IRT-test elevated

Question

Hello,
the screening of my newborn showed an increased IRT-value. Now we have to have it controlled in 2 weeks. Have now great fear that my son could suffer from CF. What is the probability?
Many thanks in advance,
M.

Answer

Hello,
your child has had a test, that is part of a newborn screening for CF. The IRT/IRT-screening, that is concerned here, has the disadvantage, that initially positive tested children need to have a second blood sample taken, what is accompanied not only by the pain for the child but also with a substantial insecurity of the parents until the second testing. According to experience, in the first testing initally the 1.0-2.5% of all samples with the highest values are regarded to be positive, depending on the performance of the test. After no later than 21 days the test is repeated, as the IRT, which can initially not only be increased due to CF, should have decreased again to normal values in those newborns who are not suffering from CF. After the second test remain about 0.02% of all tested newborns, who suffer with a high probability from CF, that has however again to be proved in a corresponding center. That means, the chance that your child is not suffering from this disease is very high.
My above statement is only true however, if it deals with a newborn screening, in which the first dry-blood card is taken within a time frame of the first 36-72 hours of life. According to my knowledge, this procedure is/was offered like this actually only in Austria. In Germany, we are seeking for the introduction of a newborn screening for CF, however in our country, it is very likely that another test protocol will be used, in here the inital IRT-testing is done right from the first dry-blood card as well as another confirming investigation.
I keep my fingers cross for you that everything turns out to be good.
Best regards,
Olaf Sommerburg

05.06.2013