Thyroid function tests radioimmunoassay

Eckersall, P. D., and M. E. Williams. 1983. Thyroid function tests in dogs using radioimmunoassay kits. Journal of Small Animal Practice 24 525-532. 

Whereas some of the recent advances in thyroid function tests have been necessitated by the new concepts of thyroid hormone physiology, others have been secondary to major technological advances in clinical chemistry, in particular the introduction of radioimmunoassay (RIA). 

A patient complains of nervousness, palpitations, sweating, and weight loss without loss of appetite, and has a goiter. Suspecting a defect in thyroid function, the physician orders a total serum T4. The test is performed by radioimmunoassay. The standard curve for the assay, which measures T4 in 0.1 ml of serum, is shown below. Normal levels of T4 = 4 — 10 pg/dl. In an assay of 0.1 ml of the patient s serum, 15% of the radioactive T4 was bound to the antibody. 

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