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Diagnostic et surveillance biologiques de l’hyperthyroïdie de l’adulte - Laboratory diagnosis and monitoring of hyperthyroidism in adults - Guidelines

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Posted on Feb 01 2000 Laboratory tests useful for the diagnosis or monitoring of hyperthyroidism Strategy for using laboratory tests to diagnose hyperthyroidism Laboratory monitoring of hyperthyroidism Posted on Feb 01 2000

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WORKING GROUP Professor Jean-Louis SCHLIENGER, specialist in internal medicine, chairman, Strasbourg Dr. Najoua MLIKA-CABANNE, Project Manager, ANAES, Paris
Patrice BLOUIN, pharmacist, Bordeaux Dr Jean-Victor BUKOWSKI, geriatrician, Roubaix Dr. Maurice CHUPIN, endocrinologist, Nantes Dr. Isabelle COLLIGNON, laboratory analyst, Marne-La-Coquette Dr. Maurice DE BOYSSON, endocrinologist, Bourges Dr. Richard ISNARD, cardiologist, Paris Dr. Jean-Luc JAMET, laboratory analyst, Tourcoing Dr. Edgar KALOUSTIAN, endocrinologist, Compiègne Dr. Jean-Luc MAS, general practitioner, Bourgoin-Jallieu MmeCatherine MASSART, laboratory analyst, Rennes Dr. Réginald MIRA, endocrinologist, Antibes Professor Vincent ROHMER, endocrinologist, Angers Professor Hugues ROUSSET, specialist in internal medicine, Pierre-Bénite Dr. Patrick SOULIÉ, general practitioner, Valderies Dr. Ewa TESLAR, general practitioner, Paris
READING GROUP Dr. Michel ALIX, specialist in internal medicine, Caen Professor Françoise ARCHAMBEAUD, specialist in internal medecine, Limoges Dr. Louis AUBERT, specialist in internal medicine, Toulon Dr. Line BALDET, endocrinologist, Montpellier Dr. Didier BEUTTER, endocrinologist, Vannes Dr. Philippe CARON, endocrinologist, Toulouse Dr. Gérard CHABRIER, endocrinologist, Strasbourg Dr. Françoise CHANTEGREIL, general practitioner, Saint-Mandé Dr. Jo‘l CHAPUIS, general practitioner, Baouhaye Professor Alain COHEN-SOLAL, cardiologist, Clichy Professor Bernard CONTE-DEVOLX, endocrinologist, Marseilles Dr. Gisèle COUPLET, laboratory analyst, Lille Dr. François DANY, cardiologist, Limoges Dr. Alain DAVER, laboratory analyst, Angers Professor Jean DOUCET, specialist in internal medicine, geriatrician, Rouen Professor Michel DREYFUS, gynaecologist-obstetrician, Caen Dr. Hubert DU ROSTU, endocrinologist, Nantes Dr. Bernard GAY, ANAES Scientific Council, Paris Dr. Philippe GIRAUD, specialist in internal medicine, endocrinologist, Angers Dr. Anne GRUSON, ANAES Scientific Council, Paris Fabrice GERBER, laboratory analyst, Bourg-D’Oisans Dr. Claudine GUILLAUSSEAU, endocrinologist, Paris Dr. Chantal HOULBERT, laboratory analyst, Alençon Dr. Robert KAHN, general practitioner, Marseilles Dr. Jacques LAGARDE, general practitioner, L’Isle-Jourdain Dr. Christian LAISNE, cardiologist, Armentières Dr. Jean-Louis LEGRAND, laboratory analyst, Toulouse Dr. Michel LÉVÈQUE, general practitioner, Thann Dr. Christian MARTINET, general practitioner, Saint-Julien-de-L’Escap Dr. Alain MILLET, general practitioner, Tarcenay Dr. Patrick NAMBOTIN, general practitioner, Dolomieu Professor Jacques ORGIAZZI, endocrinologist, diabetologist, Pierre-Bénite Dr. Patrick POCHET, general practitioner, Clermont-Ferrand Dr. Alain POTIER, gynaecologist-obstetrician, Marseilles Dr. Jean-François POUGET-ABADIE, endocrinologist, Niort Dr. Gilbert ROUANET, general practitioner, Béthune Dr. Jean-Claude RYMER, laboratory analyst, Créteil Professor Jean-Louis SADOUL, endocrinologist, Nice M. Rémy SAPIN, laboratory analyst, Strasbourg Dr. Jean TARDIEU, geriatrician, Mandelieu Dr. René THIBON, general practitioner, Nîmes Dr. Jean-Marie VETEL, geriatrician, specialist in internal medicine, Le Mans Professor Jean-Louis WEMEAU, endocrinologist, Lille Dr. Patrice WINISZEWSKI, endocrinologist, Belfort
GUIDELINES
The literature on laboratory diagnosis and monitoring of hyperthyroidism in adults consists mainly of editorials, case series, recommendations based on expert opinions, or trials conducted using a very dubious design. The guidelines below are thus essentially based on expert opinion.
