RBCs: 5.6: Normocytic w/ Intravascular Hemolysis Flashcards
What causes paroxysmal nocturnal hemoglobinuria?
an acquired defect of GPI, an anchoring protein for protective surface proteins against complement, on blood cells
What destroys the cells in paroxysmal nocturnal hemoglobinuria?
complement
Is the hemolysis in paroxysmal nocturnal hemoglobinuria intra- or extravascular?
intravascular
Shallow breathing leads to what acid-base disturbance?
respiratory acidosis
What are the lab findings of paroxysmal nocturnal hemoglobinuria?
hemoglobinemia
hemoglobinuria
hemosiderinuria (days later)
How do you screen for paroxysmal nocturnal hemoglobinuria?
give sucrose- activate complement- positive = cell destruction
How do you confirm paroxysmal nocturnal hemoglobinuria?
lack of CD55 (DAF) on RBCs or the acidified serum test
What is the main cause of death in paroxysmal nocturnal hemoglobinuria?
thrombosis (platelet destruction activates coag cascade)
What are some complications of paroxysmal nocturnal hemoglobinuria?
Fe deficiency anemia (lost in urine)
AML (bc already have 1 mutation in myeloid stem cells)
How is G6PD inherited?
X-linked
What does glutathione do?
protects RBCs against oxidative stress
What reduces glutathione?
NADPH
What produces NADPH in an RBC?
G6PD
What is the underlying problem in G6PD?
a reduced half-life of G6PD –> increased suscept. to oxidative stress in RBCs
What are the 2 variants of G6PD?
- African (mild)
2. Mediterranean (moderate)
How long is the G6PD half life in a normal pt?
as long as the RBC’s life
Name 2 diseases that are protective for falciparum malaria.
- sickle cell
2. G6PD
Name 3 drugs that cause oxidative stress to RBCs.
- primaquine
- sulfa drugs
- dapsone
Oxidative stress in RBCs precipitates hemoglobin into a ____.
Heinz body
How does a G6PD crisis present?
hemoglobinuria, back pain (nephrotoxic) within hours of exposure
What is the screening test for G6PD?
a Heinz preparation (highlights precipitated Hb)
What is the confirmatory test for G6PD?
enzyme studies after the acute episode has resolved
What is immune hemolytic anemia?
Ab mediated (IgG or IgM) destruction of RBCs
What kind of Ab causes immune hemolytic anemia?
IgG or IgM
What happens to IgG covered RBCs in immune hemolytic anemia?
the spleen macs eat the membrane –> spherocytes
Name 2 diseases associated with immune hemolytic anemia.
SLE, CLL
Name 2 drugs that can cause immune hemolytic anemia.
- penicillin
2. methyldopa
What is the tx for immune hemolytic anemia?
- stop offending drug, if applicable
- steroids
- IVIG (distraction technique)
- splenectomy
At what temperature does IgM immune hemolytic anemia prefer?
cold temps
Name 2 diseases that IgM immune hemolytic anemia are seen in.
Mycoplasma pneumo
mononucleosis
How is immune hemolytic anemia diagnosed?
Coombs test (esp direct)
How does a direct Coombs test work?
confirms the presence of Ab-coated RBCs (anti-IgG added- positive if another Ab already existed)
How does a indirect Coombs test work?
it checks for Abs in the serum (give test RBCs to see if agglutination occurs when anti-IgG is added)
What is microangiopathic hemolytic anemia?
when RBCs are destroyed as they pass thru BVs with platelet microthrombi on the sidewalls
What cells result from microangiopathic hemolytic anemia?
shistocytes
Name 5 syndromes that cause shistocytes.
- DIC
- HUS
- TTP
- HELLP
- microangiopathic hemolytic anemia
What is another name for a shistocyte?
helmet cell
