Constipation and fecal incontinence in the elderly.

Although constipation and fecal incontinence are common symptoms in the elderly, relatively little research has been done to differentiate physiologic changes in rectoanal function resulting from aging and pathologic changes resulting from diseases occurring as patients age. Certain physiologic changes occur in many older patients and may predispose them to the development of constipation or fecal incontinence. These symptoms need the same thoughtful evaluation and management in the elderly as in younger patients. Results of therapy often can be good, leading to alleviation of suffering and the ability to lead a fuller life.

Review article: the therapy of constipation.

Constipation is a common symptom that may be idiopathic or due to various identifiable disease processes. Laxatives are agents that add bulk to intestinal contents, that retain water within the bowel lumen by virtue of osmotic effects, or that stimulate intestinal secretion or motility, thereby increasing the frequency and ease of defecation. Drugs which improve constipation by stimulating gastrointestinal motility by direct actions on the enteric nervous system are under development. Other modalities used to treat constipation include biofeedback and surgery. Laxatives and lavage solutions are also used for colon preparation and evacuation of the bowels after toxic ingestions.

Diarrhea.

Diarrhea is a common symptom of many conditions, and making an accurate diagnosis can be daunting. Research efforts have expanded the differential diagnosis of chronic diarrhea and have provided improved methods for the evaluation and management of patients with diarrheal diseases. This article discusses some of these trends and presents the emerging consensus regarding appropriate pathways of caring for patients with diarrheal diseases.

Microscopic colitis syndrome: lymphocytic colitis and collagenous colitis.

Microscopic colitis is a syndrome consisting of chronic watery diarrhea, a normal or near-normal gross appearance of the colonic lining, and a specific histological picture described as either lymphocytic colitis or collagenous colitis. Since its initial descriptions a quarter of a century ago, microscopic colitis has become a frequent diagnosis in patients with chronic diarrhea. Understanding of the cause and pathogenesis of microscopic colitis remain incomplete, but potentially important clues have been discovered that shed light on predisposing factors. In particular, specific HLA-DQ genotypes may be permissive for the development of microscopic colitis, and suggest a linkage to the pathogenesis of celiac sprue. Although the differential diagnosis of chronic watery diarrhea is broad, the diagnosis of microscopic colitis is straightforward, involving endoscopic inspection of the colonic mucosa and proper pathologic interpretation of biopsy specimens. As the limitations of drugs ordinarily used for other forms of inflammatory bowel disease are being recognized, new approaches, such as the use of bismuth subsalicylate, are being evaluated. The prognosis of patients with microscopic colitis syndrome remains good, and symptomatic improvement can be expected in most patients.

AGA technical review on the evaluation and management of chronic diarrhea.

This literature review and the recommendations therein were prepared for the American Gastroenterological Association Clinical Practice and Practice Economics Committee. The paper was approved by the committee on September 27, 1998.

Clinical pharmacology and use of laxatives and lavage solutions.

Laxatives and lavage solutions are used in the treatment of constipation and toxic ingestion and also for preparation of the colon before endoscopic or surgical procedures. Several different categories of agents are available for use. These include bulking agents, osmotic agents, secretagogues and agents with direct effects on epithelial nerve or smooth muscle cells, and lubricating agents. Each category has different pharmacologic effects, side effects, and clinical indications. This review summarizes current information about these agents.

Secretory diarrhea.

Diarrhea, defined as loose stools, occurs when the intestine does not complete absorption of electrolytes and water from luminal contents. This can happen when a nonabsorbable, osmotically active substance is ingested ("osmotic diarrhea") or when electrolyte absorption is impaired ("secretory diarrhea"). Most cases of acute and chronic diarrhea are due to the latter mechanism. Secretory diarrhea can result from bacterial toxins, reduced absorptive surface area caused by disease or resection, luminal secretagogues (such as bile acids or laxatives), circulating secretagogues (such as various hormones, drugs, and poisons), and medical problems that compromise regulation of intestinal function. Evaluation of patients with secretory diarrhea must be tailored to find the likely causes of this problem. Specific and nonspecific treatment can be valuable.

A comparison of stool characteristics from normal and constipated people.

