medicine 3.3b - abdominal symptoms iib
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CALDERON, GARCIA, HARDIN, MANABAT, SOLIS, VIOLAGO 1 of 8
December 3, 2014 PLM CM
ABDOMINAL SX IIB: DIARRHEA, CONSTIPATION and WEIGHT LOSS
3.3-B
DR. TENGCO
DIARRHEA & CONSTIPATION
Among the most common patient complaints faced by internists and primary care physicians
Account for nearly 50% of referrals to gastroenterologists.
Although diarrhea and constipation may present as mere nuisance symptoms at one extreme, they can be severe or life-threatening at the other.
Even mild symptoms may signal a serious underlying gastrointestinal lesion, like: o colorectal cancer o systemic disorder (i.e. thyroid disease)
Given the heterogeneous causes and potential severity of these common complaints, it is imperative to appreciate the: o pathophysiology o etiologic classification o diagnostic strategies o therapeutic principles
NORMAL PHYSIOLOGY
Functions of the human small intestine and colon: o Digestion and assimilation of nutrients from food o secretion and absorption of water and electrolytes o storage and subsequent transport of intraluminal contents
aborally o salvage of some nutrients after bacterial metabolism of
carbohydrate that are not absorbed in the small intestine
Normal Gastrointestinal Motility: Functions at Different Anatomic Levels
Stomach and small bowel
Synchronized MMCs (Migrating Motor Complexes)in fasting
Accommodation, trituration, mixing, transit o Stomach ~3 h o Small bowel ~3 h
Ileal reservoir empties boluses
Colon irregular mixing, fermentation, absorption, transit
Ascending, transverse: reservoirs Descending: conduit
Sigmoid/rectum: volitional reservoir
It should be noted that the values above applies only to
individuals on typical "Western", low ruffage diets. In developing nations, the average stool output of individuals
can vary considerably depending on the nature of dietary intake, but is generally greater because of higher fiber intake
Diseases Contributing Factors
Diarrhea Alterations on fluid and electrolyte handling
Irritable Bowel Syndrome Chronic Diarrhea Chronic Constipation
Alterations in motor and sensory functions of the colon
NEURAL CONTROL
1. Intrinsic innervation (enteric nervous system)
Comprised of several layers: o Myenteric Plexus: regulates smooth-muscle function o Submucosal Plexus: affects secretion, absorption, and
mucosal blood flow o Mucosal Neuronal layer
Function of these layers are modulated by interneurons through the actions of neurotransmitter amines or peptides : o Acetylcholine o Vasoactive Intestinal Peptide (VIP) o Opioids o Norepinephrine o Serotonin o Adenosine Triphosphate (ATP) o Nitric Oxide (NO)
2. Extrinsic innervation
part of the autonomic nervous system
modulate motor and secretory functions
Parasympathetic fibers convey visceral sensory and excitatory pathways to the colon o Small Intestine and Proximal Colon
Conveyed via the vagus nerve along the branches of the superior mesenteric artery
o Distal Colon Supplied by sacral parasympathetic nerves
(S2-4) via the pelvic plexus Fibers course through the wall of the colon as
ascending intracolonic fibers
I. Diarrhea & Constipation
A. Normal Physiology 1. Neural Control 2. Intestinal Fluid Absorption and Secretion
3. Small Intestinal Motility 4. Ileocolonic Storage and Salvage 5. Colonic Motility and Tone 6. Colonic Motility after Meal Ingestion
7. Defecation II. Diarrhea
A. Differentials B. Acute Diarrhea
1. Acute Diarrhea from Infectious Agents 2. Acute Diarrhea from Other Causes 3. Approach to the Patient
C. Chronic Diarrhea
1. Causes a. Secretory Causes b. Osmotic Causes
c. Steatorrheal Causes d. Inflammatory Causes e. Dysmotility Causes f. Facitial Causes
g. Iatrogenic Causes 2. Approach to the Patient
III. Constipation A. Approach to the Patient
B. Investigation of Severe Constipation IV. Weight Loss
A. Physiology of Weight Regulation B. Significance of Weight Loss
C. Causes of Weight Loss D. Approach to the Patient
1. Physical Examination 2. Diagnostic Testing
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MEDICINE 1 // ABDOMINAL SYMPTOMS II: DIARRHEA, CONSTIPATION & WEIGHT LOSS 3.3-B
CALDERON, GARCIA, HARDIN, MANABAT, SOLIS 2 of 8
Reaches the proximal colon in some instances Sympathetic nerves
o modulates motor functions excitatory to sphincters and inhibitory to
nonsphincteric muscle o reaches the small intestine and colon alongside their
arterial vessels
chief excitatory neurotransmitters: o Acetylcholine o Tachykinins (substance P)
VISCERAL AFFERENTS
Convey sensation from the gut to the CNS
Course to the Spinal Cord: Course along the sympathetic fibers (Initially)
Separate as they approach the spinal cord
Have cell bodies in the dorsal root ganglion
Enter the dorsal horn of the spinal cord
Course to the Brain: Conveyed along the lateral spinothalamic tract and nociceptive
