Hepatic steatosis depresses alpha-1-antitrypsin levels in human and rat acute pancreatitis

Hepatic steatosis (HS) can exacerbate acute pancreatitis (AP). This study aimed to investigate the relation between α1-antitrypsin (AAT) and acute pancreatitis when patients have HS. Using proteomic profiling, we identified 18 differently expressed proteins pots in the serum of rats with or without HS after surgical establishment of AP. AAT was found to be one of the significantly down-regulated proteins. AAT levels were significantly lower in hepatic steatosis acute pancreatitis (HSAP) than in non-HSAP (NHSAP) (P < 0.001). To explore the clinical significance of these observations, we measured the levels of AAT in the serum of 240 patients with HSAP, NHSAP, fatty liver disease (FLD), or no disease. Compared with healthy controls, serum AAT levels in patients with NHSAP were significantly higher (P < 0.01), while in patients with HSAP serum AAT levels were significantly lower (P < 0.01). Further studies showed that acute physiology and chronic health evaluation (APACHE-II) scores were negatively correlated with serum AAT levels (r = −0.85, P < 0.01). In conclusion, low serum levels of AAT in patients with HSAP are correlated with disease severity and AAT may represent a potential target for therapies aiming to improve pancreatitis.

Laboratory diagnosis of acute pancreatitis: in search of the Holy Grail

Acute pancreatitis is an acute inflammatory condition of the pancreas, which might extend to local and distant extrapancreatic tissues. The global incidence varies between 17.5 and 73.4 cases per 100,000 and the pathogenesis recognizes alcohol exposure and biliary tract disease as the leading causes, ahead of post-endoscopic retrograde cholangiopancreatography, drugs and abdominal trauma. The diagnosis of acute pancreatitis is substantially based on a combination of clinical signs and symptoms, imaging techniques and laboratory investigations. Contrast-enhanced computed tomography is the reference standard for the diagnosis, as well as for establishing disease severity. The assessment of pancreatic enzymes, early released from necrotic tissue, is the cornerstone of laboratory diagnosis in this clinical setting. Although there is no single test that shows optimal diagnostic accuracy, most current guidelines and recommendations indicate that lipase should be preferred over total and pancreatic amylase. Although a definitive diagnostic threshold cannot be identified, cut-offs comprised between ≥ 2 and ≥ 4 times the upper limit of the reference interval are preferable. The combination of amylase and lipase has been discouraged as although it marginally improves the diagnostic efficiency of either marker alone, it increases the cost of investigation. Some interesting biomarkers have been also suggested (e.g., serum and urinary trypsinogen-1, -2 and -3, phospholipase A2, pancreatic elastase, procalcitonin, trypsinogen activated protein, activation peptide of carboxypeptidase B, trypsin-2-alpha1 antitrypsin complex and circulating DNA), but none of them has found widespread application for a variety of reasons, including the inferior diagnostic accuracy when compared with the traditional enzymes, the use of cumbersome techniques, or their recent discovery. The promising results of recent proteomics studies showed that this innovative technique might allow the identification of changes characterizing pancreatic tissue injury, thus highlighting new potential biomarkers of acute pancreatitis.

Specific Immunoassay Reveals Increased Serum Trypsinogen 3 in Acute Pancreatitis

BACKGROUND

Trypsinogen 3 is a minor trypsinogen isoform in the pancreas. In contrast with trypsin 1 and 2, trypsin 3 degrades pancreatic secretory trypsin inhibitor, which may lead to an excess of active trypsin and acute pancreatitis (AP). We developed an immunoassay for trypsinogen 3 and studied whether an assay of serum trypsinogen 3 is of clinical utility in the diagnosis of AP.

METHODS

Monoclonal antibodies were generated using recombinant human trypsinogen 3 as the antigen and used to establish a sandwich-type immunoassay. We analyzed serum trypsinogen 3 concentrations in 82 patients with AP and 63 patients with upper abdominal pain (controls). The reference interval was determined using serum samples from 172 apparently healthy individuals.

RESULTS

The measuring range of the trypsinogen 3 assay was 1.0–250 μg/L. Intra- and interassay CVs were &lt;11%, and cross-reactivity with other trypsinogen isoenzymes was &lt;0.1%. The median trypsinogen 3 concentration in serum from healthy individuals was &lt;1.0 μg/L, and the upper reference limit was 4.4 μg/L. We observed increased trypsinogen 3 concentrations in patients with mild (median 9.5 μg/L) and severe (15.0 μg/L) AP; in both groups, the concentrations were significantly higher than in controls (median &lt;1.0 μg/L) (P &lt; 0.0001). In ROC analysis, the area under the curve of trypsinogen 3 for separation between AP and controls was 0.90 (P &lt; 0.0001).

CONCLUSIONS

We established for the first time a specific immunoassay for trypsinogen 3 using monoclonal antibodies. Patients with AP were found to have increased serum concentrations of trypsinogen 3. The availability of this assay will be useful for studies of the clinical utility of trypsinogen 3.

