Adequacy of Endoscopic Biopsy Specimens for Disaccharidase Assays J.H. L E E , MD, W.J. G R I F F I T H S , MD, I. Z A N T O U T , MD, and J.D. W E L S H , MD

Intestinal mucosa from 40 patients obtained by fiber-endoscopic biopsy was assayed for disaccharidases to determine suitability of this tissue for assay. The combined specimens from each patient provided 4.7-38.7 mg of tissue, adequate in all instances for duplicate determinations of protein, lactase, sucrase, and maltase. Tissue remained for assays of palatinase in 39 instances, trehalase and cellobiase in 37, and alkaline phosphatase in 22 cases. Twenty-four subjects had normal lactose tolerance tests and normal sucrase/lactase ratios. Thirteen patients with abnormal oral lactose tolerance tests were identified as having a primary low lactase activity on the basis of elevated sucrase/lactase ratios. This ratio was most helpful in making the diagnosis of a primary low lactase, since the mucosal specimens were not obtained from comparable areas. Tissue from three subjects with an abnormally low mahase was unsuitable for diagnosis. Endoscopic biopsy of mucosa appears to be satisfactory for disaccharidase assays in most instances.

D e v e l o p m e n t of fiberoptic e n d o s c o p e s to investigate the upper-gastrointestinal tract has resulted in a n u m b e r of articles comparing the diagnostic value of these instruments with other methods, particularly radiography. Frequently o v e r l o o k e d is the endoscopic capability of obtaining intraluminal secretions (1) or m u c o s a for p u r p o s e s other than histology. F o r example, endoscopic biopsy specimens of the gastric antrum have been utilized for assays of mucosal gastrin (2, 3), and intraluminal secretions can be collected to look for Giardia lamblia. Since m a n y patients undergoing upper-gastrointestinal e n d o s c o p y h a v e s y m p t o m s compatible with lactose malabsorption, we undertook to determine if tissue obtained by endoscopic b i o p s y was adequate for disaccharidase assays.

MATERIALS AND METHODS All 40 patients in this study had clinical indications for From the Department of Medicine, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma. This work was supported by the Medical Research Service of the Veterans Administration. Address for reprint requests: Dr. J.D. Welsh, P.O. Box 26901, Oklahoma City, Oklahoma 73190.

upper-intestinal endoscopy, and informed consent was obtained for all procedures. A history concerning diarrhea and recognized milk or carbohydrate intolerance was sought from each patient. The subjects ranged from 33 to 79 years of age, and three were women. There was one American Indian. seven blacks, and the remainder were white. Of the 18 who had had no prior gastric surgery, 11 had peptic ulcer disease, two reflux esophagitis, four gastritis and one abnormal gastric and duodenal mucosal folds by x-ray. Of the remainder, 16 had had Billroth II procedures, four Billroth I, and one a gastrojejunostomy. Endoscopic examinations were performed with an Olympus GIF D-3 panendoscope and the tissue obtained with Olympus biopsy forceps (FB 12-K and FB 3K). In the unoperated patients or those with Billroth I anastomoses, three mucosal specimens were obtained in close proximity from the second or third portion of the duodenum. Patients with Billroth II anastomoses had 4-6 jejunal specimens taken sequentially during pull back over 2-4 in. at a distance of 1-2 ft from the stoma. In all instances, tissue was taken from similar areas for histologic examination. Assays of intestinal enzymes were performed in duplicate as described previously (4). Protein was determined by the method of Lowry et al (5), using dialyzed and lyophilized human serum protein as a standard. A sucrase/lactase (S/L) ratio of over 5 was considered to represent a primary low lactase activity (4). Oral lactose tolerance tests were done using 1 g lactose/kg body weight and testing of capillary blood (6). The study was approved by the Subcommittee on Human Experi-

Digestive Dtseases, Vol. 23, No. 12 (December 1978) 0002-9211/78/1200-1129505.00/1 9 1978DigestiveDiseaseSystems,Inc.



