A case of Graves' disease with false hyperthyrotropinemia who developed silent thyroiditis.
We encountered a patient who developed silent thyroiditis during the course of Graves' disease. The diagnosis of silent thyroiditis was made on the basis of a low thyroidal 131I uptake, no response to the thyrotropin releasing hormone (TRH) test, and subsequent hypothyroidism despite the presence of high titers of thyrotropin (TSH) receptor antibody (TRAb) and thyroid stimulating antibody (TSAb). The patient, in addition, had a discrepancy between serum TSH and thyroid hormone values. This was due to the presence of interfering substances that react to mouse IgG in the sera since serum TSH levels were decreased in a dose dependent manner by the addition of increasing amounts of mouse IgG to the sera. It should therefore be noted that silent thyroiditis can develop in patients with Graves' disease. Furthermore, clinicians should be aware that two-site immunoassay kits that use mouse monoclonal antibodies are subject to interference by some substances, possibly antibodies which react to mouse IgG.
Fourth Department of Internal Medicine, Saitama Medical School, Japan.
M
M
Iitaka
J
J
Ishii
N
N
Ishikawa
H
H
Yoshimura
N
N
Momotani
H
H
Saitou
K
K
Ito
D000328:Adult; D000911:Antibodies, Monoclonal; D001323:Autoantibodies / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D005260:Female; D006111:Graves Disease / Q000097:blood* / Q000150:complications*; D006801:Humans; D007037:Hypothyroidism / Q000209:etiology; D007118:Immunoassay; D007074:Immunoglobulin G / Q000502:physiology; D018828:Immunoglobulins, Thyroid-Stimulating; D007455:Iodine / Q000493:pharmacokinetics; D007457:Iodine Radioisotopes; D013966:Thyroiditis / Q000209:etiology*; D013972:Thyrotropin / Q000097:blood*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D007074:Immunoglobulin G; D018828:Immunoglobulins, Thyroid-Stimulating; D007457:Iodine Radioisotopes; D014284:Triiodothyronine; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin; D007455:Iodine; D013974:Thyroxine