DIARREAHA

Dr. Maha Arafah

Case

• A 1 year old girl is brought to clinic with 3 days of watery diarrhea, vomiting, and irritability. On exam the child is lethargic, afebrile, with sunken eyes and a weak pulse of 140/minute. Which of the following is the best management plan?

A. Check CBC and stool tests for pathogensB. Prescribe oral rehydration solutionC. Prescribe oral antibioticsD. Begin IV fluids and hospitalize

Why important?

• The loss of fluids through diarrhea can cause dehydration and electrolyte imbalances

• Easy to treat but if untreated, may lead to death especially in children

Why important?

More than 70 % of almost 11 million child deaths every year are attributable to 6 causes:

1. Diarrhea2. Malaria3. neonatal infection4. Pneumonia5. preterm delivery6. lack of oxygen at birth.

UNICEF

Fluid and small intestine

DIARREAHA DEFINITION

• World Health Organization 3 or more loose or liquid stools per day

• Abnormally high fluid content of stool – > 200-300 gm/day

CLASSIFICATION

1.Acute

2.Persistent

3.Chronic

CLASSIFICATION

1.Acute if 2 weeks,

2.Persistent if 2 to 4 weeks,

3.Chronic if 4 weeks in duration.

Is it diarrhea or not ?

• Two common conditions, usually associated with the passage of stool totaling 200 g/d, must be distinguished from diarrhea, as diagnostic and therapeutic algorithms differ.

1. Pseudodiarrhea, or the frequent passage of small volumes of stool, is often associated with rectal urgency and accompanies the irritable bowel syndrome or anorectal disorders such as proctitis.

2. Fecal incontinence is the involuntary discharge of rectal contents and is most often caused by neuromuscular disorders or structural anorectal problems.

Pathophysiology Categories of diarrhea

1. Secretory2. Osmotic3. Exudative4. Motility-related

Secretory diarrhea

• There is an increase in the active secretion• High stool output • Lack of response to fasting • Normal stool ion gap < 100 mOsm/kg Stool osmotic gap =

Stool osmolality - 2 x (stool Na + stool K)Normal fecal fluid values: Osmolality: ~290 mOsm/kg Na+: ~30 mmol/L K+: ~75 mmol/L

Secretory diarrheaCauses

1. The most common cause of this type of diarrhea is a bacterial toxin ( E. coli , cholera) that stimulates the secretion of anions.

2. Hormonally mediated: VIPoma, carcinoid, medullary carcinoma of thyroid (calcitonin), Zollinger-Ellison syndrome (gastrin)

3. Factitious diarrhea (laxative abuse); phenolphthalein, cascara, senna

4. Villous adenoma 5. Bile salt malabsorption (ileal resection; Crohn's ileitis;

postcholecystectomy) 6. Medications

PathophysiologyCholera

Cholera toxin binds to membrane receptors on enterocytes, irreversibly activating G protein that leads to enhanced cAMP production. This: (1) inhibits apical electroneutral NaCl absorption(2) induces Cl- secretion by activating apical Cl- channels.

PathophysiologyCholera

• No associated epithelial injury occurs, leaving intact apical Na+-coupled nutrient transporters (Na+-glucose, Na+-amino acid)

Osmotic diarrhea

• Excess amount of poorly absorbed substances that exert osmotic effect………water is drawn into the bowels……diarrhea

• Stool output is usually not massive • Fasting improve the condition• Stool ion gap is high, > 125 mOsm/kg• Can be the result of 1. Malabsorption in which the nutrients are left in the

lumen to pull in water e.g. lactose intolerance2. osmotic laxatives.

Osmotic diarrhea

CLUES: Stool volume decreases with fasting; increased stool osmotic gap

1. Medications: antacids, lactulose, sorbitol 2. Disaccharidase deficiency: lactose intolerance

3. Factitious diarrhea: magnesium (antacids,

laxatives)

Osmotic • As stool leaves the colon, fecal osmolality is

equal to the serum osmolality, ie, approximately 290 mosm/kg.

• Under normal circumstances, the major osmoles are Na+, K+, Cl–, and HCO3

–.

