RBC Hgb Disorders Flashcards
What are the three main broad causes of anemia?
- excessive blood loss: GI– ulcers, colon cancer, esophageal varices* (most rapid blood loss)
- excessive destruction: spleen, hemolytic anemia, sickle cell, thalassemias, enzyme deficiencies, membrane disorders
- deficient production: iron, B12, folate
What are the three main morphologic causes of anemia?
microcytic hypochromic (iron deficiency)
normocytic normochromic (Anemia of chronic disease)
Macrocytic normochromic (B12, folate anemia)
What are the three main etiologic causes of anemia?
- decreased production
- increased loss or destruction
- increased plasma volume
What is polycythemia? Types?
-a red cell abnormality characterized by too many RBC
Types:
- primary polycythemia (polycythemia vera)
- secondary polycythemia (altitude)
- benign erythrocytosis
When interpreting a CBC what do you look at first?
SIZE and then kinetics..
When trying to distinguish between destruction and production problem what lab value would you look into?
RETICULOCYTE!!!!!!!!!!!!!!!!!!!!!!!!!!!!
What is the life cycle of a red blood cell?
Stem cell to reticulocyte = 1wk
Reticulocyte to erythrocyte = 24-48hrs
*loses ribosomes, mito, and hgb.
*****This one is correct, forget what you learned in the previous deck.
When does a RBC accumulate Hgb?
during transformation between normoblast to reticulocyte.
What governs red cell production?
- erythropoiesis is governed by tissue oxygen needs, O2 content sensed by the kindey which produces EPO.
- any condition causing decreased in O2 transport in the blood produces an increase in RBC production.
Where is EPO made? How does it work?
- 90% kidney
- 10% liver
-promotes hgb synthesis, increases membrane proteins, and causes differentiation of erythroblasts.
What is most important function of erythrocyte?
-transport hgb
What factors influence O2 affinity for Hgb?
- pH
- CO2
- Temp
What structures make up hemoglobin?
- 2 alpha chains, 2 Beta chains
- 1 heme, iron, and O2 per chain.
What binds the O2 in hgb?
IRON!!
What makes up hemoglobin chain? (alpha or beta)
- heme + polypeptides
The rate of hgb synthesis depends upon what? Where is it stored?
the availability of iron.
- 80% bound to heme
- 20% stored in spleen, bone marrow, liver.
What test(s) would you order to see determine how much iron is stored in the liver or in the plasma?
- Liver: ferritin
- Plasma: transferrin
After 120 days of circulation the RBC is most likely to rupture where?
- in the trabecular network of the spleen.
- cells get fragile because their membrane lipids are decreased rendering them more susceptible for rupture in tight spots.
What happens to the contents of RBC’s after rupture?
- hgb is phagocytized by mfs (kuppfer, spleen, and bone marrow)
- mfs release iron from hgb and pass it back into the blood where its carried by TRANSFERRIN to either:
- bone marrow (new RBC)
- liver (storage in form of FERRITIN)
-porphyrin portion of hgb is converted to bilirubin which is released into the blood and later removed by secretion through the liver into the bile.
What is direct and indirect bilirubin?
direct= conjugated= plasma soluble (secreted in urine)
indirect=unconjugated=not plasma soluble, builds up in system resulting in jaundice.
What two hemoglobinopathies cause RBC hemolysis?
- abnormal substitution of an Amino Acid in the hgb molecule (valine for glutamic acid) (sickle cell anemia)
- defective synthesis of one of the polypeptide chains of hgb (thalassemias)
Sickle Cell Disease
- results from what?
- how do we acquire this disease?
- how might this disease manifest?
- affects what population most?
- point mutation in beta chain of hgb molecule, abnormal substitution of a single amino acid valine for glutamic acid.
- genetics; recessive inheritance
-sickle cell trait: heterozygous
or
-sickle cell disease: homozygous (2 HbS genes)
*concentration of HbS correlates with risk for sickling.
