Hypothyroidism Due to Seaweed Overconsumption.

Hypothyroidism presents various symptoms, ranging from commonly observed signs, such as fatigue, cold sensation, and constipation, to rare features, such as rash and pancytopenia, resembling certain rheumatological and hematological diseases. Chronic, excessive iodine consumption causes primary hypothyroidism. However, when iodine overconsumption becomes a regular part of daily dietary habits, it becomes difficult for patients to associate their symptoms with daily iodine consumption. Therefore, clinicians cannot obtain information on excessive iodine intake from the patient. Here, we present a case of hypothyroidism that was subsequently identified as caused by excessive dairy seaweed consumption for health purposes. This case report highlights the importance of a detailed dietary history in patients diagnosed with primary hypothyroidism without thyroid autoantibodies.

Dilated cardiomyopathy due to hypocalcaemia: a case report.

BACKGROUND: Hypocalcaemia is a rare, but reversible, cause of dilated cardiomyopathy causing heart failure. Several case reports have been reported on reversible cardiomyopathy secondary to hypocalcaemia. CASE PRESENTATION: We report a case of 54-year-old female Sri Lankan patient who presented with shortness of breath and was diagnosed with heart failure with reduced ejection fraction due to dilated cardiomyopathy. The etiology for dilated cardiomyopathy was identified as hypocalcemic cardiomyopathy, secondary to primary hypoparathyroidism, which was successfully treated with calcium and vitamin D replacement therapy. CONCLUSION: This adds to literature of this rare cause of reversible cardiomyopathy secondary to hypocalcemia reported from the South Asian region of the world. This case highlights the impact of proper treatment improving the heart failure in patients with hypocalcemic cardiomyopathy.

Severe primary hypothyroidism and ovarian hyperstimulation syndrome in a spontaneous pregnancy: a case report.

Background: Ovarian hyperstimulation syndrome (OHSS) is a rare ovulation induction therapy side effect. Nevertheless, it can occur in spontaneous ovulation cycles linked to multiple gestation, molar pregnancy, polycystic ovarian syndrome, and hypothyroidism. The pathogenesis of OHSS remains poorly understood. However, in recent studies, it has been observed that increased concentrations of thyroid-stimulating hormone (TSH) can potentially have stimulatory effects on the ovaries due to the homologous structure shared between TSH and gonadotropins. It is recommended to delay pregnancies until euthyroidism is achieved with replacement therapy to reduce potentially fatal problems. Case Description: We describe the case of a 22-year-old female patient who sought medical attention due to a 4-week history of abdominal discomfort and amenorrhea. Upon evaluation, it was determined that she was in the 9th week of pregnancy and experiencing OHSS due to severe primary hypothyroidism. The diagnosis was confirmed through laboratory and imaging data, enabling timely care and preventing complications arising from unwarranted surgical intervention. Administration of levothyroxine led to total regression of the ovarian cysts. Even so, the patient decided to terminate her pregnancy. Conclusions: This case illustrates the occurrence of OHSS in a woman with untreated hypothyroidism. Notably, this syndrome is relatively uncommon, and the patient's ability to conceive while having unviable thyroid hormone levels further adds to this case's exceptional nature.

Prevalence of Hypogonadism Symptoms Among Males With Hypothyroidism at a Tertiary Hospital: A Cross-Sectional Study.

Background  Hypogonadism is a condition in which the body's ability to produce sex hormones is reduced. Androgen deficiency and hypothyroidism are similar in many symptoms, and the coexistence of the two conditions is common. The aim of this study is to explore the prevalence of hypogonadism symptoms in male patients diagnosed with primary hypothyroidism. Methods  This cross-sectional study was conducted at  King Abdulaziz Medical City  in Riyadh,  Saudi Arabia, with a sample size of 120 adult male patients with primary hypothyroidism. Data collection primarily relied on one instrument, namely, the Androgen Deficiency in Aging Males (ADAM) questionnaire, which was translated into Arabic and validated by previous researchers. Results  A total of 120 adult males with hypothyroidism completed the ADAM questionnaire. Out of the 120 patients, 67.5% had a positive screen for hypogonadism. Among patients who had hypogonadism symptoms on the questionnaire, 81% had a BMI above 25, 69% were older than 40, and 65% were smokers. Conclusion  Hypogonadism symptoms are common in male patients with primary hypothyroidism. Among patients with primary hypothyroidism, increasing age and being overweight added to the likelihood of having hypogonadism symptoms.

