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Immunoreactive‘ TSH’ in urinary concentrates of Graves' disease patients: a radioimrnunoassay artefact
Author(s) -
HERLE ANDRÉ J. VAN,
ORGIAZZI JACQUES,
GREIPEL MARGARET A.,
SLUCHER JEAN A.,
HONBO KEN S.
Publication year - 1978
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.1978.tb00845.x
Subject(s) - radioimmunoassay , urinary system , endocrinology , medicine , sephadex , urine , hormone , chemistry , biochemistry , enzyme
. A double antibody radioimmunoassay was used to analyse immunoreactive thyrotrophin in urinary concentrates from fourteen patients with hyperthyroid‐ism due to Graves' disease, in three subjects with primary hypothyroidism, and in six normal subjects. Immunoreactive thyrotrophin was detectable in eleven subjects with Graves' disease, in one subject with primary hypothyroidism, and in four normal subjects. The mean urinary thyrotrophin concentration was significantly higher in Graves' disease (492 ± 99.9 μU/24h (SEM) ( n = 11)) than in normal subjects ((177 ± 26.4 μU/ 24 h (SEM) ( n = 4) (P<0.01)). The fact that bioassay‐able thyrotrophin was undetectable in urinary concentrates in Graves' disease and that radioimmunoassay of other polypeptide hormones in urine can be influenced nonspecifically, led to the suspicion that the immunoreactive thyrotrophin measured in urinary concentrates was an assay artefact. This was strongly supported by the absence of a radioimmunoassayable thyrotrophin in urinary concentrates after extensive dialysis (96 h) without loss of added 131 I‐labelled thyrotrophin, differences between the elution pattern on Sephadex G‐100 columns of 131 I‐labelled thyrotrophin and the immunoreactive thyrotrophin detected after chromato‐graphy of the urinary concentrates on the same column, and the ability of different salts in various concentration to mimic dose‐response curves in the radioimmunoassay for thyrotrophin as well as for thyroglobulin. In addition, since urinary proteins and IgG levels were elevated in concentrates of Graves' disease when compared with normal subjects, it has been suggested that the filtering mechanism of kidney is affected in Graves' disease, a disorder which has recently been associated with circulating antigen—antibody complexes.