Biochemical models as early predictors of the etiology of acute pancreatitis

Relação lipase/amilase nas pancreatites agudas de causa biliar e nas pancreatites agudas/crônicas agudizadas de causa alcoólica

RACIONAL: Pancreatites agudas de causas alcoólica ou biliar podem necessitar de abordagens terapêuticas diferentes. OBJETIVO: Verificar a validade da relação lipase/amilase em diferenciar as causas alcoólica ou biliar na pancreatite aguda/pancreatite crônica agudizada. MÉTODOS: Foram avaliados nove pacientes com pancreatite aguda/pancreatite crônica agudizada alcoólica, todos homens, com idade média (desvio padrão) de 39,8 ± 7,0 anos (grupo I) e 29 com pancreatite aguda biliar, sendo 8 homens e 21 mulheres, com idade média de 43,6 ± 19,9 anos (grupo II). As amilasemias e lipasemias foram determinadas em pacientes com sintomatologia há, no máximo, 48 horas. A relação lipase/amilase foi calculada utilizando-se valores de amilasemia e lipasemia expressas como múltiplos de seus respectivos valores superiores de referência. RESULTADOS: As médias das lipasemias (4.814 ± 3.670 U/L) e amilasemias (1.282 ± 777 U/L) no grupo I foram semelhantes às do grupo II (2.697 ± 2.391 e 1.878 ± 1.319 U/L, respectivamente), mas a média das relações lipase/amilase foi significantemente maior no grupo I (4,4 ± 3,6) do que no grupo II (2,2 ± 2,2). Relação lipase/amilase >3 foi significantemente mais freqüente no grupo I (66,7%) do que no grupo II (24,1%) e diferenciou os dois grupos com sensibilidade de 67% e especificidade de 76%. CONCLUSÕES: 1) as amilasemias e lipasemias não diferenciaram os dois grupos avaliados; 2) relação lipase/amilase >3 é mais freqüente na pancreatite aguda/pancreatite crônica agudizada alcoólica do que na pancreatite aguda biliar, e pode ser útil na diferenciação destas duas causas de pancreatite.

A critical evaluation of laboratory tests in acute pancreatitis

An ideal laboratory test in the evaluation of a patient with acute pancreatitis (AP) should, in addition to accurately establishing the diagnosis of AP, provide early assessment of its severity and identify the etiology. None of the tests available today meet all these criteria, and presently there is no biochemical test that can be considered the "gold standard" for the diagnosis and assessment of severity of AP. In the diagnosis of AP, serum amylase and lipase remain important tests. Advantages of amylase estimation are its technical simplicity, easy availability, and high sensitivity. However, its greatest disadvantage is its low specificity. A normal amylase would usually exclude the diagnosis of AP, with the exception of AP secondary to hyperlipidemia, acute exacerbation of chronic pancreatitis, and when the estimation of amylase is delayed in the course of the disease. The major advantage of lipase is an increased sensitivity in acute alcoholic pancreatitis and in patients who initially present to the emergency room days after the onset of the disease, as lipase remains elevated longer than amylase. Although once considered to be specific for AP, nonspecific elevations of lipase have been reported in almost as many disorders as amylase, thus decreasing its specificity. Simultaneous estimation of amylase and lipase does not improve the accuracy. Other enzymes for the diagnosis of AP--pancreatic isoamylase, immunoreactive trypsin, and elastase--are more cumbersome and expensive and have no clear role in the diagnosis of AP. No enzyme assay has a predictive role in determining the severity or etiology of AP. Once the diagnosis of AP is established, daily measurements of enzymes have no value in assessing the clinical progress of the patient or ultimate prognosis and should be discouraged. A host of new serological and urinary markers have been investigated in the last few years. Their main use is in predicting the severity of AP. At present, serum C-reactive protein at 48 h is the best available laboratory marker of severity. Urinary trypsinogen activation peptides within 12-24 h of onset of AP are able to predict the severity but are not widely available. Serum interleukins 6 and 8 seem promising but remain experimental.

