ORAL SALT TOLERANCE TEST PROVED SODIUM EXCRETION CURVE CHANGED AFTER SEVEN YEARS FOR THE FIRST SUBJECT

Objective: We established a novel test, oral salt tolerance test (OSTT), in 2017 to investigate sodium metabolism which could reflect the sodium excretion ability after a certain oral salt load. The aim of this study is to compare the sodium excretion ability change after seven years for the first subject.Design and method: We repeated oral salt tolerance tests for the first subject in 2017 and 2024. In each year, the subject repeated three times of oral salt tolerance test. The process of oral salt tolerance test is listed in Figure 1. Results: 1. For the same subject, the sodium excretion curve changed obviously in 2024 compared that in 2017.(Figure 2) 2. The total sodium excreted by urine until 3 hours after taking 4.5 g sodium chloride was less than half of it in 2017. (Figure 3) 3. The total sodium excreted by urine until 3 hours after taking 4.5 g sodium chloride in 2024 was only about half of that in 2017. (Figure 3) Conclusions: Repeated oral salt tolerance test after seven years revealed that the urine sodium excretion ability after a certain oral salt loading might change by age. This might be related with the whole process of sodium metabolism from absorption, buffering, transferring, storage and excretion.