RBCS Flashcards by Timothy Carll

Mentzer index

Metric to distinguish thalassemias from IDA

MCV / RBC ; if <13, likely thalassemia

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Calculations: HCT, MCH, MCHC

HCT: RBC*MCV
MCH: HGB/RBC
MCHC: HGB/HCT

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Iron deficiency anemia

Elevated transferrin and TIBC (most sensitive marker)
Decreased ferritin (in later disease)
Decreased %sat

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Anemia of chronic disease

Decreased transferrin and TIBC

Increased ferritin

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Sideroblastic anemia

Causes: Alcohol, toxins, abnormalities of ALA-S. MDS

High iron, ferritin due to failure of incorporation
Elevated ZPP?

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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

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Megaloblastic anemias - Labs

Elevated homocysteine
Elevated methylmalonic acid (B12 only)
Low serum or RBC folate (folate only)

Schiling test: Oral + Injected&raquo_space; Replace IF, then enzymes, then Abx.

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Hereditary spherocytosis

Ankyrine mutations

Increased osmotic fragility

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Hereditary elliptocytosis

Spectrin, band 4.1 mutations.

Increased osmotic fragility

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Stomatocytes - Causes

Rh null
Defect of Na/K transporter
Liver, renal disease

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G6PD deficiency

XLD, associated with heinz (Hb) bodies, bite cells.

Allele variants: B (normal), A (diseased)

Dx: Fluoro spot test, G6PD enzyme levels

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Pyruvate kinase deficiency

1 glycolytic pathway defect (still rare). AutRec

Numerous echinocytes. Elevated NADH, 2,3-DPG

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Acanthocytes

Associated with McLeod, abetalipoproteinemia

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Alkaline hemoglobin gel electrophoresis

Pattern: CSFA+ (pH 8.5)
C band: A2CEO
S band: SDG, Lepore?
HbH fast, constant spring slow

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Acid gel electrophoresis

Pattern: CSAF- (pH6.0)

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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

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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&raquo_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 >> Neutropenia Chromosome 7 abnormalities Also pancreatic insufficiency, skeletal abnormalities..