Usefulness of carbohydrate-deficient transferrin and trypsin activity in the diagnosis of acute alcoholic pancreatitis

OBJECTIVE

The aim of this study was to assess if carbohydrate-deficient transferrin (CDT) and trypsin activity differentiate acute alcoholic pancreatitis from nonalcohol-related pancreatitis, and as a secondary goal to evaluate its use in comparison to healthy controls.

METHODS

Serum levels of CDT and trypsin activity were measured in frozen sera from 70 nonconsecutive patients with acute pancreatitis and in 16 healthy controls.

RESULTS

Causes of pancreatitis were gallstones in 51%, chronic alcoholism in 23%, and other or unknown causes in 26% of the patients. Serum CDT was significantly higher in alcoholic pancreatitis than in the nonalcoholic disease (p < 0.0001) with a median (interquartile range) of 30.8 U/L (23.6-41.7 U/L) in chronic alcoholism, 16.7 U/L (13.05-21.1 U/L) in gallstones, 17.5 U/L (15.9-21.6 U/L) in unknown cause, 19.3 U/L (15.1-27.7 U/L) in other etiologies, and 16.1 U/L (12.1-18.8 U/L) in controls. At a cutoff over 22.5 U/L, CDT showed a sensitivity of 87.5% and a specificity of 85.2%. Serum levels of trypsin activity were significantly higher (p = 0.0007) in alcoholic pancreatitis, median 165 U/L (76-405 U/L) than in nonalcoholic pancreatitis, median 73 U/L (46.5-100.5 U/L). At a cutoff value over 152 U/L, the sensitivity of trypsin activity was 60% with a specificity of 100%. In the multivariate analysis, patient's age (< or = 44 yr), CDT (>22.5 U/L), and trypsin activity (>152 U/L) enabled correct prediction of acute alcoholic pancreatitis in 98% of the cases.

CONCLUSION

Serum CDT and trypsin activity are of clinical utility in differentiating alcoholic from nonalcoholic acute pancreatitis.

The Ratio of Trypsin-2-α1-Antitrypsin to Trypsinogen-1 Discriminates Biliary and Alcohol-induced Acute Pancreatitis

Background: Rapid determination of the etiology of acute pancreatitis (AP) enables institution of appropriate treatment. We evaluated the ability of trypsinogen-1, trypsinogen-2, trypsin-1-α1-antitrypsin (AAT), and trypsin-2-AAT in serum to identify the etiology of AP.

Methods: The study consisted of 67 consecutive patients with AP admitted to Helsinki University Central Hospital. Forty-two had alcohol-induced AP, 16 had biliary AP, and 9 had unexplained etiology. Serum samples were drawn within 12 h after admission. Trypsinogen-1, trypsinogen-2, trypsin-1-AAT, and trypsin-2-AAT were determined by time-resolved immunofluorometric assays. Logistic regression was used to estimate the ability of the serum analytes to discriminate between alcohol-induced and biliary AP. The validity of the tests was evaluated by ROC curve analysis.

Results: Patients with alcohol-induced AP had higher median values of trypsin-1-AAT (P = 0.065), trypsinogen-2 (P = 0.034), and trypsin-2-AAT (P &lt;0.001) than those with biliary AP, who had higher values of amylase (P = 0.002), lipase (P = 0.012), and alanine aminotransferase (P = 0.036). The ratios of trypsin-2-AAT to trypsinogen-1, lipase, or amylase efficiently discriminated between biliary and alcohol-induced AP (areas under ROC curves, 0.92–0.96).

Conclusions: Trypsinogen-2 and trypsin-2-AAT are markedly increased in AP of all etiologies, whereas trypsinogen-1 is increased preferentially in biliary AP. The trypsin-2-AAT/trypsinogen-1 ratio is a promising new marker for discrimination between biliary and alcohol-induced AP.

Usefulness of alanine and aspartate aminotransferases in the diagnosis of microlithiasis in idiopathic acute pancreatitis

CONCLUSION

Serum increases of aminotransferases, especially alanine aminotransferase (ALT), were suggestive of microlithiasis in idiopathic acute pancreatitis, particularly when assessed early after the onset of abdominal pain.

