Pancreolauryl test
The pancreolauryl test (fluorescein dilaurate test ) is a medical laboratory test that can be used to diagnose exocrine pancreatic hypofunction . It was commercially available as the pancreolauryl test and was in clinical use in the 1980s and 1990s. Nowadays it is rarely used due to its insufficient sensitivity ( sensitivity and specificity ), its long duration (three days), existing alternatives and lack of availability. It has largely been replaced by simpler methods, in particular the determination of pancreatic elastase in the stool.
execution
On the test day (T), the test person drinks ½ liter of unsweetened tea early in the morning and empties his bladder 30 minutes later . During a subsequent standardized breakfast (1 roll with 20 g butter and 1 cup of tea) he consumes fluorescein -dilauric acid ester in the form of two unchewed capsules. During the morning he drinks 1 liter of tea. Normal food consumption is permitted again after noon.
From breakfast onwards, urine is collected for 10 hours . The collection period ends after a last urinary bladder evacuation. A control (K) is usually carried out 2 days later with the same procedure, but capsules with the control substance fluorescein sodium salt are used.
Are then photometrically the amount of excreted fluorescein day of the test (T) and that of the control day (K) in the urine is measured, compared and recorded as a percentage.
Therapeutic use of pancreatic enzymes should be discontinued at least 3 days before the test. The same applies to the intake of high-dose vitamin B2 and sulfasalazine , as these drugs falsify the photometric measurement due to their inherent color.
rating
A T / K quotient of> 30% is considered normal; such a <20% makes a weakness of the enzyme excretion of the pancreas in the duodenum probable ( exocrine pancreatic insufficiency ), whereby such in the range <10% is considered highly probable. Values of 20–30% need to be checked (test repetition), whereby a quotient measured again as borderline makes pancreatic insufficiency probable.
principle
The fluorescein dilauric acid ester taken on the day of the test is split (with the help of bile acids ) by a pancreas-specific esterase (sterol ester hydrolase). This releases the water-soluble fluorescein, which is absorbed by the small intestine and excreted via the kidneys after glucuronidation of the liver. In contrast, the fluorescein sodium salt of the control day (C) does not require any action by pancreatic enzymes in order to be absorbed and excreted via the kidneys. A low excretion of the test substance in the urine indicates a weakness of the enzymatic function of the pancreas.
Problems
The test is not only dependent on the function of the pancreas, but also on the excretion of bile secretions and the function of the liver; it is also disturbed if the stomach and sprue are partially removed by surgery . It is time-consuming and labor-intensive, requires the participation of the test person and has a poorer sensitivity (approx. 75%) and specificity (approx. 50%) - both strongly dependent on the stage of the pancreatic disease - than the elastase determination in the stool (or serum), especially for mild forms of the disease. It has therefore lost a lot of its importance in diagnostics, especially since test capsules are also difficult to obtain.
Alternative tests (selection)
The determination of elastase or chymotrypsin in the stool is common.
The secretin (-caerulein or -cholecystokinin) test, the secretin-pancreozymin test , the NBT-Paba test and the pancreas stimulation with a test meal according to Lund, as well as the stool examination for undigested muscle fibers or the determination of the Fats in the stool.
literature
- L. Thomas: Laboratory and Diagnosis; Frankfurt / Main 1998
- E. Hafter: Practical Gastroenterology; Stuttgart 1978
- W. Siegenthaler et al. Internal Medicine Textbook; Stuttgart 1992
- W. Gerok et al .: Internal Medicine; Stuttgart 2000
- S. Brückel: Non-invasive quantification of exocrine pancreatic function by means of 13C-triglyceride breath test in healthy people and patients with diabetes mellitus; Dissertation Hamburg 2007