Abstract
To establish utility of single enzymatic marker for the diagnosis of acute pancreatitis. This is a cohort study. Tertiary care centre proven cases of acute pancreatitis (n = 50) admitted in surgery ward between December 2011 and May 2013 were included in the study. Serum amylase and lipase were performed along with many analytes. All relevant data including serum lab values and imaging were collected. All 50 patients included in the study had raised serum lipase, 42 patients had both amylase and lipase raised, 8 patients had amylase normal but lipase raised. In smaller hospitals where limited lab and radiological facilities are available, estimation of serum lipase will be a better choice over serum amylase in diagnosis of acute pancreatitis.
Keywords: Amylase, Lipase, Comparative study, Correlation
Introduction
For the diagnosis of acute pancreatitis, many hospitals rely on both serum amylase and lipase along with computed tomography. However, smaller hospitals and peripheral hospitals do not possess adequate diagnostic facilities and it becomes burden both on lab and patients to perform both serum amylase and lipase in diagnosis of acute pancreatitis.
Diagnosis of acute pancreatitis is based on two of the following criteria: symptoms of acute pancreatitis with typical abdominal pain, raised serum amylase or lipase, or both with levels three or more times the upper limit of normal along with findings of acute pancreatitis on computed tomography [1]. In clinical chemistry lab, many requisitions are received for both serum amylase and lipase. Question arises whether both are required for the diagnosis of same disease or single marker is sufficient. This study compares the utility of serum amylase and lipase in diagnosis of acute pancreatitis.
In acute pancreatitis, a rise in serum amylase activity occurs within 5–8 h of symptom onset; activities return to normal by the third or fourth day. A fourfold to sixfold elevation in amylase activity above the upper reference limit is usual, with maximal concentration attained in 12–72 h. The magnitude of the elevation of serum enzyme activity is not related to the severity of pancreatic involvement; however, the greater the rise, the greater the probability of acute pancreatitis. After an attack of acute pancreatitis, serum lipase activity increases within 4–8 h, peaks at about 24 h, and decreases within 8–14 days [2].
Some studies mentioned sensitivity for serum amylase was 63.6 % and for serum lipase it was 99.5 %, whereas, specificity for serum amylase 99.4 % and for lipase 99.2 % [3].
Many studies have been done in the past show that serum lipase is a better marker than serum amylase for the diagnosis of acute pancreatitis [4, 5].
Although lipase is considered to be specific for acute pancreatitis, nonspecific elevations of lipase have been reported in almost as many disorders as amylase, thus decreasing its specificity [6].
The current British Society of Gastroenterology guidelines (2005) for the management of acute pancreatitis has also agreed that estimation of lipase is better tool for the diagnosis of acute pancreatitis [7].
Serum amylase is being used since a long time for the diagnosis of acute pancreatitis and it is the only enzymatic marker available in many small hospitals. At present, majority of clinicians ask for both amylase and lipase for diagnosis of acute pancreatitis.
Presently, the smaller hospitals have facility for only amylase, whereas in tertiary care centre both amylase and lipase facilities are available. The study aims to find which single marker to be used in smaller hospitals for diagnosis of acute pancreatitis.
Materials and Methods
Fifty diagnosed patients of acute pancreatitis at tertiary care hospital between December 2011 and May 2013 were included in the study from surgical wards. Data collected included full particulars of patients with biochemical parameters and radioimaging findings. Samples were taken within 12–38 h of onset of abdominal pain. Biochemical analytes recorded were serum amylase, lipase, urea, and creatinine and liver enzymes.
Estimated on autoanalyzer Erba- XL-600 by commercially available kits from Transasia Biomedicals.
Lipase: (3rd Generation Assay)
Advanced homogenous micelle technology.
Description of Kit
Within run CV 1.16 with mean value of QC 34 and between run CV 0.65 with mean value of QC 35.
Principle of the Test
The chromogen lipase substrate 1,2-0-dilauryl-rac-glycero-3-glutaric acid ester is cleaved by the catalytic action of alkaline lipase solution to form1,2-0-dilauryl-rac-glycerol and an unstable intermediate, glutaric acid-ester. This decomposes spontaneously in alkaline solution to form glutaric acid and methylresorufin. The color intensity of the red dye formed is directly proportional to the lipase activity and can be determined photometrically.
