Diarrhea:- Part 1 – Diarrhea Lab findings

Diarrhea Lab findings

Sample for diarrhea

1. A fresh stool sample is ideal.
2. Blood may be needed for antigen and antibody testing

Definition of diarrhea

1. This is characterized by 3 loose stools per day and may be accompanied by the following:
   1. Abdominal pain.
   2. Nausea and vomiting.
   3. Fatigue.

Causes of Diarrhoea: 

1. Diarrhea may be acute or chronic.
2. This may be due to the following:
   1. Viral infections. The most common cause is retrovirus among children. Other viruses are Adenovirus, cytomegalovirus, and HIV.
   2. Bacterial infections are due to salmonellosis, Vibrio, Campylobacter, and Yersinia. Other causes are toxigenic bacteria like Staphylococcus and Bacillus cereus, Shigella, and E.Coli.
   3. Parasitic infestation, e.g., Giardia Lamblia and Entamoeba histolytica.

Pathophysiology of Diarrhea:

1. Most of the diarrhea is due to infections.
2. Age: Mostly, the young are susceptible due to poor health.
   1. Poor general health and nutrition will predispose to diarrhea.
3. Bacteria leading to diarrhea depend upon the following:
   1. A dose of the bacterial infection.
   2. Production of enterotoxin.
   3. Its ability to attach to the intestinal mucosa and to invade the mucosa.
4. Other factors for diarrhea are:
   1. Poor sanitation.
   2. Contaminated food and water.
   3. Personal hygiene, washing hands with soap after defecation, prevents the fecal-oral spread.
   4. Food stored at room temperature allows rapid bacterial growth and the production of toxins.
   5. Food stored at 4 °C cannot kill the bacteria; it can only prevent the multiplication of bacteria.
      1. Avoid keeping the food at room temperature, which leads to the rapid proliferation of the organism.
   6. AIDS has a prominent feature of diarrhea.

Types of diarrhea:

Diarrhea may be:

1. Acute.
2. Chronic.

Diarrhea may be:

1. Watery diarrhea.
2. Blood diarrhea.
3. Diarrhea with a lot of mucus.

Presentation of diarrhea	Causative agent	Source of spread	Diagnosis
Watery diarrhea (Bacterial)	Enterotoxigenic bacteria Escherichia coli others	Associated with traveling	Commercial kits are available
Watery diarrhea (Parasitic)	Intestinal parasites: Giardia lamblia	Associated with traveling Contaminated water supply Child daycare center	Fresh stool examination Look for ova and parasite Advise rapid antigen test for Giardia lamblia
Watery diarrhea (Toxin)	There are performed enterotoxin: Staphylococcus aureusus Bacillus cereus Clostridium perfringens	Food born poisoning Vomitus Diarrheal contents	No diagnostic tests available for toxins
Bloody diarrhea Dysentry Blood and mucus	Shigella sp Salmonella sp E.coli Campylobacter sp Entamoeba histolytica	Associated with traveling	Examine fresh stool Advise stool culture E. histolytica Antigen detection Antibody test
Gastroenteritis	Due to Enteric viruses Rotavirus Enteric adenoviruses Astrovirus Calicivirus	Contaminated foods	Examine fresh stool Viral antigen detection test E/M for viruses
Antibiotic-associated diarrhea (Colitis)	Drugs associated	Drugs	Cytotoxin assay H/O drugs Examine fresh stool

Diarrhea causes and diagnosis:

