Exocrine pancreatic function after gastrectomy. Specificity of indirect tests

Exocrine Pancreatic Insufficiency Following Gastric Resectional Surgery-is Routine Pancreatic Enzyme Replacement Therapy Necessary?

The data on exocrine pancreatic insufficiency (EPI) following gastric resectional surgery is variable, ranging from 26% to as high as 100%. This study aimed to document symptomatic EPI following gastric resectional surgery and to objectively document EPI, by fecal elastase (FE) testing. This was a cross-sectional study among patients undergoing gastric resection for adenocarcinoma of the stomach, at the Upper Gastrointestinal Surgical Unit at the Christian Medical College Hospital, Vellore, India. A detailed questionnaire was administered to the patients in the postoperative period, to evaluate clinical symptoms of EPI. Further, study participants were tested for FE pre- and postoperatively. Of the 60 patients in this study, the postoperative questionnaire administered to all patients during follow up. None showed symptoms suggestive of EPI. Pre- and post-operative FE testing were feasible in 27 of the 60 patients, which showed a 33% incidence of EPI. None of the patients had clinical symptoms of EPI, following gastric resectional surgery, on short-term follow-up. However, more than a third of the patients tested developed asymptomatic EPI after gastric resectional surgery, based on FE testing. This may be explained by the fact that in the early postoperative period, EPI following gastric resectional surgery perhaps has a mild, subclinical presentation. Therefore routine pancreatic supplementation after gastric resectional surgery may not be necessary. However, one needs to carefully look for worsening of symptoms of EPI on long-term follow-up, which may necessitate appropriate investigations followed by pancreatic enzyme replacement therapy.

Accelerated radiochemotherapy in pancreatic cancer is not necessarily related to a pathologic pancreatic function decline in the early period

PURPOSE

To evaluate the functional effects of ionizing radiation in patients with unresectable pancreatic cancer in the early period after accelerated radiochemotherapy (ART).

METHODS AND MATERIALS

To analyze the exocrine component, the amino acid consumption test and fecal elastase 1 were performed in 13 patients immediately before and 4-8 weeks after ART. Pancreatic duct morphology was evaluated before therapy. Weight loss and clinical steatorrhea were recorded. Endocrine parameters were examined according to standardized criteria.

RESULTS

The relative change of the amino acid consumption test results and the median elastase concentration was 41.2% and 56.4%, respectively. Five patients still had normal test results after ART and 5 patients developed pathologic values. The median relative weight loss of the total body weight was 7.7% +/- 4.5%. No steatorrhea occurred. Of the 5 patients with normal values, 3 had a mean organ dose of <40 Gy. Of the 5 patients with pathologic values, 4 had a mean organ dose of >41 Gy. The endocrine function measurements remained unchanged.

CONCLUSION

Although a nominal reduction of exocrine function parameters occurred in most patients, ART was not necessarily related to a pathologic level in the early period. Diabetes was not established. The functional impairment that was existent in the patient population presumably contributed to the weight loss. Pancreatic enzyme preparations may also play a role in maintaining an anabolic state during and after radiochemotherapy.

Is the plasma amino acid consumption test an accurate test of exocrine pancreatic insufficiency?

BACKGROUND/AIMS

The amino acid consumption test has been proposed as an accurate test of exocrine pancreatic function. The diagnostic accuracy of this test was determined by simultaneously measuring plasma amino acids and enzyme secretion during stimulation of the pancreas with cholecystokinin octapeptide (CCK-OP) in 60 consecutive patients suspected of having pancreatic insufficiency.

METHODS

All patients underwent duodenal intubation and intravenous infusion of CCK-OP (40 ng.kg-1.h-1). Pancreatic enzyme (lipase and trypsin) outputs and plasma amino acids were measured for a period of 1 hour. Total and individual plasma amino acids were quantitated by ion-exchange chromatography. The severity of pancreatic insufficiency was graded on the basis of enzyme output during CCK-OP infusion.

RESULTS

There was no relationship between pancreatic enzyme output and plasma concentrations of individual or total amino acids before or during CCK-OP stimulation. Using a total amino acid decrease of 12% as the cutoff, the amino acid consumption test was 91% sensitive, but very nonspecific (21% specificity) for detection of pancreatic insufficiency.

CONCLUSIONS

The amino acid consumption test with CCK-OP stimulation does not discriminate between patients with normal and impaired exocrine pancreatic secretion.

Function tests in the diagnosis of chronic pancreatitis. Critical evaluation

Direct pancreatic function tests, such as the secretin-pancreozymin test and the Lundh test, are--by direct measurement of the contents of duodenal secretion following exogenous (hormonal) or endogenous (test meal) stimulation--the best way to assess exocrine pancreatic function. However, these tests are time-consuming, invasive, and expensive, and therefore their use is limited to specialized centers only. Several studies have shown that indirect pancreatic function tests are a practicable alternative to direct pancreatic function tests for diagnosing exocrine pancreatic insufficiency. They allow staging of the disease and thereby facilitate comparison of different studies. They are also useful in some cases for determining whether pancreatic enzyme replacement therapy is necessary or not. In contrast to morphological procedures, they involve neither side effects, risks for the patient, nor complications for patients, investigators, and laboratory staff alike. The procedures being standardized, the test results depend to a lesser extent on the experience of the investigator, and more on the selection of and the instructions to the patient, and to some extent, on the severity of the exocrine pancreatic insufficiency. Like all pancreatic function tests, the indirect tests do not give a clue to etiology nor help investigators to differentiate between pancreatic insufficiency owing to chronic pancreatitis and that owing to pancreatic cancer. The role of pancreatic function tests in diagnosing early chronic pancreatitis in comparison to morphological examinations remains to be established.

Determination of faecal chymotrypsin concentration and 72-hour faecal chymotrypsin output in the detection of pancreatic steatorrhoea

In 96 consecutive patients who underwent a 72-h faecal fat determination because of suspected nutrient malassimilation (maldigestion and/or malabsorption) faecal chymotrypsin (F-Chym) was estimated with a commercial photometric test (Monotest Chymotrypsin), comparing F-Chym concentrations in the first 24-h stool with the total 72-h F-Chym output. In the first 24-h faeces, the F-Chym concentration, calculated as a mean of three random samples, did not significantly differ from a single value obtained after homogenization. In known pancreatic disease, a F-Chym concentration less than 3.0 U/g wet faeces distinguished well between steatorrhoic patients (n = 12) and nonsteatorrhoic (n = 13) (positive predictive value (PV), 91%; negative PV, 86%) but was less suitable as a screening test for pancreatic steatorrhoea in the unselected patient group (positive PV, 61%; negative PV, 98%). Although the estimation of 72-h F-Chym output could differentiate between various subgroups of patients to a certain extent, the positive PV for discovery of pancreatic steatorrhoea in a single patient was low. Four patients had excessively high F-Chym output and increased bile acid excretion after ileal resection (n = 3) and radiation ileitis (n = 1), respectively, possibly indicating the removal of an inhibitory mechanism of pancreatic and biliary secretion in these conditions.