| Abstract | [SUMMARY] One aspect of the history of radio-pharmaceuticals has been the constant effort to reduce radiation to the patient. The earliest isotopes used were 32P, 131I, and 198Au; these products were largely used as therapeutic agents. The diagnostic use of isotopes was a closely following secondary development, and this period of history saw the development of diagnostic in-vivo products such as 131I diagnostic capsules, RISA-125 and -131, cyanocobalamine Co-57 and Co-60, Hippuran-125 and -131, and many others. The next generation of products has been the development of the in-vivo use of very short-lived products such as 99mTc, 113mIn, 87mSr, and others, which decrease Radiation to the patient to a minimum. Concurrent with this last development has been the development of the in-vitro isotope laboratory test as an aid to diagnosis. In in-vitro testing, the patient receives no radiation whatsoever. Radiation is simply used as a tool to measure the extent of inter-reaction between a labeled chemical and a body fluid (serum) constituent, or to measure the concentration of a substance in a body fluid. Either approach may lead to a better understanding of the physical condition of the body. In-vitro isotope tests thus far developed are based on several related principles two of which are most common: 1) Saturation analysis, direct and indirect. Examples of the use of this principle are the T3 test, the LIBC test, the measurement of the total serum thyroxine, and others. 2) Immuno-assay. Examples of the use of this principle are the measurement of serum insulin levels, human growth hormone levels, and others. 3) Miscellaneous. Illustrations will cover the more recent developments in in-vitro testing including the development of tests for latent iron binding capacity, zinc binding capacity, total serum thyroxine, human growth hormone, and steroids. |
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