In people with constipation, it is not known if decreased frequency of defecation is associated with abnormalities in the weight or in the consistency of stools or if the weight or the consistency of stools correlates with the severity of various discomforts associated with bowel movements. In neither normal nor constipated subjects has the consistency of stools been carefully correlated with their relative contents of water and solids. Our aim was to gain insight into these questions. Twenty subjects with idiopathic chronic constipation and 20 age- and sex-matched control subjects were recruited by advertisement. Stools were collected for one week. After each bowel movement, the subject's perception of various discomforts associated with the bowel movement were recorded. The stools were then analyzed. The results and conclusions were as follows: (1) Stool weight per bowel movement was similar in the two groups but stool weight per week was markedly reduced in constipated subjects. (2) Reduced stool weight per week in constipated subjects was due to a nearly proportional reduction in stool water and stool solids output. (3) Using data from both groups, there was a curvilinear correlation between percent insoluble stool solids and stool hardness, as measured by a texture analyzer; hardness increased only slightly as percent insoluble solids increased between 7 and 20%, but hardness increased dramatically when percent insoluble solids exceeded 25%. (4) Only 6% of stools from constipated subjects (2 of 34) had abnormally high values for percent stool solids and physical hardness. (5) In subjects with constipation, the severity of various discomforts associated with bowel movements (such as straining) correlated poorly with the weight or the hardness of stool that was produced by the bowel movement.

Glucose-stimulated sodium transport by the human intestine during experimental cholera.

BACKGROUND & AIMS: Net sodium absorption from oral rehydration solution is increased by both glucose-sodium cotransport and solvent drag. The aim of this study was to measure the relative importance of glucose-sodium cotransport and solvent drag in the stimulation of net sodium absorption by oral rehydration solution. METHODS: Total intestinal perfusion was used in normal subjects with and without intrajejunal cholera toxin using three test solutions containing 100 mmol/L sodium and either 100 mmol/L mannitol (control), 100 mmol/L glucose, or no additional solute (hypotonic solution). The increase in sodium absorption greater than control with hypotonic solution represented sodium absorption stimulated by solvent drag; the further increase in sodium absorption induced by glucose, greater than that noted with the hypotonic solution, represented sodium absorption stimulated by cotransport. RESULTS: Without cholera toxin, solvent drag and cotransport promoted sodium absorption at rates of 62 and 33 mmol/h, respectively. With cholera toxin, solvent drag and cotransport promoted sodium absorption at rates of 44 and 71 mmol/h, respectively. CONCLUSIONS: Net sodium absorption caused by cotransport increased more than twofold after exposure of the intestine to cholera toxin (P < 0.003). This could be mediated by increased cotransport, a change in the stoichiometry of cotransport, or an increase in chloride permeability.

Validation of polyethylene glycol 3350 as a poorly absorbable marker for intestinal perfusion studies.

Polyethylene glycol (PEG) has been used as a poorly absorbable marker in intestinal perfusion studies, but there is controversy about the absorbability of PEG, particularly when glucose-sodium cotransport is occurring. Total intestinal perfusion studies were done in five normal humans using three solutions containing 1 g/liter PEG 3350 and designed to produce low rates of water absorption, high rates of water absorption, or high rates of glucose-sodium cotransport. Water absorption rates were calculated by traditional nonabsorbable marker equations and by a novel balance technique in which absorption was taken as the difference between the volumes of solution infused and recovered during steady-state conditions. Effluent PEG recovery was 99 +/- 4%, 109 +/- 2%, and 104 +/- 6% of the amount infused with each solution. Water absorption rates measured by use of PEG concentrations were similar to those calculated by the balance technique (r = 0.99). The complete recovery of PEG confirms the poor absorbability of PEG 3350, and the excellent agreement between techniques validates PEG as a poorly absorbed marker, even when glucose-sodium cotransport is occurring.

Upper gastrointestinal motility disorders and respiratory symptoms.

