chronic diarrhea causes and evaluation pptx

chronic diarrhea causes and evaluation of chronic diarrhea

1. CHRONIC DIARRHEA Dr.G.VENKATA RAMANA MBBS DNB FAMILY MEDICINE

2. Diarrhea is defined as increased liquidity/decreased consistency of stools,which may be associated with increased frequency of bowel movements,specifically more than three stools per day C lassified into acute and chronic, based on the duration of s ymptoms Acute diarrhea Diaarhea <2 weeks in duration Chronic diarrhea D iarrhea lasting longer than 4 weeks

3. Osmotic diarrhea Large amounts of poorly absorbed solute within the intestinal lumen cause osmotic retention of water in the stool C haracterized by cessation of diarrhea with fasting and an abnormally elevated stool osmotic gap (>125 mOsm /kg) Stool osmotic gap is calculated using the formula: 290 − 2 (Stool Na+ + K+) The body maintains equal fecal and serum osmolality, which is approximately 290 mOsm /kg Poorly absorbed substances within the intestinal lumen require that additional water be retained in the stool to maintain this value, resulting in an osmotic gap An osmotic gap <50 mOsm /kg is considered normal An osmotic gap >125 mOsm /kg is consistent with a pure osmotic diarrhea

4. Secretory diarrhea Intestinal secretion overcomes the absorptive capability of the small intestine and colon Secretion of incompletely absorbed electrolytes leads to retention of intraluminal water Because intestinal secretion is a constant process , diarrhea is incessant regardless of fasting state or time of the day Characterized by large amounts of watery diarrhea (1–10 L/24 hrs ) The stool osmotic gap is normal

5. Inflammatory diarrhea Inflammation and ulceration impair the absorptive and digestive functions of normal mucosa Inflammation itself often adds to stool volume through addition of mucus, proteins, fluid, and blood into the bowel lumen Secretory mechanisms may be coexistent Clinical presentation includes nocturnal diarrhea and systemic signs such as fatigue or fever

6. Steatorrhea Any process that affects digestion and absorption of fats can lead to steatorrhea Etiologies range from celiac disease to pancreatic insufficiency Inadequate contact time of bowel contents with the digestive juices and absorptive intestinal mucosa, as with altered intestinal motility, can also contribute to steatorrhea

7. Dysmotility /Functional Gut dysmotility may cause increased intestinal and colonic transit time as well as decreased contact time with intestinal absorptive mucosa Functional syndromes such as irritable bowel syndrome (IBS) include a pain component as well as a change in bowel habits

8. History Onset, duration, pattern/frequency Stool characteristics: watery, fatty, or inflammatory (blood or mucus) Systemic symptoms: fever, fatigue Abdominal pain: postprandial? Fecal incontinence Weight loss, if present, suggests decreased intake, malabsorption , neoplasm, or ischemia Significant weight loss (>10 lb ) often points to nutrient malabsorption Nocturnal/fasting symptoms Aggravating/mitigating factors such as diet, stress, medications Recent exposure to hospitals or antibiotic use Sick contacts/regional outbreak: food related

9. Past medical and surgical conditions Systemic disease: diabetes mellitus, thyroid disease, inflammatory/autoimmune disorder, HIV, immunocompromised state, cancer History of an eating disorder, malingering,or secondary gain Previous surgery: gastrectomy , vagotomy , bowel resection, cholecystectomy Previous radiation therapy A family history of inflammatory bowel disease (IBD), celiac sprue , or multiple endocrine neoplasia (MEN) syndromes A detailed medication history: use of laxatives, antibiotics, over-the-counter medications, and any new medications prior to the onset of symptoms

10. D iet history Recent changes or associated foods Intake of sugar-free substitutes, lactose, or fructose Exposure to contaminated food or water Social history Alcohol, tobacco, illicit drug use Travel/immigration history Recent travel to endemic areas may suggest traveler’s diarrhea, Giardia infection, tropical sprue Recent immigration from a developing country raises the possibility of a parasitic infection Sexual history, including any history of anal intercourse

11. Physical Examination Vital signs to assess for fever, tachycardia, or hypotension Orthostatic blood pressure changes seen in severe volume depletion from fluid loss General examination : whether the patient is toxic appearing and acutely ill Cachexia and muscle wasting may indicate a chronic process Volume status is assessed by examining orthostatic hemodynamics, mucus membranes, and skin turgor A history of oliguria supports volume loss Head and neck examination evaluates for findings of hyperthyroidism (thyroid mass, exophthalmos) and extraintestinal manifestations of IBD (eye pain or conjunctival injection, mouth ulcers)

