1. Laboratory studies are being performed on a 5-year-old boy to determine whether there is a metabolic reason for his continued failure to gain weight. In addition to having blood drawn, the patient has a sweat chloride collected, provides a random stool sample, and is asked to collect a 72-hour stool sample.

a. How can the presence of steatorrhea be screened for by testing the random stool sample?

b. How does this test distinguish among neutral fats, soaps, and fatty acids? c. What confirmatory test should be performed?

d. Describe the appearance of the stool specimens if steatorrhea is present.

e. If a diagnosis of cystic fibrosis is suspected, state two screening tests that could be performed on a stool specimen to aid in the diagnosis.

f. State a possible reason for a false-negative reaction in each of these tests.

g. What confirmatory test could be performed?