Diagnostiek van cystische fibrose; liever eenvoudige genotypering om de ziekte uit te sluiten dan starten met de zweettest

- For historical reasons, the sweat test remains the cornerstone in the diagnostic work-up for cystic fibrosis (CF).

- If CF is suspected, the sweat test (following pilocarpine iontophoresis) is usually performed first to confirm or rule out the diagnosis of CF.

- Sweat testing, however, is cumbersome to the patient, prone to technical difficulties and unreliable in young children < 4 weeks as well as in adults because of increasing chloride concentrations with age. False-positive and false-negative results do exist.

- Simple DNA testing with PCR in peripheral blood for a small number of the most common mutations causing CF, notably the ΔF508-mutation in the Dutch population, rules out CF with a likelihood of more than 99.

- Because of the high negative predictive value of DNA testing, in combination with its speed, reliability and convenience for the patient, starting the diagnostic work-up for CF with DNA testing can be justified in hospitals which possess the laboratory facilities for this type of test.