IVNAA SYSTEM IMPROVEMENT, METHODOLOGY DEVELOPMENT, AND POPULATION STUDY ON NA RETENTION AND STORAGE

Sodium (Na) is one of the most important cations in our body. There are two pools for Na metabolism, representing rapidly (soft tissue) and slowly (bone) exchangeable compartments. New studies of Na regulation in adults have found that renal involvement in total body Na regulation is complemented by regulatory mechanisms in soft tissue and bone. This suggests the effect of dietary Na intake on blood pressure is influenced by Na retention and distribution. There is growing recognition of the need to measure Na in the two compartments to fully represent Na distribution. Whether sodium retention results in sodium being stored in bone or soft tissues without a corresponding increase in water likely affects blood pressure and the risk of developing hypertension. However, measuring Na levels in bone and soft tissue in vivo is a challenging task.

Our lab developed a DD neutron generator-based in vivo neutron activation analysis (IVNAA) system to quantify elements. For Na retention study in humans, the thermal neutron flux must be enhanced to improve the system sensitivity while maintaining radiation dose. Furthermore, there is a lack of analytical methods to quantitate Na in both bone and soft tissue using IVNAA, as well as limited clinical data on Na levels in these compartments.

In this project, we proposed a novel neutron moderation method for more sensitive IVNAA system design, developed methodology for Na quantification in different compartments, and completed the first clinical study investigating the association between Na intake and Na compartmental concentration among humans with relatively high blood pressure.