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Author(s): Rebecca W. Van Dyke, M.D., 2012
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M2 GI Sequence
A GI Smorgasbord:
Common GI Problems
Rebecca W. Van Dyke, MD
Winter 2012
Industry Relationship
Disclosures
Industry Supported Research and
Outside Relationships
• None
Topics
• Bright red blood per rectum
• Iron deficiency anemia
• Patient presentation: IBD and disease/surgical
issues from a patient perspective
Bright Red Blood Per Rectum
A common problem seen in most
areas of medicine
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
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
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%:
2-7%:
5-15%:
2-5%:
Polyps (hyperplastic/adenomatous)
Colon cancer (increase with age)
Inflammatory bowel disease
Vascular lesions
arteriovascular malformations (AVMs)
– 1%:
Benign ulcers
NSAIDS, stercoral related to chronic constipation
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
Bright Red Blood Per Rectum
• Complications
– Patient discomfort/embarressment
– Iron deficiency anemia
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
Iron Deficiency Anemia
• Why does iron deficiency lead to anemia?
• Why does iron deficiency occur?
Iron Deficiency and Anemia
• Recall the structure of
hemoglobin
• Recall the role of iron in
binding and releasing
oxygen from hemoglobin
Hemoglobin
Julian Voss-Andreae, Wikimedia Commons
• No iron = no erythrocytes
• Iron deficiency = fewer and
smaller erythrocytes
Heme
ring with
oxygen
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
Normal Balance of Iron
Iron Pools
Dietary iron
(5-15 mg elemental,
1-5 mg heme)
Tissues
300 mg
Storage
100 – 400 mg
in women
1000 mg
in men
Absorption of
1 mg of iron
Loss of
1 mg of iron
Red cells
Normal
2500 mg
Medium69
Obligate loss: ~1 mg of iron from ~1 ml of blood and other losses
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
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
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.
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?
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
Etiology of Iron Deficiency
• Loss of blood
• Inadequate dietary intake
• Failure to absorb iron
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)
Gastrointestinal Blood Loss and Iron Balance
Normal Balance of Iron
Dietary iron
Dietary iron
(5-15 mg elemental,
1-5 mg heme)
Iron
Iron Deficiency
(5-15 mg elemental,
Pools 1-5 mg heme)
absorption
increases 2-3 times
Tissues
300 mg
300 mg
Storage
100 – 400 mg
in women
1000 mg
in men
Absorption of
1 mg of iron
Loss of
1 mg of iron
None
Red cells
Normal
2500 mg
Absorption
increases
Deficient
< 2000 mg
3-5 mg of iron
(i.e., gastrointestinal,
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
Loss of
1 mg of iron
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)
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.
GI Evaluation:
Iron deficiency anemia
Colonoscopy
Upper endoscopy
Small bowel biopsy (sprue)
Transglutaminase antibody
+
Pick order based on
clinical clues
Can do together
Identifies most cases
-
Treat underlying
disease
Give oral iron
Monitor response
If poor response,
consider IV iron
Dedicated small bowel
series
Capsule endoscopy
Meckel’s scan
Most recent recommendations:
depend on availability of capsule endoscopy
AGA position statement. Gastroenterology 133:1694, 2007
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 reestablish normal iron stores from oral intake.
• If patient cannot absorb oral iron, IV iron
must be given
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.
• 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.
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