DETERMINATION OF MANDIBULAR BONE CHANGES IN PATIENTS WITH PRIMARY HYPOTHYROIDISM TREATED WITH LEVOTHYROXINE SODIUM.

Background: This study aimed to assess fractal dimension (FD) and the radiomorphometric indexes on the digital panoramic radiography (DPR) of patient with primary hypothyroidism receiving levothyroxine sodium replacement therapy. Methods: A total of 115 subjects were included in this cross sectional retrospective study. According to the results of the thyroid function tests, the subjects were divided into two groups as primary hypothyroidism (levothyroxine sodium replacement therapy given), (n = 57) and the healthy control group (n = 58). The fractal dimension (FD), panoramic mandibular index (PMI), mandibular cortical width (MCW), gonial index (GI) and mandibular cortical index (MCI) values of all patients were calculated on DPRs. The statistical analysis of all data was performed with SPSS version 22. Results: The distributions of age and gender in the primary hypothroidism group were similar to control group (p = 0.19 and p = 0.62, respectively). The two groups did not differ statistically significantly in terms of FD, PMI, MCW, GI, and MCI. Conclusion: We determined that mandibular cortical and trabecular bone structure did not significantly differ between healthy individuals and patients receiving drug replacement theraphy due to hypothyroidism, but our results should be further supported with the investigation of clinical parameters.

Deiodinase Type 3 Polymorphism (rs1190716) Affects Therapeutic Response to Levothyroxine.

Objectives: Levothyroxine (LT4) is a commonly used treatment for hypothyroidism. Deiodinase enzymes control the metabolism and homeostasis of thyroid hormones (THs). Deiodinase type 3 gene (DIO3) encodes deiodinase type 3 enzyme (D3), and the genetic polymorphisms of this gene could affect the levels of THs and the response to LT4 treatment. This study aimed to investigate the single-nucleotide polymorphism (SNP), rs1190716; C > T, of DIO3 as a candidate genetic variant that might affect the clinical response to LT4 treatment. Materials and Methods: Two hundred Iraqi hypothyroid female patients aged 40 years were enrolled in this cross-sectional study. All of them were already on the LT4 treatment for at least 4 months. THs [thyroxin (T4), triiodothyronine (T3), reverse triiodothyronine (rT3), and diiodothyronine (T2)] were estimated. An allele-specific polymerase chain reaction technique was performed to detect the rs1190716; C > T SNP. Results: The genotypes distribution of rs1190716; C > T SNP was 10 (4.5%) for the wild type (CC), 50 (22.7%) for the heterozygous mutant type (TC), and 160 (72.7%) for the homozygous mutant type (TT). The patients were divided into three groups according to their genotypes. Significant differences were found in the T4, T3, and T2 levels among the patients (p=0.019, p=0.039, p=0.032, respectively). Conclusion: The rs1190716; C > T SNP could affect the activity of the D3 enzyme and the metabolic homeostasis of the THs; therefore rs1190716; C > T SNP could have an impact on the therapeutic response to LT4 in Iraqi female patients with primary hypothyroidism. Regarding DIO3 gene, this is a novel finding; hence, further studies are needed to confirm it.

Long-Term Follow-Up Over 16 Years for Pituitary Hyperplasia Due to Primary Hypothyroidism With Positive Thyroid Stimulation Blocking Antibody: A Case Report.

Primary hypothyroidism is a known risk factor for pituitary hyperplasia, which develops symptoms due to compression of the optic chiasma and increased intracranial pressure. As pituitary hyperplasia is known to improve after levothyroxine replacement therapy, there are no reports of a long clinical course of pituitary hyperplasia due to primary hypothyroidism. We describe a case of follow-up over 16 years for pathologically diagnosed pituitary hyperplasia due to primary hypothyroidism with positive thyroid stimulation blocking antibody. Repeated enlargement and shrinkage were confirmed, but observations also suggested that the pituitary gland did not always return to normal size.

Postpartum Thyroiditis Mimicking Central Hypothyroidism: The Perfect Thyming.

Hypothyroidism can be seen in postpartum women as a result of central or primary hypothyroidism. Postpartum thyroiditis is a primary hypothyroid condition in which there is likely autoimmune dysfunction leading to damage to the thyroid gland. Patients with postpartum thyroiditis often present with little to no symptoms, and the key to establishing this diagnosis is a comprehensive endocrine workup. We report the case of a 24-year-old postpartum female patient who was diagnosed with postpartum thyroiditis after initial evaluation demonstrated findings concerning central hypothyroidism.