dorsal column pathway
Projected beyond the thalamus and brainstem to the insula and cerebral cortex to be perceived
Other afferent fibers synapse in the prevertebral ganglia and reflexly modulate intestinal motility
INTESTINAL FLUID ABSORPTION AND SECRETION
Average day secretion:
Fluid that enter the GI tract: 9 L
Residual fluid that reaches the colon: ~1 L Stool excretion of fluid: 0.2 L/d
Fluid reabsorbed by the colon: 4X its usual volume of 0.8 L/d
Colon o Has a large capacitance and functional reserve o May recover up to 4x its usual volume of 0.8 L/d, provided
the rate of flow permits reabsorption to occur o Colon can partially compensate for excess fluid delivery to
the colon because of intestinal absorptive or secretory disorders
o Sodium absorption in the colon: Predominantly electrogenic Uptake takes place at the apical membrane Compensated for by the export functions of the
basolateral sodium pump
Neural and Non-neural mediators that regulate colonic fluid and electrolyte balance o Cholinergic o Adrenergic o Serotonergic
Angiotensin and aldosterone o Also influence colonic absorption o Reflects the common embryologic development of the
distal colonic epithelium and the renal tubules
SMALL INTESTINAL MOTILITY
Migrating Motor Complex (MMC) o Intestinal Housekeeper o serves to clear nondigestible residue from the small
intestine o propagated series of contractions lasts on average 4 mins o occurs every 6090 min o usually involves the entire small intestine
After ingestion, small intestine produces irregular, ixing contractions of relatively low amplitude o Except in the distal ileum where more powerful
contractions occur intermittently and empty the ileum by bolus transfers
ILEOCOLONIC STORAGE AND SALVAGE
Distal Ileum o Acts as a reservoir, emptying intermittently by bolus
movements o Allows time for salvage of fluids, electrolytes and nutrients
Segmentation by haustra compartmentalizes the colon o Function: Mixing Retention of residue Formation of solid stools
o There is increased appreciation of the intimate interaction between the colonic function and luminal ecology
The resident bacteria in the colon are necessary for the digestion of unabsorbed carbohydrates vital source of nutrients to the mucosa
o also keeps pathogens at bay by a variety of mechanisms
Ascending and transverse colon function as reservoirs (average transit, 15 h)
Descending colon acts as a conduit (ave transit, 3 h)
Colon o Efficient at conserving sodium and water o Important function in sodium-depleted patients in whom
the small intestine alone is unable to maintain sodium balance
DISEASES CONTRIBUTING FACTORS
DIARRHEA Alterations in the reservoir function of the proximal colon or the propulsive function of the left colon
CONSTIPATION Same as above Disturbances of the rectal or sigmoid
reservoir o Typically as a result of dysfunction
of the pelvic floor, anal sphincters, or the coordination of defecation
COLONIC MOTILITY AND TONE
The small intestinal MMC only rarely continues into the colon.
Short duration or phasic contractions, the presominant contractions in the colon, are irregular and non-propagated mix colonic contents
High-amplitude propagated contractions (HAPCs) (>75 mmHg) are sometimes associated with mass movements through the colon and normally occur approximately five times per day, usually on awakening in the morning and postprandially
Colonic tone o refers to the background contractility upon which phasic
contractile activity (typically contractions lasting
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MEDICINE 1 // ABDOMINAL SYMPTOMS II: DIARRHEA, CONSTIPATION & WEIGHT LOSS 3.3-B
CALDERON, GARCIA, HARDIN, MANABAT, SOLIS 3 of 8
often associated with rectal urgency and accompanies irritable bowel syndrome or anorectal disorders like proctitis
o Fecal incontinence involuntary discharge of rectal contents and is most
often caused by neuromuscular disorders or structural anorectal problems
Although severe diarrhea and urgency my aggravate or cause incontinence
o Overflow diarrhea may occur in nursing home patients due to fecal
impaction that is readily detectable by rectal examination
A careful history and physical examination generally allow these conditions to be discriminated from true diarrhea.
ACUTE DIARRHEA
90% - infectious agents 10% - medications, toxic ingestions, ischemia, and other
conditions.
ACUTE DIARRHEA FROM INFECTIOUS AGENTS often accompanied by vomiting, fever, and abdominal pain
fecal-oral transmission via direct personal contact or, more commonly, via ingestion of food or water contaminated with pathogens from human or animal feces
In the immunologically competent person, the resident fecal microflora, is rarely the source of diarrhea and may actually play a role in suppressing the growth of ingested pathogens.
