Diarrhea and Constipation

Risk Factors

• older age

• female gender

• physical inactivity

• low income/education

• depression

Diagnosis

• Check for precipitating medications

  • TCAs

  • Iron supplement

  • Opioids

  • Verapamil

• Digital rectal exam

  • assess for defecatory disorders (normal exam doesn't exclude this diagnosis)

    • significant straining

    • need for perianal or vaginal pressure to aid in defecation

    • feeling of incomplete evacuation

    • failure to respond to various laxative

    • anorectal manometry with balloon expulsion after DRE

      • MR defecography if results are inconclusive

• Colonoscopy only in the case of alarm features

Lab Results

• In the absence of other clinical features, metabolic tests such as TSH are not recommended

Treatment

• Polyethylene glycol

• Senna

• Lubiprostone

Diagnosis

• Rome IV criteria

Treatment

• First line: traditional laxatives

• Second line: peripherally-acting Mu-opioid receptor antagonists

  • naloxegol

  • methylnaltrexone

• insufficient evidence to recommend use of lubiprostone

Risk Factors

• >90% of patient's with factitious diarrhea are women

• history of work in the healthcare field

• extensive healthcare utilization

Diagnosis

• stool testing for...

  • sodium

  • potassium

  • magnesium

  • phosphate

Lab Findings

• Stool magnesium >90 mEq/L - suggests magnesium-induced diarrhea

• Stool phosphate >33 mmol/L - suggests phosphate-induced diarrhea

• Osmotic gap >75 - can be due to laxatives containing magnesium, sorbitol, lactose, lactulose, or PEG

• Osmotic gap <75 - can be seen with secretory laxatives or in an osmotic diarrhea from sodium containing laxative

• There is currently no laxative screen for mineral oil

Diagnosis

• Rome IV criteria

  • 2 or more of the following associated with abdominal discomfort for 1 or more days/wk in the last 3 months (on average)

    1. related to defecation (either improving or worsening)

    2. associated with a change in stool frequency

    3. associated with a change in stool form (appearance)

Treatment

• First Line: Soluble Fiber

  • wheat dextrin, psyllium husk

  • Side effects - bloating, gas

  • insoluble fiber (ex. wheat bran) is NOT recommended - may worsen abdominal pain and bloating and has shown no efficacy for IBS-C

• Polyethylene glycol (PEG)

  • inexpensive, effective osmotic laxative

  • improves constipation but not abdominal pain

  • typical dose 17 g dissolved in 8 oz of water, titratable

  • Side effects - bloating, abdominal pain

• Linaclotide

  • an oligo-peptide agonist of guanylate cyclase 2C (GC-C) that remains in the GI tract when taken orally

    • Activation of GC-C increases cGMP

    • Elevated cGMP stimulates secretion of chloride and bicarbonate and water into the intestinal lumen via cystic fibrosis transmembrane conductance regulator (CFTR) of ion channel activation.

    • This results in increased intestinal fluid and accelerated transit.

    • By elevating cGMP, linaclotide also reduces activation of colonic sensory neurons (nociceptors), reducing pain; and activates colonic motor neurons, which increases smooth muscle contraction, promoting bowel movements.

  • constipation unresponsive to polyethylene glycol (PEG)

  • improvement in stool consistency, straining, and number of spontaneous BMs per week

  • improvement in abdominal pain/discomfort and bloating

  • Side effects - diarrhea, nausea

• Lubiprostone

  • prosecretory agent that activated chloride channels on the small intestine enterocytes, leading to water secretion into the lumen

  • does NOT improve abdominal pain

  • Side effects - pain and cramping

• Dicyclomine

  • an anticholinergic antispasmodic medication that directly affects intestinal smooth muscle relaxation

  • used in IBS-C if abdominal pain persists after constipation is aggressively treated and controlled

  • Side effects - constipation

• Tegaserod

  • increases colonic motility

    • approved for IBS-C but withdrawn from IS market due to serious cardiovascular side effects

• No data to support the use of SSRIs in IBS

• Low FODMAP diet (fermentable oligo-, di-, and monosaccharides and polyols)

  • In IBS with abdominal bloating or pain

Diagnosis

• Rome IV criteria

  • 2 or more of the following associated with abdominal discomfort for 1 or more days/wk in the last 3 months (on average)

    1. related to defecation (either improving or worsening)

    2. associated with a change in stool frequency

    3. associated with a change in stool form (appearance)

• Check celiac serologies with suspected IBS-D

  • particularly in high risk groups (Down's syndrome, type 1 diabetes, Turner syndrome)

  • anti-tissue transglutaminase (TTG) immunoglobulin A (IgA)

  • total IgA (to ensure the patient is not IgA deficient)

• Colonoscopy with random biopsy if microscopic colitis is suspected (middle aged female with watery diarrhea)

• Check CBC to assess for iron deficiency

  • colonoscopy in the setting of anemia to rule out malignancy or IBD

• Colonoscopy in the case of alarm features or onset in those >50 yo

• If without alarm features, normal CRP and fecal calprotectin can be used to rule out IBD without colonoscopy

• May trial lactose exclusion or lactose hydrogen breath testing (time consuming) if history is suggestive of lactose intolerance

• Check medications

  • SSRIs have a side effect of diarrhea (can also cause microscopic colitis)