Isolated adrenocorticotropic hormone deficiency following immune checkpoint inhibitors treatment often occurs in polyglandular endocrinopathies.

BACKGROUND: With the increasing application of immune checkpoint inhibitors (ICI) in cancer therapy, the occurrence of isolated adrenocorticotropic hormone deficiency (IAD), as an adverse effect, is also on the rise. Nevertheless, there are only a few studies regarding IAD induced by ICI. This study aimed at investigating the characteristics of IAD induced by ICI and its relationship with other endocrine adverse events. METHODS: A retrospective study was conducted in the Endocrinology Department from January 2019 to August 2022 to investigate characteristics of patients with IAD. Clinical features, laboratory findings and treatment information were collected. All patients underwent a follow-up of 3-6-month. RESULTS: 28 patients with IAD were enrolled. All patients received treatment with anti-PD-1/ PD-L1. The median occurrence time of IAD was 24 (18-39) weeks after initiation of ICI treatment. Over half of the patients (53.5%) had an additional endocrinopathy, including primary hypothyroidism and fulminant type 1 diabetes mellitus (FT1DM), while other types of endocrinopathies were not identified. The interval between the occurrences of two gland damages was between 4 and 21 weeks or simultaneous. Primary hypothyroidism (46.4%) was more prevalent than FT1DM (7.1%). Fatigue and nausea were common symptoms, with a frequent occurrence of hyponatremia. All patients continued on oral glucocorticoids during follow-up. CONCLUSIONS: IAD induced by ICI could manifest independently, or more frequently in combination with hypothyroidism or FT1DM. This damage could happen at any point of ICI treatment. Given that IAD can be life-threatening, it is critical to evaluate pituitary function dynamically in patients undergoing immunotherapy.

The Clinical Septet of Van Wyk-Grumbach Syndrome: A Case Series from a Tertiary Care Centre in Kalyana Karnataka, India.

Van Wyk-Grumbach syndrome is a rare, female juvenile hypothyroidism disorder that is characterized by precocious puberty with clinical, radiological and hormonal pathologies. We present a case series of three patients with this unusual condition who were evaluated and followed up over a 3-year period between January 2017 and June 2020. All three patients presented with short stature (<3rd centile), low weight (<3rd centile), absence of goitre, no axillary or pubic hair, delayed bone age by more than 2 years, elevated thyroid-stimulating hormone with low T3 and T4 (primary hypothyroidism), and raised follicle-stimulating hormone with pre-pubertal levels of luteinizing hormone. Abdominal ultrasonography showed bilateral multi-cystic ovaries in two patients and a right-sided bulky ovary in the third patient. One of the patients also had a pituitary 'macroadenoma'. All the patients were successfully managed with levothyroxine. We discuss the pathophysiological mechanisms with a brief literature review.

Resultados maternos y fetales en pacientes con preeclampsia severa e hipotiroidismo primario. Estudio de casos y controles / Maternal and perinatal outcomes in patients with severe preeclampsia and primary hypothyroidism. Case and control study

Introducción: El hipotiroidismo primario tiene efectos adversos maternos y fetales que en el escenario de la preeclampsia severa (PS) su impacto sobre el binomio puede ser mayor. Objetivo: Comparar los resultados maternos y fetales en pacientes con PS e hipotiroidismo primario. Material y métodos: Se trató de un estudio de casos y controles en 58 pacientes embarazadas con PS admitidas en la Unidad de Cuidados Intensivos de una Unidad de Alta Especialidad de la Ciudad de México atendidas de enero del año 2018 a diciembre del 2021. El grupo de casos se formó con 29 pacientes con hipotiroidismo primario pregestacional y el grupo de controles con 29 enfermas pareadas por la edad con función tiroidea pregestacional normal. Se compararon sus datos generales y los resultados maternos y fetales. Se utilizó estadística descriptiva, prueba chi cuadrada y la prueba «t» de Student con el programa SPSS versión 20. Fue significativo el valor p<0,05. Resultados: No se encontraron diferencias en la edad (p=0,8292), paridad (p=1), presión arterial sistólica (p=0,7229) y diastólica (p=0,5498), operación cesárea (p=0,812), hemorragia intraparto (p=0,3558), técnica anestésica (p=0,5786), complicaciones obstétricas, estancia en la Unidad de Cuidados Intensivos (p=0,6181) y mortalidad. No hubo diferencias en los productos: embarazo único (p=0,912), edad gestacional (p=0,8901), peso (p=0,3338), calificación de Apgar minuto uno y cinco, prematuridad (p=0,8701), cuidados intensivos (p=0.0623), mortalidad in útero (n=4 vs n=4) y mortalidad al nacimiento (n=2 vs n=0). Conclusiones: Los resultados maternos y fetales fueron similares. Los casos con descontrol tiroideo no mostraron efectos clínicos adversos.(AU)