Gallstone-induced acute pancreatitis

In the care of acute pancreatitis, a prompt search for the etiologic condition of the disease should be conducted. A differentiation of gallstone-induced acute pancreatitis should be given top priority in its etiologic diagnosis because it is related to the decision of treatment policy. Examinations necessary for diagnosing gallstone-induced acute pancreatitis include blood tests and ultrasonography. Early ERCP/ES should be performed in patients with gallstone-induced acute pancreatitis if a complication of cholangitis and a prolonged passage disorder of the biliary tract are suspected. The treatment for bile duct stones with the use of ERCP/ES alone is not recommended in cases of gallstone-induced pancreatitis with gallbladder stones. Cholecystectomy for gallstone-induced acute pancreatitis should be performed using a laparoscopic procedure as the first option as soon as the disease has subsided.

When is pancreatitis considered to be of biliary origin and what are the implications for management?

Acute pancreatitis is a disease caused by gallstones in 40-60% of patients. Identification of these patients is extremely important, since there are specific therapeutic interventions by endoscopic sphincterotomy and/or cholecystectomy. The combination of trans-abdominal ultrasound (stones in the gallbladder and/or main bile duct) and elevated serum alanine transaminase (circa >60 IU/l within 48 h of presentation) indicates gallstones as the cause in the majority of patients with acute pancreatitis. In the presence of a severe attack this is a strong indication for intervention by endoscopic sphincterotomy. The presence of a significant main bile duct dilatation is also strongly indicative of gallstones and should prompt the use of endoluminal ultrasonography: >8 mm diameter with gallbladder in situ, or >10 mm following cholecystectomy if aged <70 years and >12 mm, respectively, if > or = 70 years. In mild pancreatitis surgically fit patients should be treated by cholecystectomy, and intra-operative cholangiography, as pre-operative biliary imaging is not efficient in this setting. Patients who are not fit for cholecystectomy should undergo prophylactic endoscopic sphincterotomy to prevent further attacks. In the post-acute-phase, pancreatitis patients in whom the aetiology is uncertain should undergo endoluminal ultrasonography. Thisis the most sensitive method for the detection of cholelithiasis and choledocholithiasis and may reveal alternative aetiological factors such as a small ampullary or pancreatic cancer. A number of recent studies have shown that bile crystal analysis, a marker for microlithiasis, increases the yield of positive results over and above endoluminal ultrasonography, and should be considered as part of the modern investigative algorithm.

Disialotransferrin, determined by capillary electrophoresis, is an accurate biomarker for alcoholic cause of acute pancreatitis

OBJECTIVES

Serum disialotransferrin is a specific marker of heavy alcohol consumption. We tested its accuracy and probability in detecting alcoholic cause of acute pancreatitis (AP).

METHODS

Blood samples from 271 consecutive AP patients, admitted to the Helsinki University Central Hospital emergency unit, were analyzed.

RESULTS

The median (range) disialotransferrin value was significantly higher (P = 0.001) in AP patients with alcoholic (n = 172) 1.6% (0.3%-14.4) than with biliary (n = 60) 0.7% (0.3%-1.3%) or other causes (n = 39) 0.8% (0.3%-4.1%). In receiver operating curve analysis, disialotransferrin, as a single analyte, was significantly (P = 0.001-0.0001) more accurate (area under the curve [AUC], 0.88; 95% confidence interval [CI], 0.84-0.92) in detecting alcoholic AP as compared with glutamyl transferase (AUC, 0.51; 95% CI, 0.45-0.57), aspartate aminotransferase (AUC, 0.57; 95% CI, 0.51-0.63), alanine aminotransferase (AUC, 0.63; 95% CI, 0.57-0.69), erythrocyte mean cell volume (AUC, 0.72; 95% CI, 0.67-0.78), amylase (AUC, 0.74; 95% CI, 0.67-0.78), C-reactive protein (AUC, 0.65; 95% CI, 0.59-0.71), and bilirubin (AUC, 0.55; 95% CI, 0.49-0.62). At a disialotransferrin cutoff of 1.2%, giving an 8% false-positive rate, the positive likelihood ratio was 8.47. Thus, a positive disialotransferrin test result, performed within 24 hours of admission, increased the probability of alcoholic AP from pretest 64% to posttest 94%.

CONCLUSIONS

Disialotransferrin, determined by capillary electrophoresis, is accurate, simple, and a rapid single biomarker of the alcoholic cause of AP.

Biochemistry and clinical role of trypsinogens and pancreatic secretory trypsin inhibitor

Trypsinogens and PSTI/TATI/SPINK1 are expressed, usually together, at high levels by the pancreas but also by many other normal and malignant tissues. The present review describes studies on the expression and putative functions of trypsinogens and PSTI/TATI/SPINK1 in the human body. The clinical aspects are discussed, including the correlations between expression of trypsinogens and PSTI/TATI/SPINK1 in tissues, serum, and urine of patients with pancreatitis or cancer and clinicopathological characteristics, i.e., the roles of trypsinogens and PSTI/TATI/SPINK1 in spontaneous and hereditary pancreatitis, tumor progression, and prognosis.

