Les thyroïdites sont, avec les goitres, les affections endocriniennes les plus fréquentes. Ce terme regroupe des maladies d'étiologie, de présentation et d'évolution - aiguë, subaiguë ou chronique - très différentes. Cette revue fait le point sur la physiopathologie, le diagnostic, le traitement des différentes thyroïdites.

OBJECTIVES:The outcome of dysthyroidism and the presence of antithyroid antibodies in patients with chronic hepatitis C virus (HCV) infection receiving interferon-α therapy is clearly established. However, the prevalence and the specificity of antithyroid antibodies in HCV patients before interferon-α therapy remain controversial. The aim of the present study is to clarify within a large population of HCV patients the prevalence of antithyroid antibodies before interferon-α therapy and to determine whether their immunodominant antigen is the same as described in autoimmune thyroiditis.METHODS:Sera from 99 patients with chronic hepatitis C before (n = 99) and after (n = 37) interferon-α treatment were investigated for the presence of antimicrosomal and antithyroperoxidase antibodies assessed by indirect immunofluorescence and ELISA, respectively. Dot blotting on human thyroid lysate was designed to further characterize these autoantibodies. Data were compared to those obtained with sera of patients with autoimmune thyroiditis (n = 75) and healthy subjects (n = 96).RESULTS:In HCV patients, antimicrosomal antibodies were found with a higher proportion before interferon-α therapy (12.1%) than after therapy (8%). Thyroperoxidase constitutes the main antigen in only 4% before treatment, a prevalence similar to that observed in healthy controls.CONCLUSIONS:The prevalence of antithyroid antibodies is low in patients with chronic hepatitis C before interferon-α therapy. Thyroperoxidase may not be their main target. Further studies are required to determine whether HCV infection leads to a breakdown of tolerance to a thyroid self-protein other than thyroperoxidase.

The evidence that there is a genetic susceptibility to systemic lupus erythematosus (SLE) in humans is based on its high concordance rate (29% to 57%) in identical twins and on the relatively high incidence (10% to 12%) of familial cases ( 1 Arnett FC Jr. The genetics of human lupus. In: Wallace DJ, Hahn BH, eds. Dubois’s Lupus Erythematosus. 5th ed. Baltimore: Williams and Wilkins; 1997:77–117. Google Scholar ). Since the production of a wide range of autoantibodies and immune complexes may lead to tissue injury in SLE, genes encoding receptors for immunoglobulin G (or FcγR) that result in variations in the clearance of immune complexes are logical candidates for the susceptibility to SLE ( 2 Ravetch J.V Kinet J.P Fc receptors. Ann Rev Immunol. 1991; 9: 437-492 Crossref Scopus (1281) Google Scholar ). The FcγRIIA gene (CD32), which encodes a widely expressed low-affinity receptor for IgG, is of particular interest. It has two expressed isoforms that differ by a single amino acid at position 131 ( 2 Ravetch J.V Kinet J.P Fc receptors. Ann Rev Immunol. 1991; 9: 437-492 Crossref Scopus (1281) Google Scholar , 3 Salmon J.E Millard S Schachter L.A et al. FcγRIIA alleles are heritable risk factors for lupus nephritis in african-americans. J Clin Invest. 1996; 97: 1348-1354 Crossref PubMed Scopus (413) Google Scholar ) and that have different abilities to bind aggregated IgG2 and IgG1: the arginine (R131) isoform, which results from an A to G substitution at nucleotide 494, has a lower Fc affinity than the histidine (H131) isoform ( 3 Salmon J.E Millard S Schachter L.A et al. FcγRIIA alleles are heritable risk factors for lupus nephritis in african-americans. J Clin Invest. 1996; 97: 1348-1354 Crossref PubMed Scopus (413) Google Scholar ).

BACKGROUND Automated electrophoresis combined with enzymatic cholesterol staining might improve routine assessment of LDL- and HDL-cholesterol (LDLC and HDLC), as an alternative to the Friedewald equation and precipitation. A new method (Hydrasys; SEBIA) that adapts the cholesterol esterase/cholesterol oxidase reaction within urea-free gels was evaluated. METHODS Fresh sera from 725 subjects (512 dyslipidemics) were analyzed by electrophoresis, in parallel with sequential ultracentrifugation, beta-quantification, calculation, and precipitation. RESULTS Electrophoresis was linear up to 4 g/L cholesterol, with a detection limit of 0.042 g/L cholesterol/band. Within-run, between-run, between-batch, and between-operator imprecision (CVs) were 1.6%, 2.0%, 1.5%, and 2.7% for LDLC, and 3.9%, 4.3%, 5.5%, and 4.9% for HDLC, and remained unchanged up to 6.3 g/L plasma triglycerides (TGs). Precision decreased with very low HDLC (<0.25 g/L). Serum storage for 3-7 days at +4 or -80 degrees C did not interfere significantly with the assay. Agreement with beta-quantification was stable for LDLC up to 5.07 g/L (r = 0.94), even at TG concentrations >4 g/L (r = 0.91). Bias (2.88% +/- 12%) and total error (7.84%) were unchanged at TG concentrations up to 18.5 g/L. Electrophoresis predicted National Cholesterol Education Program cut-points with <0.04 g/L error, exactly and appropriately classified 79% and 96% of the subjects, and divided by 2.4 (all subjects) and 5.8 (TGs >1.5 g/L) the percentage of subjects underestimated by calculation. One-half of the patients with TGs >4 g/L had LDLC >1.30 g/L. For HDLC, correlation was better with precipitation (r = 0.87) than ultracentrifugation (r = 0.76). Error (-0.10% +/- 26%) increased when HDLC decreased (<0.35 g/L). Direct assessment of the LDLC/HDLC ratio detected 45% more high-risk subjects than the calculation/precipitation combination. CONCLUSIONS Electrophoresis provides reliable quantification of LDLC, improving precision, accuracy, and concordance over calculation, particularly with increasing plasma TGs. Implementation of methods to detect low cholesterol concentrations could extend the applications for HDLC assessment.

