Effect of colectomy with ileo-anal anastomosis on the biliary lipids

Kinetics of primary bile acids in patients after proctocolectomy and ileal pouch-anal anastomosis

BACKGROUND

The high incidence of cholesterol gallstones in patients after proctocolectomy with ileal pouch-anal anastomosis (IPAA) may be due to an increased loss of bile acids. We aimed to evaluate the kinetics of the primary bile acids cholic acid (CA) and chenodeoxycholic acid (CDCA) in these patients.

METHODS

Pool sizes, synthesis rates, and fractional turnover rates of CA and CDCA were determined by combined capillary gas chromatography/isotope ratio mass spectrometry in serum samples after administration of [¹³C]CA and [¹³C]CDCA in 6 patients and 9 healthy volunteers.

RESULTS

In patients with IPAA, pool sizes of CA and CDCA were 11.5 (8.2-23.8) and 12.1 (6.7-20.1) µmol/kg, respectively, and were significantly lower than in healthy controls [36.0 (24-47) and 29.0 (21-42) µmol/kg, respectively; p < 0.05, each]. Fractional turnover rates of CA [1.19 (1.06-1.82) vs. 0.31 (0.13-0.54) per day] and CDCA [1.01 (0.50-1.63) vs. 0.23 (0.09-0.36) per day] were increased fourfold in patients with IPAA (p < 0.05, each). Synthesis rates of CDCA [10.2 (5.2-32.9) vs. 6.6 (2.7-10.5) µmol/kg per day, p = 0.05] and CA [15.1 (9.3-39.4) vs. 11.5 (3.1-20.5) µmol/kg per day, n.s.] tended to be higher in patients with IPAA than in controls.

CONCLUSION

The reduced pool size of primary bile acids may contribute to the high incidence of cholesterol gallstones in patients after proctocolectomy and IPAA.

Evolution of the restorative proctocolectomy and its effects on gastrointestinal hormones

Gastrointestinal (GI) peptide hormones are chemical messengers that regulate secretory, mechanical, metabolic, and trophic functions of the gut. Restorative proctocolectomy (RPC) or resection of the colon and rectum with maintenance of intestinal continuity through the construction of an ileal pouch reservoir and preservation of the anal sphincters has become the standard of care for the surgical treatment of ulcerative colitis and familial adenomatous polyposis. The manipulation of the digestive system to create the ileal pouch involves altering gut-associated lymphoid tissue among other anatomic changes that lead to changes in GI peptides. In addition, the ileal pouch epithelium responds to a wide variety of stimuli by adjusting its cellularity and function. These adaptive mechanisms involve systemic factors, such as humoral and neural stimuli, as well as local factors, such as changes in intestinal peristalsis and intraluminal nutrients. There have been conflicting reports as to whether the alterations in GI hormones after RPC have actual clinical implications. What the studies on alterations of GI peptides' response and behavior after RPC have contributed, however, is a window into the possible etiology of complications after pouch surgery, such as pouchitis and malabsorption. Given the possibility of pharmacologically modifying GI peptides or select components of adaptation as a therapeutic strategy for patients with ileal pouch dysfunction or pouchitis, a clear understanding of human pouch mucosal adaptation is of paramount importance. In this review, we summarize the evolution of the RPC and its effects on the GI hormones as well as their possible clinical implications.

Impact of surgery on the development of duodenal cancer in patients with familial adenomatous polyposis

PURPOSE

Precancerous duodenal lesions in patients with familial adenomatous polyposis can be detected with duodenoscopy and treatment may prevent the development of cancer. We proposed to determine the frequency, natural history, cumulative risk, and risk factors of the precancerous duodenal lesions in a series of patients diagnosed in northern Italy.

METHODS

A prospective, endoscopic, follow-up protocol was performed in 50 patients examined by gastroduodenoscopy at two years of interval or less. The presence and severity of precancerous lesions of the duodenal mucosa were evaluated by Spigelman score. Twenty-five patients (50 percent) had proctocolectomy and ileoanal anastomosis, 15 (30 percent) had colectomy and ileorectal anastomosis, and 5 (10 percent) had proctocolectomy and definitive ileostomy from 0 to 3 years before the admission to the surveillance program. All patients showed more than a thousand adenomas in the colorectal mucosa. No patients with attenuated polyposis were found.

RESULTS

At the first endoscopy, duodenal adenomas could be detected in 19 of 50 patients (38 percent), whereas at the end of the follow-up, 43 (86 percent) had duodenal lesions. The final mean Spigelman score increased during the follow-up period (P<0.001 respect to baseline values). No duodenal cancer could be detected. Eleven patients had or developed severe precancerous duodenal lesions (Stage IV) treated with endoscopic or surgical resection. The distribution of patients with Stage IV according to the surgery of the colon was: 2 of 25 treated with ileoanal anastomosis and 8 of 15 with ileorectal anastomosis (P=0.0024, Fisher's exact test).

CONCLUSIONS

Patients with familial adenomatous polyposis are at risk of significant neoplasia. The natural history of precancerous lesions might be related to surgical treatment of colorectal neoplasms.

Bile composition in inflammatory bowel disease: ileal disease and colectomy, but not colitis, induce lithogenic bile

BACKGROUND

Inflammatory bowel disease is a risk factor for gall-bladder stones, but there is controversy about the composition of these stones and whether such patients develop lithogenic bile.