The proposed guidelines are classified as grade A, B or C depending on the level of evidence of the studies on which they are based: scientific evidence established by trials of a highA grade A guideline is based on level of evidence, for example randomised controlled trials of high power and free of major bias, and/or meta-analyses of randomised controlled trials, decision analysis based on properly conducted studies; A grade B guideline is based on presumption of a scientific foundation derived from studies of an intermediate level of evidence, for example randomised controlled trials of low power, well-conducted non-randomised controlled trials, cohort studies; of a lower level of proof, for example case-A grade C guideline is based on studies control studies, case series, etc.
If there is no evidence, the proposed guidelines are based on agreement among professionals.
The following definitions are used in this study: 1. Hyperthyroidism means thyroid gland overactivity, which increases thyroid hormone production and leads to thyrotoxicosis. A distinction is made between different types of hyperthyroidism: • Overt hyperthyroidism (also called clinical hyperthyroidism) where there is a combination of clear clinical signs and abnormal laboratory values (TSH low, T4 and/or T3high); • Subclinical hyperthyroidism (also called masked or asymptomatic hyperthyroidism) which is used to describe cases where symptoms are unclear and laboratory values are abnormal (TSH concentration low, T4and/or T3concentrations normal or at the upper limit of normal). 2. TSH, free T4(FT4) and free T3(FT3) are considered to be abnormal when values are outside the laboratory’s range of normal.
LABORATORY TESTS USEFUL FOR THE DIAGNOSIS OR MONITORING OF HYPERTHYROIDISM
The following recommendations are made concerning sampling and analysis: The laboratory should state which analytical method was used and specify the reference range of values to be used when interpreting the findings. The method used for determination of TSH should preferably be a third-generation method;
Once TSH has been determined, the serum should be kept in the laboratory (for a maximum of 7 days at +4°C). Thus further tests can be performed, without requiring a further sample to be taken from the patient;
When T4or T3recommended that only the free fraction of thehas to be measured, it is hormones be determined. Tests which are useful for positive diagnosis of hyperthyroidism, regardless of cause, are TSH, free T4, and very occasionally, free T3(for T3hyperthyroidism). For monitoring, add TSH receptor antibodies in Graves’ disease(see table):
First-line tests
Table. Usefulness of tests used for positive diagnosis of hyperthyroidism, aetiologic diagnosis, and monitoring
Second-line tests
Tests which are not useful
Positive diagnosis of hyperthyroidism
TSH
Free T4, and free T3if free T4is normal and TSH is low
TRH test, except in very unusual circumstances TPO antibodies Thyroglobulin antibodies TSH receptor antibodies Thyroglobulin Thyroxine-binding globulin Blood iodine / urinary iodine ESR, C-reactive protein (CRP) Lipids
Aetiologic diagnosis
TPO antibodies (autoimmune hyperthyroidism) TSH receptor antibodies (Graves’ disease) Thyroglobulin (thyrotoxicosis factitia) Blood iodine /Urinary iodine (iatrogenic hyperthyroidism) ESR, C-reactive protein (CRP) (subacute granulomatous thyroiditis) TRH test (TSH-secreting adenoma, resistance to thyroid hormones)
Thyroxine-binding globulin Lipids
Monitoring
TSH, free hormone (whichever was abnormal) T4or T3 TSH receptor antibodies, in Graves’ disease
Thyroglobulin Thyroxine-binding globulin Blood iodine / urinary iodine ESR, C-reactive protein (CRP) Lipids