Correcting the reticulocyte count

- formula

- interpretation

1st correction:  

(patient hct X reticulocyte count)/ 45 (normal hct)

2nd correction:

corrects for early release using table

Hematocrit            Reticulocyte maturation time

45                           1.0

35                           1.5

25                           2.0

15                           2.5

RPI = (# from 1st correction) / estimation of reticulocyte maturation time in days

Absolute reticulocyte count >100,000/μL or an RPI >3 = hemolytic process

Hemolytic anemia general findings

- peripheral smear

- bone marrow

- lab findings

Peripheral smear:

- polychromasia

- spherocytosis

- schistocytes

- target cells

- sickled cells

- acanthocytes

Bone marrow smear:

- erythroid hyperplasia

- M:E ratio = 1:1

- not needed for diagnosis

Lab findings:

- ↓ serum haptoglobin

- ↑ serum bilirubin (esp unconjugated) and development of pigmented gall stones

- hemoglobinuria, urine hemosiderin stained with Prussian blue

- ↑ LDH

- folate deficiency due to ↑ RBC production!!!

Hereditary Spherocytosis

- etiology

- clinical findings

- diagnosis

- treatment

Etiology:

- defects related to RBC membrane cytoskeleton

- autosomal dominant inheritance (usually)

- associated abnormalities

   ~ Na⁺ leak due to ↑ cell permeability

   ~ ↑ metabolic rate 2ndary to Na extrusion by Na/K ATPase resulting in increased consumption of ATP and glucose

   ~ release of lipids from RBC membrane → to decrease in cell SA and decreased deformability → inability to traverse splenic microcirculation (↑ MCHC)

   ~ destruction by splenic RECs

Clinical features:

- splenomegaly

- intermittent jaundice during periods of stress

- pigmented gall stones

- leg ulcers

Diagnosis:

- osmotic fragility test

Treatment:

- splenectomy to remove site of hemolysis; no effect on underlying metabolic defects or presence of spherocytes in peripheral blood

G6PD deficiency

- etiology

- diagnosis

- management

Etiology:

- abnormal amount of G6PD or normal amount of defective G6PD

- X-linked inheritance

- G6PD reduces glutathione which is used to reduce oxidative stressors

- low glutathione levels lead to oxidation of hemoglobin creating Heinz bodies

- Major enzyme types

  ~ B: most common form

  ~ A: normal variant (blacks)

  ~ A(-): deficient enzyme activity

  ~ Mediterranean variants: severe

- Inciting factors = drugs (primaquine, sulfa, nitrofurantoin, dapsone), infection (febrile esp), newborn period (Kernicterus in individuals affected by mor severe variants), fava beans

Diagnosis:

- fluorescent screening test- may be inaccurate after acute hemolysis when young cells with high remaining enzyme levels are circulating

Management:

- avoid inciting drugs

- transfusion when indicated

- exchange transfusion (neonates) to prevent further hemolysis and bilirubin deposition

Hemoglobinopathies

- name the diseases

Sickle cell anemia

Hemoglobin C

Hemoglobin E

Unstable hemoglobins

Sickle cell anemia

- etiology

- clinical presentation

- lab findings

- treatment

Etiology:

- substitution of valine for glutamic acid in 6th position of β-chain

- heterozygotes (Hb SA) clinically silent due to 40-45% of HbS in cells

- homozygotes have sickled cells due to polymerization in deoxygenated forms

Clinical presentation:

- misshapen cells can occlude microcirculation  causing painful crises, splenic autoinfarction, renal abnormalities, and papillary necrosis

- stressors including fever, infection, acidosis, dehydration, and hypoxia may precipitate vasoocclusive events

Lab findings:

- sickled cells in peripheral smear

- HbSS and HbSA are detected by Hb electrophoresis

Treatment:

- treat crises with hydration, supportive care, analgesics, and transfusion (severe anemia, acute chest syndrome, splenic sequestration crisis, stroke, priapism)

- hydroxyurea for HbF production

Hemoglobin C

- etiology

- clinical presentation

- lab findings

Etiology:

- β6 substitution of lysine for glutamic acid

- intracellular Hb polymerization leading to rod-shaped crystal cells

Clinical presentation:

- Double heterozygotes for HbS and HbC (HbSC) have similar vasoocclusive events but are much milder and less frequent

- Splenomegaly common

Lab findings:

- rod-shaped cell in peripheral smear due to crystallization of Hb C

Unstable hemoglobin

- etiology and findings

Etiology:

- heterogenous group of hemoglobinopathies characterized by intracellular precipitation of denatured hemoglobin (Heinz bodies)

- mild anemia due to altered oxygen affinity (right shift) or secondary polycythemia (left shift) and methemoglobinemia

Cold reactive antibodies

- Ig

- target

- causes

IgM

"I" antigen an RBCs

Causes:

- idiopathic

- infections e.g. mycoplasma, infections mono

- lymphoproliferative diseases

Warm antibodies

- Ig

- Target

- causes 

- treatment 

IgG

Rh factor

hemolysis is in the spleen → splenomegaly

Causes:

- idiopathic

- lupus and other autoimmune diseases

- lymphoproliferative diseases

- carcinomas

- viral infection

- immune deficiency syndromes

Treatment:

- treat underlying disorder

- withdraw drugs

- Steroids though not for drug induced

- High dose IV gamma globulins

Coomb's test

Direct = determination for presence of antibody on patients red cell

Indirect = determines presence of antibody in patients serum against another individuals cell

Paroxysmal cold hemoglobinemia

- etiology

- treatment

Etiology:

- IgG nonagglutinating antibody mediated diesease associated with complement activation and intravascular hemolysis

Paroxysmal Nocturnal Hemoglobinuria (PNH)

- etiology

- signs/symptoms

- diagnosis

Etiology:

- acquired clonal disorder due to mutation of pig-A gene on X-chromosome with variable deficiency of GPI anchor protein

- complement mediated destruction of RBCs

Signs/Symptoms:

- impaired granulocyte chemotaxis

- inadequate reticulocyte response reflecting bone marrow failure which progresses over time

- episodic hemoglobinuria

- lethargy

- thrombotic tendency in extremities and more unusual sites (e.g. sagittal, portal, and hepatic veins)

Diagnosis:

- anti-CD59 and anti-CD55 Abs looking for GPI-anchored proteins, will rule out PNH if present

Treatment:

- Transfusions- caution b/c adding more complement dangerous

- alternate corticosteroids and androgens

- anticoagulants

- Eculizumab-  anti-C5 complement component

Microangiopathic hemolysis

- etiology

Etiology:

- faulty mechanical heart valves

- consumptive coagulopathy

- march hemoglobinuria

- hemolytic uremic syndrome, TTP

- Burns

Specific pathogens:

- Malaria

- Babesiosis

- Bartonellosis (Oroyra fever)

- Clostridia welchii (lecithinase destruction of cell membrane)

Can be due to bodies reaction to infections e.g. antibodies, ↑ hepcidin, antigen alteration etc