A Case Report on Aplasia Cutis Congenita: Insights Into the Impact of Maternal Carbimazole Use.

Congenital aplasia cutis (CAC) is a rare neonatal condition characterized by the absence of skin at birth, often associated with diverse underlying conditions. We report the case of a newborn male admitted on the second day of life with a skin defect on the anterior abdominal wall and a lesion on the left thigh. The mother was treated with carbimazole for hyperthyroidism. Notably, there were no similar cases in the family history. The patient showed favorable progress and normal development following a successful dermo-epidermal allograft. Particular attention was given to managing the risk of infection and ensuring optimal healing through tailored wound care protocols. This case underscores the complexity of CAC, highlighting the importance of early diagnosis, multidisciplinary care, and ongoing research to understand better and effectively treat this rare condition.

Data-Driven Strategies for Carbimazole Titration: Exploring Machine Learning Solutions in Hyperthyroidism Control.

BACKGROUND: University Hospitals Dorset (UHD) has over 1,000 thyroid patient contacts annually. These are primarily patients with autoimmune hyperthyroidism treated with Carbimazole titration. Dose adjustments are made by a healthcare professional (HCP) based on the results of thyroid function tests, who then prescribes a dose and communicates this to the patient via letter. This is time-consuming and introduces treatment delays. This study aimed to replace some time-intensive manual dose adjustments with a machine learning model to determine Carbimazole dosing. This can in the future serve patients with rapid and safe dose determination and ease the pressures on HCPs. METHODS: Data from 421 hyperthyroidism patients at UHD were extracted and anonymised. A total of 353 patients (83.85%) were included in the study. Different machine-learning classification algorithms were tested under several data processing regimes. Using an iterative approach, consisting of an initial model selection followed by a feature selection method the performance was improved. Models were evaluated using weighted F1 scores and Brier scores to select the best model with the highest confidence. RESULTS: The best performance is achieved using a random forest (RF) approach, resulting in good average F1 scores of 0.731. A model was selected based on a balanced assessment considering the accuracy of the prediction (F1 = 0.751) and the confidence of the model (Brier score = 0.38). CONCLUSION: To simulate a use-case, the accumulation of the prediction error over time was assessed. It was determined that an improvement in accuracy is expected if this model was to be deployed in practice.

The Comparison of Catalytic Activity of Carbimazole and Methimazole on Electroreduction of Zinc (II) in Chlorates (VII): Experimental and Molecular Modelling Study.

With the help of electrochemical methods, including CV and EIS, the influence of methimazole, carbimazole, and the concentration of the supporting electrolyte on the kinetics and mechanism of zinc electroreduction on a mercury electrode was compared and analyzed. Moreover, molecular dynamics simulations of zinc/carbimazole and zinc/methimazole solutions were carried out to determine the effect of drugs on the hydration sphere of Zn2+ ions. It was shown that the electroreduction of Zn2+ in the presence of methimazole and carbimazole occurs in two steps and the first one determines the kinetics of the entire process. The presence of both drugs in the solution and the increase in the concentration of the supporting electrolyte reduce the degree of hydration of the depolarizer ions and the hydration of the electrode surface, what is a factor favoring the rate of electroreduction. Based on theoretical studies, the formation of stable complexes between Zn2+ and the molecules of both drugs in a solution was considered unlikely. However, active complexes can be formed between depolarizer ions and molecules adsorbed at the electrode surface. They constitute a bridge facilitating charge exchange during the electrode reaction, revealing the catalytic abilities of methimazole and carbimazole. In the range of cdrug ≤ 1 × 10-3 mol dm-3, carbimazole is a better catalyst, whereas in the range of cdrug ≥ 5 × 10-3 mol dm-3, it is methimazole. The effectiveness of both compounds in catalyzing the first stage of the electrode reaction increases with the increase in the NaClO4 concentration.

Co-administration of xylo-oligosaccharides produced by immobilized Aspergillus terreus xylanase with carbimazole to mitigate its adverse effects on the adrenal gland.

