Cystic fibrosis (CF) is the commonest major autosomal recessive disorder found in Caucasian populations in the western world. The incidence in Britain is approximately 1:2500 live births. It affects boys and girls equally. It is a multi-organ disorder with widespread dysfunction of the exocrine and mucus-secreting glands, characterized by chronic pulmonary disease, pancreatic insufficiency, liver dysfunction, and abnormally high sweat electrolytes. The CF gene was cloned in 1989 and many different mutations have now been identified and probably account for the varying clinical features of the disease.
Approximately 10% of children with CF present with meconium ileus at birth. The remainder are identified in early childhood with recurrent chest infections, failure to thrive, abdominal pain, and malabsorption. The diagnosis is confirmed by a raised concentration of sodium and chloride in the sweat on at least two tests. The immuno-reactive trypsin (IRT) test is used for screening (raised in CF) and is routinely performed in some centres. Antenatal diagnosis is also possible.
The main problem in cystic fibrosis is respiratory disease. Severe chronic lung infection leads to a gradual deterioration in pulmonary function in most children. Malnutrition has adverse effects on lung function and maintaining good nutrition has been shown to delay deterioration in lung function and improve growth and therefore survival rates.
Nutritional problems are multifactorial and include malabsorption related to the insufficiency of pancreatic enzymes, poor appetite with inadequate food intake, increased requirements due to recurrent infection, and urinary glucose losses due to diabetes.
The problems of malabsorption can be largely overcome by the use of enteric coated pancreatic enzyme supplements such as pancrease and creon which are extremely effective. The enzymes need to be taken with all food. Larger amounts are necessary with meals and smaller ones with snacks. Excessive intakes of pancreatic enzymes have been associated with colonic strictures in a small group of children and high dose lipase preparations are no longer recommended.
Nutritional requirements of children with cystic fibrosis include:
– increased energy intake to 120-150 % of average requirements
– a normal to high fat intake
– increased protein intake
– fat soluble vitamin supplements
– salt supplements in hot weather.
To achieve these increases, dietary supplements are usually necessary and in some cases supplementary tube feedings may be used. Because of the growing complexity of management and the problematic nature of some current therapy, children may require repeated stays in hospital. The treatment including the administration of antibiotics, enzyme preparations, dietary supplements, and physiotherapy take up a great deal of time. The families need much help and support. The Cystic Fibrosis Research Trust offers support and advice.