Disorders of Iron Metabolism Flashcards
1
Q
Anemia
- Definition
- Causes
A
- Anemia is when RBCs aren’t supplying enough oxygen to body
- Causes include decreased production of RBC or increased loss.
2
Q
Hypoproliferative Anemia
A
- Decreased production of RBC
- Causes include: Nutritional deficiency, Bone marrow replacement, Stem cell arrest or damage, and Hereditary or acquired defect
3
Q
Causes of increased loss of RBC
A
- Blood loss
- Accelerated destruction
4
Q
Patient History that effects Anemia
A
- When anemia began? (Congenital or Acquired )
- Severity of symptoms (Mild - Severe)
- Chronic blood loss?
- Hemolysis?
- Neurologic symptoms
- Underlying disease
- Prior anemia or therapy
- Medications, drugs, toxins
- Dietary history
- Family history
5
Q
Physical Exam of Anemia
A
Skin: pallor, jaundice, petechiae Mouth: smooth tongue Heart: cardiac dilatation Abdominal: splenomegaly Lymph nodes
6
Q
Initial Lab testing of Anemia
A
- CBC
- Differential
- Reticulocyte count
7
Q
Classification of anemia
A
2 types:
- Functional - PA uses this.
- Morphologic - we in the lab do this.
8
Q
Functional Classification of anemia
A
- Maturation: Cytoplasmic, Nuclear
- Hypoproliferative: Decreased EPO, Iron Depletion, Marrow damage
- Hemolysis or hemorrhage
9
Q
Morphologic Classification of anemia
A
- Microcytic
- Normocytic
- Macrocytic
10
Q
Microcytic Anemia
A
Most common anemia
- Iron deficiency
- Anemia of chronic inflammation
- Thalassemia/ Some Hemoglobinopathies
- Anemia of chronic blood loss
- Sideroblastic anemia: Lead poisoning, Porphyrias
11
Q
Normocytic Anemia
A
- Acute blood loss
- Hemolysis
- Bone marrow failure
- Dyserythropoiesis
- Infection
- Malignancy
12
Q
Macrocytic Anemia
A
- Megaloblastic anemia: B12/Folate Deficiency, Myelodysplastic syndromes, Medication or chemotherapy
- Marked reticulocytosis
- Liver disease
13
Q
Peripheral blood smear with anemia
A
- Coexisting leukopenia or thrombocytopenia (decrease in WBC and Platelets)
- Size and shape of RBC
- RBC inclusions
14
Q
Bone Marrow Examination
A
- used to compare with the PBS, but is usually used in WBC disorders.
- Maturation of RBC and WBC
- Presence of megakaryocytes
- M:E Ratio
- Iron stores
- Presence of abnormal elements
15
Q
Disorders of Iron and Heme Metabolism
A
- Iron Deficiency
- Anemia of Chronic Inflammation
- Sideroblastic Anemias: Lead poisoning, Porphyrias
- Iron Overload
16
Q
Normal Iron Metabolism
A
- Total body iron is 3 - 4 g
- More than 2/3 is contained within the RBC
- Each mL of blood contains 1 mg of Fe
- Ten to twenty times more Fe is used in RBC production than is absorbed each day
- Most comes from RBC degradation: Transferrin carries Fe from macrophages in spleen to bone marrow
17
Q
Iron Absorption
A
- Hepcidin: peptide produced by the liver regulates iron absorption.
Hepcidin functions:
1. Signal that limits intestinal iron absorption. - Increased levels – iron deficiency
- Decreased levels – iron overload
2. Inhibits iron release from hepatic stores
18
Q
Iron Deficiency causes
A
- Increased need: Pregnancy, Growth spurts
- Increased loss: Menstruation, Chronic bleeding
- Decreased intake (diet)
19
Q
Stages of Iron Depletion
A
Stage 1. Ferrotin decreases
Stage 2. Serum iron decreases and TIBC increases with the decreased Ferritin
Stage 3. Hemaglobin decreases with the above.
20
Q
Clinical Signs of Iron Deficiency
A
- Fatigue
- Pallor
- Koilonychia
- Craving unusual foods – ice, clay, starch, pickles
- Pica
21
Q
Pica
A
- craving unusual non-food material for iron
22
Q
Lab Values of Iron Deficiency
A
- Absence of stainable iron stores (hemosiderin)
- Hemoglobin <10 g/dL
- Microcytic (first), hypochromic
- Increased RDW
23
Q
Treatment of Iron Deficiency
A
- Treat underlying disorder
- Iron supplements: Retic counts begin rising in 5-10 days, Hemoglobin rises in 2-3 weeks
- Nutritional counseling: Lean meats, eggs, whole grains, green leafy vegetables, legumes
24
Q
Anemia of Chronic Disease
A
- Anemia that occurs in patients with chronic infections, inflammation or neoplastic disorders
- Cytokine inhibition of EPO production with impaired erythropoiesis
- Impaired release of iron from macrophages
- Mild anemia, normo to microcytic, normo to hypochromic
- Anemia precedes microcytosis
- Iron studies: Plasma iron - decreased; TIBC - decreased: Ferritin - normal or increased
25
Q
Hepcidin in Anemia of Chronic Disease
A
- Explains error in ferrokinetics: Decreased serum iron with abundant iron stores.
- Hepcidin is an acute phase reactant
- Levels increase in inflammation: Decrease in iron absorption in intenstine. Decreased iron release from macrophages.
26
Q
Sideroblastic Anemia
A
- Diseases that interfere with heme production
- Increase in total body iron
- Ringed sideroblasts in bone marrow
- *Dimorphic RBC population: Normochromic and hypochromic
27
Q
Heredity and Acquired Sideroblastic Anemia
A
Hereditary:
- Sex-linked disorder affecting men
- Due to decreased activity of ALA synthetase
- About 50% respond to Vitamin B6
Acquired:
- Refractory anemia with ringed sideroblasts – stem cell disorder
- Secondary to drugs or toxins – interference: Lead, Alcohol - inhibition of B6
- Malignancy - abnormal stem cells
28
Q
Lead Poisoning
A
- Inhibition of heme synthesis by accumulated lead: ALA dehydrase and heme synthetase
- Interferes with iron storage
- Microcytic, hypochromic anemia?? May indicate concommitant disorder
- Coarse basophilic stippling
29
Q
Porphyrias
A
- Disease characterized by impaired heme production
- Many caused by deficiencies of enzymes on heme synthetic pathway:
- Causes accumulation of products from earlier stages
- Causes sideroblastic anemia
30
Q
Hemochromatosis
A
- Hereditary disorder – autosomal recessive
- HFE gene linked to class I HLA
- Deposition of Fe in organ tissues: Pancreas, liver, spleen
- Iron release into the plasma affected by hepcidin levels
- “Bronze diabetes” skin discolorization due to Fe related fibrosis of the pancreas
- Treatment – therapeutic removal of Fe through phlebotomy or chelation therapy
