02.09.12: A GI Smorgasbord - Common GI Problems part II

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


• 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


• 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 diseaseHemorrhoidsAnal fissuresTrauma 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 ulcersNSAIDS, 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


• 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

• No iron = no erythrocytes• Iron deficiency = fewer and

smaller erythrocytes

Hemo-globin

Hemering withoxygen

Julian Voss-Andreae, Wikimedia Commons

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

Obligate loss: ~1 mg of iron from ~1 ml of blood and other losses

Iron Pools

Tissues

Storage

Red cells

Normal Balance of Iron Dietary iron(5-15 mg elemental,

1-5 mg heme)

300 mg

100 – 400 mgin women1000 mgin men

Normal 2500 mg

Absorption of1 mg of iron

Loss of1 mg of iron

Medium69

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 duodenum2. Due to mutations that disrupt liver sensing of body iron stores3. 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)

Iron Deficiency

Obligate loss: ~1 mg of iron = ~1 ml of blood (~0.5 mg of iron) + ~0.5 mg of nonblood iron

Iron Pools

Tissues

Storage

Red cells

Normal Balance of IronDietary iron

(5-15 mg elemental,1-5 mg heme)

300 mg

100 – 400 mgin women1000 mgin men

Normal 2500 mg

Absorption of1 mg of iron

Loss of1 mg of iron

Medium69

None

300 mg

Deficient< 2000 mg

Dietary iron(5-15 mg elemental,

1-5 mg heme)absorption

increases 2-3 times

3-5 mg of iron(i.e., gastrointestinal,

menses)

Absorptionincreases

Loss of1 mg of iron

Gastrointestinal Blood Loss and Iron Balance

Additional loss of blood/iron cannot be matched by gut absorption and iron deficiency/anemia worsens

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

+ -

ColonoscopyUpper endoscopy

Small bowel biopsy (sprue)Transglutaminase antibody

Treat underlying disease

Give oral ironMonitor responseIf poor response, consider IV iron

Dedicated small bowel seriesCapsule endoscopyMeckel’s scan

Pick order based on clinical clues

Can do togetherIdentifies most cases

AGA position statement. Gastroenterology 133:1694, 2007

Most recent recommendations: depend on availability of capsule endoscopy

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

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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02.09.12: A GI Smorgasbord - Common GI Problems part II