Causative agent	Source	A common source of infection	Diagnosis
Salmonella species	Animal and humans	Milk, eggs, meat, and poultry	The specimen is feces, culture on selective media.
Shigella species	Humans	Food, fomites, and feco-oral route	Stool and rectal swab on MacConkey and selective media
Escherichia coli	Humans	Food, water, fomites, and feco-oral route	Feces culture on MacConkey medium
Bacillus species	Soil	Rice	Suspected food, vomitus, and stool culture on ordinary media
Staphylococcus aureus	Septic lesion on food handlers	Dairy products and cooked meat	Suspected food, vomitus, or feces are cultures on ordinary media
Campylobacter species	Animals	Meat, milk, and poultry	Feces culture on selective medium
Clostridium perfringens	Animal	Meat pies and stews	Feces and suspected food on aminoglycoside blood agar anaerobically
Clostridium difficle	Humans	Feco-oral and overgrowth of strains in the colon	Direct detection of toxins and isolation on selective media
Vibrio cholerae	Humans	Food and water	Feces on selective medium (TCBS agar).
Yersinia species	Animal	Food and water	Isolation from feces or blood or rising antibody titer

Other types of diarrhea:

Osmotic diarrhea (Malabsorption)

1. It is defined as diarrhea with a <3 weeks to 8 weeks duration.
2. It is due to increased osmotically active solutes in the stool.
3. This type of diarrhea stops during fasting.

Secretory diarrhea:

1. It is due to abnormal electrolyte transport.
2. Secretory diarrhea is caused by increased water and chloride secretion.

Exudative diarrhea:

1. There is active inflammation of the intestinal mucosa.
2. Primarily due to infective bacteria.

Diarrhea due to motility issues:

1. There is decreased motility of the small intestine.
   1. It may be seen in hypothyroidism, diabetes mellitus, postvagatomy, and amyloidosis.
2. There may be increased motility of the small intestine.
   1. It may be seen in hyperthyroidism, carcinoid syndrome, and irritable bowel syndrome.

Diarrhea due to malabsorption:

1. It is due to defective digestion or absorption.
   1. It may be seen in lymphatic obstruction.
   2. In surgery where resection of the intestine is done.
   3. G. lamblia causing impaired absorption.

Chronic diarrhea:

1. Chronic diarrhea is defined when the diarrhea is at least 4 weeks.
2. It may be 6 to 8 weeks in duration even.
   1. It may be seen in infections like giardiasis and amoebiasis.
   2. It is seen in ulcerative colitis and collagenous colitis.
   3. In foods that contain sorbitol, fructose, caffeine, and ethanol.
   4. Drugs like antibiotics, colchicine, chemotherapy, and antihypertensive.
   5. Hormonal origins include diabetes mellitus, hyperthyroidism, hypothyroidism, and adrenal insufficiency.
   6. Infiltration of GIT by amyloidosis, scleroderma, and lymphomas.
   7. Surgery like resection of the intestine, vagotomy, and gastrectomy.
   8. Celiac sprue.
   9. Whipple disease.
   10. Allergy to some foods.
   11. It may be idiopathic in origin.

Lab. workup of the patient with diarrhea:

1. History of the patient as regards the duration of the clinical symptoms.
   1. Any history of travel to a foreign country.
   2. Food history of the other people living with the patient.
2. Take a stool sample or rectal swab.
   1. Take a sample of suspected food.
   2. Get the vomitus sample.
3. Stool examination for ova and parasites.
4. Stool cultures for pathogenic organisms.
5. Bood culture in severe cases. It is advised in very young and old patients.
6. Take a sample of the suspected food if possible.
7. Antigen tests for G.lamblia and E.Coli.
8. Antibodies tests can diagnose parasitic diseases.
9. A rapid antigen test can diagnose the retrovirus.
10. Causes of noninfectious disease are diagnosed by:
    1. Fecal fat.
    2. Lactose intolerance test.
    3. Celiac disease is diagnosed by anti-endomysial and antigliadin antibodies.
    4. Tests other than lab are colonoscopy, endoscopy, and sigmoidoscopy.
11. In case of an outbreak, advice:
    1. Fecal samples from the kitchen personnel.
    2. Food handling practices by the workers in the kitchen.

Electrolytes findings  are as follows:

Lab Test	Value
Serum Sodium	Decreased
Serum Potassium	Decreased
Serum Bicarbonate	Normal
Serum Chloride	Decreased
Urine volume	Decreased

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