Introduction: Primary hypothyroidism has adverse effects on maternal and fetal outcomes. In the scenario of severe preeclampsia (SP), the impact on the binomial may be greater. Objective: To compare maternal and fetal outcomes in patients with SP and primary hypothyroidism. Material and methods: This was a case-control study in 58 pregnant patients with SP admitted to the Intensive Care Unit of a High Specialty Unit in Mexico City attended from January 2018 to December 2021. The case group was formed with 29 patients with pre-pregnancy primary hypothyroidism and the control group with 29 age-matched patients with normal pre-pregnancy thyroid function. Their overall data and maternal and fetal outcomes were compared. Descriptive statistics, chi-square test, and Student's t-test with the SPSS version 20 programme were used. A p-value<0.05 was significant. Results: No differences were found in age (p=.8292), parity (p=1), systolic (p=.7229) and diastolic (p=.5498) blood pressure, caesarean section (p=.812), intrapartum haemorrhage (p=.812), p=.3558), anaesthetic technique (p=.5786), obstetric complications, Intensive Care Unit stay (p=.6181), and mortality. There were no differences in the products: singleton pregnancy (p=.912), gestational age (p=.8901), weight (p=.3338), Apgar score minute one and five, prematurity (p=.8701), intensive care (p=.0623), in utero mortality (n=4 vs n=4), and mortality at birth (n=2 vs n=0). Conclusions: Maternal and fetal outcomes were similar. The cases with uncontrolled thyroid did not show adverse clinical effects.(AU)

Associations between empirically derived dietary patterns and oxidative stress and inflammation in adults with primary hypothyroidism: a case-control study.

BACKGROUND: Primary hypothyroidism is a common endocrine disorder caused by impaired production of thyroid hormones. Recent studies have shown that dietary habits, oxidative stress, and inflammation may play roles in thyroid hypofunction. Thus, the present article aimed to determine the relationship between major dietary patterns and oxidative stress and inflammation in primary hypothyroid patients and healthy people in Iranian adults. METHODS: This matched case-control study was conducted on 200 participants (100 cases and 100 controls). The presence of primary hypothyroidism was determined by endocrinologists based on American Thyroid Association (ATA) criteria. Dietary intake was assessed using a validated 168-item, semi-quantitative food frequency questionnaire (FFQ). The principal component analysis (PCA) method was used to derive major dietary patterns. Statistical analysis was performed using logistic regression analysis, and the findings were reported using odds ratios (ORs) with 95% CIs. RESULTS: We identified 2 major dietary patterns (i.e., healthy and Western dietary patterns). After adjusting for confounding variables, participants in the highest tertile of the healthy eating pattern had lower odds of primary hypothyroidism. Also, there was a significant relationship between total antioxidant capacity (TAC) levels and thyroid hypofunction; however, no significant correlation was seen between the Western dietary pattern and malondialdehyde (MDA) and C-reactive protein (CRP) with hypothyroidism. CONCLUSIONS: There were statistically direct associations between healthy dietary patterns (loaded with vegetables, nuts and seeds, fruits, dried fruits, olives, garlic, black pepper, starchy vegetables, low-fat dairy, and legumes) and increased TAC levels with a decreased risk of thyroid hypofunction. However, Western dietary patterns and MDA and CRP levels did not associate with an underactive thyroid.

Observational study of diagnosis and management in adult primary hypothyroidism in southwest of Sweden.

