The use of stable isotopes for diagnosis and clinical research.

Stable, non-radioactive isotopes, so long overshadowed by radionuclides, have recently become much more widely used in clinical science. This renewed interest has been stimulated by improvements both in the increased availability and diversity of stable-isotopelabelled compounds and in mass-spectrometric methods for their quantitative analysis. In addition, there is an increasing awareness of the advantages of stable-isotope techniques for patient safety and applicability to clinical problems. The object of this review is to outline methods of stable-isotopic analysis and to survey the results of the application of 2H, 13C and 15N-labelled compounds in clinical research. Previous reviews on this topic have considered the use of 2H for the quantification of total body water and intercompartmental water movements, 13C for absorption and incorporation studies using fatty acids and triacylglycerols and 15N for metabolic studies with ammonia, urea, creatinine, uric acid and for quantitative haematological studies 11, 21. It is hoped that the present review will stimulate clinical interest in the potential use and scientific advantages of stable isotopes. In addition, we wish to emphasize the possible benefits of increased patient acceptability and applicability in cases where radioisotope measurements are impossible.