Exudative

• Results from the outpouring of blood protein, or mucus from an inflamed or ulcerated mucosa

• Presence of blood and pus in the stool.• Persists on fasting• Occurs with inflammatory bowel diseases,

and invasive infections.

Inflammatory conditions

CLUES: Fever, hematochezia, abdominal pain 1. Ulcerative colitis 2. Crohn's disease 3. Microscopic colitis 4. Malignancy: lymphoma, adenocarcinoma

(with obstruction and pseudodiarrhea) 5. Radiation enteritis

Motility-related

• Caused by the rapid movement of food through the intestines (hypermotility).

• Irritable bowel syndrome (IBS) – a motor disorder that causes abdominal pain and altered bowel habits with diarrhea predominating

• Diabetes mellitus – neurogenic dysfunction• Scleroderma – stasis of the bowel with resultant

bacterial overgrowth, steatorrhea and diarrhea

Motility disorders

CLUES: Systemic disease or prior abdominal surgery

1. Postsurgical: vagotomy, partial gastrectomy, blind loop with bacterial overgrowth

2. Systemic disorders: scleroderma, diabetes mellitus, hyperthyroidism

3. Irritable bowel syndrome

AetiologyAcute diarrhea?

• Approximately 80% of acute diarrheas are due to infections (viruses, bacteria, helminths, and protozoa).

• Viral gastroenteritis (viral infection of the stomach and the small intestine) is the most common cause of acute diarrhea worldwide.

• Food poisoning• Drugs• Others

Rotavirus the cause of nearly 40% of hospitalizations from diarrhea in children under 5

Antibiotic-Associated Diarrheas

• Diarrhea occurs in 20% of patients receiving broad-spectrum antibiotics; about 20% of these diarrheas are due to Clostridium difficile

Aetiology

• Chronic diarrhea?1. Infection ----------- e.g.Giardia lamblia .

AIDS often have chronic infections of their intestines that cause diarrhea.

2. Post-infectious. Following acute viral, bacterial or parasitic infections

3. Malabsorption4. Inflammatory bowel disease (IBD)5. Endocrine diseases6. Colon cancer7. Irritable bowel syndrome.

Complications

1. Fluids ………………Dehydration2. Electrolytes …………….. Electrolytes imbalance3. Sodium bicarbonate……. Metabolic acidosis 4. If persistent ……Malnutrition

Tests useful in the evaluation of diarrheaAcute diarrhea

Noninflammatory Diarrhea Inflammatory Diarrhea

Fecal leukocytes are not present Fecal leukocytes are present

Fecal leukocytes

Suggests a small bowel source caused by either 1. Toxin-producing bacterium

(enterotoxigenic E coli [ETEC], Staphylococcus aureus, Bacillus cereus, Clostridium perfringens)

2. other agents (viruses, Giardia) that disrupt normal absorption and secretory process in the small intestine

The presence of fever and bloody diarrhea (dysentery) indicates colonic tissue damage caused by invasion (shigellosis, salmonellosis, Campylobacter or Yersinia infection, amebiasis) or a toxin (C difficile, E coli O157:H7).

Diagnosis

• 72 H Stool collection– > 200 gm – indicates diarrhea– >1000-1500gm – suggests Secretory diarrhea– > 10 gm of fecal fat – malabsorption

– Stool pH …….5.5 or less indicates carbohydrate intolerance, which is usually secondary to viral illness and transient in nature.

– Stool anion gap …… osmolar > 100 > secretory

290 - [(Na+K) X 2].

Chronic diarrhea

Diagnosis Chronic diarrhea

MalabsorptionInflammatory bowel disease (IBD)

Endocrine diseases.

Colon cancer

Irritable bowel syndrome.

D-Xylose Test

Bile salt breath test

Hydrogen breath test

Small intestine biopsy

If osmotic gap and/or fecal fat increased

If blood and/or WBC in the stool

Infection

X-rays of the intestines

Endoscopy

cortisol and thyroid hormone

If symptoms and signs of endocrine diseases

Stool culture

Diagnosis of exclusion gluten autoantibodies