Malabsorption.

Laboratory diagnosis of malabsorption syndromes in children is more difficult for obvious 
reasons involving the collection of specimens. The early diagnosis of cystic 
fibrosis is extremely urgent, since the disease is treatable. The standard 
test is the sweat test. Over 99 percent of patients with 
this disease will have elevation of sodium and chloride in the 
sweat. Three tests are used to assess pancreatic function. First is 
the measurement of stool trypsin and chymotrypsin. Second, stimulation with hormones 
- the standard secretin and CCK tests. A third procedure tests 
carbohydrate tolerance, an increasingly important test since an ever-growing number of 
patients in late childhood and early adulthood with cystic fibrosis are 
being found to have diabetes mellitus. The commonest and most important 
hereditary disease that affects pancreatic function is cystic fibrosis. The commonest 
form of pancreatic insufficiency in childhood is mucoviscidosis or cystic fibrosis 
of the pancreas. The incidence of this disease is approximately one 
per 1000 live births. It occurs in all races, and the 
defect is transmitted as an autosomal recessive. The classic features are 
frequent bowel movements with the characteristic appearance of steatorrheic stools, and 
a failure to grow and develop normally. 