Breath Test for At-Home Monitoring of Ammonia for Individuals with Chronic Kidney Failure or with a Urea Cycle Disorder

In individuals with healthy liver and kidney function, ammonia that is produced through the normal metabolism of protein is converted to urea in the liver and cleared from the blood stream via the kidneys. However, individuals suffering from chronic kidney disease (CKD) are not able to properly clear urea from the blood stream, which leads to elevated ammonia concentrations in the blood stream. Currently no method exists for CKD patients to monitor their physiological status at home similar to what diabetics are able to do with glucose testing. Instead patients must rely on periodic visits to the clinic to have their blood tested to evaluate their kidney function. Several studies conducted over the past decade have shown that the measurement of ammonia in exhaled breath actually correlates with kidney function, thus providing a non-invasive way of potentially monitoring patients with CKD to assess the severity of their condition. While the measurement of exhaled breath ammonia thus provides a potential alternative to a blood test, currently available methods involve the use of expensive and complex diagnostic equipment that is not suited for at-home use by patients to monitor their own blood urea concentration. The objective of this research is to develop and clinically evaluate a simple, low-cost test method to measure the ammonia concentration in exhaled breath with the potential to serve as an at-home method for patients with CKD to monitor their physiological status on a routine basis.

The ability to monitor blood ammonia level by a breath test would also be extremely beneficial for individuals who have a genetic defect in one of the liver enzymes involved in the conversion of ammonia to urea, which is a condition referred to as a urea cycle disorder (UCD). Individuals with a UCD must constantly be on guard that their blood ammonia concentration does not increase beyond a critical, even life-threatening, level, which can be induced by periods of physiological stress, such as physical illness. Currently persons with a UCD have no at-home means of monitoring their blood ammonia levels, requiring trips to the emergency room whenever elevated ammonia levels are suspected to possibly be occurring.