Serum or dried blood spot (Guthrie) samples are acceptable (ensure the latter are thoroughly dried before despatch).
If elevated, a second sample should be sent, at a 5 day interval, since only prolonged high levels support a clinical diagnosis of cystic fibrosis in the neonate. Patients on IV feeding should have their ‘normal’ IRT levels confirmed once oral feeding has been resumed.
Screening for Cystic Fibrosis
The infant must have been feeding on milk for at least 2 days before specimen collection, the usual age being 5 days. Cards collected up to the age of 1 month give valid results or up to 2 months for cystic fibrosis. Blood spot cards can be tested by the lab up to 1 month after collection.
Approximately 2 weeks
Specimen Labelling Procedure