• Checking TSH is not recommended

  • likelihood of thyroid abnormalities is no greater in patients with IBS as compared to normal controls

• Yield of stool cultures is low in suspected IBS and not routinely recommended

Treatment

• Loperamide

• Bentyl

• Lomotil (diphenoxylate/atropine)

  • can improve diarrhea

  • does NOT improve abdominal pain

• Tricyclic antidepressants (TCAs)

  • Side effects - dose dependent constipation, dry mouth/eyes, drowsiness, weight gain, QT prolongation

  • used preferentially but not exclusively in IBS-D given side effect of constipation

• Eluxadoline

  • a mu and kappa-opioid receptor agonist and a delta opiod receptor antagonist in the enteric nervous system

  • approved for IBS-D but NOT for IBS-C

  • contraindicated in those with...(risk of serious pancreatitis or death)

    • prior cholecystectomy

    • suspected history of biliary duct obstruction

    • sphincter of Oddi dysfunction

    • history of pancreatitis or structural diseases of the pancreas

    • significant alcohol use (>3 drinks per day) or abuse

    • hepatic impairment

• Rifaximin

  • a nonabsorbable antibiotic

  • used for IBS with abdominal pain and bloating but NOT with constipation

• Little data addressing efficacy of SNRIs for the treatment of IBS

• No data to support the use of SSRIs in IBS

• Probiotics

  • associated with improvement in symptoms in patients with IBS but the magnitude of benefit and most effective species and train are uncertain

• Low FODMAP diet (fermentable oligo-, di-, and monosaccharides and polyols)

  • In IBS with abdominal bloating or pain

Diagnosis

• absence of response to gluten free diet

Pathology Findings

• histologically identical to Celiac disease

Lab Findings

• normal celiac serologies

Treatment

• withdrawal of olmesartan leads to complete resolution of symptoms and histology

Definition

• Collagenous colitis incidence: 4 per 100,000 person-years

• Lymphocytic colitis incidence: 5 per 100,000 person-years

• Incidence rate increases with age, peaking at 60-70 yo and with a greater risk in women

Diagnosis

• Biopsy

• Assess for alternative causes of diarrhea

• Check medications for possible triggers

  • Aspirin

  • NSAIDS

  • SSRIs

  • PPIs

  • H2 blockers

  • statins

• Check TTG IgA and total IgA in the case of persistent diarrhea

  • microscopic colitis is more common in those with celiac disease than in the general population

• There is also an association with thyroid disease

Risk Factors

• Smoking

• Median age of diagnosis is 65

  • though can be seen in younger patients

• May be associated with other autoimmune conditions

  • celiac disease (most common)

  • autoimmune thyroiditis

  • psoriasis

• Collagenous colitis

  • more prevalent in women, particularly over the age of 50

Endoscopic Findings

• Normal appearing mucosa

  • though can have subtle macroscopic findings like edema and erythema

Pathology Findings

• highest diagnostic yield in the transverse and right colon, least in the rectosigmoid

• lymphocytic colitis

  • >20 intraepithelial lymphocytes per 100 surface epithelial cells

  • focal cryptitis

• Collagenous colitis

  • scant neutrophils and eosinophils in the lamina propria

  • sub-epithelial collagen band >10 um in diameter

• Incomplete microscopic colitis

  • features of both lymphocytic and collagenous colitis

Treatment

• First line: budesonide 9 mg daily

  • if there is no improvement assess for alternative causes of diarrhea

  • discontinue possible precipitating medications (PPIs, SSRIs, ASA, NSAIDs)

• Second line: bismuth salicylate or mesalamine

• Other treatment options: aminosalicylates and cholestyramine

Definition

• bile acids are typically reabsorbed in the ileum and returned in the enterohepatic circulation

• in states of normal health, only a small amount of bile acids are not reabsorbed in the ileum and reach the colon

• in states of diseased ileum bile acids are not effectively reabsorbed and reach the colon where bacteria deconjugate and dehydroxylate them producing secondary bile acids which stimulate water secretion in the colon and diarrhea

• Causes

  • Crohn's

  • Radiation ileitis

Treatment

• Colestipol

  • a bile acid sequestrant

  • Side effect - abdominal discomfort and bloating

Definition

• used to differentiate osmotic diarrhea from secretory diarrhea

  • Osmotic

    • lactase deficiency

    • osmotic laxative use or abuse

    • factitious diarrhea due to magnesium

    • drinking high quantities of non-diet soda with fructose

      • up to 50% of healthy patients have incomplete fructose absorption

      • when the capacity of the intestine to transport fructose across the intestinal epithelium is exceeded, malabsorption occurs and leads to osmotic diarrhea

    • Sorbitol

  • Secretory

    • infections with Vibrio cholera, enterotoxigenic strains of E coli

    • VIPoma

• 290 - 2(stool Na + stool K)

  • 290 is the value of stool osmolality

  • Normal: Stool osmotic gap 50-100 mosm/kg

  • Osmotic diarrhea: > 100 mosm/kg

  • Secretory diarrhea: < 50 mosm/kg

Signs and Symptoms

• Osmotic

• Secretory

  • unaffected by fasting

Definition

• production of serotonin by the tumor

• serotonin stimulate intestinal secretion and motility and inhibits intestinal absorption

Diagnosis

• chromogranin A