Serum concentrations of 3,3',5'-triiodothyronine (reverse T3) in normal pregnancy.
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Biomedical subjects
Publications and source records attributed to C M Aickin.
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An accurate and reproducible method for measurement of radioactive species in blood after in vivo injection of labelled iodothyronines is described. By extraction with high-affinity antisera, radioactive reverse T3 and T3 are separated from serum quantitatively. Radioiodide is quantitatively separated from radio-thyronine species and serum proteins by Sephadex G50 filtration. The residual mixture of radio-T4 and iodoprotein is quantitatively resolved by ion-exchange adsorption. Minimal misclassification of radiospecies occurs, and can be corrected for. Mean recoveries of various radiospecies added to serum were: radioiodide 98.9%, radio-rT3 87.6%, radio-L-T3 94.5%, radio-T4 98.0% and radioiodoprotein 94.5%. The performance of the method is superior to that of chemical methods such as trichloracetic acid precipitation, ion-exchange or alkaline Sephadex extraction, and chromatographic separation.
Thyroid function and serum levels of triiodothyronine (T3) and thyroxine (T4) were investigated in 79 euthyroid geriatric patients. Of the 59 inpatients and 20 outpatients 35 (59%) and 2, respectively, had low T3 levels. In contrast, 7 (12%) and 6 (30%), respectively, had raised T4 levels. Two further patients were excluded from the study because of raised levels of thyroid-stimulating hormone. Thyroxine-binding globulin was greatly increased in both groups of patients, but low serum albumin levels were present in 31 (39%). Despite these changes free T3 and T4 indices closely followed total T3 and T4 levels. The difference between the two groups of patients did not correlate with body weight, diagnostic categories, age, drug treatment, or duration of stay in hospital.