PROJECT SUMMARY/ABSTRACT
Central diabetes insipidus (DI), caused by a deficiency of the hormone vasopressin, is a rare disease that
affects 1 in 25,000 individuals. Individuals who lack vasopressin can quickly have high sodium levels and are
vulnerable to dangerous dehydration, leading to frequent hospitalizations. Treatment for DI includes
pharmacologic vasopressin replacement and careful regulation of fluid intake. While under-treatment of DI
causes hypernatremia (high blood sodium levels) and dehydration, over-treatment causes hyponatremia (low
blood sodium levels), which can lead to seizures, permanent neurological injury, multi-system organ
impairment, and even death. The most substantial barrier to optimal DI management, and to preventing
complications and hospitalizations, is the lack of readily available, quick, and accurate blood sodium
measurements. Individuals with severe DI travel to hospitals frequently and the delay in return of sodium levels
due to unavailability of rapid tests leads to preventable complications from mismanagement of DI. There is
therefore a substantial unmet need for in-home sodium monitoring in the target pediatric DI population as well
as an exciting potential of a sodium monitor specifically designed and approved for in-home use.
Currently available blood electrolyte analyzers are expensive laboratory instruments, accept venous blood at
volumes much higher than fingersticks, and are not practical for routine in home testing for blood sodium. The
overall goal of this program is to develop an in-home, cost-effective sensor product that accurately measures
blood sodium. A rapid and simple electrochemical test to quantify the blood levels of sodium meets a
critical need within DI care. Giner will develop a handheld blood sodium monitor and demonstrate
quantitative detection of sodium using small volume fingerstick blood volumes (< 100 µl), within a broad linear
range of 100-360 mM (normal range is 138-146 mM). Giner will utilize a modified ion-selective electrode (ISE)
approach that will allow for rapid (single-step), label-free, and reagent-free operation similar to a blood glucose
test. The Aims of the Phase I feasibility program are: 1) Development of a sodium test strip modified with
sodium ion selective membrane (ISM) formulations; 2) Development of sample handling techniques and
sensor calibration for point-of-care operation; and 3) Adapting sensor for blood analysis, testing with blood
plasma samples, and benchmarking performance against the standard clinical chemistry methodologies.