Disturbance of the flora by antibiotics o Lead to diarrhea by reducing the digestive function or by
allowing the overgrowth of pathogens, such as C. difficile
Acute infection or injury occurs when the ingested agent overwhelms the host's mucosal immune and nonimmune (gastric acid, digestive enzymes, mucus secretion, peristalsis, and suppressive resident flora) defenses.
Established clinical associations with specific enteropathogens may offer diagnostic clues.
HIGH RISK GROUPS
Travelers
Latin America, Africa, and Asia traveler'sdiarrhea
Enterotoxigenic or EnteroaggregativeE.coli
Campylobacter
Shigella
Aeromonas Norovirus
Coronavirus
Salmonella
Russia (especially St. Petersburg)
Giardia-associated diarrhea
Nepal Cyclospora
Campers, backpackers, and swimmers in wilderness
areas
Giardia
Cruise ships Norwalk virus
Consumers of certain foods
Consumption at a picnic, banquet, or restaurant
Salmonella Campylobacter or Shigella (chicken)
Undercooked hamburger E. coli (O157:H7) enterohemorrhagic
Fried rice Bacillus cereus
Mayonnaise or creams Staphylococcus aureus or Salmonella
Eggs Salmonella
Uncooked foods or soft cheeses
Listeria
Seafood, especially if raw Vibrio species, Salmonella, or acute hepatitis A
Immunodeficient persons (person with AIDS)
Primary Immunodeficiency
IgA Deficiency Common Variable Hypogammaglobulinemia Chronic Granulomatous Disease Secondary Immunodeficiency States (More Common) AIDS Senescence Pharmacologic suppresion Common enteric pathogens often cause a more severe and protracted diarrheal illness, particularly in individuals with AIDS:
Mycobacterium spp. CMV Herpes simplex Cryptosporidium Isospora belli Microsporida Blastocystis hominis Agents transmitted venereally per rectum may contribute to proctocolitis in patients with AIDS: Neisseria gonorrhea Treponema pallidum Chlamydia Patients with hemochromatosis are especially prone to invasive, even fatal, enteric infections and should avoid raw fish: Vibrio Yersinia
Daycarepaticipants and their family members
Shigella
Giardia Cryptosporidium
rotavirus
Institutionalized persons
Infectious diarrhea is one of the most frequent categories of nosocomial infections in many hospitals and long-term care facilities
most commonly C. difficile The pathophysiology underlying acute diarrhea by infectious
agents produces specific clinical features that may also be helpful in diagnosis
PATHOGENS REMARKS
Preformed Bacterial Toxins
Associated with profuse watery diarrhea secondary to small-bowel hypersecretion after ingestion
Diarrhea associated with: o Marked vomiting o Minimal or no
fever Occurs within few hours after ingestion
Enterotoxin-producing Bacteria
Enteroadherent pathogens
Less vomiting Greater abdominal cramping or bloating Higher fever
Cytotoxin-producing and invasive microorganisms
ALL causes high fever and abdominal pain
Invasive Bacteria and E. histolytica
Often cause bloody diarrhea, referred to as dysentery
Yersinia Invades the terminal ileal and proximal colon mucosa May cause especially severe abdominal pain with tenderness mimicking acute appendicitis
Infectious diarrhea may be associated with systemic
manifestations
PATHOGENS RELATED SYSTEMIC DISEASE
Salmonella Campylobacter Shigella Yersinia
Reactive arthritis (Reiters Syndrome) Arthritis Urethritis Conjunctivitis
Yersinia Autoimmune-type thyroiditis Pericarditis Glomerulonephritis
EHEC (O157:H7) Shigella
Hemolytic Uremic Syndrome
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MEDICINE 1 // ABDOMINAL SYMPTOMS II: DIARRHEA, CONSTIPATION & WEIGHT LOSS 3.3-B
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The syndrome of postinfectious IBS has now been recognized as a complication of infectious diarrhea
Acute diarrhea can also be a major symptom of several systemic infections including: o Viral hepatitis o Listeriosis o Legionellosis o Toxic Shock Syndrome
ACUTE DIARRHEA FROM OTHER CAUSES
CAUSES REMARKS
Side Effects From Medications
Probably the most common noninfectious causes of acute diarrhea
Etiology may be suggested by a temporal association between use and symptom onset
Medications: o Antibiotics o Cardiac antidysrhythmics o Antihypertensives o NSAIDS o Certain antidepressants o Chemotherapeutic agents o Bronchodilators o Antacids o Laxatives
Occlusive or Nonocclusive Ischemic Colitis
Typically occurs in persons > 50 years
Often presents as acute lower abdominal pain preceding watery, then bloody diarrhea
Generally results in acute inflammatory changes in the sigmoid or left colon while sparing the rectum
Colonic Diverticulitis
May present with acute diarrhea
Ingestion of Toxins
Organophosphate insecticides Amanita and other mushrooms
Arsenic
Preformed environmental toxins in seafood o Ciguatera o Scombroid
Conditions Causing Chronic Diarrhea
Can also be confused with acute diarrhea early in their course
May occur in: o Inflammatory Bowel Disease o Other inflammatory chronic
diarrheas that may have an abrupt rather than insidious onset and exhibit features that mimic infection
APPROACH TO THE PATIENT
The decision to evaluate acute diarrhea depends on its severity and duration and on various host factors.
