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Labs Medicine > Hemolytic Anemias > Flashcards

Hemolytic Anemias Flashcards

1
Q

What is hemolysis?

A

premature destruction of circulating red cells

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2
Q

What is hemolytic anemia?

A

hemolysis when the bone marrow cannot compensate

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3
Q

What is compensated hemolytic anemia?

A

when body has increased the red cell production (reticulocytosis) in the bone marrow

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4
Q

What are the 5 general categories of hemolytic diseases?

A 
membrane defects
metabolic defects
hemoglobin defects
mechanical destruction
immune destruction
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5
Q

Where does extravascular hemolysis occur?

A

typically in the spleen (reticuloendothelial system), but also sometimes in liver and bone marrow

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6
Q

What gets released when a red cell lyses?

A

lots of things - but LDH and hemoglobin

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7
Q

What binds to the free hemolglobin to carry to the liver?

A

haptoglobin

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8
Q

So what labs do you see with intravascular hemolysis?

A

haptoglobin goes down
LDH goes up
products of hemoglobin breakdown go up

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9
Q

What effects in the urine can be seen from hemolysis?

A

when severe, hemoglobinuria (alpha-beta dimers in the urine) and hemosiderinuria (RTCs take up and metabolize the dimers to form hemosiderin granules in the urine - not good for the kidney)

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10
Q

What percent of red cells are destroyed extravascularly every day?

A

11%

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11
Q

WHat cells degrades these RBCs in the spleen?

A

macrophages

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12
Q

Do you see a decrease in haptoglobin in pathologic extravascular hemolysis?

A

yes, because some free Hgb will spill into the circulation

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13
Q

What is the heme broken down to?

A

bilirubin, so you get an increase in unconjugated bili

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14
Q

What will happen due to that increased unconjugated bilirubin?

A

gallstones
biliary obstruction
increased fecal and urinary urobilinogen

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15
Q

What will you see in the bone marrow due to hemolytic anemia?

A

erythroid hyperplacia, thinning of cortical bones/bony deformities

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16
Q

Hemolytic anemia will usually be ___chromic and ____cytic

A

normochromic

normocytic

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17
Q

What will RBC morphology look like in hemolytic anemia?

A

Poikilocytosis (red cell shape changes)

plus extra reticulocytes

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18
Q

What is the term for elevated levels of circulating nucleated red cells?

A

erythroblastemia

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19
Q

What happens in a chronic hemolytic anemia-aplastic crisis?

A

erythroid aplasia iwth severe exacerbation of anemia

usually from parvovirus B19 erythroid maturation arrest

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20
Q

Again, what do you need to correct the reticulocyte count for?

A

the degree of anemmia

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21
Q

How long can it take for a reticulocyte response to occur after hemolysis becomes severe enough to cause anemia?

A

up to 72 hrs

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22
Q

WHat produces haptoglobin?

A

the liver

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23
Q

Why might a haptoglobin be normal even if someone is hemolyzing?

A

haptoglobin is also an acute phase reactant

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24
Q

Low haptoglobin can also be seen in what other conditions?

A 
advanced liver disease
recent massive transfusion
genetic variant
megaloblastic anemias
hematoma breakdown
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25
Q

WHy is LDH such a nonspecific test?

A

it increases due to ANY type of tissue damage

26
Q

Which LDH isoenzyme is most useful for hemolysis?

A

LDH1

27
Q

Why does the unconjugated biliruin increase if the liver is just fine in hemolysis?

A

because the unconjugated bili is so high the liver can’t keep up

28
Q

What are some other causes of indirect bili elevation?

A

crigler najjar, gilbert’s breast milk jaundice

29
Q

What lab can confirm there’s free hgn in the plasma?

A

easy - a plasma free hgb level

30
Q

What kind of other anemia does Dr. D get all hot and bothered about mistaking for hemolytic anemia

A

megaloblastic anemia (bc the big precursors get broken down in the bone marrow)

31
Q

What lab tests can differentiate between hemolytic anemia and megaloblastic anemia?

A

reticulocyte count (should be low in megaloblastic and high in hemolytic)

and blood smear for morphology (look very different)

32
Q

What are the main hereditary RBC membrane defects?

A

defects in spectrin of ankyrine = hereditary spherocytosis

33
Q

What are some presentations of hereditary spherocytosis?

A

highly variable from nearly asymptomatic to death in utero

clinical clues are anemia, jaundice, splenomegaly, biliary obstruction, gallstones and aplastic crisis due to pB19

34
Q

What lab clues will tip you off to hereditary spherocytosis?

