[Rare differential diagnosis of hyperthyroidism]. / Seltene Ursache einer Hyperthyreose - Fall 4 / 2016.

HISTORY AND ADMISSION FINDINGS: A 54-year-old female patient is admitted for evaluation of her thyroid function after two cycles of ipilimumab therapy. The decision for the anti-cytotoxic-T-lymphocyte-antigen-4-therapy (anti-CTLA-4) was made two months earlier because of malignant melanoma with pulmonary metastases. The patient was euthyroid before initiation of treatment and without known thyroid disease. INVESTIGATIONS: The laboratory reveals thyrotoxicosis with elevated anti-thyroid peroxidase and anti-thyroglobulin antibody levels. The anti-thyroid stimulating hormone receptor antibody levels are within the normal range. Thyroid ultrasound shows a normal-sized, inhomogenous, hypoechogenic thyroid gland, consistent with autoimmune thyroiditis. DIAGNOSIS, TREATMENT AND COURSE: Diagnosis of hyperthyroidism due to ipilimumab-induced autoimmune thyroiditis is made. The patient does not receive any thyroid-specific medication, with regular control of the thyroid hormone levels. When the patient becomes euthyroid, the ipilimumab therapy is continued. Three weeks later, the patient develops hypothyroidism and a supplementation with L-thyroxine is initiated. CONCLUSIONS: An anti-CTLA-4 therapy may cause thyroid dysfunction. Therefore, before initiation and in the course of the treatment, regular controls of the thyroid hormone levels are required.

Individualized Follow-up of Pregnant Women with Asymptomatic Autoimmune Thyroid Disease.

Maternal hormones are essential for the normal fetal development during pregnancy. Autoimmune thyroid disease is a frequent pathology in our iodine replete region. The aim of this study is to evaluate the occurrence of subclinical hypothyroidism (SCH) in cases with known autoimmune thyroid disease, which were in a euthyroid state prior to pregnancy, and to assess the association between supplemental treatments administered and the outcome of the pregnancy. The study is a prospective interventional controlled study. The two cohorts comprise the interventional group, consisting of 109 pregnant women with known autoimmune asymptomatic thyroid disease, without any levothyroxine (LT4) treatment and an aged-matched control group, with an unknown thyroid disease. After the pregnancy, a monthly evaluation of TSH, FT3, and FT4 was performed. Offspring evaluation was made at birth time. 88.8% of the women developed SCH in the first four weeks of pregnancy. Average LT4 doses increased as the pregnancy progressed. The monthly adjustment was 12.5 or 25 µg. All SCH cases developed in the first trimester of pregnancy. There was no significant difference regarding the gestational week, weight, or length at birth between the interventional group and controls, when TSH values were in the optimal range, during the whole pregnancy. Premature birth was described in one case in the interventional group.

[Thyroid gland and pregnancy - summary of important findings]. / Stítná zláza a gravidita - souhrn dulezitých poznatku.

Thyroid hormones play fundamental role in conception and pregnancy and are essential for normal adult health, fetus and childhood development. Many studies have shown an association between maternal thyroid diseases esp. hypothyroidism with obstetric problems and/or psychomotoric impairment in the offspring. The prevalence of undiagnosed lower thyroid function in pregnancy is present in about 4-8 % of pregnant women, and euthyroid women with thyroid autoimmunity (6-8 %) are further candidates for thyroid disorders in pregnancy. The thyroid gland needs to produce 50 % more thyroxine in pregnancy to maintain an euthyroid state to keep TSH ideally 2.5 mIU/l in the first trimester of pregnancy and TSH 3.0 mIU/l in the second and third trimester. Consequently, there is a need to start the substitution therapy as soon as diagnosis of subclinical and /or overt hypotyroidism is established, and in majority of euthyroid women with autoimmune thyroid disease there is a need to start therapy as well. Most women on levothyroxine therapy before pregnancy require an increase in dose when pregnant. As maternal thyroid disease is a quite prevalent condition and often asymptomatic, but easily diagnosed and for which an effective, safe and cheap treatment is available, endocrinological societies including CES CLS JEP worldwide are suggesting the need of thyroid dysfunction screening as a simple prevention attitude. Hormone determination of TSH and TPOab antibodies should be performed early during the first trimester, using trimester-specific reference values. Furthermore, adequate iodine supplementation during pregnancy is critical and if feasible it should be initiated before the woman attempts to conceive.

