Microcytic Anemia Flashcards
Anemia
- Definition
- Symptoms
- Decrease in the number of RBCs in the blood, resulting in reduced oxygen-carrying capacity
- Symptoms: fatigue, dyspnea (on exertion), weakness
***With more severe anemia, may see confusion, tachycardia, hypotension, syncope, and death
Anemia
- How to categorize? (4)
Size, Color, Chronicity, Etiology
Hypochromic Microcytosis
What is a normal Hb in Males? Females?
Males = 14 to 17.5 g/dL
Females = 12 to 15 g/dL
What is a normal Hct in Males? Females?
Males = 42-50%
Females = 36-44%
What is a normal RBC count in Males? Females?
Males = 4.5 - 6.0 Million
Females = 4.0 to 5.0 Million
What is a normal MCV?
80-100 fL
What is a normal MCH?
30-34 pg
What is a normal MCHC? (i.e. Hgb/Hct x 100)
30-36%
What is a normal RDW? (Red Cell Distribution Width)
13-15%
What does a large RDW mean? small?
Large = Size is all over the map
Small = Uniform in size
Iron
- Absorption
- Where is it absorbed?
- Forms?
First and second portions of the duodenum
Forms:
- Reduced +2 (Ferrous) or +3 (Ferric) state (Ferric is useless to us)
- Heme Iron
- Gluconate, sulfate
- Role of pH, food (absorbed better in low pH/acidic)
Iron
- Dietary Sources
- Most easily absorbed?
- Plants/Vegetarians?
- Geritol?
- Heme iron is most easily absorbed
- Plants are a poor source (have Fe 3+ if they do)
- Vegetarians at risk for deficiency
Supplement with Geritol
Iron Absorption at the Enterocyte
- Describe the Process
***Heme Iron is absorbed by heme transporter then bound to Mucosal Ferritin (protects from redox reactions)
- Fe 2+ leaves the enterocyte into the extracellular space via Ferroportin 1 (inhibited by Hepcidin), is oxidized by Hephaestin (copper containing molecule) to Fe 3+ (Ferric form)
- Binds Plasma Transferrin in the blood
***Nonheme iron does the same, except is converted to Fe 2+ by Duodenal Cytochrome B first and then taken up by DMT 1
Hepcidin
- Role
- Upregulation
- Downregulation
Role: Reduces iron absorption by blocking ferroportin
Upregulated: by IL-6, high circulating ferritin
Downregulated: by low ferritin, hypoxia
Erythropoietin
- Produced where?
- Use in Anemias?
- Therapeutic Use
Produced by renal fibroblasts in response to hypoxia
Not useful in anemias that are already EPO-abundant (e.g. iron deficiency)
Should be co-administered with parenteral iron
Iron Distribution in the Body
4 parts
Circulating RBCs 2500 mg
Fe-containnig Proteins (e.g. Ferritin) 400 mg
Transferrin-bound 3-7 mg
Storage (marrow, RES) 1000 mg
Iron Loss
- Insensible loss
- Vascular loss
Insensible: sweat and endothelial sloughing
Vascular:
- External loss (traumatic)
- Sequestration (hematoma)
- Menstrual
- Internal loss (GI) –> Gastroduodenal (ulcer, espophageal varices), Colonic (tumors, diverticulitis)
Iron Deficiency Anemia
- Lab Values
- Hgb/Hct
- MCV
- Ferritin
- Transferrin Saturation
- TIBC
- Reticulocytosis
Hgb/Hct low
MCV low
Ferritin low (both intracellular (can’t be measured) and vascular)
- Very accurate indirect measurement of total iron body stores
- Ferritin of 10 or less is 99% sensitive/specific for ***Iron deficiency anemia***
Transferrin Saturation low (Transferrin itself will be high)
TIBC high (measures transferrin ^^^)
Reticulocytosis
Reticulocytosis
Normal Lab Values
- Serum Fe
- TIBC
- Saturation
- Ferritin
Serum Fe 60-150 mcg/dL
TIBC 300-360 mcg/dL
Saturation 20-50%
Ferritin 40-200 mcg/L ***Excellent indicator of total body iron***
Iron Deficiency Anemia
- Common Causes
- Detailed history is essential
- > 50 y.o. GI malignancy until proven otherwise
- IBD
- Ulcer/esophagitis
- Vascular malformations
- Hematoma, sequestration (rare)
- Gynecologic loss
Iron Deficiency
- Signs and Symptoms (5)
Pica (chewing ice)/Pagophagia (chewing on/eating clay)
Restless Legs Syndrome
Pallor/Pale palmar creases/Pale Conjunctiva
Glossitis
Nail Changes
How much iron can be absorbed per day if given orally?
