EXAM #1: MICROCYTIC ANEMIA Flashcards
What is the most important point to remember about anemia?
Anemia is NOT a concluding diagnosis; it is a manifestation of disease
What is the definition of anemia?
Decreased RBC resulting in decreased oxygen carrying capacity
What are the common symptoms of anemia?
- Fatigue
- Dyspnea
- Weakness
What is the normal MCV of RBCs?
80-100 fL
What is the definition of microcytic anemia?
Less than 80 fl MCV
What is the rule of thumb for determining the size of a RBC on PBS?
- Lymphocyte nucleus
- Central pallor is roughly 1/3 of the RBC width
What are the hallmark features of microcytosis on PBS?
- Microcytic
- Hypochromic
What is a normal Hb for men?
14-17 g/dL
What is a normal Hb for women?
12-15 g/dL
What is a normal Hct in men?
42-50%
What is a normal Hct in women?
36-44%
What is the normal MCH?
Mean Corpusucular Hb
30-34pg
What is the normal MCHC?
Mean Corpusucular Hb Concentration
30-36%
What is the normal RDW?
Red Cell Distribution Width
13-15%
Note that the smaller the RDW, the more UNIFORM the size
What are the three causes of iron deficiency?
1) Inadequate absorption
2) Inadequate utilization
3) Excessive loss****
*****This is the most common cause
How much iron can be absorbed per day?
1-3mg
Where in the body is iron absorbed?
First and second parts of the duodenum
What is the difference between ferrous and ferric iron?
Fe++= ferrous Fe+++= ferric
What form of iron is most efficiently absorbed?
Heme iron
Are plants a good source of iron?
NO
- Low in iron to begin with
- Most is Fe+++
What transporter is important for the absorption of Fe++?
DMT-1
Divalent Metal Transporter
What happens to Fe++ once it is absorbed into the enterocyte?
Binds ferretin
How does iron/ferretin leave the enterocyte?
Ferroportin transporter
How is iron transported in the blood?
Plasma transferrin i.e. carrier protein
What blocks the ferroportin transporter?
Hepcidin (made in the liver)
What is the iron cycle?
1) Iron enters the gut and into the circulation
2) Transferrin transports iron in the blood to the bone marrow
3) Bone marrow to makes RBCs
4) Old RBCs are recycled in the spleen and iron is stored
5) Iron is released back into the blood to repeat the cycle
What upregulates hepcidin?
IL-6
High circulating ferretin
What downregulates hepcidin?
Low ferretin
Hypoxia
What organ produces EPO? What is the function of EPO?
- Kidneys (renal fibroblasts)
- EPO stimulates erythropoiesis
How much iron is circulating in the RBCs?
2,500mg
How much iron is in iron-containing proteins?
400mg
How much iron is transferrin-bound?
3-7mg
How much iron is stored?
1,000mg
Is iron excreted from the body? How is iron lost?
NO
- Most in insensible
- Vascular loss
1) External/traumatic
2) Sequetration/ hematoma
3) Menstrual
4) Internal loss (GI)
What is the defining laboratory characteristics of iron deficiency anemia?
- Low Hb/ Hct
- Small MCV
- Low ferretin (10 or less)*****
- Low transferrin SATURATION
- TIBC high
- Reticulocytes
What is the most specific lab value for iron deficiency anemia?
Low ferritin, less than 10
What is a normal Serum Fe?
60-150 mcg/dL
What is a normal TBIC?
300-360 mcg/dL
What is a normal iron saturation?
20-50%
What is a normal ferritin?
40-200 mcg/L
What is the diagnosis for the underlying cause of anemia in a 50 y/o (or older)?
GI malignancy until proven otherwise
What are the signs of iron deficiency?
Pica Koilonychia Pale palmar crease Pale conjunctiva Glossitis
How is iron deficiency anemia treat?
1) Find bleeding
2) Stop bleeding
3) Replace blood
- Fluids
- Blood
- Iron supplement
How is iron supplemented?
PO- max 25mg per day
IV- 500 mg
IM is NOT recommended b/c of side effects
What is the antibacterial effect of Hepcidin?
Limits Fe-dependent electron transport in bacteria
What are the cytokines that will stimulate the production of hepcidin?
IL-6
TNF
IF-a
IF-g
What is Rouleaux formation characteristic of?
ACD–autoimmune induced e.g. RA
What are the characteristics of Anemia of Renal Disease?
Normochromic b/c is is caused by a lack of EPO
How many hb-alpha alleles are on each chromosome? What chromosome?
Chromosome 16
- 4
How many beta alleles are on each chromosome? What chromosome?
Chromosome 11
- 1
How are Thalassemias named?
1) Gene that is deficient
2) null or += all genes or not
What is Hb-H and Hb-barts?
Both are tetramers WITHOUT alpha globin
H= Beta4 Barts= Gamma4
List the a-thalassemias.
1) aa/aa= normal= Asx.
2) -a/aa= silent carrier= Asx.
3) -a/-a= thalassemia trait= mild
4) –/-a= Hb-H disease= severe
5) –/–= “fetal hydrops”= lethal
Fetal hydrops is INCOMTATABLE WITH LIFE
Differentiate the ppt examples of alpha-Thalassemia.
N/A
List the B-thalassemias.
1) B+= trait/ minor= mild
2) B0= major= severe and transfusion dependent
Intermedia= 2x defective genes BUT partially functioning
Outline the pathophysiology of B-Thalassemia.
1) Increased RBC destruction
2) Fe overload in the spleen, marrow, and liver
3) Anemia and hypermetabolic marrow result, BUT the patient is iron overloaded from the destruction of misshaped RBCs
Requires a balance between phlebotomy and transfusion.
Outline the phenotypic characteristics of Beta-Thalassemia.
- Large forehead
- Distended abdomen with slenomegaly and heptaomegaly
- Pale
Differentiate ppt examples of Beta-thalassemia.
N/A
What is sideroblastic anemia?
Anemia with ringed siderblasts i.e. rings of iron around the nucleus
Identify ppt. examples of sideroblastic anemia.
N/A
What is the enzyme defieincy of hereditary sideroblastic anemia?
ALA Synthase
What are the causes of acquired Sideroblastic Anemia?
1) Myelodyplastic Syndrome
2) Alcohol
3) Drug induced
4) Lead poisoning
5) Cooper deficiency
What is a Pappenheimer Body?
Abnormal granules of iron found inside red blood cells on routine blood stain