SELENIUM STATUS IN AUTOIMMUNE THYROIDITIS.

UNLABELLED: Selenium (Se) is an important element that exerts its effects through selenoproteins. The thyroid gland has the highest Se concentration and specific selenoprotein enzymes families are crucial in the thyroid hormone metabolism. There is little evidence on the link between Se and thyroid autoimmune disease, therefore future studies are required to elucidate the nature of this associ ation. AIM: To evaluate the Se status in euthyroid subjects with autoimmune thyroiditis. MATERIAL AND METHODS: From January 2014 to January 2015 we recruited 100 consecutive euthyroid subjects with autoimmune thyroiditis, living in the same region and with normal iodine intake. Serum concentrations of Se, thyroid antibodies (antithyroperoxidase--TPOAb--and antithyroglobulin--TgAb), thyroid-stimulating hormone (TSH), and thyroid ultrasound were performed in all patients. RESULTS: Mean age of the study group was 48.87 ± 12.83 years, range: 18-82 years. Since thyroid pathology is more frequent in the 5th - 6th decades of life we selected the age of 50 for the comparative analysis of the results (51% of patients were under 50). No statistical age-group differences in antibody levels were found: mean TPOAb = 420.95 IU/ml, p = 0.840; mean TgAb = 327.98 IU/ml, p = 0.977. TSH mean was 2.14 [µIU/ml, with no significant age-group differences (p = 0.176). Se levels ranged between 8.05 - 998.50 µg/ with a mean value of 294.96 µg/L and no significant differences between age groups (p = 0.158). Thyroid ultrasound showed inhomogeneity in 89%, nodules in 35% of patients, and a mean thyroid volume of 11.72ml, with no significant age-group differences (p = 0.366). The low TSH levels were associated with low Se levels in 11.6% of cases, but the direct correlation was statistically insignificant (r = 0.116; R2 = 0.0161; p = 0.371). Depend ing on TSH percentiles, mean Selevels showed no significant differences, however pointing out the highest mean value at the 25th percentile (F = 0.441, df = 61, p = 0.646). A negative correlation trend was found between Se and TPOAb (r = -0.2276) or TgAb (r = -0.2190) but lacking statistical significance (p=0.099). CONCLUSION: Our results showed a weak negative correlation between Se and antithyroid antibodies, suggesting that selenium supplementation may improve the course of thyroid autoimmunity.

The chronic autoimmune thyroiditis quality of life selenium trial (CATALYST): study protocol for a randomized controlled trial.

BACKGROUND: Patients with chronic autoimmune thyroiditis have impaired health-related quality of life. The thyroid gland has a high selenium concentration, and specific selenoprotein enzyme families are crucial to immune function, and catalyze thyroid hormone metabolism and redox processes in thyroid cells. Previous randomized controlled trials have found that selenium supplementation decreases thyroid-disease-specific antibody levels. We hypothesize that selenium might be beneficial in the treatment of chronic autoimmune thyroiditis. METHODS/DESIGN: The CATALYST trial is an investigator-initiated randomized, blinded, multicentre clinical trial of selenium supplementation versus placebo in patients with chronic autoimmune thyroiditis. INCLUSION CRITERIA: age ≥18 years; serum thyroid peroxidase antibody level ≥100 IU/ml within the previous 12 months; treatment with levothyroxine and written informed consent. EXCLUSION CRITERIA: previous diagnosis of toxic nodular goitre, Graves' hyperthyroidism, postpartum thyroiditis, Graves' orbitopathy; previous antithyroid drug treatment, radioiodine therapy or thyroid surgery; immune-modulatory or other medication affecting thyroid function; pregnancy, planned pregnancy or breastfeeding; allergy towards any intervention or placebo component; intake of selenium supplementation >55 µg/day; inability to read or understand Danish or lack of informed consent. The trial will include 2 × 236 participants. The experimental intervention and control groups will receive 200 µg selenium-enriched yeast or matching placebo tablets daily for 12 months. The experimental supplement will be SelenoPrecise®. The primary outcome is thyroid-related quality of life assessed by the Thyroid Patient-Reported Outcome (ThyPRO) questionnaire. Secondary outcomes include serum thyroid peroxidase antibody concentration; serum triiodothyronine/thyroxine ratio; levothyroxine dosage; adverse reactions and serious adverse reactions and events. DISCUSSION: In this pragmatic trial, participating patients follow their usual treatment at their usual hospitals. In order to collect high-quality data on the clinical course and quality of life, and to minimize missing data, an elaborate trial management system has been designed. 12 months intervention duration was selected in consideration of the primary outcome, thyroid-related quality of life. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT02013479.

