Medicine 3.3b - Abdominal Symptoms Iib

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

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



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



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



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



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


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



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.


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



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

Medicine 3.3b - Abdominal Symptoms Iib

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