02.09.12: A GI Smorgasbord - Common GI Problems part II
1. Author(s): Rebecca W. Van Dyke, M.D., 2012
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3. M2 GI Sequence
A GI Smorgasbord:
Common GI Problems
Rebecca W. Van Dyke, MD
Winter 2012
4. Industry Relationship
Disclosures
Industry Supported Research and
Outside Relationships
• None
5. Topics
• Bright red blood per rectum
• Iron deficiency anemia
• Patient presentation: IBD and disease/surgical
issues from a patient perspective
6. Bright Red Blood Per Rectum
A common problem seen in most
areas of medicine
7. Bright Red Blood Per Rectum
• Passage of small amounts of BRBPR is
common
– Affects at least 20% of general public at one
time or another
– Usually trivial, but can reflect serious disease
• BRBPR – location
– On toilet paper
– Streaks on stool
– Dripping into toilet bowl
– On underwear
8. Bright Red Blood Per Rectum
• Differential diagnosis:
– think types of diseases that could cause small
amounts of bleeding
– usually in distal colon or anorectal area:
• Trauma
• Neoplasia
• Infection/inflammatory
• Vascular
9. Bright Red Blood Per Rectum
• Diagnoses after full investigation:
– 20+%: Nothing found – presumably tissue tears had
healed at the time of investigation
– 50+%: Anorectal disease
Hemorrhoids
Anal fissures
Trauma with tissue tears (ask patient )
– 20-40%: Polyps (hyperplastic/adenomatous)
– 2-7%: Colon cancer (increase with age)
– 5-15%: Inflammatory bowel disease
– 2-5%: Vascular lesions
arteriovascular malformations (AVMs)
– 1%: Benign ulcers
NSAIDS, stercoral related to chronic constipation
10. Bright Red Blood Per Rectum
• Goal: Find a disease you would treat
• Evaluation – little evidence to guide you
– Can do full colonoscopy in everyone
– Alternative: no clues to disease, no family history of
CRC:
• <40, reassure or just do flex sig and Rx constipation
• 40-49: flex sig or colonoscopy
• >50: full colonoscopy
– If disease clues (diarrhea, frequent/continued bleeding,
iron deficiency, pain) or family history CRC:
• full colonoscopy and other indicated evaluations
11. Bright Red Blood Per Rectum
• Complications
– Patient discomfort/embarressment
– Iron deficiency anemia
12. Iron Deficiency Anemia
• You will learn in hematology next week
how to diagnose iron deficiency anemia
• This is a common problem that is often
referred to gastroenterologists
• Today lets look at this problem in more
detail to learn how to determine the cause
of iron deficiency anemia in patient
13. Iron Deficiency Anemia
• Why does iron deficiency lead to anemia?
• Why does iron deficiency occur?
14. Iron Deficiency and Anemia
• Recall the structure of
hemoglobin Hemo-
globin
• Recall the role of iron in
binding and releasing
oxygen from hemoglobin
Julian Voss-Andreae, Wikimedia Commons
• No iron = no erythrocytes
Heme
• Iron deficiency = fewer and ring with
smaller erythrocytes oxygen
15. Iron Cycle: Facts
• Iron is high toxic at high concentrations
– Therefore absorption of iron is tightly
controlled
• Iron is absorbed by the duodenal mucosa
• Iron is efficiently recycled between RBCs,
the reticuloendothelial system and the
bone marrow
• Daily loss is about 1 mg a day
16. Normal Balance of Iron Dietary iron Iron Pools
(5-15 mg elemental,
1-5 mg heme)
Tissues
300 mg
Storage
100 – 400 mg
in women
1000 mg
in men
Absorption of Red cells
1 mg of iron
Normal
Loss of 2500 mg
1 mg of iron
Medium69
Obligate loss: ~1 mg of iron from ~1 ml of blood and other losses
17. Iron Storage/Transport
• Iron is not very water soluble
• It is transported in blood to and from
tissues bound to transferrin
• Iron is stored in cells by the protein ferritin
• Measurements of body iron stores
– Percent transferrin saturation (Fe/total iron
binding capacity x 100)
– Serum ferritin concentration
18. Iron cycle reviewed:
1) 1 unit of blood = 250 mg iron - thus ~1/10 of a unit is recycled daily
2) iron absorption and recycling is controlled by liver/hepcidin
19. FYI: Genetic Hemochromatosis
1. A disease of uncontrolled iron absorption from the duodenum
2. Due to mutations that disrupt liver sensing of body iron stores
3. Hepcidin is suppressed and iron absorption is increased.
20. Today:
Approach to Iron Deficiency
+/- Anemia
• How do you identify iron deficiency?
• Why does iron deficiency develop?
• How do you evaluate causes of iron
deficiency in patients?
• How do you treat iron deficiency?
