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Lab Diagnosis > RBC Morphology > Flashcards

RBC Morphology Flashcards

1
Q

what does a CBC provide info about?

A 
RBCs
WBCs
platelets
nutritional status
inflammation
specific disease states
hydration
occult blood loss
many more...
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2
Q

RBCs compose what %age? how many made a second? shape? size? nucleus?

A

99%
2-3 million/sec
7 micrometers in diameter but can pass through capillaries small as 3 micrometers wide
no nucleus (room for hemoglobin)

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3
Q

what molecule contributes to buffering capacity of blood?

A

hemoglobin & oxygen (& CO2)

hgb acts as buffer by picking up H+

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4
Q

what hormone signs the bone marrow stem cells to increase production of RBCs? what is it regulated by?

A

erythropoietin

regulated by O2 levels detected by kidneys

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5
Q

what can lead to an increase in EPO?

A 
decreased O2 states:
-high altitude
-COPD
-heart disease
-smoking
-hypoxic events
improper excretion:
-renal carcinoma or tumors
-hepatic carcinoma or tumors
-adrenal gland tumors
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6
Q

what can lead to depressed EPO?

A
  • renal failure
  • increased prod of IL-1 or TNF
  • severe malnutrition
  • hypothryroidism
  • malignancy
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7
Q

where does erythropoiesis occur in adults?

A

bone marrow of long or flat bones

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8
Q

what is the cell maturation path for RBCs? how long do they live for?

A

undifferentiated stem cell acted on by colony stimulating factor–> rubriblast–> prorubicyte–> rubricyte–> metarubricyte–> looses nuc–> reticulocyte–> released into cir & matures in about 24 hrs–> ERYTHROCYTE (mature RBC, lives 120 d)

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9
Q

where do metarubricytes lose their nuclei?

A

on erythroblastic islands; nurse MO

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10
Q

how long do reticulocytes live in the blood?

A

24 hrs until becomes mature RBC

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11
Q

are reticulocytes smaller or larger than mature RBCs? color? how does anemia affect them?

A

larger than mature RBCs
bluish appearance due to residual RNA
non-anemic= mature in peripheral circ in 24 hrs
anemic= maturation time increased in proportion to severity of anemia

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12
Q

when should you see an increase in reticulocytes?

A

when body is responding to anemia or hemorrhage

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13
Q

what does anemia w/low reticulocytes indicate?

A

failure of bone marrow (aplastic anemia)
EPO deficiency (renal failure)
bone marrow malignancy (leukemia)
anemia of chronic dz

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14
Q

what are 2 interfering factors with reticulocyte counts?

A

pregnancy: may see increased count secondary to increased fluid vol, hypoxia
howell-holly bodies (nuclear remnants): may be miscounted by techs or machines

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15
Q

reticulocyte index in pts with good marrow responses to anemia should be what? what does an RI<2% indicate?

A

2-3% indicating increased RBC production

<2% indicates, even w/elevated ritic counts, that the response is inadequate (hypoproliferative)

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16
Q

when do you see increased levels of reticulocytosis?

A

hemolytic anemia
hemorrhage
hemolytic disease of the newborn
treated deficiency anemias

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17
Q

when do you see decreased levesl of reticulocytopenia?

A 
pernicious anemia
nutrient deficiencies
aplastic anemia
radiation therapy
marrow failure
chronic diseases
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18
Q

RBC counting by machine is independent of what? what do automated RBC counts allow for?

A

cell shape, color & density

allow for hematocrit calculation

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19
Q

primary polycythemia has what EPO level?

A

low EPO

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20
Q

bone marrow proliferative disorder and dehydration has what EPO level?

A

normal EPO

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21
Q

renal proliferative disorder and secondary polycythemia leads to what EPO level?

A

elevated EPO

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22
Q

what is a decrease in RBCs called? what is it due to?

A

ANEMIA= erythrocytopenia

due to malnutrition, malabsorption, inflam, hemorrhage, hemolytic, BM failure, renal dz, etc.

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23
Q

what are interfering factors with RBC counts?

A

pregnancy (decreased counts)
high altitude (increased count)
hydration (increase or decrease
drugs that increase: gentamycin, methyldopa
drugs that decrease: chloramphenicol, quinidine

24
Q

what is hematocrit?

A

portion of blood composed of erythrocytes
% of total blood vol
indirect measure of # of RBCs and their total blood volume

25
Q

what is anisocytosis? causes? result of?

A

any significant variation in size of RBC
found in anemias & leukemias
results from abnormal cell development often due to deficiency in raw material

26
Q

what is RDW?

A

Red blood cell distribution width
statistical measure of variation in RBC size
calculated from MVC & RBC
indicator of degree of anisocytosis

27
Q

what do increases in RDW signify? are decreases significantly significant?

A 
iron deficiency anemia
B12 or folaic acid deficiency anemia
hemoglobinopathies
hemolytic anemias
posthermorrhagic anemia
decreases in RDW not clinically significant
28
Q

what are macrocytes?

A

increased size
greater than 8 micrometers
well hemoglobinized (lacks central pallor)

29
Q

what are the two types of macrocytes and what does each signify?