Most episodes of acute diarrhea are mild and self-limited, and they do not justify the cost and potential morbidity of diagnostic or pharmacologic interventions.
Indications for evaluation include: o profuse diarrhea with dehydration o grossly bloody stools o fever 38.5 C o duration >48 h without improvement o new community outbreaks o associated severe abdominal pain in patients older than 50
years of age, and elderly (>70 years) o immunocompromised patients
In some cases of moderately severe febrile diarrhea associated with fecal leukocytes (or increased fecal levels of the leukocyte proteins) or with gross blood, a diagnostic evaluation might be avoided in favor of an empirical antibiotic trial.
The cornerstone of diagnosis in those suspected of severe acute infectious diarrhea is microbiologic analysis of the stool.
Workup includes:
o Cultures for bacterial and viral pathogens o Direct inspection for ova and parasites
o Immunoassays for: Certain bacterial toxins (C. difficile) Viral antigens (Rotavirus) Protozoal antigens (Giardia, E. histolytica)
If a particular pathogen or set of possible pathogens is so implicated:
o Whole panel of routine studies may not be necessary o Special cultures may be appropriate (Rare)
Enterohemorrhagic and other types of E. Coli
Vibrio spp. Yersinia
If stool studies are unrevealing, flexible sigmoidoscopy with biopsies and upper endoscopy with duodenal aspirates and biopsies may be indicated.
Brainerd Diarrhea o Abrupt-onset diarrhea that persists for at least 4 weeks,
but may last 13 years o Thought to be of infectious origin o May be associated with subtle inflammation of the distal
small intestine or proximal colon To exclude Inflammatory Bowel Disease (IBD), ischemic
colitis, diverticulitis, or partial bowel obstruction
o Structural examination by sigmoidoscopy o Colonoscopy o Abdominal CT scanning
o or other imaging approaches
CHRONIC DIARRHEA
Diarrhea lasting more than 4 weeks warrants evaluation to exclude serious underlying pathology.
Most of the causes of chronic diarrhea are noninfectious
Classification of chronic diarrhea is by pathophysiologic
mechanism
o Facilitates a rational approach to management
CAUSES Secretory Causes
Secretory diarrheas are due to derangements in fluid and electrolyte transport across the enterocolic mucosa.
They are characterized clinically by watery, large-volume fecal outputs that are typically painless and persist with fasting.
Medications o Side effects from regular ingestion of drugs and toxins are
the most common secretory causes of chronic diarrhea. o Surreptitious or habitual use of stimulant laxatives [e.g.,
senna, cascara, bisacodyl, ricinoleic acid (castor oil)] o Chronic ethanol consumption d/t enterocyte injury with
impaired sodium and water absorption as well as rapid transit other alterations
Environmental toxins (e.g., arsenic)
Bowel resection, mucosal disease, or enterocolic fistula o inadequate surface for reabsorption of secreted fluids and
electrolytes o worsen with eating o resection of
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MEDICINE 1 // ABDOMINAL SYMPTOMS II: DIARRHEA, CONSTIPATION & WEIGHT LOSS 3.3-B
CALDERON, GARCIA, HARDIN, MANABAT, SOLIS 5 of 8
Hormones
Metastatic gastrointestinal carcinoid tumors or, rarely, primary bronchial carcinoids
May produce: o Watery diarrhea (May exist alone) o Carcinoid Syndrome
Episodic Flushing Wheezing Dyspnea Right Sided Valvular Disease
Diarrhea is due to the release into the circulation of potent intestinal secretagogues including Serotonin, histamine, prostaglandins, and various kinins
Pellagra-like skin lesions m ay rarely occur as the result of serotonin overproduction with niacin depletion
Gastrinoma Gastrin One of the most common
neuroendocrine tumors
Most typically present with refractory ulcers
Diarrhea most often results from fat maldigestion owing to pancreatic enzyme inactivation by low intraduodenal pH.