mentation of The University of Oklahoma Health Sciences Center. RESULTS The 3-6 mucosal specimens taken from each patient provided 4.7-38.7 mg of tissue for enzyme assays. This amount of mucosa was adequate for determination of protein content and for assays of lactase, sucrase, and maltase activities in all 40 cases. Enough tissue was still available for assays of platinase activity in 39 instances, trehalase and cellobiase in 37, and alkaline phosphatase in 22 cases. On the basis of the oral lactose tolerance tests and the biopsy locations (4), results were arranged into five groups. Normal Lactase Activity. Fourteen patients, including four with Billroth I anastomoses and one with a gastrojejunostomy, had normal lactose tolerance tests with rises in blood sugar of 37 mg/dl or more (Table 1). Intestinal histology was normal and the S/L ratios below 4.5. They were considered as control group 1. All but one were white, and the remainder an American Indian. Six had a history of diarrhea, and of these one recognized milk and three carbohydrate intolerance. All but one of the patients with diarrhea had had prior gastric surgery.


Ten of those with Billroth II anastamoses had normal intestinal histology and normal oral lactose tolerance tests (group II, Table 1). All were white men; six had diarrhea, four milk intolerance, and six carbohydrate intolerance. Mean disaccharidase activity values were higher than in group I, since all specimens were from the jejunum, although S/L ratios were similar in both groups. One subject had a previous intestinal biopsy with a peroral biopsy tube and enzyme assays which confirmed the normal disaccharidase activities. Primary Low Lactase Activity. Group II1 (Table I) is composed of seven individuals with abnormal oral lactose tolerance tests. One had had a Billroth I, while the others had had no prior surgery. Two were women and four black. Six had a history of diarrhea and all seven recognized milk intolerance. None had carbohydrate intolerance. Lactase activities were 7 units/g protein or less, and S/L ratios were 5.4 or higher. Six had Billroth 11 anastomoses (group IV) and abnormal oral lactose tolerance tests. All were men and three black. Four had diarrhea, while five recognized milk intolerance and three carbohydrate intolerance. S/L ratios were 6 or higher. One patient in group III and one in group IV had a primary lac-


Group Group I control N = 14 Group II Control Billroth II N = 10 Group III Lowlactase activity N=7 Group IV L o w lactase activity Billroth II N=6 Group V Unsatis. or abn. m u c o s a N=3

Oral lactose tol. test (glucose mg/dl)*

Lactase (units/g protein)

Sucrase (units/g protein)

Maltase (units/g protein)

S/L ratio

Weight of specimen (rag)

28 • 16 (11-77)

54 • 21 (26-111)

195 --- 65 (131-401)

2.1 • 0.8 (1.3-4.4)

19.0 • 11.1 (5.4-38.7)

101 • 46 (45-197)

52 + 34 (11-113)

74 • 42 (37-149)

293 • 127 (142-539)

2.1 __- 1.1 (1.1-3.6)

18.6 • 10.0 (4.7-34.4)

13 • 8 (5-20)

6 • 1 (3-7)

58 • 18 (34-80)

179 • 47 (92-214)

11.1 • 4.3 (5.4-17.0)

13.9 --+ 4.4 (6.7-19.4)

9 • 4 (5-13)

8 --+-2 (57-134)

106 • 34 (169-437)

321 • 92 (18-41)

15.1 • 6.0 (6.0-23.4)

21.0 • 5.4 (11.6-26.1)

14 • 6 (%21)

5 • 1 (4-6)

10 • 5 (6-15)

22 • 21 (0--42)

2.0 • 0.6 (1.5-2.6)

11.4 • 2.2 (9.4-13.7)

75 • 23t (37-I 11)$

*Rise o v e r fasting. +Mean • SD. :~Range.