Interferon-γ and tumor necrosis factor-α sustain secretion of specific CXC chemokines in human thyrocytes: a first step toward a differentiation between autoimmune and tumor-related inflammation?

CONTEXT: Chemokines are chemotactic cytokines responsible for the attraction and recruitment of different cell types during leukocyte infiltration, the histopathological hallmark of autoimmunity. Previous data demonstrate that thyrocytes secrete CXC chemokines, particularly CXCL8 and CXCL10. However, the physiopathological significance of such secretion and the effects of a combination of proinflammatory stimuli in terms of preferential CXCL8 and CXCL10 release remain unclear. OBJECTIVE: The aim of this study was to investigate whether the secretion of chemokines by human thyrocytes is a generalized inflammatory response or whether it is dependent upon specific proinflammatory stimuli. METHODS: CXCL8 and CXCL10 were measured in supernatants of human thyrocytes in primary cultures basally and after 24 h stimulation with interferon-γ (IFNγ) (1000 U/ml) and TNFα (10 ng/ml), alone or in combination. RESULTS: CXCL8 but not CXCL10 was detected in basal conditions. The two chemokines showed differences in their response to proinflammatory cytokines. Indeed, significant secretion of CXCL10 was induced by IFNγ (P < 0.01) and not TNFα, whereas CXCL8 was secreted in response to TNFα (P < 0.01) being inhibited by IFNγ (P < 0.01). The combination of TNFα plus IFNγ synergistically increased the IFNγ-induced CXCL10 secretion (P < 0.01) and reversed the TNFα-induced CXCL8 secretion (P < 0.01). CONCLUSIONS: These results confirm that human thyrocytes secrete CXC chemokines and demonstrate that the secretion of CXCL8 and CXCL10 is sustained by specific proinflammatory cytokines or their combination, which ultimately determines the nature of the infiltrating lymphocytes in human thyroid diseases. These results indirectly support a major role for CXCL10 in thyroid autoimmunity whereas CXCL8 might be involved in tumor-related inflammation.

Chronic autoimmune thyroiditis in industrial areas in Brazil: a 15-year survey.

PURPOSE: To investigate whether there is an increased incidence of chronic autoimmune thyroiditis (CAT) in individuals living in the vicinity of industrial plants that manufacture petroleum byproducts in the state of São Paulo, Brazil. METHODS: Between 1989 and 2004, 6,306 patients of both sexes, from 5 to 78 years old were divided in two groups according to their home location: Group 1: 3,356 residents living near industrial plants that manufacture petroleum byproducts (Region A), and Group 2: 2,950 residents living far from Region A in an area with predominantly steel industries (Region B). For all patients, we measured the serum levels of antithyroglobulin antibody, antithyroperoxidase antibody, triiodothyronine, thyroxine, free thyroxine and thyrostimulating hormone. Sonographic scans of the thyroid gland were also conducted. RESULTS: The proportion of patients with CAT coming from Region A increased from 2.5 % (5 patients with CAT/200 total patients) in 1992 to 57.6 % (106 patients with CAT/184 total patients) in 2001. This striking increase was highly significant (p < 0.001). Similar findings were not observed in Region B. The difference in the number of patients with CAT between 1989 and 2004 coming from Region A and Region B was highly significant (p < 0.001), with 905 CAT patients (83.95 %) in Region A and 173 CAT patients (16.05 %) in Region B. CONCLUSION: Our results showed a striking increase in the incidence of CAT in residents in the vicinity of large industrial plants that manufacture petroleum byproducts compared with residents living near steel industries, which opens the field to new areas of research.

Vitamin D and autoimmune thyroid diseases.