VIPoma VIP pancreatic cholera (a.k.a Watery Diarrhea Hypokalemia Achlorhydria Syndrome)
Secretory diarrhea is often massive with stool volumes >3L/d
May be accompanied by: o Life-threatening dehydration o Neuromuscular dysfunction from
associated hypokalemia, hypomagnesemia or hypercalcemia
o Flushing o Hyperglycemia
Medullary carcinoma of the thyroid
Calcitonin Present with watery diarrhea caused by
calcitonin, other secretory peptides, or prostaglandins
Systemic mastocytosis
Histamine May be associated with the skin lesion
urticarial pigmentosa
May cause diarrhea: o Mediated by histamine o Due to intestinal infiltration by
mast cells
Colorectal villous adenomas
Prostaglandins
May rarely be associated with a secretory diarrhea that may cause hypokalemia
Mediated by prostaglandins
Inhibited by NSAIDS
Congenital defects in ion absorption o Congenital chlorridorrhea (Defective Cl/HCO3 exchange):
results in alkalosis o Congenital Sodium Diarrhea (Defective Na+/H+ exchange):
results in acidosis o Addison's disease
Osmotic Causes
Osmotic diarrhea occurs when ingested; poorly absorbable, osmotically active solutes draw enough fluid lumenward to exceed the resorptive capacity of the colon.
Fecal water output increases in proportion to such a solute load
Osmotic diarrhea characteristically ceases with fasting or with discontinuation of the causative agent
Osmotic laxatives (Mg2+
, PO43
, SO42
) o magnesium-containing antacids, health supplements, or
laxatives o stool osmotic gap (>50 mosmol/L) Serum osmolality (typically 290 mosmol/kg) - [2 x (Fecal
Sodium + Potassium Concentration)] o Measurement of fecal osmolarity is no longer
recommended May be erroneous because carbohydrates are
metabolized by colonic bacteria, causing an increase in osmolarity
Carbohydrate malabsorption o Due to defects in brush-border disaccharidases and other
enzymes o Leads to osmotic diarrhea with low pH o lactase deficiency and other disaccharide deficiencies o Lactase Deficiency One of the most common cause of chronic diarrhea in
adults
Diarrhea ensues because of malabsorbed lactose from diet (milk and other dairy products)
Nonabsorbable carbohydrates o Sorbitol o Lactulose o Polyethylene glycol
Steatorrheal Causes
Fat malabsorption may lead to greasy, foul-smelling, difficult-to-flush diarrhea often associated with weight loss and nutritional deficiencies due to concomitant malabsorption of amino acids & vitamins.
Increased fecal output is caused by the osmotic effects of fatty acids and by the neutral fat especially after bacterial hydroxylation
STEATORRHEA - stool fat >7 g/d; o Rapid-transit diarrhea may result in fecal fat up to 14 g/d o daily fecal fat averages 15 to 25 g with small intestinal
diseases o often exceeds 32 g with pancreatic exocrine insufficiency
Intraluminal maldigestion o Bacterial overgrowth in the small intestine may
deconjugate bile acids and alter micelle formation, impairing fat digestion and occurs in: Stasis from blind-loop Small-bowel diverticulum or dysmotility Especially likely in elderly
o Most commonly results from pancreatic exocrine insufficiency Occurs when >90% of pancreatic secretory function is
lost o Chronic pancreatitis
Usually a sequel of ethanol abuse Most frequently causes pancreatic insufficiency
o Cirrhosis or biliary obstruction may lead to mild steatorrhea due to deficient intraluminal bile acid concentration
o Bariatic surgery o Liver disease o Other Causes:
Cystic fibrosis Pancreatic duct obstruction Somatostatinoma
Mucosal Malabsorption o Celiac sprue/ Gluten-sensitive enteropathy Most common, affects all ages villous atrophy and crypt hyperplasia (+) fatty diarrhea associated with multiple nutritional
deficiencies Can mimic IBS
o Tropical sprue May produce a similar histologic and clinical syndrome
but occurs in residents of or travelers to tropical climates Abrupt onset and response to antibiotics suggest an
infectious etiology o Whipple's disease due to the bacillus Tropheryma whipplei and histiocytic
infiltration of the small-bowel mucosa less common cause of steatorrhea that most typically
occurs in young or middle-aged men frequently associated with arthralgias, fever,
lymphadenopathy, and extreme fatigue may affect the central nervous system and endocardium
o Mycobacterium avium-intracellulare infection in patients with AIDS.
o Abetalipoproteinemia Rare defect of chylomicron formation and fat
malabsorption in children associated with acanthocytic erythrocytes, ataxia, and
retinitis pigmentosa o Infections: Giardia o Medications (e.g., colchicine, cholestyramine, neomycin) o Amyloidosis o Chronic ischemia
Postmucosal lymphatic obstruction o Due to: congenital intestinal lymphangiectasia or acquired
lymphatic obstruction secondary to trauma, tumor, or infection
o May lead to: Fat malabsorption Enteric losses of protein (often causing edema) Lymphocytopenia
o Carbohydrate and amino acid absorption are preserved
Inflammatory Causes
Inflammatory diarrheas are generally accompanied by pain, fever, bleeding, or other manifestations of inflammation.