Carbimazole has disadvantages on different body organs, especially the thyroid gland and, rarely, the adrenal glands. Most studies have not suggested any solution or medication for ameliorating the noxious effects of drugs on the glands. Our study focused on the production of xylooligosaccharide (XOS), which, when coadministered with carbimazole, relieves the toxic effects of the drug on the adrenal glands. In addition to accelerating the regeneration of adrenal gland cells, XOS significantly decreases the oxidative stress caused by obesity. This XOS produced by Aspergillus terreus xylanase was covalently immobilized using microbial Scleroglucan gel beads, which improved the immobilization yield, efficiency, and operational stability. Over a wide pH range (6-7.5), the covalent immobilization of xylanase on scleroglucan increased xylanase activity compared to that of its free form. Additionally, the reaction temperature was increased to 65 °C. However, the immobilized enzyme demonstrated superior thermal stability, sustaining 80.22% of its original activity at 60 °C for 120 min. Additionally, the full activity of the immobilized enzyme was sustained after 12 consecutive cycles, and the activity reached 78.33% after 18 cycles. After 41 days of storage at 4 °C, the immobilized enzyme was still active at approximately 98%. The immobilized enzyme has the capability to produce xylo-oligosaccharides (XOSs). Subsequently, these XOSs can be coadministered alongside carbimazole to mitigate the adverse effects of the drug on the adrenal glands. In addition to accelerating the regeneration of adrenal gland cells, XOS significantly decreases the oxidative stress caused by obesity.

Locally injected bone marrow-derived mesenchymal stem cells reverts the histopathological changes in the tongue of carbimazole-induced hypothyroidism of male rats.

OBJECTIVE: To decipher the role of locally injected bone marrow mesenchymal stem cells (BM-MSCs) in the tongue of hypothyroid rats. DESIGN: A total 24 male Wister rats were utilized and allocated into 3 groups (n = 8). As for the control group, rats received distilled water via oral gavage. In the hypothyroid group, rats administered carbimazole 5 mg/ 250 g/ day for 6 successive weeks, for hypothyroidism induction. The BM-MSC treated hypothyroid group (BM-MSC group); hypothyroid rats received local injection of 0.5 million BM-MSCs in tongue. Six weeks after BM-MSC injection, tongue samples were processed for Hematoxylin and eosin (H and E) staining, Ki67-immunohistochemistry and histomorphometric analysis. RESULTS: The hypothyroid group revealed degenerative alterations in the lingual papillae, and apparent thinning of the inferior lingual epithelium compared to their controls. Tongues of the BM-MSC group depicted restoration of the normal tongue histology. The Ki67 immunoreaction was apparently decreased in the lingual epithelium of hypothyroid group compared to their controls, however the BM-MSC group regained Ki67 immunostaining. CONCLUSION: Our data suggest that administration of BM-MSCs rescued the degenerative changes in the lingual mucosa and one of the possible underlying mechanisms could be the restoration of cellular proliferation in the lingual epithelium.

Antioxidant effects of α-lipoic acid against epididymal oxidative damage in adult offspring rats exposed to maternal hypothyroidism stress.

It is well known that the epididymis promotes post-testicular sperm maturation events. However, its malfunction during congenital hypothyroidism is relatively less understood as compared to the testis. The present study evaluated the probable effect of α-lipoic acid on epididymal oxidative stress parameters in rats exposed to antithyroid drug, carbimazole during fetal period. Time-mated pregnant rats in unexposed and carbimazole (1.35 mg/Kg body weight exposed were allowed to deliver pups and weaned. At postnatal day 100, the F1 male pups were assessed for epididymal endpoints. Among the epididymal regions, significant elevation of lipid peroxidation levels, superoxide anion, and hydrogen peroxide contents with a concomitant reduction in the activity levels of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and reduced glutathione levels were observed in cauda epididymis of carbimazole exposed rats over controls. Significant elevation in sperm DNA fragmentation (comet assay), accelerated cauda epididymal sperm transit time and reduction in epididymal sialic acid content was observed in carbimazole exposed rats. RT-qPCR studies revealed that embryonic exposure to carbimazole resulted in down regulation of androgen receptor, nuclear factor eryrthoid 2 like 2, 5α-reducatse 1 mRNA levels, while up regulation of caspase 3 mRNA was observed in epididymal regions of rats. In addition, fetal exposure to carbimazole resulted in disorganization of cauda epididymal architecture in rats. Conversely, supplementation of α-lipoic acid (70 mg/Kg bodyweight) during PND 3 to 14 restored epididymal functions in carbimazole exposed rats and the ameliorative effects of lipoic acid could be attributed to its antioxidant and steroidogenic effects.

Carbimazole-associated Pancreatitis: Report From Western India.