METHODS

In 54 gallstone-free inflammatory bowel disease patients and 13 non-inflammatory bowel disease patients with cholesterol-rich gallstones, we measured the biliary cholesterol saturation indices, nucleation times and bilirubin concentrations, and determined the bile acid composition and molecular species of phosphatidylcholine, in gall-bladder bile.

RESULTS

Patients with Crohn's colitis or ulcerative colitis had less saturated bile (mean cholesterol saturation index, 0.9) and longer nucleation times (median, 21 days) than those with ileal Crohn's disease (1.5; 14 days) or those who had undergone colectomy (1.6; 5 days). In patients with ileal Crohn's disease, the mean biliary bilirubin concentration was two- to three-fold higher than that in the other groups, and was associated with a decrease in the percentage of biliary deoxycholate and an increase in the percentage of ursodeoxycholate, compared with disease controls, but phosphatidylcholine species were similar.

CONCLUSIONS

Patients with small bowel Crohn's disease, or who have undergone colonic resection, have supersaturated bile and an increased risk of cholesterol gallstone formation. In patients with ileal disease, the presence of high biliary bilirubin concentrations and low percentage of deoxycholic acid may also favour the formation of mixed, pigment-rich, gallstones.

Biliary bile acid composition in gastric cancer

Bile reflux into the stomach has been considered carcinogenic. Secondary bile acids, and in particular deoxycholic acid, have been shown to act experimentally as co-carcinogens in the colon and are increased in patients with colorectal adenocarcinoma. No information is available with respect to biliary bile acid composition in patients with gastric cancer. We studied biliary bile acid composition in 11 patients with gastric cancer and 23 healthy controls. Bile acids were measured using high-performance liquid chromatography. The site of gastric cancer was the antrum in 6 patients and body in 5. There were 6 intestinal-type and 5 diffuse adenocarcinomas. Only 2 patients had Helicobacter pylori infection. Deoxycholic acid constituted 24% +/- 2% of biliary bile acid in gastric cancer patients versus 22% +/- 2% in healthy controls (NS). Similarly, no differences were found between the two groups for all other bile acids. Deoxycholic acid constituted 23% +/- 3% of biliary bile acid (NS vs. controls) in patients with antral adenocarcinoma and 25% +/- 2% (NS vs. controls) in patients with intestinal-type gastric adenocarcinoma. Gastric adenocarcinoma is not associated with an increase in the more-toxic secondary bile acids, and deoxycholic acid in particular. This reduces the importance of bile acid composition as a promotor in gastric carcinogenesis.

Abnormal duodenal bile composition in patients with acalculous chronic cholecystitis

OBJECTIVE

Our goal was to characterize biliary lipid composition in patients with the syndrome of chronic biliary pain, absence of gallstones, and inflammation of the gallbladder mucosa (acalculous chronic cholecystitis).

METHODS

Duodenal bile, obtained from 27 patients with a history of right upper quadrant pain and with negative imaging studies of the biliary tract, was analyzed enzymatically for bile acids, phospholipids, and cholesterol. Fifteen patients were found to have inflammation and/or fibrosis of the gallbladder at cholecystectomy.

RESULTS

The 15 patients with abnormal gallbladder histology had more dilute duodenal bile, as indicated by a low bile acid concentration and a lower proportion of phospholipids (p < 0.01) when values were compared with those of duodenal bile samples from postmenopausal women without gallbladder disease or from radiolucent gallstone subjects participating in the National Cooperative Gallstone Study. Cholecystectomy relieved pain in 9 of 14 patients.

CONCLUSIONS

Some patients with acalculous chronic cholecystitis have duodenal bile samples characterized by a decreased bile acid concentration and a decreased proportion of biliary phospholipids. The low biliary bile acid concentration may result from impaired gallbladder contraction and/or secretion by the biliary tract epithelium. The low proportion of phospholipid may result from posthepatic hydrolysis of luminal phosphatidylcholine followed by absorption of the hydrolysis products. The latter process could be caused by and/or contribute to mucosal inflammation and would also elevate the cholesterol saturation of bile, increasing the risk for cholesterol gallstone formation.

Metabolic consequences of total colectomy

Colectomy is performed for inflammatory bowel disease, familial polyposis syndrome and colorectal carcinoma. Surgical procedures are ileostomy with or without pouch, ileorectal anastomosis or ileal pouch-anal anastomosis. One of the major functions of the intact large intestine is to absorb water and electrolytes. After colectomy, as much as 400-1000 ml of nearly isotonic ileostomy fluid may be excreted, resulting in a chronic salt and water depletion. This is compensated for by an activation of the renin-angiotensin-aldosterone system. Reduced urine volumes may cause kidney stones. Both dehydration and renal sodium retention are probably less frequent in patients with ileal pouch-anal anastomosis. Absorption of nutrients in general is not impaired by colectomy. The large intestine salvages energy from malabsorbed organic matter through absorption of the short-chain fatty acids produced in bacterial fermentation. In ileostomy patients, fermentation is negligible, which leads to a significant loss of energy in the ileostomy fluid. Pouches are colonized by a bacterial flora similar to colonic bacteria. In these patients conservation of energy from malabsorbed substrate may be similar to healthy subjects. Resection of ileum and bacterial colonization may lead to malabsorption of vitamin B12 and bile acids. The latter may cause increased incidence of biliary cholesterol stones. Pouchitis is a frequent problem which may be caused by a deficiency of short-chain fatty acids and glutamine in the pouch contents. It is concluded that although the colon is not essential as a digestive organ in man, colectomy results in a number of metabolic changes. The ileal pouch-anal anastomosis may in part substitute for the functions of the large intestine.