Mechanism of diarrhea: o Exudation o Fat malabsorption
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o Disrupted fluid/electrolyte absorption o Hypersecretion or hypermotility from release of cytokines
and other inflammatory mediators
The unifying feature on stool analysis is the presence of leukocytes or leukocyte-derived proteins such as calprotectin o Can lead to anasarca if exudative protein loss is severe
Idiopathic inflammatory bowel disease o Crohn's disease and chronic ulcerative colitis most common organic causes of chronic diarrhea in
adults Range in severity from mild to fulminant and life-
threatening May be associated with:
- Uveitis - Polyarthralgias - Cholestatic liver disease (Primary Sclerosing
Cholangitis) - Skin Lesions (Erythema nodosum, Pyoderma
gangrenosum)
Microscopic colitis o includes both lymphocytic and collagenous colitis o an increasingly recognized cause of chronic watery
diarrhea, especially in middle-aged women and those on NSAIDS
o Biopsy of a normal-appearing colon is required for histologic diagnosis
o May coexist with symptoms suggesting IBS or with celiac sprue
o responds well to anti-inflammatory drugs (e.g., bismuth), to the opioid agonist loperamide, or to budesonide
Immune-related mucosal disease o Primary or secondary forms of immunodeficiency o Lead to prolonged infectious diarrhea o With selective IgA deficiency or common variable
hypogammaglobulinemia, diarrhea is particularly prevalent and often the result of giardiasis, bacterial overgrowth or sprue
o Eosinophilic Gastroenteritis Eosinophilic infiltration of the mucosa, muscularis or
serosa at any level of the GI tract may cause diarrhea, pain, vomiting, or ascites (+) atopic history, Charcot-Leyden crystals (d/t extruded
eosinophilic contents) and peripheral eosinophilia (50-75% of patients)
While hypersensitivity to certain foods occurs in adults, true food allergy causing chronic diarrhea is rare
Infections o Invasive bacteria, viruses, parasites o Brainerd diarrhea
Other Causes: o Radiation enterocolitis o Chronic Graft-vs-host disease o GI malignancies o Behet's syndrome o Cronkite-Canada syndrome
Dysmotility Causes
Primary dysmotility is an unusual etiology of true diarrhea o Dysmotility induced diarrhea is usually as secondary to
other conditions Hypermotility with resultant diarrhea:
o Hyperthyroidism o Carcinoid syndrome o Certain drugs (e.g., prostaglandins, prokinetic agents)
Stasis with secondary bacterial overgrowth causing diarrhea: o Primary visceral neuromyopathies o Idiopathic acquired intestinal pseudo-obstruction
Intestinal dysmotility: o Diabetic diarrhea, often accompanied by peripheral and
generalized autonomic neuropathies
Disturbed intestinal and colonic motor and sensory responses: o Irritable bowel syndrome symptoms of stool frequency Typically cease at night Alternate with periods of constipation Accompanied by abdominal pain relieved with
defecation Rarely result in weight loss
Postvagotomy
Facitial Causes accounts for up to 15% of unexplained diarrheas
Either as a form of Munchausen syndrome (deception or self-injury for secondary gain) or eating disorders
Some patients covertly: o Self-administer laxatives o Surreptitiously add water or urine to stool sent for analysis
(para kunwari may sakit sila para maka gain ng attention or para pumayat due to diarrhea)
Patients are: o Typically women o Often with histories of psychiatric illness o Disproportionately from careers in health care
Hypotension and hypokalemia are common co-presenting features
The evaluation of such patients may be difficult: o Contamination of the stool with water or urine is suggested
by very low or high stool osmolarity,respectively o Such patients often deny this possibility when confronted
but they do benefit from psychiatric counseling when they acknowledge their behaviour.
Iatrogenic Causes
Cholecystectomy Ileal resection
Bariatic surgery
Vagotomy, fundoplication
APPROACH TO THE PATIENT
The laboratory tools available to evaluate the very common problem of chronic diarrhea are extensive, and many are costly and invasive.
As such, the diagnostic evaluation must be rationally directed by a careful history and physical examination, and simple triage tests are often warranted before complex investigations are launched.
The history, physical examination, and routine blood studies should attempt to: o characterize the mechanism of diarrhea o identify diagnostically helpful associations o assess the patient's fluid/electrolyte and nutritional status
Patients should be questioned about the: o Onset o Duration o Pattern o Aggravating factors (especially diet) o Relieving factors o stool characteristics of their diarrhea o Family history of IBD or sprue
Look for: o presence or absence of fecal incontinence o fever o weight loss o pain o certain exposures (travel, medications, contacts with
diarrhea) o common extraintestinal manifestations (skin changes ,
arthralgias, oral aphthous ulcers)
Blood chemistries may demonstrate electrolyte, hepatic, or other metabolic disturbances.