21. Identification of Iron Deficiency
• Low ferritin
– < ~100 ng/ml
• Low saturation of iron binding proteins
– Iron/TIBC < 15-20%
• Microcytic anemia
– MCV (mean corpuscular volume) < 80-85
• Thrombocytosis (in severe cases)
• Absence of iron in the bone marrow
22. Etiology of Iron Deficiency
• Loss of blood
• Inadequate dietary intake
• Failure to absorb iron
23. Etiology of Iron Deficiency
• Loss of blood
– Menstrual losses/childbirth
–Gastrointestinal blood loss
– Hematuria
• Inadequate diet (rare in USA)
• Failure to absorb iron
– Celiac sprue
– Loss of duodenal surface area (surgical scar present)
24. Gastrointestinal Blood Loss and Iron Balance
Normal Balance of Iron Iron Deficiency
Dietary iron Dietary iron
(5-15 mg elemental, (5-15 mg elemental,
1-5 mg heme) Iron Pools 1-5 mg heme)
absorption
increases 2-3 times
Tissues
300 mg 300 mg
Storage
100 – 400 mg
in women
1000 mg None
in men
Absorption of Absorption
1 mg of iron
Red cells increases
Normal
Loss of Deficient 3-5 mg of iron
1 mg of iron
2500 mg Loss of
< 2000 mg (i.e., gastrointestinal, 1 mg of iron
menses)
Medium69
Obligate loss: ~1 mg of iron = ~1 ml of blood (~0.5 mg of iron) + ~0.5 mg of nonblood iron
Additional loss of blood/iron cannot be matched by gut
absorption and iron deficiency/anemia worsens
25. Evaluation of Iron Deficiency
• Find source of blood loss
– GI evaluation is most important
– Check for hematuria
• Ask patient about diet
• Ask patient about surgery on stomach or
duodenum (? iron malabsorption)
• Look for malabsorption (celiac sprue)
26. Evaluation in USA
• Iron deficency in men is always pathologic: must
evaluate
• Prior to menopause, women are frequently iron
deficient: evaluate if severe or if other clinical
clues to disease are present
• GI blood loss accounts for most iron deficiency
outside of menstrual/birth losses
– always work up GI tract
– fecal occult blood tests of little value as they are
insensitive and non-specific. If patients are iron
deficiency, we have to look for blood loss no matter
what the results of fecal occult blood tests are.
27. GI Evaluation: Iron deficiency anemia
Pick order based on
Colonoscopy clinical clues
Upper endoscopy Can do together
Identifies most cases
Small bowel biopsy (sprue)
Transglutaminase antibody
+ -
Dedicated small bowel
Treat underlying series
disease Capsule endoscopy
Meckel’s scan
Give oral iron
Monitor response
If poor response,
consider IV iron
29. Iron Administration
• Oral iron may work if patients are
nutritionally deficiency or are losing blood
only slowly
– Follow patient carefully to make sure its
working (what tests would you follow?)
– Be patient – it can take 6-12 months to re-
establish normal iron stores from oral intake.
• If patient cannot absorb oral iron, IV iron
must be given
30. IV Iron
• Iron dextran – oldest form
– May give 1-1.5 grams of iron at a single infusion
– Rare but real anaphylaxtic reactions
• Iron sucrose (Venofer) or sodium ferric
gluconate complex (Ferrlecit)
– Developed for use as small doses (100-125 mg) given
by rapid IV push for dialysis patients
– Can give 200-500 mg at a single infusion if necessary
• In iron deficiency you have to replace the
missing erythrocytes AND storage pool.
31. • In this sequence you have learned
about a large number of GI diseases
• Some present with inflammation and/or
iron deficiency or both.
• Some have cures,some are chronic
diseases with consequences
• Today we have a patient to help us
understand the patient perspective of
some of these problems.
32. Additional Source Information
for more information see: http://open.umich.edu/wiki/CitationPolicy
Slide 14: Julian Voss-Andreae, Wikimedia Commons, http://upload.wikimedia.org/wikipedia/commons/6/68/Heart_of_Steel_(Hemoglobin).jpg
CC:BY-SA, http://creativecommons.org/licenses/by-sa/3.0/deed.en
Notes de l'éditeur
Figure 2. Gastrointestinal Blood Loss and Iron Balance. Normal obligate daily iron loss is from blood loss (presumably from gastrointestinal mucosal microerosions or microulcerations) and iron in sloughed epithelial cells of the gut. Total daily iron loss is approximately 1 mg. The usual Western diet contains mostly elemental iron, of which about 10 percent is absorbed. Heme iron, derived primarily from myoglobin in meats, is preferentially absorbed and accounts for 60 to 80 percent of the iron absorbed per day. Under normal circumstances, iron homeostasis is tightly regulated, and daily iron loss is precisely balanced by iron absorption. Iron deficiency results only when the dynamic, but limited, absorptive capacity of the small intestine is exceeded by iron loss. The time required for the development of iron deficiency depends on the size of initial iron stores, the rate of bleeding, and intestinal iron absorption. Iron deficiency generally occurs only with loss of more than 5 ml of blood per day. Anemia is a late manifestation of the iron-depleted state. The red cells indicate bleeding and potential sites of blood loss.
