borderline IRT test

Question

I have an 8 months old baby girl that weighs 8.8 Kg and is 73 cm tall. The first IRT test at the maternity ward was borderline (126), the second one at 21 days of life negative (52). We have visited a gastronenterologist when she was 3 months old because her stools had blood and mucus. We were told she was allergic to milk and prescribed us a special kind of milk. Due to her good growth the doctors exclude the possibility of CF. She had once a mild bronchiolitis when she was 7.5 months old and was treated at home. The parents have not been genetically tested, we intend to do so when we gather the money. I am worried though. We have not done a sweat test, because the family environment does not consider it necessary since the paediatrician has not recommended it and they think I am obsessed. Does jaundice affect the IRT results and could it be the reason we had a borderline test the first time? Is it necessary for the baby not to gain much weight for a CF diagnosis? Thank you!

Answer

Dear friend,
You have an 8 months old baby girl with good weight and height. When she had blood in her stools at the age of 3 months you had a diagnosis of allergy to milk.
She also had a positive IRT test (at birth), which when repeated at 21 days of life came up negative. This is a way for the early diagnosis of CF. The IRT test is performed during the first 3-5 days of life, and, if positive, is repeated at day 21. If the second test comes up positive as well, further checking is required immediately. If not, there is no need to do anything.
You do not have to do a genetic testing. If you are worried, you can contact our center at Agia Sofia Hospital for an appointment for a sweat test and to discuss the situation with me, or leave your number to call you back, if you reside in or nearby Athens.
Yours friendly,
Dr. Stavros Doudounakis

19.05.2014