How much can be given IV?
Absorbed Orally: 25 mg
IV: 500 mg
Anemic of Chronic Disease
- Hepcidin
- What is it?
- Effects?
- Induced/Stimulated by?
Hepcidin
- An acute phase reactant
- Has an antibacterial effect (presumably by limiting Fe-dependent electron transport)
- IL-6 is a potent stimulator of hepcidin production
- TNF, IFa, IFy also induce hepcidin (elevated in anemias of autoinflammation, cancer)
What is this and what disease does this patient have?
Microcytic Hypochormic Anemia
(with Rouleaux formation (i.e. clumping of cells))
Seen in Rheumatoid Arthritis (i.e. Anemia of Chronic Disease)
Anemia of Renal Disease
- Type of Anemia
- Mechanism
Usually a normochromic anemia
Increased RBC destruction (lysis with azotemia (minor contribution))
Anemia unrecognized by diseased renal fibroblasts
NO erythropoietin surge
NO marrow stimulation
Thalassemia
- Alpha-like globins (1 major)
- Beta-like globins (4 major)
Alpha-like: alpha, zeta, and xi
Beta-like: beta, gamma, delta, epsilon
***Important***
How many alpha alleles do we have and on which chromosome?
Two alpha alleles per chromosome (4 total)
Chromosome 16
***only one copy of all Betas on chromosome 11***
How are Thalassemias named?
For the gene that is deficient
a+-thalassemia
- Missing one allele
- Missing two alleles
- Missing three alleles
Missing…
One: a2B2 –> Silent carrier —> asymptomatic
Two: 85-95% a2B2 –> a+-thal trait –> mild anemia (no tx. required)
Three: 5-30% Hgb H (B4) “Hgb H disease”
a0-thalassemia
(no alpha chains) B4, Y4 –> a0-thal –> Fetal Hydrops (Lethal)
What is a hallmark for Thalassemias on PBS?
Target Cells
alpha-thalassemia trait
Hemoglobin H Disease ( –/-a, B4)
Hemoglobin Bart’s Fetal Hydrops (NO functional hemoglobin)
B-Thalassemia
- B+-Thalassemia
- B0-Thalassemia
B+-Thalassemia: B-thal trait or B-thalassemia minor
B0-Thlassemia: B-thalassemia major
- No Hb A, Mostly Hb F and some Hb A2
- Severe, transfusion-dependent
***B-Thalassemia tends to be more severe, as there are only 2 B genes***
B-Thalassemia
- Thalassemia Intermedia
Two defective but partially functional B genes
***Severity is between Minor and Major***
B-Thalassemia
- Disease
Increased RBC destruction
Iron (Fe) overload
Anemia, hypermetabolic marrow
Therapeutic phlebotomy (bleeding)
Transfusion Requirement
Sideroblastic Anemias
- Marrow Effects?
- Iron Stores?
- Cause
- All sideroblastic anemias produce ringed sideroblasts in the marrow
- Irone stores are sufficient, usually high
- Not making porphyrin
Bone Marrow with Ringed Sideroblasts
Sideroblastic Anemias
- Congenital
- Acquired (primary vs secondary)
- X-linked and involve ALA synthase deficiency
- Primary (myelodysplastic syndrome - pre-malignant)
Secondary (alcohol abuse, drug induced (isoniazid, chloramphenicol), lead poisoning, copper deficiency)
Sideroblastic Anemias
- Characteristics
May be normocytic
May have a dimorphic appearance
May demonstrate hemolytic changes
May show iron deposits (***Pappenheimer Bodies***)
***Transfusion to treat anemia, therapeutic phlebotomy to treat iron overload***
Pappeheimer Body (precipitated iron granules)
Sideroblastic Anemia
- Dimorphism
- Hypochromic
- Teardrop shapes
Sideroblastic Anemia
- Summary
- Treatment
- Total body iron overload, insufficient heme iron
- Treated with Pyridoxine, Transfusion, Phlebotomy, Chelation, Marrow Transplantation
Summary of Anemia Testing