Methodology in Diagnostic Laboratory Test Research in Clinical Chemistry and Clinical Chemistry and Laboratory Medicine

Background: The application of epidemiologic principles to clinical diagnosis has been less developed than in other clinical areas. Knowledge of the main flaws affecting diagnostic laboratory test research is the first step for improving its quality. We assessed the methodologic aspects of articles on laboratory tests.

Methods: We included articles that estimated indexes of diagnostic accuracy (sensitivity and specificity) and were published in Clinical Chemistry or Clinical Chemistry and Laboratory Medicine in 1996, 2001, and 2002. Clinical Chemistry has paid special attention to this field of research since 1996 by publishing recommendations, checklists, and reviews. Articles were identified through electronic searches in Medline. The strategy combined the Mesh term “sensitivity and specificity” (exploded) with the text words “specificity”, “false negative”, and “accuracy”. We examined adherence to seven methodologic criteria used in the study by Reid et al. (JAMA1995;274:645–51) of papers published in general medical journals. Three observers evaluated each article independently.

Results: Seventy-nine articles fulfilled the inclusion criteria. The percentage of studies that satisfied each criterion improved from 1996 to 2002. Substantial improvement was observed in reporting of the statistical uncertainty of indices of diagnostic accuracy, in criteria based on clinical information from the study population (spectrum composition), and in avoidance of workup bias. Analytical reproducibility was reported frequently (68%), whereas information about indeterminate results was rarely provided. The mean number of methodologic criteria satisfied showed a statistically significant increase over the 3 years in Clinical Chemistry but not in Clinical Chemistry and Laboratory Medicine.

Conclusions: The methodologic quality of the articles on diagnostic test research published in Clinical Chemistry and Clinical Chemistry and Laboratory Medicine is comparable to the quality observed in the best general medical journals. The methodologic aspects that most need improvement are those linked to the clinical information of the populations studied. Editorial actions aimed to increase the quality of reporting of diagnostic studies could have a relevant positive effect, as shown by the improvement observed in Clinical Chemistry.

Trypsinogen-2 and trypsinogen activation peptide (TAP) in urine of patients with acute pancreatitis

BACKGROUND AND AIMS

There is an obvious clinical need for a simple test that can identify patients at risk of developing severe acute pancreatitis. In this work we compared urinary trypsinogen-2 with urinary trypsinogen activation peptide (TAP) and serum C-reactive protein (CRP) for early differentiation between mild and severe acute pancreatitis.

PATIENTS AND METHODS

The study population consisted of 127 consecutive patients with acute pancreatitis of whom 29 had severe disease. Urinary trypsinogen-2 was measured by a quantitative immunofluorometric assay and TAP by a competitive immunoassay. Serum CRP was determined by immunoturbidimetry.

RESULTS

The sensitivity and specificity to identify severe acute pancreatitis on admission was 72% and 81% for urinary trypsinogen-2, 64% and 82% for urinary TAP, and 29% and 93% for serum CRP, respectively. At 24 h after admission, the values were 82% and 78% for urinary trypsinogen-2, 52% and 92% for urinary TAP, and 84% and 72% for serum CRP, respectively. Receiver-operating characteristics curve analysis showed that the area under the curve was larger for urinary trypsinogen-2 than for urinary TAP and serum CRP on admission and 24 h after admission. On admission the positive likelihood ration for urinary trypsiongen-2 was 3.7, for urinary TAP 3.6, and 4.3 for serum CRP, respectively. The corresponding negative likelihood ratios were 0.34, 0.43, and 0.76, respectively.

CONCLUSION

Urinary trypsinogen-2 was superior to serum CRP and as god as or even better than urinary TAP and in the early prediction of disease severity in acute pancreatitis. These results suggest that it could be a valuable adjunct in the early assessment of the severity of acute pancreatitis.

New laboratory tests in acute pancreatitis

Acute pancreatitis (AP) is a common disease with wide variation of severity. The diagnosis of AP is usually based on high serum amylase or lipase values but the accuracy of these methods is considered unsatisfactory. One in five of the patients develops a severe disease and carries a considerable risk of development of organ failure and high mortality. Early detection of patients with severe AP and especially those with increased risk of organ failure is importance since such patients seem to benefit from treatment in an intensive care unit started as soon as possible after presentation. In addition to enzymological methods, increasing interest has been focused on laboratory markers reflecting the level of inflammatory response in AP. At present, in routine clinical work the most commonly used severity marker is serum C-reactive protein, the concentration of which rises too slowly to be used for early prediction of severity. New therapies aiming at modifying the course of systemic inflammation in AP are being developed and therefore monitoring the patient's immune inflammatory status is needed. In this review article we present the current knowledge of laboratory tests, which has been evaluated for diagnostic and prognostic purposes in AP.