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

Journal Article · Wed Feb 01 04:00:00 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), Journal Name: J. Nucl. Med.; (United States) Vol. 25:2; ISSN JNMEA
• Country of Publication: United States
• Language: English

Related Subjects

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