RBC Morphology Flashcards
what does a CBC provide info about?
RBCs WBCs platelets nutritional status inflammation specific disease states hydration occult blood loss many more...
RBCs compose what %age? how many made a second? shape? size? nucleus?
99%
2-3 million/sec
7 micrometers in diameter but can pass through capillaries small as 3 micrometers wide
no nucleus (room for hemoglobin)
what molecule contributes to buffering capacity of blood?
hemoglobin & oxygen (& CO2)
hgb acts as buffer by picking up H+
what hormone signs the bone marrow stem cells to increase production of RBCs? what is it regulated by?
erythropoietin
regulated by O2 levels detected by kidneys
what can lead to an increase in EPO?
decreased O2 states: -high altitude -COPD -heart disease -smoking -hypoxic events improper excretion: -renal carcinoma or tumors -hepatic carcinoma or tumors -adrenal gland tumors
what can lead to depressed EPO?
- renal failure
- increased prod of IL-1 or TNF
- severe malnutrition
- hypothryroidism
- malignancy
where does erythropoiesis occur in adults?
bone marrow of long or flat bones
what is the cell maturation path for RBCs? how long do they live for?
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)
where do metarubricytes lose their nuclei?
on erythroblastic islands; nurse MO
how long do reticulocytes live in the blood?
24 hrs until becomes mature RBC
are reticulocytes smaller or larger than mature RBCs? color? how does anemia affect them?
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
when should you see an increase in reticulocytes?
when body is responding to anemia or hemorrhage
what does anemia w/low reticulocytes indicate?
failure of bone marrow (aplastic anemia)
EPO deficiency (renal failure)
bone marrow malignancy (leukemia)
anemia of chronic dz
what are 2 interfering factors with reticulocyte counts?
pregnancy: may see increased count secondary to increased fluid vol, hypoxia
howell-holly bodies (nuclear remnants): may be miscounted by techs or machines
reticulocyte index in pts with good marrow responses to anemia should be what? what does an RI<2% indicate?
2-3% indicating increased RBC production
<2% indicates, even w/elevated ritic counts, that the response is inadequate (hypoproliferative)
when do you see increased levels of reticulocytosis?
hemolytic anemia
hemorrhage
hemolytic disease of the newborn
treated deficiency anemias
when do you see decreased levesl of reticulocytopenia?
pernicious anemia nutrient deficiencies aplastic anemia radiation therapy marrow failure chronic diseases
RBC counting by machine is independent of what? what do automated RBC counts allow for?
cell shape, color & density
allow for hematocrit calculation
primary polycythemia has what EPO level?
low EPO
bone marrow proliferative disorder and dehydration has what EPO level?
normal EPO
renal proliferative disorder and secondary polycythemia leads to what EPO level?
elevated EPO
what is a decrease in RBCs called? what is it due to?
ANEMIA= erythrocytopenia
due to malnutrition, malabsorption, inflam, hemorrhage, hemolytic, BM failure, renal dz, etc.
what are interfering factors with RBC counts?
pregnancy (decreased counts)
high altitude (increased count)
hydration (increase or decrease
drugs that increase: gentamycin, methyldopa
drugs that decrease: chloramphenicol, quinidine
what is hematocrit?
portion of blood composed of erythrocytes
% of total blood vol
indirect measure of # of RBCs and their total blood volume
what is anisocytosis? causes? result of?
any significant variation in size of RBC
found in anemias & leukemias
results from abnormal cell development often due to deficiency in raw material
what is RDW?
Red blood cell distribution width
statistical measure of variation in RBC size
calculated from MVC & RBC
indicator of degree of anisocytosis
what do increases in RDW signify? are decreases significantly significant?
iron deficiency anemia B12 or folaic acid deficiency anemia hemoglobinopathies hemolytic anemias posthermorrhagic anemia decreases in RDW not clinically significant
what are macrocytes?
increased size
greater than 8 micrometers
well hemoglobinized (lacks central pallor)
what are the two types of macrocytes and what does each signify?
round= liver dz oval= B12/folic acid deficiency, pernicious anemia
what are microcytes?
decreased size
smaller than 6 micrometers
increased central pallor due to decreased hgb concentrations
what causes microcytes?
iron deficiency
blood loss
sideroblastic anemia
what is good about peripheral smear evaluation? why is it good to use/
inexpensive & diagnostic
determine is cells appear normal in size, shape & count
not required in all pts
what is poikilocytosis?
RBC variation in shape
excessive variation in normal RBC shape
what are target cells? what causes it?
dark center & periphery separated by pale area
caused by: thalassemia, splenectomy, liver disease, iron deficiency, hemoglobinopathies, decreased osmotic fragility
what are spheroctyes?
sphere or globe w/dense appearance (no central pallor), increased hgb content, increased thickness of cell & decrease in diameter
when do you see spherocytes?
autoimmune hemolytic anemia
hereditary spherocytosis
what is the problem with spherocytes? what do pts present w/?
problem is they burst more readily when exposed to osmotic pressure due to increased osmotic fragility
pts present w/anemia, splenomegaly & jaundice
what are schistocytes? what dz states cause?
fragmented cells from trauma to membrane artificial heart valve hemolytic uremic syndrome disseminated intravascular coagulation thrombotic thrombocytopenia purpura
what are echinocytes?
multiple tiny spicules even distributed over cell surface
from exposure of certain substances to cell surface
what are acanthocytes?
also known as spur cells
spheroid RBCs w/few lg thorny projections
5-10 spicules per cell
hard to differentiate from echinocytes
what causes acanthocytes?
post splenectomy
alcoholics
cirrhois
various hemolytic anemias
what are dacrocytes? when do you see them?
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
what are elliptocytes? when do you see an increase up to 10%? acquired or congenital?
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?
what happens to hgb in sickle cell? RBCs? blood flow?
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
in sickle cell what do pts start out with and progress to?
start w/splenic enlargement but eventually spleen size has tremendously reduced in size due to continual stasis & infarctions
what are howell-jolly bodies? when do pts present usu?
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
when are heinz bodies formed?
formed by damage to hbg through oxidative stress= irreversible hemichrome oxidation & precipitation
when do you see heinz bodies?
alpha thalassemia
congenital hemolytic anemia
G5PD deficiency
what does basophilic stippling indicate?
toxic injury to bone marrow
severe anemia: megaloblastic
lead poisoning
myelofibrosis
what is erythrocyte sedimentation rate used to detect? diagnostic?
simple & inexpensive lab to test overall inflammation
track progress of a dz or to monitor tx (sickness index)
not diagnostic
why would ESR increase? what is it called when RBCs stack up on one another?
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
why is ESR useful?
in general as dz worsens ESR increases & as dz resolves ESR decreases
can be used to monitor therapy esp for inflam autoimmune dz
what are the limitations to ESR?
nonspecific, nonsensitive
may NOT be elevated in active dz
many factors can alter test results
what are specific interfering factors for ESR?
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
what dzs can increase ESR?
chronic renal failure malignant dzs bacterial infxn inflam/autoimmune dzs necrotic diseases, MI dzs associated w/increased plasma proteins
what 2 dzs does ESR assist in the diagnosis of?
polymyalgia rheumatica and temporal arteritis
what can cause falsely decreased levels in ESR?
sickle cell dz
hereditary spherocytosis
hypofibrinogenemia
polycythemia vera
