[Contribution of TRH test and anti-TPO antibody assay in the screening of infraclinical hypothyroidism].
The upper limit of normal TSH levels, determined with a second generation kit (RIA-Gnost TSH, Behring) was set at 2.8 microU/ml. These TSH levels define pituitary reactivity in euthyroid subjects. The upper limit for TSH 20 minutes after injection of TRH was set at 23 microU/ml. The diagnosis of infraclinal hypothyroidism should be made in patients with a normal hormone level, normal baseline TSH and a positive response to TRH defined as a TSH above the upper limit 20 minutes after injection. A large percentage of these patients were positive for anti-TPO antibodies, emphasizing the risk of developing patent hypothyroidism. Clinicians should be aware of the need to lower the upper limit for baseline TSH, often set a 4 or even 6 microU/ml. A level of 2.8 to 4 microU/ml is recommended as the upper limit. Within this interval, the TRH test should always be performed since 50% of the TSH values obtained under in such patients are abnormal.
Hermans
J
J
Service d'oncologie et de médecine nucléaire, Hôpital de Jolimont, Haine-Saint-Paul, Belgique.
Wadeleux
P
P
Bodart
F
F
Beauduin
M
M
D001323:Autoantibodies / Q000097:blood*; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000517:prevention & control*; D007453:Iodide Peroxidase / Q000276:immunology*; D008403:Mass Screening; D013963:Thyroid Hormones / Q000097:blood; D013972:Thyrotropin / Q000097:blood*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D001323:Autoantibodies; D013963:Thyroid Hormones; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin; D007453:Iodide Peroxidase
Apport du test à la TRH et du dosage des anticorps anti-TPO dans le dépistage de l'hypothyroïdie subclinique.