Lecture 17 Disorders of Iron Heme Metabolism Flashcards
1
Q
Anemia Classifications
A
- Microcytic (usually hypochromic
- Normocytic (usually normochromic)
- Macrocytic (usually normochromic)
2
Q
Microcytic Anemias
A
- sideroblastic anemias
- iron deficiency
- anemia, chronic inflammation
- globin deficiency (thalassemia)
3
Q
Iron Deficiency Anemia (IDA)
A
Etiology (cause):
- inadequate intake (not enough to meet demand)
- increased need: infants, children, teens, pregnant/lactating women
- impaired absorption: ex. celiac disease, decreased stomach acidity
- chronic loss: ex. slow hemorrhage, hemolysis, menstruation
4
Q
The three iron compartments
A
- storage (ferritin in blood, BM, macrophages, liver cells)
- transport (serum transferrin)
- functional (Hgb, myoglobin, cytochromes)
5
Q
Stage 1 IDA
A
- progressive loss of stored iron
- iron reserve sufficient to supply transport and functional compartments
- RBC development still normal
- no signs of IDA on PBS; no symptoms
- serum ferritin would be decreased, BM iron would also be decreased
6
Q
Stage 2 IDA
A
- defined by storage
- RBC production normal (transport iron being used)
- Hgb drops but still could be in ref. range (still subclinical)
- ferritin decreased, serum iron decreased, TIBC increased
- RDW may start to increase
- FEP increased
- Transferrin receptors on cells increased
- no iron stores in BM when stained with Perl’s Prussian Blue
7
Q
Stage 3 IDA
A
- “Frank anemia”
- Hgb and Hct decreased
- storage iron depleted
- transport iron decreased
- abnormal RBC development
- microcytosis/normochromic -> microcytic/hypochromic
- ferritin markedly decreased
- FEP, transferrin receptors all increased
8
Q
Physical symptoms of Stage 3 IDA
A
- fatigue
- weakness especially with exertion
- pallor
- pica
- etc.
9
Q
Anemia of Chronic Inflammation (ACI)
A
- etiology: underlying condition: arthritis, TB, HIV, malignancies etc.
- pathophysiology: impaired ferrokinetics
- hepcidin is an acute phase reactant
- hepcidin destoys ferritin
- iron gets trapped in macrophages and hepatocytes
- when neutrophil die off, granules release lactoferrin -> lactoferrin binds iron (prevents bacteria from using iron)
- ferritin (acute phase reactant) binds some iron and contribute to ACID as RBCs have no ferritin receptor
- in BM: release of iron from macrophages is impaired by hepcidin and RBCs are deprived of iron and can’t develop
10
Q
ACID Laboratory Diagnosis
A
- mild anemia (90-110 g/L)
- no reticulocytosis (b/c erythropoiesis disrupted)
- leukocytosis/thrombocytosis
- may appear normocytic/normochromic in early stages of disease
- may co-exist with IDA
- iron studies:
- low serum iron
- low TIBC
- transferrin saturation normal or low
- serum ferritin is usually elevated due to inflammatory state
- FEP elevated
11
Q
Treatment of ACID
A
- erythropoietin concurrently with iron
- inflammation - treatment/control of underlying condition
12
Q
Sideroblastic Anemias
A
Pathophysiology - inadequate heme production - BM iron abundant - iron awaiting incorporation into heme - hallmark is ringed sideroblasts Disorders - Hereditary: - X-linked - Autosomal - Acquired: - Primary sideroblastic anemia (refractory) - Secondary sideroblastic caused by drugs and BM toxins
13
Q
Lead Poisoning
A
- acquired sideroblastic anemia/ porphyria
- interferes with porphyrin synthesis
- usually normocytic/normochromic
- repeated/prolonged exposure -> micro/hypo
- retic count high
- basophilic stippling (also present in thalassemias)
Treatment - remove source
- chelation EDTA therapy
14
Q
Iron Studies in Sideroblastic Anemia
A
- increase in serum iron and ferritin
- increase in BM iron with the exclusive presence of ringed sideroblasts
15
Q
Iron Overload
A
- Primary: genetic defect ex. hereditary hemochromatosis
- Secondary: Blood transfusions