12. Flushing, wheezing, and cardiac murmurs can rarely be seen in secretory diarrhea, especially carcinoid syndrome A detailed abdominal examination assesses for tenderness, peritoneal signs, hepatomegaly, masses, and ascites Surgical scars indicate past surgery Bowel sounds are evaluated for hyper and hypoactivity Anorectal examination focuses on sphincter tone/contractility, fistulas, fissures, perianal abscess, and blood on the examining finger Other areas examined include the peripheries for edema, arthritis, lymphadenopathy; a skin examination for rashes and flushing, and a neurologic examination for neurologic deficits and peripheral neuropathy

13. L aboratories Complete blood cell count with differential For anemia, leukocytosis (infection), or eosinophilia (neoplasm, allergies, parasites, eosinophilic gastroenterocolitis ) Comprehensive metabolic panel F or electrolyte abnormalities, coexistent liver disease, hypoalbuminemia / dysproteinemia (malnutrition, protein-losing enteropathy ), or diabetes TSH, FT4 for hyperthyroidism HIV testing

14. Stool studies Leukocytes, lactoferrin , calprotectin if there is suspicion of inflammatory diarrhea Fecal occult blood test Osmolarity , electrolytes (Na, K) to calculate osmotic gap Infectious: bacterial culture, Clostridium difficile toxin ×3, O&P ± microscopy ×3, stool wet mount for amebiasis in sexually active male homosexuals or travel to endemic areas Fat: qualitative/Sudan stain versus 24,48,or72-hour quantitative collection on a 100g fat/day diet (<6 g/24 hrs is normal ,> 14 g/24 hrs suggests malabsorption / maldigestion , >8% suggests pancreatic insufficiency) pH <5.6 suggests carbohydrate malabsorption (colonic fermentation by bacteria) Mg level Laxative screen α1-Antitrypsin: elevated in protein-losing enteropathy Chymotrypsin or elastase concentration: elevated in pancreatic insufficiency

15. Urine studies Urinalysis: for protein loss in the urine Laxative screen Secretory diarrhea S erum levels of VIP, gastrin, calcitonin, pancreatic polypeptide, somatostatin , tryptase , serum protein electrophoresis, immunoglobulins U rinary excretion of 5-hydroxyindoleacetic acid, metanephrines , and histamine A drenocorticotropin stimulation test Blood sugar Parathyroid hormone Serum calcium Serum protein electrophoresis

16. Celiac disease Antitissue transglutaminase antibody (IgA, preferred test for patients >2 years of age), deamidated gliadin peptide (IgA and IgG , alternative test in high probability patients or supplementary in children <2 years of age), and serum IgA levels (up to 10% of patients will be IgA deficient and have a false-negative result) HLA-DQ2/DQ8 testing should only be used to rule out the disease in patients with equivocal small bowel histology, those on a gluten free diet at the time of testing, those with serology/history discrepancies, refractory cases, or in patients with Down syndrome

17. IBD and immunocompromised patients Cytomegalovirus (CMV) DNA polymerase chain reaction (PCR) and C. difficile toxins Rectal swab in those active in anal intercourse (gonorrhea, Chlamydia, herpes simplex virus [HSV])

18. Imaging To assess for structural/inflammatory disease of the small intestine and pancreas: Small bowel follow-through CT enterography MR enterography Dual-phase CT scan of the pancreas Abdominal ultrasonography Endoscopic ultrasonography

19. Diagnostic Procedures Endoscopy with biopsies Upper endoscopy with small bowel biopsies for the evaluation of celiac disease (minimum of four duodenal biopsies), Whipple disease, proteinlosing enteropathy , eosinophilic gastroenteritis, giardiasis, amyloidosis Small bowel aspirate to evaluate for small intestinal bacterial overgrowth Flexible sigmoidoscopy is acceptable in cases of acute diarrhea with suspicion for diffuse colitis, such as graft-versus-host disease, or chronic diarrhea in patients with significant comorbidities or pregnancy Colonoscopy for evaluation of IBD, microscopic colitis, eosinophilic colitis, amyloidosis, colorectal neoplasia or screening, HIV patients, or in cases with significant blood loss

20. Endoscopic ultrasonography to evaluate for chronic pancreatitis Breath tests for specific carbohydrate malabsorption (lactose, sucrose) and SIBO (glucose, lactulose, 14C-xylose, 14C-glycocholate) Secretin test to assess for pancreatic exocrine insufficiency

