RBCS Flashcards
Mentzer index
Metric to distinguish thalassemias from IDA
MCV / RBC ; if <13, likely thalassemia
Calculations: HCT, MCH, MCHC
HCT: RBC*MCV
MCH: HGB/RBC
MCHC: HGB/HCT
Iron deficiency anemia
Elevated transferrin and TIBC (most sensitive marker)
Decreased ferritin (in later disease)
Decreased %sat
Anemia of chronic disease
Decreased transferrin and TIBC
Increased ferritin
Sideroblastic anemia
Causes: Alcohol, toxins, abnormalities of ALA-S. MDS
High iron, ferritin due to failure of incorporation
Elevated ZPP?
Megaloblastic anemias - Causes
B12 deficiency - More common, especially in pernicious anemia (parietal cell antibodies sensitive, IF antibodies specific)
Folate deficiency - Quite rare due to widespread supplementation
Megaloblastic anemias - Labs
Elevated homocysteine
Elevated methylmalonic acid (B12 only)
Low serum or RBC folate (folate only)
Schiling test: Oral + Injected»_space; Replace IF, then enzymes, then Abx.
Hereditary spherocytosis
Ankyrine mutations
Increased osmotic fragility
Hereditary elliptocytosis
Spectrin, band 4.1 mutations.
Increased osmotic fragility
Stomatocytes - Causes
Rh null
Defect of Na/K transporter
Liver, renal disease
G6PD deficiency
XLD, associated with heinz (Hb) bodies, bite cells.
Allele variants: B (normal), A (diseased)
Dx: Fluoro spot test, G6PD enzyme levels
Pyruvate kinase deficiency
1 glycolytic pathway defect (still rare). AutRec
Numerous echinocytes. Elevated NADH, 2,3-DPG
Acanthocytes
Associated with McLeod, abetalipoproteinemia
Alkaline hemoglobin gel electrophoresis
Pattern: CSFA+ (pH 8.5)
C band: A2CEO
S band: SDG, Lepore?
HbH fast, constant spring slow
Acid gel electrophoresis
Pattern: CSAF- (pH6.0)
SCD testing
Metabisulfite test: Add reagent, examine microscopically for sickle cells.
Dithionate solubility: Add reagent to a HEMOLYSATE, observe turbidity due to tactoid body formation.
*also picks up HbC-Harlem
SCD variant patterns
HbSS: >50% S, 20% F, 4% A2
Sickle trait: 50% A1, little A2 or F
S+Alpha: 35% S, mild phenotype
S+Beta: >50% S, severe phenotype
Variant Hb, other than S
HbE: Southeast asians, associated with mild microcytic anemia.
HbH: Beta-tetramer, “golf-ball” on supravital stains
Hb Barts: Gamma-tetramer, ineffectual
Lepore: Beta-delta fusion
PNH - Markers
RBC: CD55/59
Monocytes: CD14
Granulocytes: CD16/66, FLAER
PNH - Diagnosis
Ham serum lysis test: 6 beakers, containing patient serum and either patient or control RBCs. Acidification of serum should lyse patient but not control RBCs.
Sucrose lysis: Cheap screening assay, nonspecific
Flow: Gold standard.
RBC inclusions and composition
Howell-Jolly bodies: Nuclear remnant Heinz bodies: Denatured hemoglobin Basophilic stuppling: RNA Pappenheimer bodies: Iron Cabot rings: Microtubules Dohle bodies: Ribosomes, rER
Congenital dyserythropoietic anemias
I (CDAN1): Chromatin bridging, twin erythroblasts
II (SEC23B): MOST COMMON. HEMPAS. Binucelation
III (CDAN3): Gigantoblasts
Delta-beta trait
Presents like beta-thalassemia. Homozygosity»_space; microcytic, hypochromic anemia
Normal HbA2, elevated HbF.
Cyanmethemoglobin quantitation method
React Hb with ferricyanide to form metHb (540nm). Detects all variants except sulfhemoglobin.
Osmotic fragility testing
Expose cells to hypotonic saline solution
Increased fragility: Anything with decreased SA:volume
Decreased fragility: Thalassemias, IDA, SCD, HbC
Hypothyroidism
Causes macrocytic anemia!
HbSC - Peripheral smear findings
Rare sickle cells
Target cells
“Taco cells” / “Clam shell cells”
Acute intermittent porphyria
Deficiency of uroporphyrinogen I synthetase.
ALA accumulates, but no tetrapyrrole rings, so no photosensitivity.
Psych symptoms.
Reticulocyte counting
Usually automated: Based on optical properties on coulter analysis.
Manual: Requires supravital dye, count 1000+ cells.
Erythropoietic protoporphyria
Caused by ferrocheletase deficiency. Protoporphyrin IX accumulates.
Photosensitive rash.
What conditions cause elevation of HbA2?
Beta-thalassemia
B12/folate deficiency?
Hyperthyroidism?
Antiretroviral therapy?
Neonatal MCV
Starts high (>100fL), then nadirs at 6mo (75fL), then rises to normal/expected levels.
Secondary polycythemias
Renal transplant
High affinity hemoglobinopathies (incl acquired, eg CO)
Cyanotic heart disease
Renal tumors
RI, RPI
RI: %retic x (Hct/nmlHct)
RPI: (%retic x Hct) / (nmlHct x CF)
*CF starts at 1.0 for Hct >35%, maxes at 2.5 for Hct <15%
Hereditary persistence of fetal hemoglobin
Heterozygotes: 2-15% HbF
Homozygotes: 100% HbF
LAP scores
High: Leukemoid
Low: CML, PNH
Fanconi anemia
Defective DNA repair. AutRec, polygenic.
Short stature, cafe au lait spots, abnormal thumbs/radii.
Bone marrow failure, many cancers.
Dyskeratosis congenita
Inherited neutropenia
Triad of oral leukoplakia, lacy reticular skin pigmentation, and nail dysgenesis
Diamond-Blackfan anemia
RPS19 abnormality
Normal bone marrow cellularity; just isolated anemia. No dysplasia.
Short stature, thumb shit, craniofacial abnormalities.
Schwachman-Diamond Syndrome
SBDS mutations»_space; Neutropenia
Chromosome 7 abnormalities
Also pancreatic insufficiency, skeletal abnormalities..