Comparative Study of Rapid Trypsinogen 2 Strip Test to Serum Amylase and Serum Lipase Estimation as a Screening Test in Acute Pancreatitis

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1 Print ISSN: Online ISSN: DOI: /SUR/2017/71 Original Article Comparative Study of Rapid Trypsinogen 2 Strip Test to Serum Amylase and Serum Lipase Estimation as a B J Sharath Chandra 1, S Nitesh 2 1 Professor, Department of General Surgery, JSS Medical College, Karnataka, India, 2 Resident, Department of General Surgery, JSS Medical College, Karnataka, India Abstract Introduction: Acute pancreatitis is a common presentation in emergency department, presenting with acute abdomen. With numerous differential diagnosis for acute abdomen, arriving at diagnosis in a case of acute pancreatitis in quick time is of importance. Urinary trypsinogen-2 strip test has shown promising results in various studies and gaining importance due to its rapid results. Materials and Methods: The patients presenting with acute abdomen which is suspicious of acute pancreatitis are taken in this study. Serum amylase and lipase are sent in these cases as a routine and along with that, the urinary trypsinogen-2 dipstick test is performed after receiving a urine sample. A total of 51 cases were taken up for the study. Further confirmation of the study was done using radiological investigations, either ultrasonography or contrast-enhanced computed tomography abdomen or both. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and receiver operating characteristic (ROC) curve were calculated. Results were compared. Results: Out of the 51 cases conducted in this study, 40 cases were diagnosed with acute pancreatitis, and 11 cases served as control. In all the 40 cases, the urine dipstick test was positive and in 11 control cases, it came negative. It should 100% sensitivity and specificity and the area under the ROC curve was 1. In comparison to the serum amylase and lipase done, if both the tests were considered together, the sensitivity was 95% and specificity was 45.4% with the area ROC curve being Conclusion: The urinary trypsinogen-2 dipstick test has proven to be a reliable and accurate test in screening of acute pancreatitis. The results were obtained within 5 min helping in rapid establishment of diagnosis. This study shows that the dipstick test has high PPV and NPV and can be considered for regular use for diagnosing pancreatitis along with the conventional methods. It emphasizes on requirement of controlled trials for confirming its reliability in daily use. Keywords: Acute pancreatitis, Amylase, Lipase, Screening, Trypsinogen 2 dipstick INTRODUCTION Incidence of acute pancreatitis in developing countries and the mortality associated with severe pancreatitis is on the raise. Early diagnosis of acute pancreatitis is crucial to ensure rapid and appropriate treatment. The most patients with acute pancreatitis have mild and self- limited disease that resolves spontaneously, but Access this article online Month of Submission : Month of Peer Review : Month of Acceptance : Month of Publishing : about 20% of attacks are severe with a mortality of about 10-25%. 1 Nonavailability of investigative set ups in peripheries for screening of the disease leading to delayed management. The clinical features of acute pancreatitis can be difficult to distinguish from those of other acute abdominal conditions and could be misdiagnosed. Determination of amylase in serum or urine is the principal laboratory method for diagnosing acute pancreatitis. Hyperamylasemia is absent in 19% of cases. 1-3 Increase in pancreatic enzyme levels can occur in the patients with acute abdominal pain of extrapancreatic in origin. 4-6 The human pancreas secretes isoforms of trypsinogen: Cationic (trypsinogen-1), anionic (trypsinogen-2), Corresponding Author: Dr. S Nitesh, 897, Guru Om, Kantharaj Urs Road, Laxmipuram, Mysore , Karnataka, India. Phone: nitesh897@gmail.com 48