A

high retic
high indirect bili
high LDH
spherocytes on blood smear

35
Q

What is the confirmatory test for herditary spherocytosis?

A

flow cytometry to look for the altered spectrin

used to do osmotic fragility test, but not anymore

36
Q

What is the important metabolic congenital cause of hemolysis?

A

glucose 6 phosphate dehydrogenase deficiency

you need G6PD to charge the NADPH to reduce glutathione in order to reduce the ROS in the RBCs from oxygen carriage

37
Q

In G6PD deficiency you end up getting crystalized oxidized hemoglobin collecting in the RBCs, called what?

A

Heinz bodies, which then get destroyed in the spleen

38
Q

What are some drugs associated with hemolysis in G6PD deficiency?

A 
antimalarials
sulfonamides
nitrofurantoin
sulfones
dimercaprol
napthalene
methylene blue
TNT
fava beans (not a drug)
39
Q

WHat will be seen on blood smear for G6PD deficiency?

A 
Heinz bodies (need a special heinz body prep)
(and their byproducts):
Bite cells
Helmet cells
Veil cells
40
Q

What are some congenital causes of mechanical hemolyssi?

A

AVMs

heart valve defect

41
Q

Congenital immune hemolysis is usually caused by what antibodies?

A

mom’s IgG (since that’s what Goes across the pkacenta)

42
Q

WHat are some clinical presentations of acquired hemolytic anemia?

A 
fever
abdominal pain
back/limb pain
CV symptoms (dyspnea, angina, tachy)
jaundice
dark urine
maybe even shock and renal failure
43
Q

Overal, what labs should you test for an acquired hemolytic anemia?

A 
CBC
type and screen
blood smear eval
reticulocyt count
LDH
Bili
Heptoglobin
Direct antiglobulin test
coags

then consider urine hemosiderine, plasma free hgb, radioactive isotope labeled RBC scan

44
Q

What is an example of an acquired clonal neoplastic membrane defect? Super rare.

A

paroxysmal nocturnal hemoglobinuria

45
Q

What acquired membrane defect do patients get with extensive thermal burns?

A

spectrin will denature!

46
Q

What are some examples of acquired mechanical hemolysis?

A 
malignant HTN
prosthetic heart valves
DIC
TTP/HUS
Autoimmune vasculitis
March hemoglobinuria
47
Q

What do you see on a blood smear in mechanical hemolysis?

A

schistocytes

48
Q

What are the two types of autoimmune hemolytic anemia?

A

Warm agglutinins

cold agglutinins

49
Q

What are the usual causes for warm AIHA?

A

mostly idiopathic, but also drugs and lymphoma

50
Q

What is the typical presentation for warm AIHA?

A

jaundice and splenomegaly, usually abrupt onset

51
Q

What are the usual causes for cold AIHA?

A

mostly idiopathic, but also lymphoma and infections (mycoplasma, EBV, CMV)

52
Q

How does the presentation for cold AIHA differ from warm?

A

cold is usually insidious and usually no jaundice or splenomegaly

53
Q

Wram AIHA is Ig__

A

IgG

54
Q

What is the classic laboratory clue to warm AIHA?

A

positive “Screen” on the type and screen

or blood bank struggling to cross match

55
Q

Cold AIHA is Ig__

A

IgM

56
Q

What is the classic lab clue for cold AIHA?

A

CBC difficult bc red cells stick together from the cold agglutinin and Hgbx3-Hct is more than +2

57
Q

What test will detect immunoglobulins absorbed to the red cells?

A

direct antiglobulin test

58
Q

If the DAT is positive, how do you know what the antibody on the surface of the RBC is directed again?

A

use the red cell eluate test

you wash the antibody off the red cell and then test it against lab red cells that have known antigoens (so do an indirect AT on the eluate)

59
Q

What are the situations where you’ll see an alloimmune hemolytic anemia?

A

from blood transfusion
during or after pregnancy
hematopoietic stem cell transplant

60
Q

What are two antibiotics that will nonspecifically bind to RBC membrane and then we make an antibody against the combo?

A

penicillin and cephalosporins

can lead to a drug-induced immune mediated hemolytic anemia

(particularly common in people with CF!!)

they’ll get a positive DAT but negative RBC eluate test bc the RBCs in the IAT part of the eluate test will not have the antibiotic bound to them

Labs Medicine (27 decks)

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