The role of vitamin D as an immune modulator has been emphasized in recent years, and low levels of the hormone were observed in several autoimmune diseases including multiple sclerosis and systemic lupus erythematosus. Vitamin D mediates its effect though binding to vitamin D receptor (VDR), and activation of VDR-responsive genes. While VDR gene polymorphism was found to associate with autoimmune thyroid diseases (AITDs), few studies examined levels of vitamin D in these patients and those that did yielded conflicting results. We therefore undertook to evaluate the levels of vitamin D in patients with AITDs compared to patients with non-AITDs and healthy controls. Serum vitamin D (25-OH) levels were measured in 50 patients with AITDs, 42 patients with non-AITDs and 98 healthy subjects, utilizing the LIAISON chemiluminescence immunoassay (DiaSorin, Saluggia, Italy). Vitamin D deficiency was designated at levels lower than 10 ng/ml. Antithyroid antibodies, thyroid functions and demographic parameters were evaluated in all patients. The prevalence of vitamin D deficiency was significantly higher in patients with AITDs compared with healthy individuals (72% versus 30.6%; P<0.001), as well as in patients with Hashimoto's thyroiditis compared to patients with non-AITDs (79% versus 52%; P<0.05). Vitamin D deficiency also correlated to the presence of antithyroid antibodies (P=0.01) and abnormal thyroid function tests (P=0.059). Significantly low levels of vitamin D were documented in patients with AITDs that were related to the presence of anti thyroid antibodies and abnormal thyroid function tests, suggesting the involvement of vitamin D in the pathogenesis of AITDs and the advisability of supplementation.

[Autoimmune thyroiditis: diagnosis and treatment]. / Autoimmunthyreoiditis: Diagnostik und Therapie.

Autoimmune thyroiditis (AIT) is an autoimmune disease with genetic background. Women are more likely to develop AIT. In adulthood, AIT is the most frequent cause for acquired hypothyroidism. Cytotoxic T-lymphocyte antigen (CTL-4) may play a role in the etiology of the disease. Diagnosis is made by determination of elevated antibodies against thyroid peroxidase and thyroglobulin, and a hypoechoic pattern in ultrasound. In case of hypothyroidism a substitutive therapy with levothyroxine is necessary. AIT may occur as postpartum thyroiditis or as a special entity as consequence of therapy with cytokines.

Persistence of goitre in children post-salt iodization in Islamic Republic of Iran: autoimmune status.

We evaluated the prevalence of autoimmune thyroiditis in a random sample of 1188 schoolchildren aged 8-13 years with normalized iodine intake in the Islamic Republic of Iran. The prevalence of goitre was 39.6%; the majority had palpable but non-visible goitre. Of a subsample of 500 children, median urinary iodine excretion (18/8 microg/dL) indicated normal iodine intake. Thyroid peroxidase (TPO) antibody was positive in 3.7% of children and was significantly correlated with the prevalence of goitre and hypothyroidism. No correlation was seen between urinary iodine excretion and positive TPO antibody, mean TPO antibody, hypothyroidism or prevalence of goitre. Autoimmune thyroiditis explains some cases of goitre but other goitrogenic factors need to be evaluated.

[Clinical guideline for the diagnosis and treatment of subclinical thyroid dysfunction in pregnancy. Working Group on Subclinical Thyroid Dysfunction of the Spanish Endocrinology Society]. / Guía clínica para el diagnóstico y el tratamiento de la disfunción tiroidea subclínica en la gestación. Grupo de Trabajo sobre la Disfunción Tiroidea Subclínica de la Sociedad Española de Endocrinología.

Subclinical thyroid disease is a biochemical diagnosis and is common during pregnancy. Because of the physiological hormonal changes that take place during pregnancy and the absence of normal ranges for thyroid hormones during this period, subclinical thyroid disease is difficult to interpret during pregnancy. Subclinical hyperthyroidism during pregnancy has few clinical consequences and no treatment is required. In contrast, subclinical hypothyroidism seems to improve with thyroxine treatment. Iodine supplements during pregnancy and lactation, even in iodine-sufficient areas, are also indicated.

[Hypothyroidism: from the desire for pregnancy to delivery]. / Hypothyroïdie: du désir de grossesse à l'accouchement.