Physical findings may offer clues such as : o thyroid mass o wheezing o heart murmurs o edema o hepatomegaly o abdominal masses o lymphadenopathy o mucocutaneous abnormalities o perianal fistulae o anal sphincter laxity
Therapeutic trial is often appropriate, definitive, and highly cost effective when a specific diagnosis is suggested on the initial physician encounter
Persistent symptoms require additional investigation.
Certain diagnoses may be suggested on the initial encounter
However, additional focused evaluations may be necessary to confirm the diagnosis and characterize the severity or extent of
disease so that treatment can be best guided
Cause of chronic diarrhea remains unclear after initial
encounter in 2/3 of cases and further testing is required
o Quantitative stool collection and analyses Can yield important objective data that may
establish a diagnosis or characterize the type of
diarrhea as a triage for focused additional studies l analyses
should be performed:
- Electrolyte concentration - pH
- Occult blood testing - Leukocyte inspection (or leukocyte protein
assay)
- Fat quantitation
- Laxative screens
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MEDICINE 1 // ABDOMINAL SYMPTOMS II: DIARRHEA, CONSTIPATION & WEIGHT LOSS 3.3-B
CALDERON, GARCIA, HARDIN, MANABAT, SOLIS 7 of 8
Initial Management Based on Accompanying Symptoms or Features
b. Evaluation Based on Findings From a Limited Age Appropriate Screen for Organic Disease
CONSTIPATION
persistent, difficult, infrequent, or seemingly incomplete defecation
Because of the wide range of normal bowel habits, constipation is difficult to define precisely.
Stool frequency alone is not a sufficient criterion for the diagnosis of constipation because many constipated patients describe a normal frequency of defecation but complains of: o excessive straining o hard stools o lower abdominal fullness o sense of incomplete evacuation
Stool form and consistency are well correlated with the time elapsed from the preceding defecation.
Hard, pellety stools = SLOW transit
Loose, watery stools = RAPID transit
Hard, pellety stools and very large stools are more difficult to expel.
Psychosocial factors may also be important.
Chronic constipation generally results from inadequate fiber or fluid intake or from disordered colonic transit or anorectal function
Idiopathic constipation o Patients exhibit delayed emptying of the ascending and
transverse colon with prolongation of transit (often in the proximal colon) and a reduced frequency of high-amplitude propagated contractions (HAPCs)
Outlet obstruction to defecation or evacuation disorders - delayed colonic transit o Usually corrected by biofeedback retraining of the
disordered defecation
Constipation of any causes may be exacerbated by hospitalization or chronic illnesses that lead to physical or mental impairment and may result in inactivity or physical immobility.
APPROACH TO THE PATIENT
A careful history should explore the patient's symptoms and confirm whether he or she is indeed constipated based on: o frequency (e.g., 40 years flexible sigmoidoscopy plus barium enema or colonoscopy alone to exclude structural diseases, e.g., cancer or stricture
Patients with more troublesome constipation may be helped by bowel-training regimen o Osmotic laxative o Evacuating with enema or glycerine suppository as
needed o 15-20 min distraction- and straining-free bowel
movement after breakfast Excessive straining hemorrhoids Weakness of pelvic flor or injury to pudendal nerve
obstructed defecation from descending perineum syndrome
A good diet and medication history and attention to psychosocial issues are keys.
INVESTIGATION OF SEVERE CONSTIPATION
Patients who do not respond to simple measures (~5%) are assumed to have severe or intractable constipation
Measurement of colonic transit o
taken after 5 days should indicate passage of 80% of the markers out of the colon
o Radioscintigraphy is used to characterize colonic function over 24-48 hours with low radiation exposure and to assess gastric, small bowel and colonic transit
Pelvic floor dysfunction o Inability to evacuate the rectum, a feeling of persistent
rectal fullness, rectal pain, the need to extract stool from the rectum digitally, application of pressure on the posterior wall of the vagina, support of the perineum during straining, and excessive straining
Simple clinical test to document a nonrelaxing puborectalis muscle o Have the patient strain to expel the index finger during
digital rectal exam o Motion of the puborectalis posteriorly during straining
indicates proper coordination of pelvic floor muscles
Measurement of perineal descent o Patient in left decubitus o Inadequate descent (4 cm) - excessive perineal descent
Anorectal manometry detects excessively high resting (80 mmHg) or squeeze anal sphincter tone, and identifies rare syndromes, e.g., Hirschsprungs disease
Defecography reveals soft abnormalities, e.g., changes in rectoanal angle and anatomic defects of the rectum
WEIGHT LOSS
SIGNIFICANT UNINTENTIONAL weight loss in a previously healthy individual is often a harbinger of underlying systemic disease
Inquiry should always be made about changes in weight
>LOSS OF 5% OF BODY WEIGHT OVER 6 TO 12 MONTHS should prompt further evaluation.