The aim of this study was to test the hypothesis that antimicrosomal antibodies, found in patients with hepatitis C virus infection (HCV) before interferon (INF) therapy, are directed against a microsomal protein distinct from the thyroperoxidase. Sera from 99 HCV patients were analysed, before INF therapy, by ELISA and indirect immunofluorescence (IF). We confirm that antithyroid microsomal antibodies (TMA) detected in HCV patients before INF therapy are directed against a thyroid protein other than the usual thyroperoxidase autoantigen of autoimmune thyroiditis.

Long term complications are the first causes of mortality and morbidity in diabetic patients. In Europe, many diabetologists speculated for a long time that a tight blood glucose control was the best way to avoid these complications, but without any complete evidence. In 1993, the results of the Diabetes Control and Complications Trial (DCCT), the first controlled, randomized, long term trial designed to study the link between metabolic control and complications in a large cohort of patients, has confirmed this hypothesis: in insulin-dependent diabetes mellitus, intensive insulin-therapy, as compared with conventional therapy, significantly reduces the risk of developing microvascular and neuropathic complications. Nevertheless, in some patients, the risk of hypoglycemia may outweight the benefit of intensive insulin therapy, and the results of the DCCT raises some questions about indications, the risk/benefit ratio and the cost/benefit ratio of intensive treatment.

Des concentrations seriques normales de TSH ne sont pas rares chez les patients porteurs d'un nodule thyroidien chaud et extinctif: 9% dans notre experience. Seule la scintigraphie permet le depistage de ces cas. Huit de ces patients ont ete etudies. La reponse de la TSHemie a la TRH etait normale. Lorsque ces tests ont ete effectues, la stimulation par la TSH exogene a retabli la captation de l'isotope par le parenchyme sain et l'administration de LT3 n'a pas supprime la fixation de l'iode 123 par le nodule chaud. Chez six patients, le nodule chaud a ete enleve chirurgicalement et la scintigraphie realisee apres l'ablation a montre une captation normale de l'iode par le parenchyme restant. Chez ces patients, l'etude des variations circadiennes de TSHemie avant et au moins 8 jours apres ablation a indique que le pi nocturne etait absent avant ablation et reapparaissait apres l'intervention

L'antigène microsomal thyroïdien, impliqué dans de nombreuses pathologies autoimmunes thyroïdiennes, a été identifié en 1985 à la thyroperoxydase (TPO). Nous avons comparé les résultats des dosages d'anticorps antithyroperoxydase obtenus par radioimmunologie (RIA) et d'anticorps antimicrosomaux obtenus par immunofluorescence indirecte (IFI) sur coupe de thyroïde humaine, dans les sérums de 184 sujets se répartissant comme suit : 22 provenant de patients atteints de myxœdème, 35 de patients atteints de maladie de Basedow, 23 de goitre euthryoïdien, 14 de thyroïdite d'Hashimoto, 5 de goitre toxique, 35 de sujets présentant une pathologie autoimmune associée et 50 témoins. Il existe une très bonne corrélation entre les deux méthodes de dosage (r = 0,98). Notre étude montre que l'IFI reste une technique compétitive puisque de sensibilité (0,68 à 0,93 en fonction de la pathologie) et de spécificité (0,98) identiques au dosage RIA.

The long-term outcome (mean follow-up period 5.7 years) for 20 patients with anorexia nervosa was assessed on a comprehensive battery of self-report inventories and a structured clinical interview. Two thirds of the cohort were improved to a clinically significant degree at follow-up, but the majority still showed higher than normal scores on inventories of anorexic symptomatology, social maladjustment, anxiety, and hostility. The remaining one third were unimproved and demonstrated a broad range of impairment including distorted attitudes toward eating, overconcern about body shape, poor social functioning, high levels of anxiety, hostility, depression, and external locus of control. Moderate to strong correlations were found across outcome measures. Longer duration of eating difficulties before presentation was a strong predictor of poor long-term outcome, suggesting a chronic relapsing form of the disorder occurred in a subgroup of patients.

