A New Radioimmunoassay for Plasma l-Triiodothyronine: Measurements in Thyroid Disease and in Patients Maintained on Hormonal Replacement

Abstract

A B s T R A C T A niewN, proce(dure for the radlioitimutinoassay of i-triiodothyronine ( T:) inl h1uIm1ain plasima is (lescribed in whiclh the iodothivronine.s are separatedl frollm the pl)asma proteins before incubation with a specific anitiserumii to Ta. The antibody bound and free T. are separated with dextran-coated charcoal. In this system, the mean recovery of T added to l)lasma was 97.9% aand botlh in vitro conversion of L-thyroxine (T4) to T:. and crossreaction between T. and the anti-T3 antibody were undetectable (less thani 0.1% ). The assay procedure allowed the measuremiienit of T:, in up to 0.5 ml of plasma resulting in iml)roved assay sensitivity (6 ng/100 ml).The mean plasma T3 in normal subjects was 146±24 ng/100,ml (SD). Mean Ti concentration was increased in hyperthyroidism (665±289 ngj/100 ml') and decreased in hypothyroidism (44±26 ng/100 nml). In patients witlh severe hypothyroidism, pllasma T3 was betweeni 7 and 30 ng/100 nml. Plasnma T: concenitrationi was relatively constant throughout the day in three euthyroid subjects.In contrast, in hypothyroid subjects onI replacement therapy with T3, a T4: T3 comiibiniation or desiccated thyroid plasma T:, was markedly elevated for several hours after ingestion of the mledication. Plasma T. was unchanged throughout the day in patients treated with T.

Effect of 3,5,3'L-triiodothyronine administration on serum thyroid hormone levels in hypothyroid patients maintained on constant doses of thyroxine.

“…On the other hand, serum T3 concentrations were elevated after T3 administration in patients maintained on constant doses of T4. Previous studies (Surks et al, 1972;Saberi and Utiger, 1974) have shown that serum T3 concentrations were increased transiently within the first 1-8 hrs after ingestion of both T4 and T3, and returned to the initial value about 24 hr after ingestion. In order to minimize the influence of ingested T3 on serum T3 concentrations, serum were obtained just before the administration of the next daily dose in the present study.…”

Thyroid hormone: a “prime suspect” in human immuno deficiency virus (hiv/aids) patients?

“…Protein depletion or its calorie malnutrition depresses immune responses of the subjects or have other adverse effects (Haskova et al 1978;Scrimshaw et al 1968;Theofilopoulos et al, 1976;Reinhold, 1969). Starvation or under-nutrition impairs immunoglobulin (1g) and serum albumin levels; causes diminished mean absolute concentrations of total proteins, albumin, α 2 -globulins and β-globulins but had little or no significant effects on gamma globulin concentrations (Surks et al 1972;Samuel et al 1979).…”

“…Thyroid stimulating Hormone (TSH) was assessed using the double antibody RIA procedure of Surks, et al (1972) as specified by WHO International Laboratories (Kits) for Biological Standard London; courtesy of Chemical Pathology UCH, Ibadan. The kits were purchased locally from NUMS Diagnostics which is a subsidiary of UNIS Medical Laboratory Diagnostia Centre Ltd. Ameritek USA.…”

Relationship between the Accumulation of Pituitary Growth Hormone and Nuclear Occupancy by Triiodothyronine in the Rat

“…Plasma concentrations of T3 were measured by the radioimmunoassay procedure of Surks et al (16). The dose-response relationship was analyzed by the four parameter logistic equation described by Rodbard (17) with a computer program (APL) written in our laboratory (CYBER 74, University of Minnesota Computer Center, Minneapolis, Minn.).…”

“…These doses were selected because they are known to saturate the nuclear sites for the period of the experiment. At designated intervals (3,6,12,16,20, and 24 h) after the injection, rats were killed and pituitary GH content was measured. As shown in Fig.…”