoxicosis at disease onset.

METHODS

In the period 1997-2000, we prospectively identified all patients diagnosed with incident primary overt thyrotoxicosis in a Danish population cohort and classified patients into ten well-defined nosological types of disease (n=1082). Untreated levels of serum T3, T4, and T3:T4 ratio were compared and related to sex, age, level of iodine deficiency, smoking status, alcohol intake, iodine supplement use, co-morbidity, and TSH receptor antibodies (TRAbs) in multivariate models.

RESULTS

Graves' disease (GD) patients had much higher levels of T3 and higher T3:T4 ratio at diagnosis compared with other thyrotoxic patients, but with a profound negative association between hormone levels and age. In GD, patients diagnosed in the area with more severe iodine deficiency had lower levels of T3 and T4. TRAb-negative GD patients had biochemically mild thyrotoxicosis. Higher age was also associated with lower degree of biochemical thyrotoxicosis in nodular toxic goiter. We found no association between serum T3 and T4 and sex, smoking habits, iodine supplements, alcohol intake, or co-morbidity in any type of thyrotoxicosis.

CONCLUSIONS

The study gives new insight into the hormonal presentation of thyrotoxicosis and showed that young age, positive TRAb levels, but also residency in the area with higher iodine intake was positively associated with biochemical disruption in GD.

Thyroid profiles in a patient with resistance to thyroid hormone and episodes of thyrotoxicosis, including repeated painless thyroiditis

BACKGROUND

Thyrotoxic disease can be difficult to recognize in patients with resistance to thyroid hormone (RTH) because the clinical symptoms of thyrotoxicosis cannot be observed, and thyrotropin (TSH) may not be suppressed because of hormone resistance. Painless thyroiditis is a relatively common cause of thyrotoxicosis, but its occurrence in RTH has not been reported. We assessed the thyroid profile in a patient with RTH and episodes of thyrotoxicosis who experienced repeated painless thyroiditis.

PATIENT FINDINGS

A 44-year-old Japanese woman with RTH, which was confirmed by the presence of a P453A mutation in the thyroid hormone receptor β (TRβ) gene, showed a slight elevation of the basal levels of thyroid hormones, which indicated that her pituitary RTH was mild. She experienced a slight exacerbation of hyperthyroxinemia concomitant with TSH suppression. A diagnosis of painless thyroiditis was made because of the absence of TSH receptor antibodies, low Tc-99m pertechnetate uptake by the thyroid gland, and transient suppression followed by a slight elevation of TSH following the elevation of thyroid hormones. The patient's complaints of general malaise and occasional palpitations did not change throughout the course of painless thyroiditis. Three years later, painless thyroiditis occurred again without any deterioration of the clinical manifestations.

CONCLUSIONS

Mild pituitary RTH can be overcome by slight exacerbation of hyperthyroxinemia during mild thyrotoxicosis. When pituitary resistance is severe and TSH is not suppressed, thyrotoxicosis may be overlooked.

Lithium toxicity precipitated by thyrotoxicosis due to silent thyroiditis: cardiac arrest, quadriplegia, and coma

BACKGROUND

Lithium is widely used to treat bipolar disorders. Lithium toxicity is generally caused by inappropriately high doses of lithium or impaired lithium excretion. Most lithium is eliminated via the kidneys and, since thyroid hormone increases tubular reabsorption of lithium, thyrotoxicosis could contribute to the development of lithium toxicity. We report a case of severe lithium toxicity that was apparently precipitated by the onset of thyrotoxicosis resulting from silent thyroiditis and dehydration.

PATIENT FINDINGS

The patient was a 64-year-old woman who was admitted for muscle weakness in the lower extremities, diarrhea, and palpitations. She had bipolar disorder and was being treated with lithium carbonate, which she discontinued one week before admission. Her circulating lithium levels had been monitored yearly. Early in her admission she was dehydrated and had febrile episodes, paroxysmal atrial fibrillation, and muscle weakness. Initially, fluid therapy was started, but she lost consciousness and had a cardiac arrest for 2 minutes due to prolonged sinus arrest. Chest compression and manual artificial ventilation were performed, and body surface pacing was started. Serum lithium was markedly elevated to 3.81 mEq/L (therapeutic range, 0.4-1.0 mEq/L), and thyroid hormone levels were increased (free triiodothyronine, 8.12 pg/mL; free thyroxine, 4.45 ng/dL), while thyrotropin (TSH) was suppressed (<0.01 μIU/mL). Hemodialysis was performed, and a temporary pacemaker was inserted for severe sinus bradycardia. The serum thyroglobulin was 4680 ng/mL (reference range, <32.7 ng/mL). A TSH receptor antibody test was negative. Glucocorticoid therapy and inorganic iodine (100 mg) were administered and continued until day 11. However, her neurological symptoms deteriorated with floppy quadriplegia and deep coma. She gradually recovered. On day 36, she was discharged without any neurological symptoms or thyrotoxicosis.

SUMMARY

A 64-year-old woman taking lithium for bipolar disorder developed lithium toxicity in the setting of what seemed likely to be a recent onset of thyrotoxicosis due to silent thyroiditis.

CONCLUSIONS

Thyrotoxicosis may be a contributing cause of lithium toxicity, particularly if it is abrupt in onset and even with cessation of lithium therapy if renal function is compromised. Thyroid function should be assessed immediately in patients with suspected lithium toxicity.