[Recent developments of measurements for pituitary-thyroid hormones: evaluation of five immunometric assay methods (RI and non RI methods].

We evaluated five commercially available immunoassay kits for pituitary-thyroid function tests. The possible interference in analysis by immunoglobulin G (IgG) has also been examined. The BeriLux TSH assay kit (Hoechst co. FRG) was compared with two other non-RI methods (AIA-1200 and IMx) and two other immunoradiometric assays (RIA-gnost TSH IRMA and EIKEN IRMA kits) in 32 normal subjects and 92 patients with Graves' disease. The new ICMA BeriLux kit had a marked improved analytical and clinical sensitivity. The minimal detectable level of TSH in the assay was 0.006 mU/l. The precision was 2.8% and 6.1% at 0.093 +/- 0.003 mU/l and 0.028 +/- 0.002 mU/l, respectively, whereas the levels for the other methods were above 17.2% and 59.4% respectively. The TSH pattern was always less than 0.006 mU/l with the BeriLux kit, before and after TRH administration whereas the other methods showed random fluctuations which indicated their low accuracy at this concentration. This new ICMA BeriLux kit appears far more reliable than the ordinary immunometric assay kits.