Evaluation of an immunoextraction procedure for the estimation of free thyroxine concentration

Journal Article · Wed Feb 01 00:00:00 EST 1984 · J. Nucl. Med.; (United States)

OSTI ID:5242620

Witherspoon, L R; Shuler, S E; Gilbert, S S

The authors have examined the performance of a commercial free-thyroxine assay in which a radiolabeled T/sub 4/ derivative permits the competitive quantitation of extracted T/sub 4/ in the presence of serum proteins. After the total T/sub 4/ pool had been radiolabeled with either I-125 T/sub 4/ or I-131 T/sub 4/, the solid-phase antibody was found to be associated with 4-8% of the total T/sub 4/ present in the assay tube. Of this, 15-60% was displaceable (antibody-bound). The assay estimated free T/sub 4/ to be 0.6-1.8 ng/dl in euthyroid patients, and distinguished them from hyperthyroid (sensitivity 91%) and hypothyroid patients (sensitivity 91%) without apparent TBG dependence. In patients with severe nonthyroidal illnesses, the assay correctly quantitated a reduced extracted mass in some. In other patients, however, the assay results were inappropriately lower than the actual extracted mass, in agreement with the FTI but not with the measurements of free T/sub 4/ by dialysis. This assay appears to produce clinically appropriate results in most patients. In some nonthyroidally ill patients however, the indicated free T/sub 4/ is spuriously low.

• Research Organization: Ochsner Clinic, New Orleans, LA
• OSTI ID: 5242620
• Journal Information: J. Nucl. Med.; (United States), Vol. 25:2
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
59 BASIC BIOLOGICAL SCIENCES
ENDOCRINE DISEASES
DIAGNOSIS
IODINE 125
RADIOIMMUNOASSAY
IODINE 131
THYROXINE
ANTIBODIES
BLOOD SERUM
HYPERTHYROIDISM
HYPOTHYROIDISM
PATIENTS
AMINO ACIDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
DAYS LIVING RADIOISOTOPES
DISEASES
ELECTRON CAPTURE RADIOISOTOPES
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
PEPTIDE HORMONES
RADIOASSAY
RADIOISOTOPES
THYROID HORMONES
TRACER TECHNIQUES
550601* - Medicine- Unsealed Radionuclides in Diagnostics
550900 - Pathology