Influence of erythrocyte iodothyronine-binding proteins on radioimmunoassay of thyroxin in dried blood spots
Three erythrocyte proteins, one identified as hemoglobin, bind thyroid hormones. Using a dextran/charcoal radioimmunoassay for thyroxin in dried blood spots, we demonstrate that such binding differs with the buffer used. Barbital, phosphate, and borate buffers significantly enhance the binding more than glycine and tris(hydroxymethyl)methylamine buffers. Binding is not affected by agents commonly used to inhibit thyroxin binding to serum proteins. A highly significant nonlinear direct relationship between sample storage (temperature and duration) and increased thyroxin-erythrocyte binding is documented, together with an associated decrease in assayed concentrations of thyroxin. However, concomitant serial measurement of thyroxin with polyethylene glycol and combined double-antibody/polyethylene glycol radioimmunoassays produced no evidence of interference by erythrocyte proteins in the radioimmune reaction. We conclude that erythrocyte proteins act only as low-affinity secondary binders in radioimmunoassay for thyroxin.
- Research Organization:
- Christchurch Hospital, New Zealand
- OSTI ID:
- 5639400
- Journal Information:
- Clin. Chem. (Winston-Salem, N.C.); (United States), Vol. 28:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COMPLEXES
RESPONSE MODIFYING FACTORS
THYROXINE
RADIOIMMUNOASSAY
BLOOD
ERYTHROCYTES
HEMOGLOBIN
INHIBITION
IODINE COMPOUNDS
PATIENTS
SAMPLE PREPARATION
TEMPERATURE EFFECTS
UPTAKE
AMINO ACIDS
BIOLOGICAL MATERIALS
BLOOD CELLS
BODY FLUIDS
CARBOXYLIC ACIDS
GLOBIN
HALOGEN COMPOUNDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HORMONES
ISOTOPE APPLICATIONS
MATERIALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PEPTIDE HORMONES
PIGMENTS
PORPHYRINS
PROTEINS
RADIOASSAY
THYROID HORMONES
TRACER TECHNIQUES
550601* - Medicine- Unsealed Radionuclides in Diagnostics