We report the case of a 62-year old woman in euthyroidism who presented with a thyroid cancer located within a hot nodule. The nodule was partially extinctive, and the triiodothyronine test showed incomplete suppression. Fine needle cytology showed no malignant cells. Systematic lobectomy was performed, and the diagnosis of cancer was made at pathology. This rate situation does not mean that all non-toxic hot nodules must be removed, but if surgery is decided an extemporaneous histological examination is mandatory. Besides, such cases provide an additional argument in favour of surgery or treatment of toxic adenomas.

We report the case of a 62-year old woman in euthyroidism who presented with a thyroid cancer located within a hot nodule. The nodule was partially extinctive, and the triiodothyronine test showed incomplete suppression. Fine needle cytology showed no malignant cells. Systematic lobectomy was performed, and the diagnosis of cancer was made at pathology. This rare situation does not mean that all non-toxic hot nodules must be removed, but if surgery is decided an extemporaneous histological examination is mandatory. Besides, such cases provide an additional argument in favour of surgery or treatment of toxic adenomas.

"Sensitive" thyrotropin (TSH), thyroglobulin (TG) and even thyrotropin binding inhibiting immunoglobulins (TBII) assays are now widely available. The objective of the present study was to determine the most accurate of these three parameters to predict the relapse of Graves' disease during the year following treatment discontinuation and to evaluate whether the assay of three markers is able to improve the prediction. TSH, TG and TBII were measured in the sera of 67 Graves' disease patients after at least 12 months of medical treatment. In 52 patients, TBII had also been determined before the beginning of the medical treatment. Under treatment, all the patients were clinically and biologically euthyroid, but in 9 goitrous patients it was impossible to lower the doses of carbimazole without an immediate relapse. The TSH levels of these 9 patients were still low in all cases but one; TG and TBII levels were abnormal in all. In the other 58 patients, the treatment was discontinued; 22 relapsed within one year, more frequently when a goiter was present. The most reliable parameter for the prediction of relapse was found to be TBII, as its specificity was high (94.5%), although its sensitivity was poor (45%); TG was more sensitive (64%) but far less specific (57%); TSH and "initial" TBII appeared to be of a little interest. When TBII was elevated prior to the withdrawal of treatment, the determination of TG was useful: abnormal values of both TBII and TG were always associated with a relapse. When TBII testing was negative, the relapse risk fell to 0.26, and to 0.08 when three criteria were matched: no goiter, negative TBII, normal TG.

Low TSH levels are frequently encountered in patients presenting with goiter. We assayed TSH in 599 goitrous patients who were referred to us for scintigraphy and ultrasonography. When TSH levels were low or when a hot nodule was discovered at scintigraphy, free T3, free T4 and sex hormone-binding globulin (SHBG) were also assayed. TSH levels were always low in overt hyperthyroidism with elevated free T3. TSH levels were also low in patients with normal free T3 and free T4 in circumstances leading to mild hyperthyroidism such as hot nodules that suppressed extranodular thyroid tissue uptake, toxic multinodular goiter, De Quervain thyroiditis and some patients on amiodarone treatment. Low TSH levels were also encountered in 29% of the clinically euthyroid patients presenting with a multinodular goiter with normal iodine uptake, no hot area and normal free T3 levels. In diffuse goiter, low TSH and normal free T3 levels were more frequently associated when iodine uptake was low, mainly due to subacute thyroiditis which can be clinically silent. Low TSH levels were rarely observed in patients with "simple" goiter or uninodular goiter without hot areas. SHBG, which was elevated in 94% of the Graves' disease patients tested, was normal in all but two patients with low TSH and normal free T3 levels. This assay appeared to be of little relevance in goiter. In addition to imaging techniques which are usually performed first, TSH should be systematically assayed in goiter, except in cases of solitary cold nodules. When low, the patient is at risk of developing overt hyperthyroidism. Conversely, when an isolated low TSH level is observed, scintigraphy should be performed.

More than 500 sera were assayed for TBII under routine conditions using "Trak" assay in order to evaluate the sensitivity, specificity and prognostic interest of this determination in hyperthyroidism. The sensitivity for the diagnosis of Graves' disease was 83.5%, better in ophthalmopathic patients (93%) than in non ophthalmopathic patients (75%). The specificity was 99.4% with only one false positive in a hypothyroid patient. TBII level significantly decreases with carbimazole treatment except in patients who remain hyperthyroid. Determination of TBII before stopping carbimazole treatment or after surgery has a prognostic significance as a positive value indicates a relapse in almost all cases. Conversely, a fall of TBII to normal levels with treatment is insufficient to assess recovery. High levels are frequently observed after radioiodine therapy but do not indicate a poor prognosis.