The association between upper gastrointestinal (GI) motility disorders and respiratory problems is reviewed. Upper GI motility disorders, such as gastroesophageal reflux disease, gastroparesis, and achalasia, have been associated with respiratory problems, including aspiration, airway obstruction, asthma, bronchospasm, chronic cough, and laryngitis. These associations, which had been based solely on clinical observation, have recently been supported by physiologic studies and treatment trials. The association of reflux disease with asthma has the most support. Up to 80% of persons with asthma have evidence of pathologic gastroesophageal reflux, and in several studies antireflux therapy with prokinetic agents, antisecretory drugs, or fundoplication surgery has been found to reduce asthma symptoms and the need for medication in some patients. Reflux has also been associated with chronic cough and laryngitis, and antireflux therapy can reduce respiratory symptoms. Gastroesophageal reflux, gastroparesis, and achalasia are all associated with aspiration. In addition, in rare instances, the megaesophagus associated with achalasia can produce mechanical airway obstruction. Effective therapy for these GI motility disorders can eliminate complicating respiratory problems.

Determinants of decreased fecal consistency in patients with diarrhea.

BACKGROUND/AIMS: Loose stools are a common and troublesome feature in diarrhea. The purpose of this study was to investigate factors that determine different degrees of stool looseness in diarrhea. METHODS: Fecal consistency was measured visually. Stools were analyzed for content of water and solids. Water-holding capacity of insoluble solids was measured in vitro. RESULTS: Formed stools from normal subjects had a near constant ratio of water to solids despite a sevenfold variation in daily stool weight. In diarrhea, loose consistency was correlated directly with percent fecal water. For any level of percent water, steatorrhea stools were looser than nonsteatorrhea stools. Ingestion of psyllium reduced stool looseness without changing the percent water. Both the effect of fat and psyllium could be explained by consideration of the ratio of fecal water to water-holding capacity of insoluble solids. CONCLUSIONS: (1) The normal intestine delivers stools that differ widely in quantity but maintains percent fecal water within a narrow range. (2) Stool looseness in diarrhea is determined by the ratio of fecal water to water-holding capacity of insoluble solids. (3) In patients with diarrhea with normal stool weight, loose stools are due to low output of insoluble solids without the concomitant reduction in water output that occurs in normal subjects when insoluble solids are low.

Review article: anti-diarrhoeal pharmacology and therapeutics.

Anti-diarrhoeal drugs reduce the symptoms of diarrhoea (loose stool consistency, frequency of defecation and excessive stool weight) by effects on intestinal transit, mucosal transport or luminal contents. Opiates and opioids are the most useful antidiarrhoeal agents. Opiates have major effects on intestinal transit; pro-absorptive and anti-secretory effects are less well documented, but may be important for some of these drugs. Alpha-adrenergic agonists, somatostatin analogues and several other agents have had limited clinical use; these drugs may modify mucosal transport in addition to slowing transit. Adsorbents, bismuth and stool texture modifiers are used frequently by the public, but their efficacy is largely unproven. Oral rehydration solutions have had the greatest impact in saving lives and continue to be improved. Many new approaches to the treatment of diarrhoea are yet to be exploited.

Diagnostic value of fasting plasma peptide concentrations in patients with chronic diarrhea.

To evaluate the utility of screening for multiple gastrointestinal peptides in the evaluation of patients with chronic diarrhea, we studied 193 patients referred for evaluation of chronic diarrhea and eight patients with known peptide-secreting tumors as a reference group. Fasting plasma samples were assayed for motilin, neurotensin, pancreatic polypeptide, somatostatin, substance P, vasoactive intestinal polypeptide, gastrin-releasing peptide, and calcitonin during a protocol evaluation for causes of chronic diarrhea. Although none of the referred patients were found to have tumors, abnormal levels of one or more peptides were found in 86 of 193 patients (45%). Abnormal plasma peptide levels were sometimes as high in these patients as in patients with known peptide-secreting tumors and would have led to mistaken diagnoses of tumors much more often than they would have led to correct diagnoses. The positive predictive value of elevation of any assayed peptide was < 2% at realistic prevalence rates for peptide-secreting tumors; the negative predictive value of a series of normal results was > 99%, but much of this was due to the rarity of these tumors. Patients with chronic diarrhea should not be screened routinely with a panel of plasma peptide assays in an effort to detect tumors; instead, peptide levels should be ordered selectively. Elevated fasting concentrations of the plasma peptides measured in this study are most likely epiphenomena due to diarrhea and should not be the sole basis for invasive diagnostic or surgical management of these patients.

