Instrument design considerations and clinical applications of stable isotope analysis.

stable isotopes of carbon, hydrogen, and nitrogen offer a number of advantages in clinical work: problems of preparation, storage, and disposal are negligible, health monitoring requirements are eliminated, and most significantly, the absence of radiochemical hazard to the patient permits their use in obstetric and pediatric measurements. It is our belief that the potential of stable isotope analysis in these areas, in mass screening applications, and as long-term replacements for radioactive isotopes warrants an extensive development of the necessary instrumentation for routine clinical use. This report describes some of the considerations governing the development of such an instrument, its present status in our laboratory, and an example of its application to studies conducted at the Mayo Clinic. The widespread use of ‘4C and H in current metabolic studies is attributable to, and a tribute to, the development of liquid scintillation counting techniques. Since their introduction in the early 1950’s (1), liquid scintillation spectrometers have made it possible to count samples accurately, with great sensitivity, in a routine manner. Moreover, these instruments have proved to be reliable in operation, capable of handling numerous samples in an automatic mode, and adaptable to a variety of other radioactive isotopes. It is safe to say that stable isotope analysis must become at least competitive with the existing liquid scintillation counting systems if it is to be generally applied in the clinic.