Simultaneous in vivo measurement of total body nitrogen by neutron-activation analysis and of protein turnover in humans and animals

Abstract

A knowledge of body protein content and turnover obtained by non-destructive analysis is of great value in many areas of clinical science and agriculture, concerned for example, with nutrition, growth and development. Measurement of nitrogen can be used as an indicator of protein and we describe what we believe to be some of the first simultaneous in vivo measurements of total body nitrogen and protein turnover in individuals and demonstrate that our techniques are suitable for sequential studies both in humans and animals as small as juvenile rats. In vivo neutron-activation analysis is used for total body nitrogen while mass-spectrometric measurement with a ¹⁵N-labelled amino acid tracer is used for protein turnover. Neutron activation is compared with a chemical method in animal carcasses.