Pancreatitis is a very rare complication of methimazole and carbimazole therapy. We describe a case of possible carbimazole-associated pancreatitis. A 41-year-old Asian man (with no comorbidities) reported to the hospital with atrial fibrillation and a fast ventricular rate. He was diagnosed with hyperthyroidism due to Graves disease. His rhythm was reverted with amiodarone, and carbimazole was initiated at 15 mg daily for the medical management of Graves disease. Fifteen days later, he presented with acute severe abdominal pain and vomiting with elevated serum amylase 387 U/L (reference range, 28-100 U/L) and lipase levels 206 U/L (reference range, 13-60 U/L). Magnetic resonance imaging showed a bulky pancreas with extensive extrapancreatic fat stranding suggestive of acute pancreatitis. Considering the possibility of carbimazole-related pancreatitis, the drug was withheld. He was managed conservatively, and his pancreatic enzymes normalized within 1 week. The observation suggests that the pancreatitis was a consequence of the therapy with carbimazole. Although it is a rare occurrence, patients taking carbimazole who report abdominal discomfort and vomiting should be evaluated for pancreatitis.

Carbimazole-Resistant Grave's Thyrotoxicosis is a Diagnostic and Therapeutic Dilemma, Case Report with Literature Review.

Background: Carbimazole (CBZ) (or methimazole) is the most used drug inducing and maintaining remission in thyrotoxicosis, especially Grave's disease (GD). Rarely, situations arise when patients do not respond to recommended or even supratherapeutic doses of CBZ. It poses a challenge to diagnose drug resistance and ultimately manage hyperthyroidism, which can otherwise be fatal if left untreated. Propylthiouracil (PTU) has been used as an alternative in such patients amid increased side effect risks. Additionally, definitive therapy has been recommended with ablation or surgery. However, the best modality of inducing euthyroidism in drug-resistant patients is yet to be established. On literature search, twenty similar cases were found in the literature search. This study summarizes the past literature with addition of a new case of anti-thyroid drug resistant (ATDR) GD. Case Presentation: A 34-year-old female presented with a 5-day history of progressively worsening fatigue, heat intolerance, sweating, and palpitations. She was diagnosed with GD based on her thyroid function tests (TFTs) and started on CBZ and propranolol. Despite being compliant with CBZ 20 mg once daily and then twice daily, her TFTs remained unchanged for 4 months. However, patient revisited the emergency with continued thyrotoxicosis and unchanged TFTs. Her dose was eventually increased to 20 mg thrice daily, and administration under supervision did not improve her TFTs. The patient was shifted to PTU 150 mg thrice daily with steroids, with minimal improvement. The patient eventually underwent thyroidectomy to avoid long-term PTU use. Conclusion: ATDR GD is rare and remains a diagnostic and therapeutic challenge. Optimal management should focus on carefully excluding other possibilities and shared decision-making in its management. Most patients may require definitive therapy; hence, arrangements should be made timely with simultaneous attempts to reduce the thyrotoxic state, which otherwise poses a continued threat to patients' life with potentially serious complications.

Unilateral Graves' Disease in a Bilobar Thyroid Gland: A Very Unusual Cause of Hyperthyroidism.

Graves' disease (GD) is an autoimmune condition that affects both thyroid gland lobes. Patients with GD with unilateral thyroid scan uptake are rare. These patients present with classic Graves' symptoms, occasionally with Graves' ophthalmopathy characteristics and increased thyroid hormones, and scintigraphic assessment reveals radiotracer uptake in only 1 lobe of the thyroid gland. In this case, a 48-year-old female presented with symptoms and signs indicative of thyrotoxicosis. Laboratory results revealed that TSH was undetectable, whereas free thyroxine and free triiodothyronine were in the high-normal range. Positive results were observed for both thyroid-stimulating Ig and TSH receptor antibodies. Ultrasonography of the thyroid gland revealed an enlarged left lobe with heterogeneous echotexture and a hyperemic gland without any focal lesions, distinct nodules, or cysts. Thyroid scintigraphy revealed enlarged and increased radioisotope uptake in the left lobe and decreased uptake in the right lobe, with no hot or cold nodules. The most likely diagnosis was unilateral GD. The patient was administered carbimazole and within 8 weeks had improved clinically and biochemically.

A Case of Aplasia Cutis Congenita in the Setting of Maternal Carbimazole Use in the First Trimester.