OBJECTIVE: The objective was to explore the management of newly diagnosed hypothyroidism in adults regarding laboratory diagnostics and treatment in Region Halland (RH). In addition, to investigate whether current recommendations were followed regarding diagnostics. DESIGN: Retrospective observational study. SETTING: A population-based study utilizing healthcare registry data from all public primary health care (PHC) clinics in RH during 2014-2019. SUBJECTS: Newly diagnosed patients with hypothyroidism according to ICD-10, aged ≥18 years when diagnosed and living and receiving health care in RH. There were 2494 patients included in the study. MAIN OUTCOME MEASURES: Registrations of thyroid laboratory values, diagnostic codes, and drug treatment was collected. Demographic data were also recorded. Laboratory values were checked also after 12-24 months after initial diagnosis. The main outcome was the proportion with elevated TSH and TPO and how the TSH value had changed at the follow-up. RESULTS: There were 1431 (61%) patients who had elevated TSH at the onset of the disease and TPO was tested in 1133 (46%) of the patients. Elevated TPO was found in 566 (23%) of the patients. After one year, there were 1908 (76%) patients who obtained a prescription for levothyroxine. In 1127 (45%) patients, TSH had normalized within one year. CONCLUSION: There were 39% of the patients diagnosed with hypothyroidism despite normal or subclinical TSH. There was an underuse of TPO in diagnosis and this advocated that the criteria for diagnostics according to current guidelines be followed to avoid unnecessary treatment.

One third were diagnosed with hypothyroidism despite normal thyroid blood tests at onset.Thyroid peroxidase antibodies were used in less than half of the patients diagnosed for hypothyroidism at onset.Less than half of the patients had improved TSH level despite high medication ratio after one year.

Effect of morning versus night-time administration of proton pump inhibitor (pantoprazole) on thyroid function test in levothyroxine-treated primary hypothyroidism: a prospective cross-over study.

BACKGROUND: One of the common causes of suboptimal control of thyroid stimulating hormone (TSH) in levothyroxine-treated hypothyroidism is coadministration of proton pump inhibitors (PPIs). Morning administration of pantoprazole has been shown to suppress intragastric pH to a greater extent. We therefore aimed to determine the effect of pantoprazole at different time points of the day on thyroid function test (TFT) in levothyroxine-treated overt primary hypothyroidism. METHODS: In this single centre, hospital based, prospective, two arm cross-over study (AB, BA), participants were randomized into 2 groups based on morning (6:00 am - 7:00 am simultaneously with the scheduled levothyroxine tablet) (group M) and evening (30 min before dinner) intake of 40 mg pantoprazole tablet (group N). After the initial 6 weeks (period 1), a washout period of 1 week for pantoprazole was given, and then both the groups crossed over for another 6 weeks (period 2). Patients were instructed to continue the same brand of levothyroxine tablet at empty stomach 1-hour before breakfast. Serum TSH was measured at baseline, week 6, and week 13. RESULTS: Data from 30 patients, who completed the study with 100% compliance, were analysed. Mean TSH values of the study participants were significantly higher both at week 6 and week 13 compared to the baseline. Mean baseline serum TSH concentrations for groups M and N were 2.70 (± 1.36), and 2.20 (± 1.06) µlU/mL, respectively. Mean serum TSH concentrations at the end periods 1 and 2 for group M were 3.78 (± 4.29), and 3.76 (± 2.77) while the levels in group N were 3.30 (± 1.90), and 4.53 (± 4.590) µlU/mL, respectively. There was a significant rise in serum TSH concentration across periods 1 and 2 in both the groups (F2, 58 = 3.87, p = 0.03). Within group changes in TSH across periods 1 and 2 were not statistically significant. Similarly difference in TSH between the groups, either at 6 weeks or at 13 weeks, were also not statistically significant. CONCLUSIONS: Concomitant use of pantoprazole, even for 6 weeks, leads to significant elevation in serum TSH in levothyroxine-treated patients who are biochemically euthyroid, irrespective of timing of pantoprazole intake. Early morning and night-time administration of pantoprazole have similar effect on TFT in these patients.

Higher CSF/serum free-T4 ratio is associated with improvement of quality of life during treatment with L-thyroxine.

