12. Extrinsic Defects Flashcards
1
Q
Extravascular Lab Findings
A
- Increased serum bilirubin
- Increased urine and fecal urobilinogen
- Spherocytes may be seen (due to macrophages plucking abnormalities from RBC)
2
Q
Extrinisc Hemolytic Anemia can be caused by:
A
- Immune anemias
- non-immune (infections, mechanical, chemical, physical)
3
Q
Immune Hemolytic Anemias
and Lab findings
A
- Alloimmune
- Autoimmune
- Drug-induced
Lab findings:
- spherocytes (HgB normal)
- polychromasia
4
Q
Alloimmune
A
- antibodies react to foreign RBC antigens
- Usually associated with transfusions, pregnancy, or transplant
- Acute hemolytic transfusion reactions - usually IgM (ABO incompatibility)
- Delayed hemolytic transfusion reactions - usually IgG (Patient is sensitized by previous exposure, Anamnestic response)
5
Q
IgM
A
- large antibodies that activate complement in the plasma
- typically cause intravascular hemolysis
6
Q
IgG
A
- small antibodies capable of crossing the placenta
- tags RBC to be hemolyzed in the spleen (Extravascular hemolysis)
7
Q
Hemolytic Disease of the Newborn
A
- Alloimmune response of mother against antigens on fetal RBC
- Usually IgG, RH blood group system, anti-D
- Erythroblastosis fetalis
8
Q
Erythroblastosis fetalis
A
- hemolytic anemia in newborn infant
- numerous nucleated RBCs
- hyperbilirubinemia
- leads to neural cell death.
- Putting baby under UV light or even sunlight can help bilirubin levels lower.
9
Q
Autoimmune Hemolytic Anemia
- types
- diagnosis
A
Warm:
- Secondary to infection, immunologic disorders, pregnancy.
- 70% of AIHA
- Usually IgG
Cold:
- Cold agglutinin
- Paroxysmal cold hemoglobinuria
Diagnosis: Variable anemia, positive DAT, spherocytes, increased poly, increased retic, increased bilirubin.
10
Q
Cold Agglutinin Syndrome
A
- Antibody has wide thermal range (optimum 4 degrees C)
- Usually IgM, anti-I specificity
- May be secondary to infections (mycoplasma)
- IgM anti-i secondary to infectious mononucleosis
- RBC clumping at room temperature may cause technical problems in CBC
11
Q
Paroxysmal Cold Hemoglobinuria
A
- Very rare
- Associated with viral disorders: measles, mumps, flu, etc.
- Anti-P specificity, biphasic hemolysin (binds at cold temperature but destroys red blood cell at warm temperature)
12
Q
Drug-Induced Immune Hemolytic Anemia
A
- Autoimmune
- Drug Adsorption
- Immune Complex
13
Q
Drug-Induced: Autoimmune
A
- 70% of all cases of drug-induced hemolytic anemia
- drugs cause patient to make antibodies against self
- IgG antibodies, RBC destroyed in spleen
- Patients may demonstrate antibody long after discontinuing drug
- Seen in hypertensive drugs (Aldomet, l-dopa)
14
Q
Drug-Induced: Drug Adsorption
A
- Hapten
- Penicillins, cephalosporins
- Drug is adsorbed to RBC surface
- Drug-RBC complex illicits antibody response
- IgG, extravascular hemolysis
15
Q
Drug-induced: Immune complex
A
- Quinidine, phenacetin
- Antibody is formed against drug and forms complex with drug
- Complex adsorbs onto patients RBC and activates complement
- Activated complement = typically associated with intravascular hemolysis
