Setting: office
CC: “I’ve had diarrhea for months!”
VS: BP: 110/72 mm Hg; P: 76 beats/minute; T: 98° F; R: 14 breaths/minute
HPI: A 28-year-old woman with persistent diarrhea over several months visits you at your office. She has lost 15 lb in the last 6 months. She bruises easily and her menstrual periods are heavy. Her stool has a “greasy” quality and does not flush down the toilet easily because it floats at the top of the water. The entire bathroom is abnormally malodorous after bowel movements.
PMHX:
Iron deficiency ascribed to heavy menstruation
Medications:
Ferrous sulfate
PE:
General: thin and tired
Abdomen: soft, nontender, normal sized organs
Lung, Heart: normal
Skin: several bruises on legs
Initial Orders:
Stool culture, WBCs, ova/parasites
CBC
CHEM-20
Even though an infection is very unlikely to persist for several months, you must first exclude an infectious cause in diarrhea before going to other tests such as endoscopy. It is also very unlikely to have a 15-lb weight loss from an infectious diarrhea.
Report:
Stool Culture, WBCs, Ova/Parasites: negative
CBC: hematocrit 30%; MCV 85 fL; WBCs 3,200/μL (low); platelets 118,000/μL (low)
RDW 25% (markedly elevated)
CHEM-20: albumin 4.5 g/dL; calcium 6.8 mg/dL (low)
Some Iron-Deficient Cells + Some Vitamin B12-Deficient Cells = Dimorphic or Two Distinct Cell Problems
Normal MCV + High RDW = Dimorphic Red Blood Cell Population
What is the fastest way to diagnose vitamin B12 deficiency?
a. Vitamin B12 level
b. Peripheral smear
c. Methylmalonic acid (MMA) level
d. Schilling test
e. Anti-intrinsic factor antibody
Answer b. Peripheral smear
In vitamin B12 deficiency, the smear will show hypersegmented neutrophils. Vitamin B12 levels, if low, are very specific, but they can be in the normal range in 20% to 30% of those with vitamin B12deficiency. MMA levels are elevated in vitamin B12 deficiency also. A Schilling test is never done—it is an old test to determine the etiology of vitamin B12 deficiency.
Normal average number of WBC lobes = 3.5
The Interval History shows the patient continues to have diarrhea, has lost another 2 lb of weight in the last 3 weeks, and continues to have “oily” stool. The peripheral smears shows hypersegmented WBCs are present with target and hypochromic cells.
What is the best initial test for the presence of fat in stool?
a. Colonoscopy
b. Sudan black stain
c. Maltese cross
d. A 72-hour fecal fat
Answer b. Sudan black stain
Sudan black is a fat stain. A 72-hour fecal fat is an antiquated test for fat malabsorption. Maltese crosses are for detecting fat in urine. Colonoscopy is not a good test for fat malabsorption. Fat is not absorbed in the colon. Water and salt are absorbed in the colon.
The colon absorbs no fat.
Reports:
Sudan black stain of stool: fat globules
Vitamin B12 level: low
Stool heme: negative
Serum iron: low
Ferritin: low
Total iron-binding capacity: elevated
PT and aPTT: both prolonged
What is the mechanism of iron deficiency?
a. Bleeding
b. Duodenal malabsorption
c. Gastric malabsorption
d. Colon malabsorption
Answer b. Duodenal malabsorption
The duodenum is the site of absorption of all divalent cations such as calcium, magnesium, and iron. The stomach does not absorb iron. This patient has no blood in the stool, so it is not bleeding. The reason the iron deficiency is not from menstruation is that the MCV is normal, not low.
Divalent cations absorbed at duodenum:
• Calcium (Ca++)
• Iron (Fe++)
• Magnesium (Mg++)
Vitamin K malabsorption can cause bruising.
The patient returns in a week to discuss her laboratory results, which show that she has fat malabsorption with iron and vitamin B12 deficiency as well as hypocalcemia
Low calcium etiology:
• Duodenal malabsorption
• Decreased fat-soluble vitamin absorption (vitamins A, D, E, and K)
• Decreased vitamin D
Low Vitamin D = Low Phosphate
Orders:
Antitissue transglutaminase
Antiendomysial antibodies
Antigliadin antibodies
Which of these is safe to eat in this disorder?
a. Wheat
b. Rice
c. Oats
d. Barley
e. Rye
Answer b. Rice
Foods safe in gluten-sensitive enteropathy are rice, corn, soy, and potatoes. Flour based on these foods are safe.
All of the antibody tests (transglutaminase, endomysial, and gliadin) are positive. You explain to the patient that she has gluten-sensitive enteropathy or celiac disease. Iron deficiency is caused by destruction of villi in the duodenum. Calcium deficiency is caused both by loss from duodenal absorption as well as loss of vitamin D because of fat malabsorption. You advise the patient to remove all foods with gluten from her diet, such as wheat, rye, oats, and barley.
Vitamin B12 is lost because of terminal ileum destruction.
Coagulopathy and bruising are caused by vitamin K malabsorption.
The Step 3 examination likes to ask you “what will you tell the patient about his or her prognosis?” They expect you to be able to communicate appropriately with patients about what will happen to them in the future.
The patient asks what she can expect after removing gluten (wheat, rye, oats, barley) from her diet.
What do you tell her about the future?
a. She will have instant symptom resolution in 24 to 48 hours.
b. She will experience a gradual resolution of symptoms and all malabsorption over a few weeks.
c. She will have no change in symptoms, but bruising and bone, iron, and vitamin B12 abnormalities will resolve.
d. She can restart eating gluten-containing foods 6 to 12 months after abstention. It will all resolve permanently.
Answer b. She will experience a gradual resolution of symptoms and all malabsorption over a few weeks.
Celiac disease is based on circulating antibodies. It takes several weeks for them to resolve even after stopping exposure to gluten. The disorder, however, is permanent. If she begins to eat gluten again, it will all recur. There is no cure for celiac disease. Symptoms resolve with removing the gluten antigen over time, but the hypersensitivity will recur with reexposure.
What is the basis of the autoantibody?
a. IgA
b. IgG
c. IgM
d. IgE
Answer a. IgA
Most of the autoantibodies in celiac disease are IgA autoantibodies. Antitissue transglutaminase, antiendomysial antibodies, and antigliadin antibodies are all largely IgA antibodies.
Bone loss is from secondary hyperparathyroidism in celiac disease.
The patient stops all gluten-containing food. On her return in 6 weeks, symptoms of diarrhea start to improve. The consistency of her stool stops being oily and floating. She gains 3 lb.
Orders:
Repeat antibody titers
Calcium level
CBC
Small bowel biopsy
Antibody titers should improve with the elimination of gluten from the diet.
Repeat titers improve as does the calcium level and hematocrit. The small bowel biopsy must be done to exclude bowel wall lymphoma. Repeat small bowel biopsy is done after several months to check for restoration of the flattened villi.