Digestive Diseases, Vol. 23, No. 12 (December 1978)

ENDOSCOPIC BIOPSY TISSUE ENZYMES tase deficiency confirmed by a previous per oral small bowel biopsy and enzyme assays. Unsatisfactory Specimens. Group V was composed of three white male subjects, all with diarrhea and a history of milk intolerance. Oral lactose tolerance tests yielded abnormal blood glucose increases of 21 mg/dl or less over fasting. Maltase activities were below 45 units and sucrase below 20 units. The highest S/L ratio was 2.6. Weights of the specimens were similar to those in the other four groups. In one instance there were severe mucosal changes on microscopic examination, but the size of the biopsy specimen did not permit a definitive diagnosis. However, this could account for the secondary disaccharidase deficiency (7). The reason for the low enzyme activities in the other two instances is not cle~Lr, DISCUSSION Adequate tissue can be obtained during a per oral fiber-endoscopic examination to assay for a primary low intestinal lactase activity. From the present study, it would appear that three biopsy specimens are usually sufficient. Since specimens may be obtained from the duodenum or the jejunum when a patient has had prior surgery, and since there is a gradation of enzyme activity along the intestinal tract (8, 9) the sucrase/lactase ratio is more helpful than the actual enzyme levels in making a diagnosis. By history, 9 of the 16 patients who had had Billroth II procedures recognized milk intolerance; however, this was due to a low intestinal lactase activity in only five. Milk intolerance not due to a low intestinal lactase activity is occasionally noted following gastric surgery (8). In 3 of the 40 cases described in this report all enzymes assayed were decreased and the oral lactose tolerance tests abnormal. This suggested a secondary disaccharidase deficiency (7), although it was not substantiated by abnormal mucosal histology or other findings in two instances. However, mucosal specimens obtained by endoscopic biopsy are

Digestive Diseases, Vol. 23, No. 12 (December 1978)

quite small for good histologic examination and may be misleading. Discordant histology and enzyme activity due to spotty mucosal changes could account for the finding (10), since the assays and histologic examinations were performed on specimens obtained at different sites. When all the enzymes assayed are low and the histology appears normal, the specimens should be considered unsatisfactory. Therefore, it is suggested that when per endoscopic biopsy specimens are used for enzyme assays, maltase activity should be done in addition to determinations of lactase and sucrase. If the maltase level is inappropriately low, the patient has either a secondary disaccharidase deficiency, or the specimen is unsatisfactory. REFERENCES 1. Foss, DC, Laing RR: Detection of gallbladder disease in patients with normal oral cholecystograms. Am J Dig Dis 22:685-689, 1977 2. Hughes WS, Hernandez AJ: Antral gastrin concentration in patients with vagotomy and pyloroplasty. Gastroenterology 71:720-722, 1976 3. Creutzfeldt W, Arnold R, Creutzfeldt C, Track NS: Mucosal gastrin concentration, molecular forms of gastrin, number and ultrastrncture of G-cells in patients with duodenal ulcer. Gut 17:745-754, 1976 4. Welsh JD: Isolated lactase deficiency in humans: Report on 100 patients. Medicine 47:257-277, 1970 5. Lowry OH, Rosebrough NJ, Farr AL, Randall RJ: Protein measurement with the Folin phenol reagent. J Biol Chem 193:265-275, 1951 6. Welsh JD: On the lactose tolerance test. Gastroenterology 51:445, 1966 7. Welsh JD, Zschiesche OM, Anderson J, Walker A: Intestinal disaccharidase activity in celiac sprue (gluten sensitive enteropathy). Arch Intern Med 123:33-38, 1969 8. Welsh JD, Shaw RW, Walker A: Isolated lactase deficiency producing post-gastrectomy milk intolerance. Ann Intern Med 64:1252-1258, 1966 9. Newcomer AD, McGill DB: Distribution of disaccharidase activity in the small bowel of normal and lactase-deficient subjects. Gastroenterology 51:481-488, 1966 10. Welsh JD, Rohrer GV, Drewry R, May JC, Walker A: Human intestinal disaccharidase activity. II. Diseases of the small intestine and deficiency states. Arch Intern Med 117:495-503, 1966


Adequacy of endoscopic biopsy specimens for disaccharidase assays.

Adequacy of Endoscopic Biopsy Specimens for Disaccharidase Assays J.H. L E E , MD, W.J. G R I F F I T H S , MD, I. Z A N T O U T , MD, and J.D. W E L...
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