PHYSIOLOGY OF WEIGHT REGULATION
Appetite and metabolism are regulated by an intricate network of neural and hormonal factors.
Weight loss occurs when energy expenditure exceeds calories available for energy utilization.
Mechanisms of weight loss include: o decreased food intake o malabsorption o loss of calories o increased energy requirements
Food intake may be influenced by a wide variety of factors: o visual, olfactory, and gustatory stimuli o genetics o psychological factors o social factors
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MEDICINE 1 // ABDOMINAL SYMPTOMS II: DIARRHEA, CONSTIPATION & WEIGHT LOSS 3.3-B
CALDERON, GARCIA, HARDIN, MANABAT, SOLIS 8 of 8
SIGNIFICANCE OF WEIGHT LOSS
Unintentional weight loss, especially in the elderly, is not uncommon and is associated with increased morbidity and mortality rates
Cancer patients with weight loss have decreased: o performance status o response to chemotherapy o median survival
Marked degrees of weight loss also predispose to infection. Patients undergoing elective surgery, who have lost more
than 10 lb (4.5 kg) in 6 months, have higher surgical mortality rates.
CAUSES OF WEIGHT LOSS
CAUSES OF WEIGHT LOSS
ELDERLY Depression
Cancer
Benign gastrointestinal disease
YOUNGER INDIVIDUALS
Diabetes mellitus Hyperthyroidism
Psychiatric disturbances (including eating disorders)
Infection (especially with HIV)
Lung and gastrointestinal cancer are the MOST COMMON MALIGNANCIES in patients presenting with weight loss.
In YOUNGER individuals, patients with medical causes of weight loss usually have S/S that suggest involvement of a particular organ system.
Gastrointestinal tumors, including those of the pancreas and liver, may affect food intake early in the course of illness, causing weight loss before other symptoms are apparent.
Lung cancer, depression and isolation, Chronic pulmonary disease and CHF can produce anorexia and may also increase resting energy expenditure.
Presenting sign of infectious diseases such as HIV infection, tuberculosis, endocarditis, and fungal and parasitic infections.
Hyperthyroidism or pheochromocytoma
New onset DM is often accompanied by weight loss, reflecting glucosuria and loss of the anabolic actions of insulin.
Adrenal insufficiency may be suggested by increased pigmentation, hyponatremia, and hyperkalemia.
APPROACH TO PATIENT Confirm that weight loss has occurred.
Almost half of patients who claim significant weight loss have no actual change in wt. when it is measured objectively.
If (+) weight loss: o determine the time interval over which it has occurred o In the absence of documentation, changes in belt notch
size or the fit of clothing may help confirm loss of weight. Routine documentation of weight during office visits is
therefore important.
ROS: o focus on s/s that are associated with disorders that
commonly cause weight loss o These include: Fever Pain SOB or cough Palpitations Changes in pattern of urination Evidence of neurologic disease
GI disturbances, including difficulty eating, dysphagia, anorexia, nausea, and change in bowel habits.
Use of cigarettes, alcohol, and all medications should be reviewed
Ask about previous illness or surgery as well as diseases in family members.
Signs of depression, evidence of dementia, and social factors, including financial issues that might affect food intake.
PHYSICAL EXAMINATION
Weight determination and documentation of VS. Skin
o Pallor o Jaundice o Turgor o Scars from prior surgery o Stigmata of systemic disease
Search for: o oral thrush or dental disease o TG enlargement o Adenopathy o Respiratory or cardiac abnormalities o Detailed examination of the abdomen often lead to clues
for further evaluation Rectal exam, including prostate exam and testing of stool for
occult blood, should be performed in men
All women should have a pelvic examination, even if they have had a hysterectomy.
Neurologic examination should include mental status assessment and screening for depression.
DIAGNOSTIC TESTING
Laboratory testing should confirm or exclude possible diagnoses elicited from the Hx & PE
If GI s/s are present, upper and/or lower endoscopy and abdominal imaging with either CT or MRI have a relatively high yield.
Flexible sigmoidoscopy plus barium enema or colonoscopy particulary for patients >40y/o to exclude structural diseases (cancer or strictures) o Colonoscopy - most cost-effective o Barium enema - Advantageous to patients with isolated
constipation Melanosis Coli indicates usage of anthraquinone laxatives
Megacolon or cathartic colon may be detected by colonic radiography
Measurement of serum Ca, K, and TSH -> identify px w/ metabolic d/o
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