Acute renal failure in people with cystic fibrosis

The putative gene in cystic fibrosis (CF) encodes a protein, cystic fibrosis transmembrane conductance regulator (CFTR), which has an important role in transepithelial salt transport.¹ The major organ affected in CF is the lung, with remorseless and intense chronic airway infection resulting from disabled clearance of dehydrated airway surface liquid.² Airway inflammation leading to end stage lung damage is associated with respiratory morbidity and early death. The outlook for people with CF has improved considerably with a proactive approach to treatment of airway infection as one of the cornerstones of its management. Recent data from the US CF registry suggest a continuing improvement in median predicted survival to over 35 years (http://www.cff.org/research/2006NACFC/Plenary III). With an improving outlook, perspectives have changed and expectations of people with CF and their carers have broadened. A survey of acute renal failure (ARF) in patients with CF published in this issue of Thorax (see p 541) is particularly timely when reflecting on how best to achieve the goal of increased survival while balancing risks to patients.³

ACUTE RENAL FAILURE AND CF

There are several reasons why people with CF are at risk of ARF. The salt transport defect makes people with CF prone to salt loss and consequently fluid imbalance and dehydration.^4,5 The impact of CFTR dysfunction on pancreatic function and architecture results in significant hypoinsulinaemia (CF-related diabetes) in a significant proportion of older patients with CF, again posing a challenge to fluid balance and the long-term possibility of diabetic kidney disease.^6,7 Finally, as a cohort, these patients are exposed to industrial quantities of potentially nephrotoxic chemotherapeutic agents (in our CF centre some children have received a cumulative intravenous dose of over 300 g of the aminoglycoside tobramycin). Given cumulative exposure to potentially …