Ch. 5 - Microcytic anemia Flashcards
What is the MCV needed to have a microcytic anemia?
what actually causes the microcytosis?
an extra division of the erythroblast to maintain the proper Hgb concentration within the RBC
What are the four types of microcytic anemia?
- iron deficiency anemia2. anemia of chronic disease3. sideroblastic anemia4. thalessemia
Decreased levels of iron lead to decreased levels of (blank) which leads to decreased Hgb causing microcytic anemia
heme
What is the world’s most common nutritional deficiency?
iron def.
What form is the iron from vegetable derived forms
non-heme
Where in the GI tract does iron absorption ocurr?
duodenum
Is heme or non-heme iron more readily absorbed?
heme iron
(blank) transports iron from the gut lumen to the blood vessel
enterocytes
enterocytes use what protein to move iron into the blood?
ferroportin
What is iron bound to in the blood?
transferrin
what and where is iron bound in the storage form?
bound to ferritin in the liver and bone marrow macrophages
What does TIBC measure?
number of transferrin molecules in the blood?
what does % saturation measure? what is normal?
number of transferrin molecules bound to iron; 33% is normal
What does serum ferritin tell us?
reflects the levels of ferritin in the liver macrophages
What is the most common causes of iron def. anemia in infants?
breast feeding; low iron intake
What is the most common causes of iron def. anemia in children?
poor diet
What is the most common causes of iron def. anemia in adults 20-50?
peptic ulcer in males and menorrhagia in females (or pregnancy)
What is the most common causes of iron def. anemia in elderly?
Western world: colon polyps or carcinomaRest of world: hookworm
What two species of hookworm can cause iron def. anemia?
Ancylostoma duodonale and Necator americanus
How can malabsorption lead to iron def. anemia?
If you can’t take the iron in (lets say in Celiac), then you are def.
How can a gastrectomy cause iron def. anemia?
Gastric acid keeps iron reduced to the Fe2+ state; lower acid levels leads to the less available form of Fe3+
What are the clinical features of iron def?
Pica, anemia, and koilonychia
Describe the changes in RBC morphology in iron def. anemia?
increased RDW, hypochromic, microcytic
Describe the four steps of iron def. anemia progression
- Iron stores depleted2. Serum iron depleted3. Normocytic anemia4. Microcytic, hypochromic anemia
What two lab values identify that iron stores are depleted in the first stage of iron def. anemia?
Decreased ferritin and increased TIBC
What two lab values identify that serum iron is depleted in the second stage of iron def. anemia?
Decreased serum iron and decreased percent saturation
Why does iron anemia first present as normocytic before microcytic?
bone marrow is able to produce normal cells still, just an acceptably lower number of them
All together, what are the lab findings that support iron def. anemia?
decreased ferritinincreased TIBCdecreased serum irondecreased % saturation
How do you treat iron def. anemia?
ferrous sulfate
What is Plummer-Vinson Syndrome?
iron def. anemia with esophogeal webbing, atrophic glossitis, dysphagia, and BEEFY RED TONGUE
What type of anemia is associated with chronic inflammation?
Anemia of chronic disease (ACD)
What is the most common type of anemia in hospitalized pts?
ACD
Chronic disease leads to production of (blank) from the liver, including hepcidin
acute phase reactants
What are the two methods by which hepcidin sequesters iron?
- limit iron transfer from macrophages to erythroid precursors2. suppress EPO
What is the big picture reason why hepcidin hides iron in chronic inflammation?
body thinks its fighting bacteria, bacteria need Fe to grow
Why does ACD present as a microcytic anemia?
low iron means low heme means low Hgb means small cells
What are the following lab values in ACD?1. Ferritin2. TIBC3. Serum Iron4. % saturation5. FEP
- increased ferritin2. decreased TIBC3. decreased serum iron4. decreased % sat5. increased FEP
How do you treat ACD?
treat the underlying cause
Sideroblastic anemia is due to a defect in (Fe/protoporphyrin) useage
protoporphyrin synth
What is the rate limiting step of protoporphyrin synth?
Succ-CoA to ALA
What enzyme catalyzes the rate limiting step of protoporphyrin?
ALAS
What vitamin cofactor is necessary for the rate limiting step of protoporphyrin?
B6!!!
Where in the cell does Fe bind to protoporphyrin to make heme?
mitochrondria
in sideroblastic anemia, in what cellular structure is the iron sequestered?
mitochondria
t/F: sideroblastic anemia is only acquired
false; can be congenital from ALAS defect
What are the three major causes of acquired sideroblastic anemia?
- Alcoholism; mito poison2. Lead poisoning; inhibits ALAD and ferrochelatase3. Vit. B6 def.; seen as a SE from isoniazid Tx for TB
What are the following lab values in sideroblastic anemia?1. ferritin2. TIBC3. serum iron4. % saturation
- increased ferritin2. decreased TIBC3. increased serum iron4. increased % satruationIRON OVERLOADED STATE
What other liver disease has lab values similar to sideroblastic anemia?
hemachromotosis
in what cell type is the iron accumulating in sideroblastic anemia?
erythroblasts
How many alpha globulin chains are present on csome 16?
4
Is alpha-thal caused by gene deletion or mutation?
deletion
what happens when one alpha globulin gene is deleted?
pt. is asymptomatic
what happens when two alpha globulin genes are deleted?
mild anemia
What lab value is associated with a two alpha globulin gene deletion?
increased RBC count
Is the cis or trans deletion of two alpha globulin genes worse?
cis; offspring have high chance of severe anemia
In what racial pool do we see cis deletions in alpha-thal?
asians
in what racial pool do we see trans deletions in alpha-thal?
blacks