Update on endoscopic pancreatic function testing

Hormone-stimulated pancreatic function tests (PFTs) are considered the gold standard for measuring pancreatic exocrine function. PFTs involve the administration of intravenous secretin or cholecystokinin, followed by collection and analysis of pancreatic secretions. Because exocrine function may decline in the earliest phase of pancreatic fibrosis, PFTs are considered accurate for diagnosing chronic pancreatitis. Unfortunately, these potentially valuable tests are infrequently performed except at specialized centers, because they are time consuming and complicated. To overcome these limitations, endoscopic PFT methods have been developed which include aspiration of pancreatic secretions through the suction channel of the endoscope. The secretin endoscopic pancreatic function test (ePFT) involves collection of duodenal aspirates at 15, 30, 45 and 60 min after secretin stimulation. A bicarbonate concentration greater than 80 mmol/L in any of the samples is considered a normal result. The secretin ePFT has demonstrated good sensitivity and specificity compared with various reference standards, including the "Dreiling tube" secretin PFT, endoscopic ultrasound, and surgical histology. Furthermore, a standard autoanalyzer can be used for bicarbonate analysis, which allows the secretin ePFT to be performed at any hospital. The secretin ePFT may complement imaging tests like endoscopic ultrasound (EUS) in the diagnosis of early chronic pancreatitis.This paper will review the literature validating the use of ePFT in the diagnosis of exocrine insufficiency and chronic pancreatitis. Newer developments will also be discussed, including the feasibility of combined EUS/ ePFT, the use of cholecystokinin alone or in combination with secretin, and the discovery of new protein and lipid pancreatic juice biomarkers which may complement traditional fluid analysis.

Pancreatic function testing: Here to stay for the 21st century

The diagnosis of Chronic Pancreatitis （CP） is based on the detection of abnormal structure or function of the diseased pancreas. The pancreatic function tests more accurately determine the presence of CP than tests of structure, especially for early stage disease. The function tests can be divided into two categories： non- invasive and invasive. The invasive ＂tube＂ tests can reliably detect mild, early CP, but are only available at a few referral centers and tend to be poorly tolerated by patients. The non-invasive tests are easy to obtain, but tend to perform poorly in patients with early, mild disease. Therefore, no one test is useful in all clinical situations, and a detailed understanding of the rational, pathophysiologic basis, strengths, and limitations of various tests is needed. This review highlights the role of various pancreatic function tests in the diagnosis of CP including fecal fat analysis, fecal elastase, fecal chymotrypsin, serum trypsin, the secretin stimulation test, the cholecystokinin （CCK） stimulation test, the combined secretin-CCK stimulation test, the intraductal and endoscopic secretin stimulation tests, and the functional magnetic resonance imaging of the pancreas after secretin stimulation.

Staging chronic pancreatitis with exocrine function tests: Are we better?

Chronic pancreatitis(CP) is an inflammatory disease of the pancreas evolving in progressive fibrotic disruption of the gland with exocrine and endocrine pancreatic insufficiency. Although imaging features of CP are well known, their correlation with exocrine pancreatic function tests are not obvious, particularly in the early stage of the disease. There are many clinical classification of CP, all suggested for better distinguish and manage different forms based on etiological and clinical factors, and severity of the disease. Recently, a new classification of CP has been suggested: the M-ANNHEIM multiple risk factor classification that includes etiology, stage classification and degree of clinical severity. However, more accurate determination of clinical severity of CP requires a correct determination of exocrine function of the pancreas and fecal fat excretion. Recently, Kamath et al demonstrated that the evaluation of exocrine pancreatic function by acid steatocrit and fecal elastase-1(EF-1) was helpful, but EF-1 was able to detect exocrine pancreatic insufficiency in more patients, upgrading some patients in higher stage of disease according to M-ANNHEIM classification. So, EF-1 is a more accurate test to determine exocrine pancreatic insufficiency and to stage chronic pancreatitis in the M-ANNHEIM classification. On the contrary, EF-1 determination shows low sensitivity in detecting exocrine pancreatic insufficiency in early stage of the disease.

Endoscopic ultrasound for the diagnosis of chronic pancreatitis

Endoscopic ultrasound(EUS) has become a well accepted test for the diagnosis of chronic pancreatitis.Advantages include its ability to detect subtle and severe changes of the pancreatic duct and parenchyma,and its relative safety compared with endoscopic retrograde cholangiopancreatography.Limitations include inter-and intraobserver variability,operator dependence,and an incomplete understanding of its true accuracy.The Rosemont classif ication has recently been proposed as a weighted,standardized method that may improve EUS chronic pancreatitis scoring.This paper reviews the published evidence regarding the accuracy of EUS in chronic pancreatitis diagnosis,and enumerates the emerging technologies that have been recently studied which may ultimately improve endosonographic imaging of the pancreas.

Comparing acid steatocrit and faecal elastase estimations for use in M-ANNHEIM staging for pancreatitis

AIM To compare two tests for exocrine pancreatic function(EPF) for use in M-ANNHEIM staging for pancreatitis. METHODS One hundred and ninety four consecutive patients with acute pancreatitis(AP; n = 13), recurrent acute pancreatitis(RAP; n = 65) and chronic pancreatitis(CP; n = 116) were enrolled. EPF was assessed by faecal elastase-1(FE-1) estimation and stool fat excretion by the acid steatocrit method. Patients were classified as per M-ANNHEIM stages separately based on the results of the two tests for comparison. Independent Student's t-test, χ~2 test, Kruskal-Wallis test, Mann-Whitney U test and Mc Nemar's test were used as appropriate. RESULTS Sixty-one(52.5%) patients with CP had steatorrhoea when assessed by the acid steatocrit method; 79 (68.1%) with CP had exocrine insufficiency by the FE-1 test(χ~2 test, P < 0.001). The results of acid steatocrit and FE-1 showed a significant negative correlation(Spearman's rho =-0.376, P < 0.001). A statistically significant difference was seen between the M-ANNHEIM stages as classified separately by acid steatocrit and the FE-1. Thirteen(6.7%), 87(44.8%), 89(45.8%) and 5(2.5%) patients were placed in M-ANNHEIM stages 0,?Ⅰ, Ⅱ, and Ⅲ respectively, with the use of acid steatocrit as against 13(6.7%), 85(43.8%), 75(38.6%), and 21(10.8%) respectively by FE-1 in stages 0,?Ⅰ, Ⅱ, and Ⅲ thereby altering the stage in 28(14.4%) patients(P < 0.001, Mc Nemar's test). CONCLUSION FE-1 estimation performed better than the acid steatocrit test for use in the staging of pancreatitis by the M-ANNHEIM classification since it diagnosed a higher proportion of patients with exocrine insufficiency.