The link between hypothyroidism and infertility is still a matter of debate. Hypothyroidism can result in cycle disturbances, such as oligomennorhea and functional bleeding. Additionally, several studies have shown that thyroid autoimmunity (detection of anti peroxydase antibodies) may account for the occurrence of repetitive miscarriages. In infertility work-up, screening thyroid function should be specifically recommended for women with clinical hypothyroidism, with a personal, familial history of thyroid or other auto immune diseases (such as type I diabetes) as well as for women with unexplained anovulation or functional bleeding. Moreover, detection of thyroid antibody seems to be worthwhile for the assessment of recurrent miscarriages, due to the potential benefit of thyroid supplementation. In pregnant women, assessment of thyroid function seems specifically crucial to ensure adequate foetal development. Indeed, it has been well established that untreated maternal hypothyroidism may be associated with disturbances of brain development and low intellectual quotient. Additionally, other foetal (growth deficiency, premature birth, low birth weight) as well as maternal (gestational hypertension, pre-eclampsia...) complications have been also reported in pregnant women with untreated hypothyroidism. Consequently, screening of thyroid function should be performed in every woman at risk of thyroid disease. Recent studies even advocate that thyroid screening should be extended to the overall pregnant population. The objective is to adjust L-thyroxin supplementation to maintain serum TSH concentrations below the threshold of 2.5 mUI/l. Finally, iodine deficiency, currently observed in pregnant women, should be prevented by iodine supply prior to conception, during pregnancy and during breast feeding as well.

Difficulties in diagnosing and managing coexisting primary hypothyroidism and resistance to thyroid hormone.

OBJECTIVE: To report a case of resistance to thyroid hormone compounded by autoimmune primary hypothyroidism and to discuss the unusual pattern of results of thyroid function tests. METHODS: A clinical case history is presented and illustrated with laboratory findings. The difficulty of monitoring the patient's response to levothyroxine supplement is also discussed, and relevant issues are addressed, including reviews of the literature. RESULTS: A 45-year-old woman presented with longstanding and nonspecific symptoms of general anxiety and lethargy. Clinically, she was assessed to be euthyroid with no goiter. Her thyrotropin (thyroid-stimulating hormone or TSH) level was 43.6 (1/4)IU/mL, free thyroxine was 27.6 pmol/L, and free triiodothyronine was 7.8 pmol/L. Her anti-thyroid peroxidase titer was 1:102,400. Primary hypothyroidism was diagnosed, and treatment with 50 (1/4)g of levothyroxine daily was initiated, with progressive dose escalation. The patient, however, had thyrotoxic symptoms when her TSH was rendered "normal." The patient then discontinued her levothyroxine therapy, with a consequent elevation of her TSH level to 170.8 (1/4)IU/mL in conjunction with severe lethargy and lassitude. Biochemical evidence of metabolic disturbances was also present at the time, with hypercholesterolemia and elevated creatine kinase concentration. Rechallenge with levothyroxine resulted in considerable improvement in her biochemical findings and symptoms. CONCLUSION: This patient has an interesting combination of autoimmune primary hypothyroidism and resistance to thyroid hormone. Levothyroxine replacement therapy was complicated by the nonspecificity of symptoms and the lack of an established TSH target value in this condition. Consideration should be given to using the affected family members' mean TSH level, when available, as a target guide for replacement therapy.

[Bilateral shoulder-hand syndrome revealing hypothyroidism and colon carcinoma]. / Syndrome épaule-main bilatéral révélateur d'une hypothyroïdie et d'un carcinome du côlon.

The autors describe a case of a bilateral shoulder-hand syndrome. A Hashimoto's thyroiditis bound hypothyroidism was retained as promoting factor. Rheumatic manifestations amended slowly with a treatment of corticosteroids associated to thyroid hormones replacement. Eighteen months after the onset of the rheumatic complaints, a colorectal cancer was also diagnosed. The respective role of hypothyroidism and cancer in the emergence of this severe shoulder-hand syndrome is discussed.

Fine-needle aspiration biopsy of the thyroid in an area of endemic goitre: influence of restored sufficient iodine supplementation on the clinical significance of cytological results.

OBJECTIVE: The iodine status of the population of Poland has markedly improved over the past years. The aims of this paper were: (i) to examine the diagnostic value of fine-needle aspiration biopsy (FNAB) of the thyroid in goitre endemic regions (in conditions of improved iodine supply), and (ii) to find whether the changes in iodine supply have already influenced the clinical interpretation of cytological results. METHODS: Cytological diagnoses, based on 3782 aspirates, obtained from 3572 patients during the years 1985-1999, were verified by reference to the results of postoperative examinations. The relative occurrences of selected cytological results in 1992-1999 were also compared (patients not subjected to surgery were included). RESULTS: We have found that the frequency of neoplastic lesions significantly decreased throughout the examined period (P<0.02). The ratio of the papillary carcinoma frequency to the follicular carcinoma frequency increased from 1.7 during 1992-1993 up to 8.0 during 1998-1999 (P<0.05). The frequency of cytologically diagnosed chronic thyroiditis increased from 1.5% in 1992 to 5.7% in 1999 (P<0.001); the percentage of cytological diagnosis of "follicular neoplasm" decreased during the same time (P<0.001). The risk of malignancy significantly lowered in the cytological diagnoses of "follicular neoplasm" from 15% during 1985-1993 to 6% during 1996-1999 (P<0.05). CONCLUSIONS: The diagnostic value of FNAB during the period without proper iodine prophylaxis did not differ significantly from that during the last examined period. However, the changes in iodine supply have markedly and promptly affected the clinical significance of particular cytological results.