Aplasia cutis congenita (ACC) is one of several congenital malformations associated with antithyroid/thiourylene drug use in pregnancy. While uncommon among the general population (1-3/100 000 cases), the risk among those on thiourylenes is between 1.6% and 3%. The scalp is the most common site for this congenital anomaly. We present the case of a male infant with multifocal ACC of the scalp discovered at birth and born to a mother with Graves disease that was controlled during pregnancy using carbimazole. Thyroid function tests were normal throughout the pregnancy. There was no involvement of underlying subcutaneous tissue or structures. At age 18 months, the single largest lesion remained with only partial coverage. Prospective management involved periodic surveillance with planned 2-stage repair. This case reinforces the association between the antithyroid drugs carbimazole (CMZ) and methimazole (MMI) and supports the proposition of an MMI/CMZ embryopathy. It adds to a literature of case reports in which malformations arise in offspring of such mothers whose thyrotoxicosis is controlled antenatally, thereby challenging the suggestion that ACC is attributable to poorly controlled disease rather than thiourylenes. As yet the underlying mechanism is not understood, nor is it known why MMI and CMZ may cause potentially significant embryopathy while congenital defects attributable to the structurally similar propylthiouracil are typically less severe.

Therapeutic Management and Long-Term Outcome of Hyperthyroidism in Patients with Antithyroid-Induced Agranulocytosis: A Retrospective, Multicenter Study.

BACKGROUND: Antithyroid drug-induced agranulocytosis (AIA) (neutrophils <500/µL) is a rare but serious complication in the treatment of hyperthyroidism. METHODOLOGY: Adult patients with AIA who were followed up at 12 hospitals in Spain were retrospectively studied. A total of 29 patients were studied. The etiology of hyperthyroidism was distributed as follows: Graves' disease (n = 21), amiodarone-induced thyrotoxicosis (n = 7), and hyperfunctioning multinodular goiter (n = 1). Twenty-one patients were treated with methimazole, as well as six patients with carbimazole and two patients with propylthiouracil. RESULTS: The median (IQR) time to development of agranulocytosis was 6.0 (4.0-11.5) weeks. The most common presenting sign was fever accompanied by odynophagia. All of the patients required admission, reverse isolation, and broad-spectrum antibiotics; moreover, G-CSF was administered to 26 patients (89.7%). Twenty-one patients received definitive treatment, thirteen patients received surgery, nine patients received radioiodine, and one of the patients required both treatments. Spontaneous normalization of thyroid hormone values occurred in six patients (four patients with amiodarone-induced thyrotoxicosis and two patients with Graves' disease), and two patients died of septic shock secondary to AIA. CONCLUSIONS: AIA is a potentially lethal complication that usually appears around 6 weeks after the initiation of antithyroid therapy. Multiple drugs are required to control hyperthyroidism before definitive treatment; additionally, in a significant percentage of patients (mainly in those treated with amiodarone), hyperthyroidism resolved spontaneously.

Carbimazole-induced atypia - A mimicker of malignancy in fine-needle aspiration cytology.

A 20-year-old female presented with complaints of thyroid swelling and showed signs and symptoms of thyrotoxicosis and fine-needle aspiration cytology (FNAC) was requested by the surgeon. On examination of FNAC smear, it showed thyroid follicular cells with atypical features like bizarre giant cells, pseudo nuclear inclusions, and mitotic figure. Correlation between clinical history and cytomorphologic features was done and it was reported as atypical changes in thyroid probably due to carbimazole-induced changes. It helped the patient, as radical surgery and its untoward complications were avoided.

Safety of Antithyroid Drugs in Avoiding Hyperglycemia or Hypoglycemia in Patients With Graves' Disease and Type 2 Diabetes Mellitus: A Literature Review.