BACKGROUND

It has been shown that biochemical laboratory values only are useful parameters in distinguishing gallstone from nongallstone acute pancreatitis. We assessed the diagnostic usefulness of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) for identification of occult microlithiasis in idiopathic acute pancreatitis.

METHODS

Ninety-one patients with idiopathic acute pancreatitis who underwent microscopic examination of stimulated duodenal bile sediments were retrospectively studied. According to earliness of ALT and AST assay after the onset of abdominal pain, patients were divided into two groups: group A, within the first 24 h (n = 56) and group B, between 24 and 72 h (n = 35).

RESULTS

ALT and AST values expressed as number of elevations of the upper limits of normal were higher in group A patients with positive biliary drainage than in group B. Median (range) ALT and AST values were 2.5 (0.1-18.1) vs 0.4 (0.1-8.6) and 3 (0.3-17.4) vs 0.5 (0.3-11.9), respectively. In the univariate analysis and receiver operating characteristic (ROC) curves, ALT within the first 24 h showed a sensitivity of 73%, specificity of 86%, and positive predictive value of 92% for a cutoff of 1.2 elevations of the upper limit of normal. These values were slightly higher, although without statistically significant differences, than those of AST (73, 80, and 89%, respectively).

A scoring system for early differentiation of the etiology of acute pancreatitis

BACKGROUND

The purpose of this study was to find a new scoring system for early differentiation between the two commonest etiologies of acute pancreatitis (biliary and alcoholic), because biliary pancreatitis can be treated early by endoscopic sphincterotomy, whereas such treatment is unnecessary in alcoholics.

METHODS

One hundred and forty-five patients satisfied the requirements for participation in the study and were divided into groups A (alcoholic pancreatitis) and B (biliary pancreatitis). Seven variables (serum and urine amylase, aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), alkaline phosphatase (ALP), lipase/amylase (L/A) ratio, and erythrocyte mean corpuscular volume (MCV)) that differed in a statistically significant manner between patients of the two groups were included in the scoring system. Each parameter was counted as 0 or 1 on the basis of its values, so the patients reached scores from 0 to 7.

RESULTS

Scores > or =4 (P < 0.0001) were consistently present in biliary pancreatitis, whereas alcoholics scored <4, with a sensitivity of 92.04% and a specificity of 93.75%.

CONCLUSIONS

Our new scoring system could be important in the early diagnosis of the etiology of acute pancreatitis in a manner that is non-invasive, easy to calculate, inexpensive, and readily available.

Trypsin activity. A new marker of acute alcoholic pancreatitis

A normal serum amylase level is found in up to 32% of patients with acute alcoholic pancreatitis. This underlines the need for more sensitive diagnostic tests in this frequent cause of pancreatitis. Animal and human studies have shown that chronic alcohol consumption leads to important modifications in trypsinogen metabolism. The present work has prospectively analyzed admission serum trypsin activity with a new biochemical test and usual markers such as amylase, lipase, and immunoreactive trypsin in 32 attacks of acute pancreatitis. Seventeen were due to alcohol and 15 to other causes, including 11 with gallstone pancreatitis. High trypsin activity (median: 235 units/liter; range: 165-853) was found in all patients with acute alcoholic pancreatitis even when the amylase level was normal on admission (3/17: 18%). Trypsin activity did not differ between nonalcoholic pancreatitis (N = 15): 84 units/liter (42-98), alcoholic controls (N = 15): 77 units/liter (40-122), and healthy controls (N = 62): 81 units/liter (15-143). The difference was not related to the severity of disease or circulating alpha 2-macroglobulin, alpha 1-protease inhibitor, or immunoreactive trypsinogen levels. Lipase/amylase ratio was less discriminant than trypsin activity between alcoholic and nonalcoholic diseases. We conclude that serum trypsin activity seems specific to acute alcoholic pancreatitis and should be included in new prospective studies assessing biochemical testing of alcohol-related pancreatic diseases.