Oftalmopatía de Graves y disfunción tiroidea: hipertiroidismo e hipotiroidismo / Grave's ophtalmopathy and thyroid dysfunction: hyperthyroidism and hypothyroidism

Se presenta el caso de dos pacientes adoles-centes con oftalmopatía infltrativa y bocio difuso, pero con una afectación funcional tiroidea muy distinta: hipertiroidismo (enfermedad de Graves) e hipotiroidismo (tiroiditis de Hashimoto). A la oftalmopatía tiroidea o de Graves cabría considerarla como una entidad nosológica propia que, si bien generalmente se acompañará de tirotoxicosis, puede asociarse con alteraciones tiroideas muy variadas (AU)

Fatal heatstroke in a young woman with previously undiagnosed Hashimoto's thyroiditis.

Heatstroke represents the most severe form of the heat-related illnesses. Potentially fatal, heatstroke most often affects the elderly, obese, or chronically ill. Thyroid disease, which may interfere with the normal regulation of body temperature, has not previously been reported in cases of heatstroke. A fatal case is reported in a young woman discovered unconscious in a sauna who was found to have preexisting Hashimoto's thyroiditis on subsequent autopsy. The diagnosis of hypothyroidism in heatstroke rests on clinical information and morphologic observations. This case underscores the importance of evaluating the thyroid in unusual cases of heatstroke.

Prevalence of chronic lymphocytic thyroiditis in adolescent girls.

Chronic lymphocytic thyroiditis (CLT) is the most common cause of thyroid enlargement in children and adolescents in iodine sufficient areas. The prevalence and pattern of CLT in adolescent girls in iodine deficient regions supplemented with iodine is as yet not known. We therefore, carried out clinical examination for the presence of goitre in 330 healthy girls from Delhi in the age group of 16-20 years and those with goitre were further subjected to detailed biochemical (T3, T4, TSH), immunological (ATg ad ATm) and cytomorphological examination. The prevalence of goitre was found to be 40%. Fine needle aspiration cytology (FNAC) carried out in 94 girls with goitre (74%) revealed finding consistent with CLT in 13 (13.8%), colloid goitre with non-specific thyroiditis in 7 (7.4%), colloid goitre in 71 (75.5%) and specimen was inadequate in 3 (3.2%) girls. Thyroid antibodies were estimated in 114 of the goitrous subjects and both ATg and ATm were positive in 11 (9.6%) cases. Overall prevalence of CLT in this population was 4.0% and among those with goitre was 13.8%. When thyroid antibodies were also considered as an indicator of thyroiditis, prevalence rose to 14.4% among goitrous girls. Thyroid function tests were found to be within normal limits in all goitrous girls. This study for the first time reveals a high prevalence of CLT in goitrous adolescent girls from iodine supplemented region and underscores the need to study the prevalence of CLT in different age and sex groups from different regions of the country.

[Thyroid changes in the pregnant woman]. / Les altérations thyroïdiennes chez la femme enceinte.

In Belgium the iodine intake is restricted and even marginally insufficient. During pregnancy, the insufficient iodine supply is associated with chronic stimulation of the thyroid gland, leading to the development of gestational goiters and to an increased risk of foetal goitrogenicity. Also, approximately one third of pregnant women exhibit relative hypothyroxinemia. Moreover, women who present chronic autoimmune thyroiditis and in whom thyroid function is normal at the onset of pregnancy carry a significant risk of developing thyroid insufficiency during gestation. In conclusion, healthy pregnant women should be given the benefit of iodine supplementation, both during pregnancy and breastfeeding. This will allow them to maintain a well adapted thyroid function, prevent goitrogenicity, and ensure adequate foetal hormone production. For women with autoimmune thyroiditis, thyroid function should be closely monitored during pregnancy and the slightest indication of thyroid insufficiency should prompt the administration of thyroid hormone substitution.