The self-limited nature of chronic idiopathic diarrhea.

BACKGROUND: Little is known about the clinical presentation and natural history of previously healthy patients in whom chronic idiopathic diarrhea develops. METHODS: We reviewed the case records of 152 patients with chronic diarrhea who had no history of gastrointestinal surgery and who were evaluated in detail as part of a chronic-diarrhea protocol from 1985 to 1990. Patients were considered to have chronic idiopathic diarrhea if they had persistently loose stools for more than four weeks, no systemic illness, and no identifiable cause of diarrhea. RESULTS: Seventeen patients (10 men and 7 women) ranging in age from 33 to 72 years met the criteria for chronic idiopathic diarrhea. Each patient had a history of a relatively abrupt onset of symptoms, often soon after returning home from a trip, starting two to seven months before evaluation. Their diarrhea did not occur during a local outbreak of diarrhea, and other family members did not become ill. Stool frequency ranged from 5 to 25 movements per day, stool weights ranged from 417 to 1480 g per day, and fecal electrolyte and osmolality values were consistent with a diagnosis of secretory diarrhea. The results of biopsies of the small intestine and colon were normal, as were small-bowel roentgenograms. Extensive studies for infectious causes of diarrhea were negative, and no patient responded to antibiotic therapy. In every patient the diarrhea stopped without specific therapy after 7 to 31 months (mean, 15) and did not recur during a follow-up period averaging 38 months. CONCLUSIONS: Sporadic idiopathic chronic diarrhea is a recognizable syndrome that can last many months, but is self-limited.

Subepithelial collagen table thickness in colon specimens from patients with microscopic colitis and collagenous colitis.

Microscopic colitis and collagenous colitis are similar conditions that are differentiated by the presence or absence of subepithelial collagen table thickening. To better understand the relationship between these two disorders and the role of collagen table thickening in the pathogenesis of diarrhea, colonic mucosal biopsy specimens from 24 patients with microscopic or collagenous colitis and 9 control subjects were analyzed using a computer-assisted morphometric method to evaluate the average thickness of the subepithelial collagen table. The collagen table thickness in colitis patients taken together formed a multimodal rather than a unimodal distribution. There was no tendency for collagen table thickening to increase with age or with duration of symptoms. In general, the types and distribution of inflammatory cells were similar in patients with normal and thickened collagen tables. Stool weight correlated with lamina propria cellularity but not with collagen table thickening. The multimodal distribution of collagen table thickening and the lack of correlation with age, duration of symptoms, or inflammation suggest that microscopic colitis and collagenous colitis are discrete conditions, although the inflammatory changes in the two conditions are similar. Moreover, because stool weight correlates with lamina propria cellularity but not with collagen table thickening, diarrhea probably is caused by the inflammatory changes and not by collagen table thickening per se.

Treatment of severe steatorrhea with ox bile in an ileectomy patient with residual colon.

Patients with ileectomy can present with severe steatorrhea due to bile acid depletion. While exogenous bile acid would seem to be ideal therapy for this condition, it is not often used because it is thought that the bile acid would be malabsorbed and would enter the colon, producing a secretory diarrhea. This report describes a patient who had an ileectomy and partial right colon resection for Crohn's disease and then developed severe steatorrhea due to bile acid malabsorption. Although steatorrhea was reduced from 134 to 9 g/24 hr with chronic ingestion of ox bile extract, stool weight did not increase with ox bile (stool weight 669 g/24 hr before therapy and 507 g/24 hr after therapy). In this patient, oral bile acid supplementation reduced fat excretion markedly, but did not aggravate diarrhea, even though the colon was still present. This result may have been due to impaired solubility of bile acid in fecal fluid due to an acid pH or to binding of bile acid with particles of solid stool. Ingestion of ox bile extract does not necessarily increase stool weight in patients with defective fat absorption due to bile acid malabsorption and can be tried with caution in an effort to diminish steatorrhea.