AmBeR

Evaluation and validation of a breath ammonia measurement technology for the improved management of patients with urea cycle defects

Summary

There is a group of rare genetic disorders termed Urea Cycle Defects (UCDs) which mostly affect children. When you eat protein, it contains the element nitrogen, which can be poisonous if not removed from your body.

Nitrogen is normally safely removed in urine as part of a larger molecule called urea. However, children with UCDs are not able to change the nitrogen to urea. Instead, the nitrogen can become part of another molecule called ammonia. You may have heard of ammonia being used as

a chemical, for instance, as cleaning fluid and so it can be quite dangerous. It is also poisonous if it builds up inside the body. This is what can happen to children with UCDs. If this happens, the ammonia can poison the brain, leaving the children with learning difficulties or can lead to coma and death.

In many cases, there is no cure for this disease and these children and their families live with this condition all of their lives. Mostly, they are quite healthy; as long as they are careful about how much protein they eat and never leave it too long between carbohydrate meals. Most patients also

need to take medication to help clear the ammonia that builds up naturally in order that it can be removed by the kidneys. However, if they become unwell with something like a cold or a tummy bug, this can upset their ammonia levels and they can become extremely unwell very quickly. It is

very difficult for their parents to be sure whether they are just a little bit sick, or whether they will get really sick with high ammonia and so they must always bring them into the hospital to have their ammonia levels checked. This causes daily worry and regular disruption to their lives.

At the moment, the best way the doctor can tell if a child is sick is to test the ammonia in their blood, which is particularly difficult to do, as well as not being pleasant for the patient. What might help patients would be a way that they could easily monitor their own ammonia levels at home, regularly and conveniently, so that they could be sure if their child was developing high ammonia levels or not. This could even mean that the doctors could tell the parents what to do to make things better, without having to go to the hospital, or at least only having to bring them in because they really were sick.

A device has been invented which measures the ammonia in your breath. It is believed that the ammonia in your breath is related to how much ammonia is in your blood. However, this needs to be properly tested. If this were found to be true, and if the patients and their families could regularly measure the breath ammonia by themselves, it might allow children with UCDs to live longer, healthier, happier lives, while also saving money. This research wants to see if this is the case.