Cystic fibrosis (CF) is the most common life limiting genetic disorder of white populations. There are over 6000 patients in the UK with this condition and at least 30 000 in the USA.¹ This review focuses on the challenges of diagnosis, clinical complications, and management of children with CF.

DIAGNOSIS OF CF

CF is a multisystem disorder with a wide spectrum of clinical manifestations, and patients may present to a range of medical specialists. Table 1 lists some of the clinical features, which may lead to a presentation of CF. The diagnosis can be confirmed by sweat and/or genetic testing. In 2001, the UK’s Department of Health announced that newborn screening for CF would be introduced nationally and it is likely that this will be implemented by 2006. By identifying infants with CF at an early age, newborn screening will have a considerable impact on the investigation of children with suspected CF. However, in most areas of the country, for many years there will be a large cohort of children and adults with CF who have not been diagnosed as part of a neonatal screening programme and who will need to be investigated by sweat and/or genetic testing. Sweat testing will also continue to play a role in the investigation of the infant where the screening tests suggest CF.

Sweat chloride > 60 mmol/l is considered diagnostic of CF. Values of sweat chloride of 40–60 mmol/l are considered highly suggestive of CF, and in this situation the sweat test should be repeated and/or genetic testing conducted. Although in CF patients there is a fall in sweat chloride with age, the magnitude of this fall is not sufficient to cause diagnostic confusion, if these criteria are used.² Sweat sodium measurements are less reliable as concentrations of 60–80 …