T4 can be measured directly by radioassay (or, more recently, by enzyme-linked assay). Radioassay involves competition of patient hormone and radioactive hormone for a hormone binder. In T4by radioimmunoassay (T4-RIA) the binder is anti-T4antibody; in T4 competitive binding (T4-CPB) or T4 displacement methods (T4-D) the binder is T4-binding serum protein. After patient T4 and radioactive […]