A 
round= liver dz
oval= B12/folic acid deficiency, pernicious anemia
30
Q

what are microcytes?

A

decreased size
smaller than 6 micrometers
increased central pallor due to decreased hgb concentrations

31
Q

what causes microcytes?

A

iron deficiency
blood loss
sideroblastic anemia

32
Q

what is good about peripheral smear evaluation? why is it good to use/

A

inexpensive & diagnostic
determine is cells appear normal in size, shape & count
not required in all pts

33
Q

what is poikilocytosis?

A

RBC variation in shape

excessive variation in normal RBC shape

34
Q

what are target cells? what causes it?

A

dark center & periphery separated by pale area

caused by: thalassemia, splenectomy, liver disease, iron deficiency, hemoglobinopathies, decreased osmotic fragility

35
Q

what are spheroctyes?

A

sphere or globe w/dense appearance (no central pallor), increased hgb content, increased thickness of cell & decrease in diameter

36
Q

when do you see spherocytes?

A

autoimmune hemolytic anemia

hereditary spherocytosis

37
Q

what is the problem with spherocytes? what do pts present w/?

A

problem is they burst more readily when exposed to osmotic pressure due to increased osmotic fragility
pts present w/anemia, splenomegaly & jaundice

38
Q

what are schistocytes? what dz states cause?

A 
fragmented cells 
from trauma to membrane
artificial heart valve
hemolytic uremic syndrome
disseminated intravascular coagulation
thrombotic thrombocytopenia purpura
39
Q

what are echinocytes?

A

multiple tiny spicules even distributed over cell surface

from exposure of certain substances to cell surface

40
Q

what are acanthocytes?

A

also known as spur cells
spheroid RBCs w/few lg thorny projections
5-10 spicules per cell
hard to differentiate from echinocytes

41
Q

what causes acanthocytes?

A

post splenectomy
alcoholics
cirrhois
various hemolytic anemias

42
Q

what are dacrocytes? when do you see them?

A

teardrop shaped cells seen meylofibrosis w/myeloid metaplasia
usu indicate significant bone marrow failure
seen in megaloblastic anemia, renal failure, severe iron deficiency & thalassemia major

43
Q

what are elliptocytes? when do you see an increase up to 10%? acquired or congenital?

A

known as ovalocytes
normally <1% of RBCs, can increase up to 10% in cases of thalassemia of deficiencies of iron or folate, can also get w/hereditary elliptocytosis?

44
Q

what happens to hgb in sickle cell? RBCs? blood flow?

A

abnormal hbg prone to crystallization when O2 tension low

RBCs change shape into sickles that get stuck in capillaries and further decrease blood low & O2 tension

45
Q

in sickle cell what do pts start out with and progress to?

A

start w/splenic enlargement but eventually spleen size has tremendously reduced in size due to continual stasis & infarctions

46
Q

what are howell-jolly bodies? when do pts present usu?

A

small 1 mm inclusions of nuclear chromatin remnants or fragments
most present post splenectomy b/c spleen would normally remove these RBCs from circulation
also see in hemolytic anemia

47
Q

when are heinz bodies formed?

A

formed by damage to hbg through oxidative stress= irreversible hemichrome oxidation & precipitation

48
Q

when do you see heinz bodies?

A

alpha thalassemia
congenital hemolytic anemia
G5PD deficiency

49
Q

what does basophilic stippling indicate?

A

toxic injury to bone marrow
severe anemia: megaloblastic
lead poisoning
myelofibrosis

50
Q

what is erythrocyte sedimentation rate used to detect? diagnostic?

A

simple & inexpensive lab to test overall inflammation
track progress of a dz or to monitor tx (sickness index)
not diagnostic

51
Q

why would ESR increase? what is it called when RBCs stack up on one another?

A 
inflam proteins (acute phase reactants, mainly fibrinogen) neutralize negative charge usu on cellular surface (zeta potential) which normally repels RBCs
RBCs overcome zeta potential & stack up on one another= rouleaux formation= settles faster
52
Q

why is ESR useful?

A

in general as dz worsens ESR increases & as dz resolves ESR decreases
can be used to monitor therapy esp for inflam autoimmune dz

53
Q

what are the limitations to ESR?

A

nonspecific, nonsensitive
may NOT be elevated in active dz
many factors can alter test results

54
Q

what are specific interfering factors for ESR?

A 
low results if test not set up w/in 3 hrs of sample
pregnancy
menstruation may elevate
sedimentation tube must be vertical
some anemia's falsely increase
polycythemia & sickle cell decreases
protein-producing malignancies falsely increases ESR 
any bubble in column invalidates test
55
Q

what dzs can increase ESR?

A 
chronic renal failure
malignant dzs
bacterial infxn
inflam/autoimmune dzs
necrotic diseases, MI
dzs associated w/increased plasma proteins
56
Q

what 2 dzs does ESR assist in the diagnosis of?

A

polymyalgia rheumatica and temporal arteritis

57
Q

what can cause falsely decreased levels in ESR?

A

sickle cell dz
hereditary spherocytosis
hypofibrinogenemia
polycythemia vera

Lab Diagnosis (5 decks)

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