CASE 1

Case 1

1. Define all unknown terms:

The students were told to use any source necessary to define all unknown terms in the case. The following texts are required: Medical dictionary, Robbins pathology text, Bates' physical diagnosis text and Greene's Clinical Medicine.("is a work stimulated by and intended for medical students. It is primarily designed to help bridge the chasm between the basic science and the wards. The format identifies the problems e.g. pruritus, cough - that patients describe and helps the student move through the history, physical examination and laboratory data to arrive at a diagnosis,"). Harrison's and Cecil's textbooks of medicine are recommended.

2. Cite the primary clinical problem (not the diagnosis).

Diarrhea or Steatorrhea (may state malabsorption)

3. What characteristics define this clinical problem?

The definition of diarrhea is controversial and may differ according to the patient's or physician's perspective. Generally patients consider diarrhea as being increase in daily frequency of bowel movements or an increase in stool volume or an increase in stool liquidity or an urgency to defecate.

Scientifically, diarrhea may exist if more than 300 grams of stool is passed daily (normal is less than 200 grams) when the patient is on a Western diet. Clinically, diarrhea may be defined as more than 3 bowel movements per day.

Emphasize to the student that they must not accept the patient's statement that they have diarrhea without taking an accurate, detailed history.

4. What points or questions would you cover when taking a history from a patient with this clinical problem?

The student should compare the patient's usual ("normal") frequency and pattern of bowel movements with the current frequency and pattern. Ask the patient about the characteristics of the bowel movement: description (watery, bulky, color, etc.), presence of blood or pus or mucus, presence and odor of flatus. Timing: frequency, duration, continuous or intermittent, association with precipitating event, food, drug, etc., causes for relief, time of day or night. Associated symptoms: fever, nausea, vomiting, pain, anorexia, weight loss, other. Circumstances or predisposition: travel, diet, drug history, age, gender, family history, past medical or surgical problems.

5. How would you differentiate the acute form of this clinical problem from the chronic form?

Acute diarrhea usually lasts less than two weeks and is self limiting, requiring no diagnostic workup (with some exceptions). Chronic diarrhea lasts longer than two weeks or is an intermittent problem over months/years. This form requires a diagnostic and therapeutic strategy.

6. Classify the chronic form of this clinical problem into groups and subgroups, explaining the pathogenesis (mechanism) for the development of each type. Develop a general differential diagnosis of the patient's clinical problem by using this classification system. Cite some examples in each category.

A. Steatorrhea

Steatorrhea is defined as the passage of stool containing an excessive amount of fat (greater than 7 grams per day or more than 10% of indigested fat). The mechanisms vary dependent on the step in the digestive process which becomes abnormal (defective) because of the particular disease.

Intraluminal Stage:

-Deficiency of pancreatic enzymes -chronic pancreatitis

-Deficiency of bile acids -biliary tract disease

-Bacterial overgrowth in the small bowel -decreased motility in a diabetic

Intestinal Stage:

-Damage to the absorptive surface (mucosa) - celiac disease

Removal Stage:

-Damaged lymphatic channels -Whipple's disease

B. Watery Diarrhea

1. Osmotic diarrhea - a consequence of increased amounts of poorly absorbable, osmotically active solutes in the lumen of the intestine.

Causes include:

-Disaccharidase deficiency -lactase deficiency

-Ingestion of drugs such as laxatives and antacids containing magnesium or phosphate

-Chewing gum sorbitol

2. Secretory diarrhea - secretion of electrolytes and water exceed absorption or absorption of electrolytes and water are impaired

-Certain laxatives - castor oil

-Bacterial toxins - infection

3. Exudative diarrhea - inflammation of the bowel mucosa may result in loss of pus, mucus, blood, protein

-Entamoeba histolytica infection
-Giardia

4. Abnormal motility

-Increased motility - thyrotoxicosis

-Delayed transit time with bacterial overgrowth - blind loop syndrome or diabetic neuropathy

Faculty: Ask the students how they could clinically differentiate osmotic diarrhea from secretory diarrhea: Alter diet or fast.

7. Classify the acute form of this clinical problem into two broad groups, citing subgroups (by etiology/pathogenesis) and appropriate clinical examples.

A. Infectious Diarrhea

-Viruses

-Bacteria

-Toxins - S.aureus, C. difficile, toxigenic E.coli

-Invasion - Shigella, Salmonella

-Parasites - Giardia, Cryptosporidium

Emphasize special situations such as nosocornial diarrhea, travelers diarrhea, AIDS, food-borne diarrhea.

B. Non-infectious

-Drugs -laxatives, antacids, alcohol, antibiotics

-Food toxins - seafood

-Metabolic - hyperthyroidism

-Functional

8. Under what circumstances would you work‑up a patient with the acute form of this clinical problem? What diagnostic tests would you order? What is the significance of finding pus in the stool?

A patient with acute diarrhea does not usually require a diagnostic workup unless there is evidence of tissue invasion (blood or pus in the stool, fever,leukocvtosis) or the diarrhea is severe enough to produce significant fluid and electrolyte loss.

The diagnostic workup might include stool analysis for ova and parasites,

blood, leukocytes and C. difficile toxin. Stool culture may be necessary. Proctosigrnoidoscopy should be performed. Pus in the stool suggests an infectious or non-infectious inflammation.

9. Develop a diagnostic workup for the chronic form of this clinical problem. Be prepared to describe and discuss the key diagnostic tests.

Stool analysis for fat,pus.blood

A. Positive Fat (72 hour fat test) - Steatorrhea

1. Normal d-xylose test - pancreatic disease

2. Abnormal d-xylose test - small bowel disease

*Students should be able to explain the nature of the d-xylose test and how it is used to gauge intestinal absorption.

B. Negative fat, pus, blood - Watery diarrhea

1. Fast reverses diarrhea - osmotic. CHO tolerance test, laxative screen and stool culture may be helpful

2. Fast does not reverse diarrhea - secretory. A variety of tests are used to identify one of many possible causes.

C. Negative fat, Positive blood and pus - Colonic disease

Sigmoidoscopy, stool culture, serology for ameba, C.difficile toxin.

10. What is the diagnosis?

-Malabsorption secondary to chronic pancreatitis (insufficiency)

-Cystic Fibrosis

11. What diagnostic test results would you expect in this patient?

-Negative: pus, blood, stool culture, ova/parasites

-Greater than 6 grams of fat/24 hrs. in stool

-Greater than 25% of d‑xylose found in urine 5 hrs. after ingesting 25 grams of xylose

-Normal jejunal mucosa

-Abnormal CAT scan of pancreas

12. How would you treat this patient'

Pancreatic enzyme supplements

13. What nutritional deficiencies might be present in a patient with this problem?

Vitamins A, D, E, K deficiency

Faculty note: emphasize the vitamin deficiencies reflect defects in pancreatic and biliary tract secretions.

14. What is your diagnosis if a 42 year old woman had a similar clinical problem associated with ingestion of certain grain-containing food? Describe the pathology associated with this diagnosis.

-Celiac sprue

-Pathology - jejunal biopsy. Varying degrees of damage and atrophy of the intestinal villi. Villi may be flat. Intense infiltration of lamina propria by lymphocytes/plasma cells.