Graves' disease (GD) may increase the difficulty of glucose control in patients with type 2 diabetes mellitus (T2DM). Therefore, selecting a drug with limited blood glucose side effects is an important issue in patients with T2DM and GD. Antithyroid drugs (ATDs) including propylthiouracil (PTU), methimazole, and carbimazole are commonly prescribed for the treatment of GD. Here, we review and summarize the literature from the last 10 years and discuss the effects of current ATDs used for GD for blood glucose control in patients with T2DM. A search of the literature published between January 1, 2012 and December 1, 2022 was conducted using three major medical databases: Google Scholar, Ovid Medline, and Scopus. An initial search was conducted on PubMed using the MeSH terms "propylthiouracil," "methimazole," "carbimazole," and "hyperglycemia" or "hypoglycemia" in academic databases. All articles included "Graves' disease" and "type 2 diabetes mellitus" in the title. Based on the results of previous studies, the hyperglycemic and hypoglycemic side effects of ATDs can be explained by several possible mechanisms. The most widely accepted hypothesis is that sulfhydryl group drugs (e.g., methimazole and carbimazole) cleave the disulfide bond of insulin and enhance its immunogenicity, resulting in hypoglycemia. Moreover, some reports have indicated that methimazole is associated with hypoglycemia; therefore, if the patient has a history of autoimmune diseases, it is necessary to consider whether to change drugs or actively track the production of autoimmune antibodies. In non-diabetic and diabetic patients with GD, the hyperglycemic and hypoglycemic side effects of PTU (on glycemic variation) were less than that of thiamazole. However, as relatively few reports have investigated the side effects of blood sugar changes, further research is necessary to confirm these effects. In addition to autoimmune diseases, drug side effects may need to be considered. These findings provide considerations for clinicians to select more appropriate ATDs for patients with GD and T2DM, and implement improved care guidelines.

Development of a Sensitive SERS Method for Label-Free Detection of Hexavalent Chromium in Tea Using Carbimazole Redox Reaction.

Tea plants absorb chromium-contaminated soil and water and accumulate in tea leaves. Hexavalent chromium (Cr6+) is a very toxic heavy metal; excessive intake of tea containing Cr6+ can cause serious harm to human health. A reliable and sensitive surface-enhanced Raman spectroscopy (SERS) method was developed using Au@Ag nanoparticles as an enhanced substrate for the determination of Cr6+ in tea. The Au@AgNPs coated with carbimazole showed a highly selective reaction to Cr6+ in tea samples through a redox reaction between Cr6+ and carbimazole. The Cr6+ in the contaminated tea sample reacted with methimazole-the hydrolysate of carbimazole-to form disulfide, which led to the decrease in the Raman intensity of the peak at 595 cm-1. The logarithm of the concentration of Cr6+ has a linear relationship with the Raman intensity at the characteristic peak and showed a limit of detection of 0.945 mg/kg for the tea sample. The carbimazole functionalized Au@AgNPs showed high selectivity in analyzing Cr6+ in tea samples, even in the presence of other metal ions. The SERS detection technique established in this study also showed comparable results with the standard ICP-MS method, indicating the applicability of the established technique in practical applications.

Thyroid Storm Masquerading as Multiple Organ Dysfunction Syndrome: Catch Me if You Can.

A 65-year-old man presented to the emergency medicine department with altered sensorium, a high-grade fever, and shock. On routine workup, he was diagnosed with acute respiratory distress syndrome with sepsis. Later, it was found that the patient had undetectable serum thyroid stimulating hormone and high triiodothyronine (T3) levels, which were diagnosed as a thyroid storm. This highlights the fact that a thyroid storm can present in any way and should be considered when determining the cause of septic shock that is not responding to standard treatment. A rare endocrine emergency, thyroid storm is a life-threatening endocrinological emergency with a considerable death rate of between 10% and 30% and multi-organ failure. It happens in thyrotoxic patients and manifests as the decompensation of several organs brought on by extreme stress. In addition to shock, the patient also had altered sensory perception, a cough, a fever, palpitations, and a sore throat. The patient was initially diagnosed with septic shock and was later treated with oral carbimazole, higher antibiotics, inotropes, and propranolol.

Graves' Disease in Children: An Update.

Graves' disease (GD) is the most common cause of hyperthyroidism in children. A common GD symptom is a goiter. The usual biochemical profile in children with GD is a decreased thyroid hormone stimulating hormone (TSH) level and high free thyroxine (FT4) and free triiodothyronine (FT3) concentrations. The presence of thyroid receptor antibodies (TRAb) is the most important specific immunological sign for diagnosing GD. The treatment choices for pediatric GD are anti-thyroid drugs (ATDs), radioiodine, and thyroidectomy, but the risks and benefits of each modality are different. Management recommendations include the first-line use of a prolonged course of ATDs for at least 3 years and potentially 5 years or more. Rituximab and Teprotumumab are new novel alternative medications for the treatment of adult patients with GD and Graves' orbitopathy respectively, but evidence of the efficacy and safety of these drugs in pediatric patients with GD is lacking.

Clinically practical pharmacometrics computer model to evaluate and personalize pharmacotherapy in pediatric rare diseases: application to Graves' disease.

