2. Anemia: Intro & Microcytic Flashcards
what blood cells should we normally see in peripheral blood?
basophil, eosinophil, bands, neutrophils, monocytes, platelets, RBCs, lymphocytes
lifespan of an RBC in peripheral blood?
120 days
a RBC contains what?
no nucleus, no organelles, no ability to synth proteins. contains hemoglobin, a few enzymes, glucose.
RBC function?
carries 02 to tissues, C02 away from tissues
erythropoiesis takes how long? where occurs?
7 days, in bone marrow
erythropoiesis: what substance declines in RBCs? what substance increases?
declines: RNA content
incr: hemoglobin
what is the last RBC form prior to release to peripheral blood?
reticulocyte. peripheral blood has 1% retics approx.
at what point does the RBC nucleus get extruded?
just prior to becoming reticulocyte.
what are the building blocks for RBCs?
iron, folate, B12
what organ senses 02 levels? what does it make to upregulate erythropoiesis?
kidney. makes erythropoietin (EPO)
what’s the diameter of an RBC?
7 microns
what percent of the RBC weight is hemoglobin?
33%
describe the outer membrane of an RBC and its internal structure
lipid bilayer, contains proteins that determine ABO blood type. fixed to reticular protein network (spectrin, ankyrin) which allow integrity but also flexibility.
normal adult Hgb is made up of what types of globin molecules?
97% Hgb A1: 2 alpha, 2 beta
2% Hgb A2: 2 alpha, 2 delta
1% fetal: 2 alpha, 2 gamma
Fetal Hgb is consists of of what?
4 globin chains: 2 alpha, 2 gamma
where is heme synthesized?
mitochondria
Hemoglobin consists of what, overall?
Heme (Fe + protoporphyrin) and Globin
Porphyria is a problem with what process?
the heme biosynthesis process in the mitochondria
thalassemia is a problem with what?
decr synthesis of the globin chain
what three things increase 02 affinity for heme?
incr pH, decr DPG, decr temp
what three things decrease 02 affinity for heme
decr pH, incr DPG, incr temp (think of what happens when the muscle exercises: lactic acidosis, incr temp, and just remember that DPG tracks along with the temp)
what is in plasma?
91% water, 7% blood proteins, 2% electrolytes, nutrients, hormones
what is the hematocrit (HCT)? approx normal value?
the percentage of blood volume (RBC + plasma) that is occupied by RBCs. should be around 45%.
what is the Hgb? unit? how does it relate to the HCT?
amount of hgb in the blood, in g/dL should be approx 1/3 HCT since 1/3 RBC weight is hemoglobin.
how does the WHO define anemia?
Hgb < 12 g/dL in women
Hgb < 13 g/dL in men
what does MCV stand for? what does it mean? normal value?
mean corpuscular volume. means the size of an average RBC. normal = 80-100
how would I estimate whether an RBC is micro-, macro-, or normocytic?
compare it to the size of a lymphocyte nucleus. normocytic if approx the same size.
MCH stands for what? means what?
mean corpuscular hemoglobin. means the average MASS of hgb per single RBC.
MCHC stands for what? means what?
mean corpuscular hemoglobin concentration. menas the CONCENTRATION of hgb in a volume of packed RBCs
in what disease states would you see low MCH? high MCH?
Low: iron def, thalassemia
high: macrocytosis
in what disease states would you see low MCHC? high MCHC?
Low: iron def, thalassemia
high: hereditary spherocytosis
in a normal RBC, how big should the central dimple be?
about 1/3 of the cell
with a low MCH/MCHC what is the appearance of the RBC?
hypochromic. big donut hole
with a high MCH/MCHC what is the appearance of the RBC?
hyperchromic. no donut hole because cell has –> spheroid.
RDW stands for what? means what? high RDW is called what?
Red Cell distribution width.
indicates variation in RBC size.
high RDW is called anisocytosis.
what percent of RBCs in peripheral blood are reticulocytes?
should be around 1%
why are they called reticulocytes?
net-like structures of rRNA inside, visible under microscope.
what are 2 reasons your reticulocytes will increase?
response to hypoxia as sensed by the liver, or if you inject EPO.
what is polychromasia? what does it indicate?
presence of reticulocytes in peripheral smear. with Wright Geimsa stain they appear bluish/grey and slightly bigger than RBCs. indicates a shift of marrow retics into the periphery in response to stimulation (EPO)
What is the Reticulocyte Production Index? what does it tell us?
Reticulocyte retains its ribosomal network for 4 days, 3 in marrow, 1 in peripheral blood. RPI tells us if retics are exiting the marrow early and spending more time in peripheral blood. indication of bone marrow response to anemia.
what is the RPI value indicating adequate bone marrow response to a low HCT?
if HCT is low, RPI should be 2 or more for an adequate response from the bone marrow.
with a normal Hgb and HCT, what is a normal RPI?
1
what are a few physical exam findings that indicate anemia?
subconjuctival pallor, pale/cold skin, low BP, dizziness, lightheadedness, syncope, fatigue
describe a bone marrow aspirate?
semi liquid bone marrow, can be analyzed by flow cytometry, chromosome analysis or PCR
describe a bone marrow core?
cylindric solid piece of bone marrow, view w microscope to see cellularity and infiltrative processes
if you have anemia AND another cell line is also decreased (ie WBCs or platelets) what should you consider?
bone marrow biopsy. go where the money is!
what defines a microcytic anemia?
