Lecture 2: Microcytic Anemias Flashcards
Definition of anemia
reduction in the volume of RBCs (Hct) or concentration (Hgb) when compared to similar values from a reference population
What are the 3 major causes of anemia and what do each include?
(1) Bone marrow underproduction- nutritional deficiency, drugs, HIV, Leukemia, Metastatic cancer, MDs, Aplastic anemia
(2) Blood loss- GI bleeding, excessive menstrual bleeds, retroperitoneal, excessive blood donation
(3) RBC destruction- intrinsic or extrinsic disorders
What is the “differential” when ordering a CBC with a differential and then a reticulocyte count?
WBC differential- the peripheral blood smear tells you this
What is the importance of the Retic and MCV counts?
They can help guide towards the cause of the anemia
- low retic suggests hypoproductive anemia
- elevated retic suggest RBC destruction
Normal RBC is about what size?
Same size as a small lymphocyte nucleus
What are the 3 types of anemia? Give some examples of each.
- Microcytic (MCV 100 cu microns)
~ megaloblastic anemia, hemolysis with
reticulocytosis, chemo, hypothyroidism, MDs
Microcytic Anemias: DDx (5)
(1) Iron deficiency Anemia
(2) Thalassemia trait
(3) Lead poisoning
(4) Sideroblastic anemia
(5) Anemia of chronic disease
What is the most common anemia in the US?
Iron deficiency anemia
What does a decrease in iron lead to?
Decreased RBCs and Small RBCs
T/F The body has no way to eliminate excess iron.
TRUE; lost ~1.5 mg/day
What are the normal body stores for iron homeostasis?
~2-3 gm
When you get an iron lab, what are the values you obtain? (5)
(1) Serum Iron (Iron)
(2) Transferrin
(3) TIBC
(4) Percent Saturation
(5) Ferritin
What will iron labs look like in iron deficiency anemia?
- low ferritin, Fe, and % sat
- high TF, TIBC
What is the most frequent cause of iron deficiency anemia?
Chronic blood loss
- Menstrual bleeding in college aged females
- NSAIDS (leads to ulcer disease)
- have to identify cause in males and post menopausal women
What is another etiology of IDA that is not chronic blood loss?
Dietary Fe++ deficiency
- pregnancy and lactation
- adolescent growth spurt
- celiac sprue or PPIs (GI malabsorption)
- Gastric bypass (bypass duodenum AND decreased gastric acid)
What are clinical symptoms of IDA? (5)
(1) MOST asymptomatic
(2) “Tired”, “weakness”, “fatigue”, “cold”
(3) Decreased exercise tolerance
(4) Pica
(5) GI bleeding (melena, hematochezia, hematemesis), GU bleeding (hematuria)
What is Pica?
Appetite for non-food items
- chalk, clay, dirt, paper, ice, etc
what are the physical exam findings for IDA?
(1) Skin pallor- conjuctiva and oral mucosa too
(2) Signs of increased CO- tachycardia, systolic murmur (“flow murmur”)
(3) Objective evidence of blood loss- melena, BRBPR, (+) stool occult blood
(4) Glossitis, cheilosis, koilonychia
What will labs look like in IDA?
- low MCV
- High RDW
- Low ferritin
- High TIBC
- Anisiocytosis and poikilocytosis on the blood smear
- cigar shaped RBCs and elliptocytes when severe
What is the first priority in management of IDA? What will you do to determine this?
Evaluate for blood loss- correct underlying cause if possible
- H&P (stool occult blood- pelvic exam)
- Upper endoscopy (esophageal/gastric disease)
- Colonoscopy (cancer, IBS)
- Urinalysis (renal/bladder bleeding)
- Radiologic imaging (malignancy)
What is the second priority in IDA management? How will you do this?
Replenish Iron
- Oral (ferrous sulfate)
~ GI side effects common
- I.V.
~ only for patients unable to tolerate oral ironOral iron
- Ferrous sulfate 325 mg po titrated to TID
- Best absorbed on an empty stomach, best tolerated with food
- Will turn stool dark color
- Vit C helps with absorption
- Tea can inhibit absorption
- ferritin, retic count, CBC should all go up
How long should you continue iron therapy after CBC normalizes?
3-6 months
When does Retic count respond? Hgb and Hct?
days; 8 weeks
What is Thalassemia?
Spectrum of diseases characterized by reduced or absent production of one or more globin chains
- The severity depends on how many of the globin chains are affected
What is the major Hgb in adults? What does it consist of?
Hemoglobin A; tetramer consisting of one pair alpha and one pair beta globin chains
At what age does fetal Hgb decrease?
6 months
The majority of adult patients have which type of thalassemia?
alpha or beta thalassemia MINOR
- asymptomatic
- Dx: presence of microcytic, hypochomic red cells with or without minor degrees of anemia
What is alpha or beta MAJOR
Alpha: incompatible with extra-uterine life
Beta: life-long transfusion-dependent anemia
In what regions are Thalassemias most common?
Alpha: Middle East and western Asia, Southeast Asia, Africa
Beta: Mediterranean region, Africa, and Southeast Asia
T/F The severity of the clinical picture does not depend on how many of the globin chains are affected.
FALSE, DOES depend. Beta is worse than alpha
Alpha thalassemia
Abnormal production of alpha-globin chains resulting in a relative excess of beta-globin chains
Gene deletions 1-4 in Alpha thalassemia
(1) Alpha thalassemia trait- silent carrier
(2) Alpha thalassemia trait- mild anemia (cis and trans deletion)
(3) Hemoglobin H disease- More marked anemia
(4) Hydrops fetalis- death in utero
Alpha Thalassemia Minima (Silent Carrier): lab vaules/smear
- Asymptomatic
- CBC, Hgb electrophoresis and smear usually normal
- Slight microcytosis (MCV) may be present
- NO TREATMENT
Alpha Thalassemia Trait (cis and trans deletion): lab values/smear
- Peripheral smear:
~hypochromia
~microcytosis
~target cell
- MCV <80
- Hgb ~10-12 g/dL
- Hgb electrophoresis normal
- NO TREATMENTHemoglobin H Disease: lab values/smear
- Peripheral smear
~hypochromia
~microcytosis
~target cells
- MCV <80
- Hgb ~7-9 g/dL
- Hgb electrophoresis shows 10-20% HgbH
- May require intermittent transfusionsBeta thalassemia
Underproduction of beta chains
- inherited defect in beta-globin chain synthesis
- alpha-globins form precipitates that damage red cell membranes
Regarding beta thalassemia: depeding on number of globin chains affected, leads to:
- intravascular hemolysis
- premature destruction of erythroid precursors results in intramedullary death and ineffective erythropoiesis
Lead Poisoning
Causes impaired heme synthesis
- Abdominal pain, behavioral problems, poor school performance
- Basophilic stippling of RBCs
- Dx: lead levels
- Tx: Elimination of lead source/ chelation therapy
Sideroblastic anemia
Rare disorder of hematopoietic stem cells and defective heme synthesis
- causes chronic anemia
