A Critical Evaluation of Separation Methods in Radiommunoassays for Total Triiodothyronine and Thyroxine in Unextracted Human Serum

Abstract

Methods for separating free and antibody-bound hormone in radioimmunoassays for total triiodothyronine (T-3) and thyroxine (T-4) in unextracted human serum are evaluated. For T-3 assay, a simplified second antibody technique has significant advantages over other methods and gives a mean interassay coefficient of variation of 7.2% over a wide range of values. For T-4 assay, polyethylene glycol is the method of choice and has a mean interassay coefficent of variation of 4.7%. By adding the separating agents initially, the assays are readily semi-automated and may be completed within a working day.

Zinc metabolism and thyroid status

“…iodothyronine (Ta) levels by a radio-immunoassay procedure utilizing rabbit anti-human T3 antiserum obtained from the National Institutes of Health, Bethesda (Ratcliffe, Challano and Ratcliffe, 1974).…”

Avian leukosis virus infection and shedding in brown leghorn chickens treated with corticosterone or exposed to various stressors

“…The sensitivity of the assay was <0.15 ng/ml, intra-and inter-assay coefficients of variation were 10% and 16%, respectively. Plasma triiodothyronine (T 3 ) level in induced-moulted hens was measured by a double-antibody radioimmunoassay (Ratcliffe et al, 1974). Full details of the procedures can be found in Williamson and Davison (1985).…”

Seasonal endocrine cycles in the European hedgehog, Erinaceus europaeus

“…Plasma thyroxin levels were determined at the School of Agriculture, University of Aberdeen, using a single sheep anti-thyroxin antibody radioimmunoassay based on the method described by Ratcliffe et al (1974). Polyethylene glycol separation of thyroxin was necessary.…”