Norm of Chymex Test For Pancreatic Function (Bentiromide Test, Chymotrypsin)
Greater than 70% of the administered dose of p-aminobenzoic acid (PABA) appears in the urine of the client within 6 hours of administration.
Usage of Chymex Test For Pancreatic Function (Bentiromide Test, Chymotrypsin)
This is a test used to evaluate pancreatic exocrine (digestive) function. It is frequently employed in the management of clients with chronic pancreatitis and may be used to determine if clients with this illness will require chronic pancreatic enzyme therapy.
Description of Chymex Test For Pancreatic Function (Bentiromide Test, Chymotrypsin)
N-Benzoyl-L-tyrosyl-p-aminobenzoic acid (BT-PABA, bentiromide) is administered orally. The pancreatic digestive enzyme chymotrypsin cleaves this material into PABA, which is then readily absorbed across the intestinal mucosa into the systemic circulation. The PABA subsequently appears in the urine. Failure of significant amounts of PABA to appear in the urine implies reduced amounts of chymotrypsin in the intestinal tract, and the diagnosis of pancreatic insufficiency is consequently established.
Professional Considerations of Chymex Test For Pancreatic Function (Bentiromide Test, Chymotrypsin)
Consent form NOT required.
Previous history of allergic reaction to BT-PABA or PABA.
Previous BT-PABA testing within 7 days of the test.
The safety of this test has not been established during pregnancy.
Central nervous system: Headache
Gastrointestinal: Diarrhea, nausea, vomiting
- There are several medications and foods that interfere with the results of this test and should be discontinued before testing (see Factors That Affect Results ).
- Pancreatic enzyme therapy can interfere with the test (creating a “false-negative” result) and should be discontinued at the discretion of the client's physician before the test.
- 500 mg of BT-PABA (bentiromide) is given to the client orally after an overnight fast.
- The bentiromide is usually administered with 250 mL of water, and oral water intake is encouraged for several hours after the agent is administered.
- All urine is collected for 6 hours after the bentiromide is given.
- Urine volume is measured, and a sample of urine is submitted to the laboratory for PABA determination. In this manner the total amount of PABA excreted in the urine can be calculated.
- The results of the test are determined as a percentage: the amount of PABA excreted in the urine (in milligrams) is divided by the amount of BT-PABA administered (500 mg), and this number is multiplied by 100.
- Complete urine output needs to be collected for 6 hours after the administration of the BT-PABA.
- Encourage oral fluid intake.
Client and Family Teaching
- The rationale behind the test should be discussed before the administration of the BT-PABA.
- The client should be informed of the necessity of collecting all urine passed during the 6 hours after the administration of the BT-PABA.
Factors That Affect Results
- Foods that interfere with urine PABA determination: prunes, cranberries (these should be eliminated from the diet for 72 hours before the test).
- Medications that interfere with urine PABA determination: acetaminophen, chloramphenicol, certain sunscreens, local anesthetic agents, thiazide diuretics, sulfonamides.
- Renal or hepatic insufficiency.
- Ongoing therapy with pancreatic enzymes.
- An empiric trial of pancreatic enzyme therapy is occasionally done in clients with presumed pancreatic insufficiency in place of a formal BT-PABA test.
- Other tests used to confirm the diagnosis of pancreatic exocrine insufficiency include the secretin test and the CCK-pancreozymin test.