To assess the effectiveness of novel medicines and gauge the severity of the deadly disease cystic fibrosis, researchers have created a test that's urine that measure it.
A newly-developed urine test can make it much easier for doctors to diagnose how badly a patient is affected by the hereditary disease cystic fibrosis, which amongst other things alters the body's respiratory, digestive and reproductive systems.
The test can also reveal the extent to which the patient's medical treatment is of benefit. This has been shown by a new study from Aarhus University and Aarhus University Hospital that has just been published in the scientific journal Annals of Internal Medicine.
Cystic fibrosis is caused by mutations in the CFTR gene that code for the ion channel called CFTR. One important function of CFTR is to regulate the production of fluid and mucus in the lungs and digestive fluids in the intestine. Loss of CFTR function leads to thick mucus in the lungs and reduced amounts of digestive fluids. The consequence is inflammations and blockages that damage the organs. CFTR is also expressed in the kidneys where it alters electrolyte handling.
Now, by focusing on the kidneys and the urine, the researchers have developed a simple test, which likely shows how effective the treatment is for the individual patient.
"The goal is for the urine test to be used as a clinical tool to determine both the severity of the genetic dysfunction and the medicine's restorative effect in individual patients with cystic fibrosis," said Professor Jens Leipziger of the Department of Biomedicine at Aarhus University, who is one of the main actors behind the study, together with Peder Berg, Consultant Majbritt Jeppesen and Consultant Soren Jensen-Fangel.
Amongst other functions, the kidneys regulate the acid-base balance in the body, and studies have shown that patients with cystic fibrosis have a greatly reduced ability to increase the excretion of base by the kidneys as compared to healthy control subjects. This finding led the researchers to test the patients' ability to increase the base content in the urine, as a measure of CFTR function and thus the severity of the disease, as well as the degree of normalisation after treatment.
Until now, measurement of the chloride concentration in sweat has been the most widely used method of evaluating a patient's CFTR function. However, this method is time-consuming, requires experienced staff, has great intra-individual variation, and does not sufficiently reflect the severity of the disease. It is thus an important discovery that the excretion of bicarbonate in the urine can be used to characterise CFTR function and thus disease severity.
There are high expectations that the new medication will significantly improve the health of patients. In this study, the researchers examined 50 adult patients with the disease both before and after treatment with Kaftrio.
Another important finding is a clear correlation between the results of the urine test and disease severity, such as the degree of reduced lung function.