2 cationic, and anionic trypsin are the major isoforms responsible for digestive protein degradation, occurring in a ratio of 2:1. The pathophysiology of acute pancreatitis involves the activation of the pancreatic proenzymes. 7 The activation of trypsinogen followed by the activation of other pancreatic zymogens occurs early in the course of pancreatitis. Pancreatic zymogens in serum are excreted in urine. Many studies have been done to assess the reliability of urinary trypsinogen-2 dipstick test The aim of this study is to assess the role of rapid urinary trypsinogen-2 strip test in screening of acute pancreatitis and to find positive predictive value (PPV) and negative predictive value (NPV) in comparison to serum amylase and lipase. MATERIALS AND METHODS The patients presenting in the emergency medicine department of JSS hospital with pain abdomen, which is acute in onset were considered for the study. He or she should not be diagnosed and referred and is first presenting directly to JSS hospital between September 2014 to September The ethical committee clearance from the JSS hospital management was obtained before beginning the study. On arrival, all patients were initially assessed with thorough history and examination. Depending on the condition of the patient, the required immediate attention and treatment was started prior to sending any investigations. Informed consent was obtained from patients who were included in the study. A suspicion of acute pancreatitis was made when the patient was having a recent history of alcohol intake, history of anorexia and vomiting, severe abdominal pain radiating to the back. On examination, if the patient had tenderness and guarding mainly in the upper abdomen, these cases were taken up for this study. Patients with pain in the lower abdomen, migrating pain from umbilicus to the right iliac fossa, radiation of abdominal pain to the groin, and associated burning micturition were not considered in this study as pancreatitis was not kept as a differential diagnosis in these patients. performed and the results were noted, along with the serum amylase and lipase levels. Patients sonological report was recorded for the study, as either positive or negative for features that are suggestive of acute pancreatitis. The patients were followed up and in diagnosed cases of pancreatitis, contrast enhanced computed tomography (CECT) abdomen and pelvis was done to know the severity and outcome. However, the report of CECT was either taken as positive or negative for pancreatitis as this study is a qualitative test for screening of acute pancreatitis. Severity and outcome is beyond the scope of this study. Statistical Analysis Sensitivity and specificity for both serum amylase and lipase and urinary trypsinogen-2 dipstick test was calculated. PPV and NPV were obtained. Significance of both the tests calculated using receiver operating characteristic (ROC) curve and area under the curve. The results were compared. RESULTS Out of 51 patients taken up for the study, 40 patients were diagnosed to have pancreatitis. Rest 11 cases included cholecystitis, acid peptic disease, and common bile duct calculus. In the 40 cases diagnosed to have pancreatitis, 6 patients were female and rest male showing predominant male dominance in this study. The predisposing cause for pancreatitis in the 40 cases that were diagnosed in our study included mainly alcohol (32 cases). Other causes were gall stones, hypertriglyceridemia. Cause of acute pancreatitis in 2 remained unknown (Tables 1-4 and Charts 1-3). ROC Curve for Serum Amylase As routinely conducted in any case of acute abdomen suspicious of pancreatitis, serum amylase and lipase was sent. The patient also underwent erect X-ray abdomen and ultrasound scan of the abdomen. The urinary trypsinogen-2 dipstick test was performed using a product called Actim pancreatitis dipstick (Medix Biochemica, Kauniainen, Finland). 13 In such patients as soon as a urine sample was obtained, either by catheterization or by voiding into a container. The test Area under curve for Serum amylase =

3 ROC Curve for Serum Lipase Chart 1: Pie chart showing different diagnosis of cases in this study Area under curve for Serum lipase = DISCUSSION The tests showed a majority of the cases being acute pancreatitis. The male patients were predominant in the study. Gallstone disease is seen to be more common in women as alcoholism is less common in females than males. In all cases of acute pancreatitis, urinary trypsinogen-2 dipstick test came positive, and the test was negative in the patients with different diagnosis. Chart 2: Bar columns showing male and female distribution in acute pancreatitis That is to say that the test had 100% sensitivity and specificity. The more commonly done tests, that is the serum amylase and lipase have shown less sensitivity and specificity. The NPV and PPV of serum amylase and lipase are in par with the statistics of other studies done previously. The dipstick method was easy to perform and results were obtained within 5 min whereas the amylase and lipase serum values took 2 h on an average. In comparison to the studies done by Kylänpää-Bäck et al., 10 the results have been similar for NPV but the urinary trypsinogen-2 dipstick test has proven to have better PPV in this study. Similar studies done by Kemppainen et al. and Hedström et al. have revealed similar results for diagnosing acute pancreatitis. 8,9 The more commonly used tests, i.e. serum amylase and lipase was done in all patients. Although not 100% sensitivity or specificity, these tests showed good results with area under ROC curve above 0.9 and nearer to 1 when both tests were considered. The one patient with acute pancreatitis and hypertriglyceridemia was a pregnant lady, whose serum Chart 3: Pie diagram showing different etiological causes in cases of acute pancreatitis amylase and lipase were both elevated and also showed urinary trypsinogen-2 dipstick test positive had severe pancreatitis and succumbed due to it. In this patient, CECT could not be done for confirmation due to several contraindications. The ROC curve revealed the optimum value of 1 for the urinary trypsinogen-2 dipstick test which indicates that the test is reliable, as per this study. The urinary trypsinogen-2 dipstick test was easily performed in this study with a small amount of urine required in every test. In patients, with acute renal failure as in cases of acute severe pancreatitis the urine sample could not be obtained and the test could not be performed. This added as a negative factor in a few cases. 50

