02.09.12: A GI Smorgasbord - Common GI Problems part II
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02.09.12: A GI Smorgasbord - Common GI Problems part II






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  • 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.

02.09.12: A GI Smorgasbord - Common GI Problems part II 02.09.12: A GI Smorgasbord - Common GI Problems part II Presentation Transcript

  • Author(s): Rebecca W. Van Dyke, M.D., 2012License: Unless otherwise noted, this material is made available under the termsof the Creative Commons Attribution – Share Alike 3.0 License:http://creativecommons.org/licenses/by-sa/3.0/We have reviewed this material in accordance with U.S. Copyright Law and have tried to maximize your ability to use,share, and adapt it. The citation key on the following slide provides information about how you may share and adapt thismaterial.Copyright holders of content included in this material should contact open.michigan@umich.edu with any questions,corrections, or clarification regarding the use of content.For more information about how to cite these materials visit http://open.umich.edu/education/about/terms-of-use.Any medical information in this material is intended to inform and educate and is not a tool for self-diagnosis or areplacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional. Please speak to yourphysician if you have questions about your medical condition.Viewer discretion is advised: Some medical content is graphic and may not be suitable for all viewers.
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  • M2 GI Sequence A GI Smorgasbord: Common GI Problems Rebecca W. Van Dyke, MDWinter 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%: 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
  • 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 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
  • 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 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
  • 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 BalanceNormal 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
  • 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 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
  • 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 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.
  • Additional Source Information for more information see: http://open.umich.edu/wiki/CitationPolicySlide 14: Julian Voss-Andreae, Wikimedia Commons, http://upload.wikimedia.org/wikipedia/commons/6/68/Heart_of_Steel_(Hemoglobin).jpgCC:BY-SA, http://creativecommons.org/licenses/by-sa/3.0/deed.en