Routine determinations of serum pepsinogens

An improved radioimmunoassay for measurement of pepsinogen in porcine blood samples

The study was conducted to develop a sensitive and specific radioimmunoassay (RIA) for the measurement of pepsinogen in porcine serum, and to use this test for the determination of pepsinogen concentrations in serum samples from fetuses and pigs of different ages. Compared to a previously described RIA, major improvements were made concerning the use of specific polyclonal antibodies and the use of an appropriate buffer. The assay was able to detect pepsinogen concentrations of >/=0.2 ng/mL. The recovery of pepsinogen was close to 95%. The intra-assay coefficients of variations ranged between 3.9 and 7.5% whereas the interassay ranged between 8.8 and 11.9%. These percentages correspond to a satisfactory accuracy and reproducibility of the assay. No cross-reactions were observed with the main commercially available products of the aspartic proteases family except porcine pepsin cross-reacted over 62.5 microg/mL. Pepsinogen concentrations increased steadily with increasing age of the fetuses and the pigs (P<0.05). Pepsinogen concentrations (+/-SE) in fetuses of 90-100 (n=24) and 100-110 days of pregnancy (n=36) were 0.5+/-0.1 and 5.3+/-1.3 ng/mL, respectively. In pigs of 21, 98, and 213 days of age, the pepsinogen concentrations were 290.6+/-10.8, 343.1+/-17.9 and 383.5+/-15.3 ng/mL, respectively. The results demonstrate that RIA is accurate and can be used easily to assess pepsinogen concentrations in pig sera. The test may constitute a valuable tool in epidemiological surveys and in studies related to gastric diseases in pigs.

Pepsinogens in health and disease

Pepsinogens, precursors of pepsins (potent and abundant digestive enzymes that are the primary products of the gastric chief cells), are members of the family of aspartic proteases. Because of the heterogeneity of pepsinogens, several classifications have appeared in the literature. I describe the recommended classification and nomenclature of the aspartic proteases and discuss their genetics, biochemistry (structure, activation of zymogens, mechanism of proteolytic activity and inhibitors), and physiology. The focus will be on the zymogens of pepsin, the so-called pepsinogens. The measurement of these enzymes in serum is a reliable noninvasive biochemical method for evaluating peptic secretion and obtaining information on the gastric mucosal status. A detailed review of the methods for the measurement of pepsinogens in serum, urine, and gastric mucosa is also provided. Data on pepsinogen levels in healthy subjects are discussed with respect to sex, age, smoking habit, and the presence of a circadian rhythm. The value of pepsinogen measurements in peptic ulcer to determine ulcer outcome and recurrence, in gastric cancer, and in Helicobacter pylori infection is reviewed. Finally, the effects of drugs on peptic secretion are discussed. In light of these data, the measurement of aspartic proteases, and in particular that of pepsinogen A and C, may be regarded as an effective biochemical approach to the evaluation and monitoring of patients with upper gastrointestinal diseases.

Variation of total pepsin activity in sera with age and under different stimulations of gastric acid secretion

The total pepsin activity in sera was measured in 660 outpatients endoscopically proven to be free of gastroduodenal lesions. A small but significant increase of total pepsin activity with age in females older than 50 years was observed. Total serum pepsin activity increased after stimulation of gastric acid secretion. This increase was small after a meal and vagal stimulation by sham feeding, but higher after maximal stimulation with Pentagastrin. Its amount, which is in general rather small and probably not relevant for clinical evaluation of gastric acid secretion, depends on the proportion of cases with high gastric secretory capacity. This might clarify the discrepancy in the results obtained by previous authors.

Elevated serum pepsinogen I and II levels differ as risk factors for duodenal ulcer and gastric ulcer

We investigated the possibility that serum pepsinogen I (PG I) and pepsinogen II (PG II) levels might differ as risk factors for duodenal ulcer and gastric ulcer. From 1967 to 1970, serum was obtained from 7498 Japanese men in Hawaii, and the cohort was followed up to 1981 for the development of peptic ulcer disease. Pepsinogen I and PG II levels in stored serum were significantly higher in the subjects who developed duodenal ulcer (n = 43) or gastric ulcer (n = 115) than in 212 control subjects. The linear trend in risk of each type of ulcer was highly significant for both PG I and PG II. An elevated serum PG I level (greater than or equal to 130 micrograms/L), however, was associated with about a threefold higher odds ratio for duodenal ulcer than for gastric ulcer (8.37 vs. 2.83), whereas an elevated PG II level (greater than or equal to 30 micrograms/L) was associated with about a threefold higher odds ratio for gastric ulcer than for duodenal ulcer (18.21 vs. 6.49). In contrast, the PG I/PG II ratio was significantly lower in the gastric ulcer than in the control and duodenal ulcer cases, and showed a significant linear trend in risk only for gastric ulcer. In addition, a PG I/PG II ratio of less than 4.0, which has been shown previously to be indicative of chronic gastritis, was associated with an almost 10-fold higher odds ratio for gastric ulcer than for duodenal ulcer (7.35 vs. 0.79). The results indicate that an elevated serum PG I level is a major risk factor for duodenal ulcer, whereas an elevated serum PG II level and a low PG I/PG II ratio are major risk factors for gastric ulcer.

Pepsinogen Group I radioimmunoassay and total serum pepsinogen colorimetric determination: a comparative study in normal subjects and in peptic ulcer patients

Pepsinogens, proteolytic enzymes produced by peptic cells of the stomach and discharged into the gastric lumen as well as into the blood have been divided into two groups: PG-I, originating from chief cells, and PG-II, mainly from antrum peptic cells. Both total serum pepsinogen (s-Pg) and PG-I have been separately reported as being significantly increased in gastric (GU) and duodenal ulcer (DU) patients and related to maximal acid output. In order to ascertain the relationship between s-Pg measured by means of the colorimetric Uete method, and PG-I determined by RIA method, these were assayed in 72 control subjects, 35 GU and 95 DU patients. s-Pg was found to be significantly increased both in GU and DU patients in comparison with control subjects. Likewise PG-I was significantly enhanced in GU and DU patients as compared with controls. A significant direct correlation between s-Pg and PG-I was found in all the subjects studied (r = 0.732).