4 Table 1: Urine trypsinogen test in diagnosis of pancreatitis Urine trypsinogen Pancreatitis Total Positive Negative Positive Negative Sensitivity=40/40=100%, Specificity=11/11=100%, Positive predictive value=40/40=100%, Negative predictive value=11/11=100% Table 2: Serum amylase in diagnosis of pancreatitis Serum amylase Pancreatitis Total Positive Negative Positive Negative Sensitivity=35/40=87.5%, Specificity=10/11=90.9%, Positive predictive value=35/36=97.2%, Negative predictive value=10/15=66.6% Table 3: Serum lipase in diagnosis of pancreatitis Serum lipase Pancreatitis Total Positive Negative Positive Negative Sensitivity=38/40=95%, Specificity=5/11=45.4%, Positive predictive value=38/44=86.3%, Negative predictive value=5/7=71.4% Table 4: Either of both positive in diagnosis of pancreatitis Serum lipase/amylase Pancreatitis Total Positive Negative Positive Negative Sensitivity=38/40=95%, Specificity=5/11=45.4%, Positive predictive value=38/44=86.3%, Negative predictive value=5/7=71.4% But having said that, on catheterization, most patients had few ml of urine that got collected which was sufficient to perform the urine dipstick test. The results were easily read and the added advantages of immediate results were noticeable. Interestingly, the routinely done serum amylase and lipase did not yield 100% results, but the results were reliable. It approximately came to around four hundred rupees per dipstick. The dipsticks are not being manufactured and marketed in India which is resulting in the higher pricing but even with that, came hundred rupees cheaper than most of the laboratory cost for serum amylase and lipase. The cost of the dipsticks can only come down, once the product is available in Indian market. CONCLUSION In a case of acute pancreatitis, immediate intervention is of utmost importance in starting appropriate management. 2 Ruling out pancreatitis in cases of acute severe abdomen also plays a role in diagnosing other causes for acute abdomen with an unusual presentation like sealed off perforation. With the dipstick test for acute pancreatitis, diagnosis is done within minutes saving a lot of precious time. The results obtained by this study show good results that substantiate results obtained by similar studies. The traditionally done serum amylase and lipase also do not have any quantitative benefits or in differentiating the severity of the pancreatitis. The PPV and NPV obtained for urine dipstick showed remarkable results. Even then, serum amylase and lipase have proven to be showing reliable results and will remain the investigation of choice for screening acute pancreatitis until further tests for urinary trypsinogen-2 dipstick tests can be done. This study puts forward a hypothesis that the dipstick method can be used as an adjunct or even to replace the conventional serum amylase or lipase in screening of acute pancreatitis. A randomized control trial and multicentric studies are warranted in the same lines of this study. REFERENCES 1. Sa ez J, Martinez J, Trigo C, Sanchez-Paya J, Company L, Laveda R, et al. Clinical value of rapid urine trypsinogen-2 test strip, urinary trypsinogen activation peptide, and serum and urinary activation peptide of carboxypeptidase B in acute pancreatitis. World J Gastroenterol 2005;11: Tenner S, Steinberg WM. Acute pancreatitis. In: Feldman M, Friedman LS, Brandt LJ, editors. Sleisenger and Fordtran s Gastrointestinal and Liver Disease. Philadelphia, PA: Elsevier Saunders Inc.; p Clavien PA, Robert J, Meyer P, Borst F, Hauser H, Herrmann F, et al. Acute pancreatitis and normoamylasemia. Not an uncommon combination. Ann Surg 1989;210: Dutta SK, Douglass W, Smalls UA, Nipper HC, Levitt MD. Prevalence and nature of hyperamylasemia in acute alcoholism. Dig Dis Sci 1981;26: Yadav D, Nair S, Norkus EP, Pitchumoni CS. Nonspecific hyperamylasemia and hyperlipasemia in diabetic ketoacidosis: Incidence and correlation with biochemical abnormalities. Am J Gastroenterol 2000;95: Terada T, Nakanuma Y. Immunohistochemical demonstration of pancreatic alpha-amylase and trypsin in intrahepatic bile ducts and peribiliary glands. Hepatology 1991;14: Borgström A, Appelros S. Activation peptides in acute pancreatitis. In: Buchler MW, Uhl W, Friess H, Malfertheiner P, editors. Acute Pancreatitis-Novel Concepts in Biology and Therapy. Berlin-Viena: Blackwell Wissenschafts-Verlag; p Hedström J, Korvuo A, Kenkimäki P, Tikanoja S, Haapiainen R, Kivilaakso E, et al. Urinary trypsinogen-2 test strip for acute pancreatitis. Lancet 1996;347: Kemppainen EA, Hedström JI, Puolakkainen PA, Sainio VS, Haapiainen RK, Perhoniemi V, et al. Rapid measurement 51

5 of urinary trypsinogen-2 as a screening test for acute pancreatitis. N Engl J Med 1997;336: Kylänpää-Bäck M, Kemppainen E, Puolakkainen P, Hedström J, Haapiainen R, Perhoniemi V, et al. Reliable screening for acute pancreatitis with rapid urine trypsinogen-2 test strip. Br J Surg 2000;87: Pezzilli R, Morselli-Labate AM, d Alessandro A, Barakat B. Time-course and clinical value of the urine trypsinogen-2 dipstick test in acute pancreatitis. Eur J Gastroenterol Hepatol 2001;13: Kemppainen E, Hedström J, Puolakkainen P, Halttunen J, Sainio V, Haapiainen R, et al. Urinary trypsinogen-2 test strip in detecting ERCP-induced pancreatitis. Endoscopy 1997;29: Medix Biochemica. Actim Pancreatitis Brochure. Kauniainen Finland, Roskilde, Denmark: Medinor; p How to cite this article: Chandra BJ, Nitesh S. Comparative Study of Rapid Trypsinogen 2 Strip Test to Serum Amylase and Serum Lipase Estimation as a. IJSS Journal of Surgery 2017;3(1): Source of Support: Nil, Conflict of Interest: None declared. 52