Free thyroxin by radioimmunoassay: evaluation of a new direct method involving a radiolabeled thyroxin analog

Journal Article · Sat Oct 01 04:00:00 EDT 1983 · Clin. Chem. (Winston-Salem, N.C.); (United States)

OSTI ID:6670235

Kubasik, N P; Lundberg, P A; Brodows, R G; Hallauer, G D; Same, D G; Lindstedt, G; Bengtsson, C; Nystroem, E

The first performance evaluation of a new direct method for free thyroxin (T4) in serum by radioimmunoassay, with use of coated tubes and a radioiodinated T4 analog (Diagnostic Products Corp.) is presented. The assay is precise and robust: within-run imprecision (CV), 3.1-6.6%; between-run imprecision, 4.0-7.9%; no demonstrable variation between technologists irrespective of experience with the method. No outliers were observed when we compared the free T4 results with serum total T4. Reference values are reported for a total of 1243 euthyroid subjects; there was no significant age effect on serum free T4 in women 26 to 72 years old. The biological variation was about +/- 35% of the mean (2 SD). Free T4 results are the same for serum and plasma. The assay performs well in hypothyroidism and hyperthyroidism, and distinguishes individuals with thyroid disease from normal individuals. Free T4 values in women taking oral contraceptives are normal. Depressed results were often observed in acute nonthyroidal illness and continuing pregnancy. These results were directly comparable with those of another commercial direct radiolabeled-T4 analog kit for free T4.

• OSTI ID: 6670235
• Journal Information: Clin. Chem. (Winston-Salem, N.C.); (United States), Journal Name: Clin. Chem. (Winston-Salem, N.C.); (United States) Vol. 29:10; ISSN CLCHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINO ACIDS
BLOOD SERUM
CARBOXYLIC ACIDS
DIAGNOSIS
DISEASES
ENDOCRINE DISEASES
EVALUATION
HORMONES
HYPERTHYROIDISM
HYPOTHYROIDISM
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
PATIENTS
PEPTIDE HORMONES
RADIOASSAY
RADIOIMMUNOASSAY
THYROID HORMONES
THYROXINE
TRACER TECHNIQUES