Normal range is: 13–60 U/L.
Amylase
CNP-G3 Kinetic–ready to use kits from Transasia Biomedicals.
Description of Kit
Within run CV 1.52 % with mean value of QC 93.2 and run to run CV 1.8 % with mean value of QC 95.2.
Principle of the Test
2-Chloro-4-nitrophenyl-α-maltotriose (CNP-G3) is a direct substrate for determination of α-amylase activity, which does not require the presence of ancillary enzymes.
The rate of 2-Chloro-4-nitrophenol formation can be monitored at 450 nm and is proportional to the α-amylase activity in the specimen.
Normal range:Up to 80 U/L.
Diagnosis of Acute Pancreatitis
The diagnosis of acute pancreatitis requires two of the following three features:
Characteristic abdominal pain.
Levels of serum amylase or serum lipase, or both, that are three or more times the upper limit of normal.
Findings of acute pancreatitis on computed tomography [1].
Results
During the study period, a total of 50 patients were assessed with proven diagnosis of acute pancreatitis by radioimaging irrespective of etiologic. However, out of 50 patients, 42 patients had both amylase and lipase raised, remaining 8 patients had amylase normal but lipase raised (Table 1). Amylase was raised up to seven times of its upper limit of normal range (Fig. 1) and lipase was raised up to ten times its upper level of normal range (Fig. 2). Sensitivity of amylase in our study is 84 % with confidence interval 0.74–0.94, whereas, sensitivity of lipase is 100 %.
Table 1.
Levels of amylase and lipase
| Acute pancreatitis (n = 50) | Raised lipase and amylase | Raised lipase with normal amylase levels | Total raised lipase levels |
|---|---|---|---|
| 42 (84 %) | 08 (16 %) | 50 (100 %) |
Fig. 1.
Levels of amylase (U/L)
Fig. 2.
Levels of lipase (U/L)
Discussion
Originally the lipase assay used an oily substance which was not very suitable for automation. This is now not the case. Amylase has always been known to have poor specificity for diagnosis of acute pancreatitis. It also has the problem that low values are observed when the patient has hypertriglyceridemia, therefore both lipase and amylase were preferred to complement one another.
Clinicians rely on the findings of serum amylase and serum lipase along with typical abdominal pain and CT findings for the diagnosis of acute pancreatitis. Several studies done in this field demonstrate different findings. Study done by Frank B et al. [8] shows that a simultaneous determination of both amylase and lipase is recommended for the evaluation of patients with abdominal pain while some studies say both are not required for the same [9]. The diagnosis of pancreatitis should not solely be based on the arbitrary value of three or four times greater than normal of pancreatic enzymes, but interpreted together with the clinical presentation [10]. According to few studies, amylase levels may remain within normal range in 19 % of patients admitted with acute pancreatitis [11, 12]. According to British Society of Gastroenterology guidelines for the management of acute pancreatitis, lipase is the main focus towards the diagnosis of acute pancreatitis [7]. Our studies goes in accordance to the previous studies [4, 5], which shows that serum lipase in a case of acute pancreatitis is better diagnostic marker than serum amylase. In a similar study done by Dhanwant Gomez et al. [13], majority of patients with acute pancreatitis had raised levels of both amylase and lipase (97 %), however, raised lipase levels were seen between 95 and 100 % of patients based on the aetiology. In Our study, 84 % of patients of acute pancreatitis had both amylase and lipase raised and 100 % of acute pancreatitis patients had lipase raised, irrespective of aetiology. Our study is in agreement with the study done by Agrawal et al. [5] and Thomson et al. [14]., who reported higher sensitivity and specificity of serum lipase in diagnosis of acute pancreatitis compared to serum amylase.
Conclusion
In smaller hospitals where limited lab and radiological facilities are available, estimation of serum lipase will be a better choice over serum amylase in diagnosis of acute pancreatitis.
Abbreviations
- CNP-G3
2-Chloro-4-nitrophenyl-α-maltotriose
- CNP
2-Chloro-4-nitrophenol
- U/L
Unit per litre
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