MCV < 80
what are a few microcytic anemias?
iron-deficient, anemia of chronic disease, sideroblastic, thalassemia
microcytosis indicates what about the hgb content of an RBC?
decr hgb content. small package, small contents!
most common cause of anemia globally?
iron deficiency.
factors contributing to iron deficiency anemia?
parasites
limited diet
poverty
majority of iron in the body is stored where? in what type of storage?
hemoglobin, liver. in ferritin (limo).
how much iron is in the plasma? in what type of storage?
very little in plasma, bound to transferrin (smart car).
ferritin exists within what cells?
macrophages of the liver, spleen.
how is iron homeostasis maintained? how do we bring iron into the body? how do we lose iron?
maintained at absorption point: duodenum.
lose iron via bleeding, desquamation. don’t have way to lose a lot of iron quickly, so maintain carefully at absorption point.
what molecule controls the absorption of iron in the duodenum? where is it made?
hepcidin.
made in liver.
two forms of iron in food? which is more bioavailable?
inorganic (Fe2+ or Fe3+) or as heme (complexed to protoporphyrin). latter is more bioavailable, exits in meat.
what will enhance absorption of iron?
Vit C
starting with absorption at the duodenum, what is the iron cycle?
Iron absorbed in duodenum, attached to transferrin in blood. Travels to bone marrow which takes it up to make RBCs. When RBCs die in spleen, spleen macrophages take iron and store it in ferritin. Some is also stored in liver ferritin. Hepcidin, made in liver, senses level of iron in liver and blocks absorption from duodenum if needed, & tells spleen macrophages to hold on to iron in their ferritin.
define transferrin. where is it found, what does it do?
major transport protein for iron in circulation. synth mainly in liver. can bind 2 irons.
define TIBC. what does it tell us?
total iron binding capacity. proxy for amount of transferring available (ie how many cars?)
define transferrin saturation. what does it tell us? normal value?
transferring saturation. how much of transferrin is bound to Fe. normally 20-50% full.
in an iron deficient state, what will happen to TIBC and transferrin saturation?
TIBC will go UP (more cars to try and scavenge any available iron)
TS will go DOWN (so many cars)
define ferritin. what is it used for?
main cellular storage protein for iron.
Serum ferritin measurement is the best test to det presence of iron deficiency.
what is the best test to det presence of iron deficiency.
serum ferritin measurement
causes of iron def anemia?
inadequate intake. inadequate absorption. gastritis, celiac, gastric resection. increased loss (bleeding). might be GI
Describe the Plummer Vinson syndrome. what are symptoms?
dysphagia, esophageal web, atrophic glossitis, koilonychia, angular cheilosis.
may also have pica, restless leg
what is koilonychia? see in what disease state?
spoon nails. seen in iron deficiency anemia
4 things you will see in a peripheral smear with iron deficiency anemia?
microcytes
hypochromism
anisocytosis (incr RDW)
poikilocytosis (varied shapes, pencil cells)
in the US, iron deficiency anemia in a patient over age 50 should be considered what?
colon cancer, until proven otherwise
sideroblastic anemia: what is their appearance?
erythroblasts accumulate iron in mitochondria without being able to produce adequate heme. cells are called sideroblasts. will find basophilic(blue) stippling in RBCs.
congenital sideroblastic anemia: what is the problem?
cannot make porphyrin and therefore cannot make heme. ALA synthase deficiency.
acquired sideroblastic anemia: some causes?
nutritional deficiency
drugs
alcohol
lead, zinc poisoning
what does lead to that contributes to anemia?
inhibits an enzyme in the porphyrin pathway. decr heme synthesis.
also inhibits globin synthesis.
causes accumulation of denatured RBA in RBCs, which yields basophilic stippling.
sideroblastic anemia: lab values. serum iron will be high or low? ferritin levels/ TIBC? TS?
serum iron high
ferritin high
TIBC normal or low
TS high
sideroblastic anemia: treatment?
rule out reversible causes (alcohol, other tixins)
try pyridoxine, folic acid (RBC precursors)
packed RBC transfusions
iron chelators (bind up excess iron)
lead poisoning: findings?
lead line on gums
neuro: motor neuropathy, abdominal pain, insomnia, irritability, psychosis
thalassemia: what is the problem?
quantitative disorder with insufficient production of alpha and beta globin chains.
what is an example of a qualitative disorder of Hb function?
sickle cell. hemoglobinopathies.
what test can you run to figure out someone’s hemoglobin composition?
serum electrophoresis. different globins will move different distances, can match up with known result.
how many alpha-globin genes do we have? what are the typical mutations?
have 4 genes. mutations are typically deletional. can survive with only 1 functioning alpha-globin gene
what is it called if all 4 alpha globin genes are mutated and nonfunctional?
hydrops faetalis
how many beta-globin genes do we have? what are the typical mutations?
we ahve 2 genes. mutations are typically point mutations. Bo = loss of globin synthesis. B+ = diminished fxn but not lost.
target cells indicate what?
beta-thalassemia
what is the genotype of thalassemia major?
Bo/Bo. both beta genes are nonfunctional. transfusion-dependent
what will we see on smear with thalassemia?
microcytosis, hypochromia, target cells
how do we diagnose thalassemia?
serum electrophoresis.
electrophoresis result with Major Thalassemia?
NO beta chains, so have no A1 type of globin. some A2 (since that is 2 alpha/2 delta). persistence of fetal Hgb.
Thalassemia Major: clinical features?
organs that can make hgb will continue to do so –> big bones of the skull, splenomegaly.
alpha thalassemia: what is the problem? how to diagnose?
problem is impaired production of alpha globin chains, results in EXCESS beta globin, which are toxic to the RBC skeleton.
diagnosis is by DNA analysis.
what type of thalassemia patients might require splenectomy?
Hgb H patients.