Objectives: Graves' disease (GD) with onset in childhood or adolescence is a rare disease (ORPHA:525731). Current pharmacotherapeutic approaches use antithyroid drugs, such as carbimazole, as monotherapy or in combination with thyroxine hormone substitutes, such as levothyroxine, as block-and-replace therapy to normalize thyroid function and improve patients' quality of life. However, in the context of fluctuating disease activity, especially during puberty, a considerable proportion of pediatric patients with GD is suffering from thyroid hormone concentrations outside the therapeutic reference ranges. Our main goal was to develop a clinically practical pharmacometrics computer model that characterizes and predicts individual disease activity in children with various severity of GD under pharmacotherapy. Methods: Retrospectively collected clinical data from children and adolescents with GD under up to two years of treatment at four different pediatric hospitals in Switzerland were analyzed. Development of the pharmacometrics computer model is based on the non-linear mixed effects approach accounting for inter-individual variability and incorporating individual patient characteristics. Disease severity groups were defined based on free thyroxine (FT4) measurements at diagnosis. Results: Data from 44 children with GD (75% female, median age 11 years, 62% receiving monotherapy) were analyzed. FT4 measurements were collected in 13, 15, and 16 pediatric patients with mild, moderate, or severe GD, with a median FT4 at diagnosis of 59.9 pmol/l (IQR 48.4, 76.8), and a total of 494 FT4 measurements during a median follow-up of 1.89 years (IQR 1.69, 1.97). We observed no notable difference between severity groups in terms of patient characteristics, daily carbimazole starting doses, and patient years. The final pharmacometrics computer model was developed based on FT4 measurements and on carbimazole or on carbimazole and levothyroxine doses involving two clinically relevant covariate effects: age at diagnosis and disease severity. Discussion: We present a tailored pharmacometrics computer model that is able to describe individual FT4 dynamics under both, carbimazole monotherapy and carbimazole/levothyroxine block-and-replace therapy accounting for inter-individual disease progression and treatment response in children and adolescents with GD. Such clinically practical and predictive computer model has the potential to facilitate and enhance personalized pharmacotherapy in pediatric GD, reducing over- and underdosing and avoiding negative short- and long-term consequences. Prospective randomized validation trials are warranted to further validate and fine-tune computer-supported personalized dosing in pediatric GD and other rare pediatric diseases.

Preconception Management of Hyperthyroidism and Thyroid Status in Subsequent Pregnancy: A Population-Based Cohort Study.

CONTEXT: Optimal thyroid status in pregnancy is essential in reducing the risk of adverse outcomes. The management of hyperthyroidism in women of reproductive age poses unique challenges and it is unclear how preconception treatment strategies impact on thyroid status in subsequent pregnancy. OBJECTIVE: We aimed to determine trends in the management of hyperthyroidism before and during pregnancy and to assess the impact of different preconception treatment strategies on maternal thyroid status. METHODS: We utilized the Clinical Practice Research Datalink database to evaluate all females aged 15-45 years with a clinical diagnosis of hyperthyroidism and a subsequent pregnancy (January 2000 to December 2017). We compared thyroid status in pregnancy according to preconception treatment, namely, (1) antithyroid drugs up to or beyond pregnancy onset, (2) definitive treatment with thyroidectomy or radioiodine before pregnancy, and (3) no treatment at pregnancy onset. RESULTS: Our study cohort comprised 4712 pregnancies. Thyrotropin (TSH) was measured in only 53.1% of pregnancies, of which 28.1% showed suboptimal thyroid status (TSH >4.0 mU/L or TSH <0.1 mU/L plus FT4 >reference range). Pregnancies with prior definitive treatment were more likely to have suboptimal thyroid status compared with pregnancies starting during antithyroid drug treatment (odds ratio 4.72, 95% CI 3.50-6.36). A steady decline in the use of definitive treatment before pregnancy was observed from 2000 to 2017. One-third (32.6%) of first trimester carbimazole-exposed pregnancies were switched to propylthiouracil while 6.0% of propylthiouracil-exposed pregnancies switched to carbimazole. CONCLUSION: The management of women with hyperthyroidism who become pregnant is suboptimal, particularly in those with preconception definitive treatment, and needs urgent improvement. Better thyroid monitoring and prenatal counseling are needed to optimize thyroid status, reduce teratogenic drug exposure, and ultimately reduce the risk of adverse pregnancy outcomes.