Up to 20% of individuals with primary hypothyroidism treated with L-thyroxine still suffer from severe symptoms. These are supposedly brain derived and involve both cognitive and emotional domains. Previously, no consistent relationship has been found between thyroid hormones (TH) or TSH levels in blood and quality of life (QoL). Recently, we reported an association between cerebrospinal fluid (CSF)/serum free-thyroxine (f-T4) ratio and QoL, in juvenile hypothyroid patients. Here, we investigated if CSF/serum f-T4 ratio and QoL estimates correlate also during L-thyroxine treatment. Moreover, the CSF biomarker neurogranin (Ng) was used as a biomarker for synaptic function and integrity in clinical research. Ng is partially controlled by TH and therefore we investigated the relationship between QoL parameters and Ng levels. Patients diagnosed with primary hypothyroidism were investigated using vital parameters, serum and CSF analyses of TH, TSH, Ng and QoL questionnaires. Similar procedures were performed after 6 months of treatment. The most marked associations with QoL were found for CSF/serum f-T4 ratio, which was strongly related to several QoL parameters such as the mental subscore of SF-36 (r = 0.83, p < .0005). Ng, which did not differ from that in our healthy controls, was lower in some patients during treatment and higher in others. However, the change in Ng during treatment was significantly correlated with QoL parameters including the mental subscore of SF-36 (r = -0.86, p < .0001). In addition, the CSF/serum f-T4 ratio correlated with the change in Ng (r = -0.75, p = .001). Our results suggest that the ratio between CSF and serum f-T4 is an important biomarker for QoL during treatment of patients with primary hypothyroidism, so far in research, but in the future maybe also in clinical settings. Moreover, this ratio also correlates with the changes in Ng levels during L-thyroxine treatment, further supporting the impact of the TH balance between serum and CSF on QoL.

Primary hypothyroidism presenting as neuropsychiatric symptoms and pituitary enlargement in a young woman: illustrative case.

BACKGROUND: Pituitary adenomas are the most common cause of pituitary enlargement and can potentially warrant surgical intervention. However, there are physiological causes of pituitary enlargement that can be reversed with hormone replacement alone. OBSERVATIONS: A 29-year-old female presented with acute onset paranoia to the psychiatry department. A computed tomography scan of the head revealed a 2.3 cm sellar mass with confirmation on magnetic resonance imaging. Testing showed a markedly elevated thyroid-stimulating hormone 1,600 µIU/mL (0.470-4.200 µIU/mL), suggesting pituitary hyperplasia. Treatment with levothyroxine replacement resulted in marked improvement in symptoms and resolution of pituitary hyperplasia on four month follow up. LESSONS: This rare presentation of severe primary hypothyroidism highlights the importance of evaluating for physiological causes of pituitary enlargement.

Spontaneous Ovarian Hyperstimulation Syndrome Associated With Primary Hypothyroidism.

Ovarian hyperstimulation syndrome is a rare condition in pregnant women. Most cases are associated with the use of ovulation induction and stimulation medications. Some studies have reported cases of this condition in non-pregnant women or women undergoing ovulation therapy. In this case report, we report the case of a 27-year-old pregnant Saudi woman presenting with a picture of severe spontaneous ovarian hyperstimulation syndrome secondary to severe undiagnosed hypothyroidism. Treatment with Eltroxin (thyroxine) led to complete improvement and regression of ovarian enlargement after empirical titrating thyroxin replacement therapy, which proved the presence of this causation. The diagnosis was confirmed by laboratory and imaging findings, which helped prompt management and prevented complications of unneeded surgical intervention.

Association Between Systemic Lupus Erythematosus and Primary Hypothyroidism: Evidence from Complementary Genetic Methods.

INTRODUCTION: Systemic lupus erythematosus (SLE) and hypothyroidism often coexist in observational studies; however, the causal relationship between them remains controversial. METHODS: Complementary genetic approaches, including genetic correlation, Mendelian randomization (MR), and colocalization analysis, were conducted to assess the potential causal association between SLE and primary hypothyroidism using summary statistics from large-scale genome-wide association studies. The association between SLE and thyroid-stimulating hormone (TSH) was further analyzed to help interpret the findings. In addition, findings were verified using a validation data set, as well as through different MR methods with different model assumptions. RESULTS: The linkage disequilibrium score regression revealed a shared genetic structure between SLE and primary hypothyroidism, with the significant genetic correlation estimated to be 0.2488 (P = 6.00 × 10-4). MR analysis with the inverse variance weighted method demonstrated a bidirectional causal relationship between SLE and primary hypothyroidism. The odds ratio (OR) of SLE on primary hypothyroidism was 1.037 (95% CI, 1.013-1.061; P = 2.00 × 10-3) and that of primary hypothyroidism on SLE was 1.359 (95% CI, 1.217-1.520; P < 0.001). The OR of SLE on TSH was 1.007 (95% CI, 1.001-1.013; P = 0.032). However, TSH was not causally associated with SLE (P = 0.152). Similar results were found using different MR methods. In addition, colocalization analysis suggested that shared causal variants existed between SLE and primary hypothyroidism. The results of the validation analysis indicated a bidirectional causal relationship between SLE and primary hypothyroidism, as well as shared loci. CONCLUSION: In summary, a bidirectional causal relationship between SLE and primary hypothyroidism was observed with complementary genetic approaches.