In people with liver disease or other metabolic disorders, blood ammonia levels can quickly climb to dangerous levels. And unfortunately, checking those levels is not a fast and easy process. A newly developed device, however, could change that.
A byproduct of the digestive process, ammonia is converted into urea by the liver, then passed out of the body in the form of urine. Problems can arise when a person's body is unable to adequately metabolize that ammonia, allowing it to accumulate in the bloodstream.
If the condition is left untreated, physical and mental problems – including brain damage – may result. In the case of newborn babies, that damage can occur within just several hours of a rise in blood ammonia levels.
What's more, testing the blood for ammonia involves transporting a cold-stored sample to a lab, then waiting at least two hours as that sample is centrifuged and subjected to a biochemical assay. Even then, it's not uncommon for the testing process to not work the first time around, requiring a second sample to be drawn and analyzed.
With these limitations in mind, scientists at Stanford University have developed a portable blood ammonia detector that can be used anywhere, delivering results in less than a minute. What's more, it only requires a single drop of the patient's blood, which is reportedly less than 1 percent the amount needed for traditional lab-based testing.
The prototype, which is about the size of a TV remote, works with cheap test strips that were designed specifically for it.
Users start by placing a drop of blood on the end of one of those strips. The fluid is subsequently drawn through a hole in the strip, down a microfluidic channel, and into a paper-lined well at the other end of the strip, which is inside the device. An inexpensive chemical within that well causes any ammonia that's present in the blood to separate from it. A sensor located directly above the well can then easily detect and quantify the ammonia, providing the user with a reading.
The prototype has already been tested on blood samples that were spiked with ammonia, and on samples drawn from patients who were known to have high ammonia levels. Its readings were in line with those obtained through conventional testing methods.
"I’ve spoken with families who have children with this condition about having this kind of device and it makes them emotional because, for them, the consequences of not getting ammonia checked accurately and quickly are so severe," says Asst. Prof. Natalia Gomez-Ospina, a member of the team that developed the detector. "For these families, it could be life-changing."
A paper on the research, which is being led by Prof. Gilbert Chu, was recently published in the journal ACS Sensors.
Source: Stanford University