21. Diagnostic Testing In osmotic diarrhea: Osmotic gap is typically >125 mOsm /kg Stool pH indicates carbohydrate malabsorption if it is acidic (pH <5.6) Stool magnesium level can assess for excessive intake of magnesium, such as in laxative abuse Secretory diarrhea Osmotic gap is usually normal (<50 mOsm /kg). Infectious etiologies need to be excluded, as some acute infections can induce a transient secretory pattern Imaging studies and endoscopy can evaluate for structural and inflammatory diseases of the small intestine and colon Specialized tests can be performed to investigate for endocrinopathies and neuroendocrine tumors

22. Inflammatory diarrhea Fecal occult blood test (FOBT) and/or fecal leukocytes can be assessed in chronic diarrhea wherein both inflammatory and secretory etiologies are being considered These tests are consistently positive in bloody diarrhea or where other features suggest an inflammatory etiology Infectious etiologies need to be excluded, even when IBD is suspected, as infectious superinfection can be seen. Imaging studies and endoscopy are useful to evaluate for structural and/or inflammatory diseases of the small intestine and colon

23. Steatorrhea Fecal fat assays are typically abnormal and the osmotic gap is >50 mOsm /kg Imaging studies and endoscopy are useful for evaluating structural and/or inflammatory diseases of the small intestine and pancreas Investigation can be performed for evaluating pancreatic exocrine insufficiency

24. TREATMENT Volume status, electrolyte disturbances, and vitamin deficiencies need to be addressed Uncomplicated, mild diarrhea is treated with oral fluids In cases of severe diarrhea, intravenous fluids (lactated Ringer or 0.9% normal saline) may be necessary to restore volume depletion and to keep up with ongoing losses Rarely, patients may require intravenous fluids long term, administered through a permanent indwelling catheter with the assistance of home healthcare nursing Total parenteral nutrition may be required in the hospital or long term at home, requiring an indwelling catheter and home healthcare nursing Vitamin deficiencies may occur due to decreased oral intake or malabsorption Vitamin levels should be monitored and supplemented if deficient, especially the fat-soluble vitamins in those with chronic steatorrhea

25. The underlying cause needs to be treated whenever possible If there is a reversible cause such as infection, dietary precipitant, medication, or tumors, then chronic diarrhea may potentially be resolved with treatment or by removal of the offending agent Microscopic (collagenous/lymphocytic) colitis Budesonide 9 mg daily with slow taper can be used when clinically appropriate Bismuth subsalicylate, cholestyramine , and mesalamine may also be used In severe or refractory cases, immunomodulators such as azathioprine or systemic steroids may be required Bile acid–induced diarrhea An empiric trial of cholestyramine (a binding resin) is both diagnostic and therapeutic . Recommended dose is 4 g TID Alternatively, colestipol may be used Lactose intolerance Empiric trial of avoiding dairy products is both diagnostic and therapeutic Lactase enzyme supplements may also be efficacious

26. SIBO Clinical response to antibiotics is often rapid C yclical antibiotics are often necessary unless the predisposing cause for bacterial overgrowth has been addressed Pancreatic enzyme replacement A therapeutic trial may be beneficial in steatorrhea Opiate antidiarrheal agents are safe in mild to moderate diarrhea Loperamide 2–4 mg QID or 4 mg followed by 2 mg after each loose stool up to a maximum dose of 16 mg/day Diphenoxylate plus atropine 4 mg QID has combined opioid and anticholinergic effects Empiric treatment with antidiarrheals without extensive investigation is appropriate for patients without alarm findings such as those with IBS

27. Psyllium can be used to increase stool bulk in those with fecal incontinence Octreotide (a somatostatin analog) may be used in secretory diarrhea to decrease the volume of stool Octreotide can be used parenterally at 50–250 μg subcutaneous BID to TID Octreotide may also be used in acute postoperative diarrhea, such as with high ostomy output Antibiotics Empiric treatment can be considered if the patient is at high risk for dehydration or systemic complications, in the setting of a high suspicion of infectious cause, or if there is high prevalence of infectious diarrhea in the community Metronidazole or fluoroquinolone may be used

28. Surgical Management T o treat the underlying cause, such as with neuroendocrine tumor, severe colitis, or malignancy Lifestyle/Risk Modification If there is an underlying mucosal cause for malabsorption , such as celiac disease or disaccharidase deficiency, diet should exclude the offending agent (i.e., gluten- or lactose-free diets) Vitamin levels should be evaluated and supplemented if deficient Prophylactic supplementation may be recommended with daily multivitamin, calcium, vitamin D, and B complex Probiotics are not routinely recommended , given the lack of regulations and consensus on their benefits However, these agents may be beneficial in chronic diarrhea in the setting of IBS