*person w/ sickle cell trait who has less HbS has little tendency to sickle except during severe hypoxia and is virtually asymptomatic.
-african americans
Pathophysiology of Sickle Cell Disease
- at low O2 HbS sickles, results in formation of elongated crystals inside the RBC. This makes it nearly impossible for RBC to pass through many small capillaries, spiked ends of crystals can also rupture membranes leading to sickle cell anemia.
- times of low O2: infection, cold, stress, physical exertion, acidosis
Why is sickle cell so common in africa?
-malaria resisitance
Sickle Cell disease manifestation
- pain and organ failure d/t vessel occlusion
- severe hemolytic anemia
- chronic hyperbilirubinemia (Jaundice)
- acute pain episodes anywhere: bones, joints, chest** (most common cause of mortality)
- infarction
- Acute Chest Syndrome: atypical pneumonia resulting from pulmonary infarction
- painful bone crisis from marrow infarcts of the bones of hands and feet.
- neurologic complications from vessel occlusion: stroke
- spleen damage (more susceptible to encapsulated organisms (streptococcus pneumo., H. Flu B, klebsiella
Acute Chest Syndrome
-describe the pathophys
- red cell sickling leading to pulmonary capillary vessel occlusion
- pulmonary infarction is associated with atypical pneuomonia
- pulmonary infiltrates (pus, blood, or protein) leading to SOB, fever, chest pain, and cough
- respiratory insufficiency w/ hypoxia leading to even greater sickling. (organ failure)
***leading cause of death in sickle cell disease
Sickle Cell Disease
- Dx & screening
- management
- tx
-prenatal dx done by analysis of fetal DNA via amniocentesis
management:
- no cure
- avoid situations that precipitate sickling
Treatment:
- pain control
- hydration
- manage complications:
- agressive tx of infections
- -blood transfusion
- prophylactic care – penicillin and immunizations during 1st 3 years of life because of high risk of morbidity/mortality of encapsulated organisms.
- -hydroxyurea: sythesizes more HbF and less HbS decreasing sickling.
Thalassemia
- caused by?
- manifests as what type of anemia?
- types?
- Caused by absent or defective synthesis of alpha or beta chains of adult hgb
- hypochromic microcytic anemia
- alpha and beta thalassemia
- in alpha thalassemia there is impaired production of alpha globin chains»>excess beta globin chains. Vice versa for Beta.
Thalassemia
- how does anemia occur?
- how does this affect hgb function?
- imbalance in globin chain production leads to deficient hgb synthesis
- thereby lowering hgb’s oxygen carrying capacity.
Where are Beta thalassemias most common? alpha?
Beta: common in mediterranean populations in itally and greece
Alpha: Asians
BOTH are common in africans
Which type of thalassemia would you expect to see hienz bodies in?
Beta thalassemia
What are the possible types of gene deletions of alpha thalassemia?
-snythesis is controlled by?
1 gene deletion: silent carrier, asymptomatic
2 gene deletion: mild hemolytic anemia, show trait
3 gene deletion: chronic moderate hemolytic anemia, HbH (unstable aggregates of Beta chains)
4 gene deletions: Hydrops fetalis (Hb Barts) has extremely high o2 affinity, cannot release O2 to tissues, incompatible with life. alpha chains get replaced by gamma chains which have a very high affinity for O2.
-synthesis is controlled by two PAIRS of genes.
What are the possible types of gene deletions in beta thalessemia?
Minor: one normal gene in heterozygous person, increased HbA2/HbF
Major: 2 beta genes, severe, failure to thrive, sig HbF
*spelnomegaly, hepatomegaly, iron overload, chipmunck facies?
What is the most prevalent form of thalassemias?
beta thamalassemia trait/minor, increased hgb A2 and HbF
Majority of the time a microcytic anemia will be caused by?
-iron deficiency
What specific lab tests help you to suspect a thalassemia?
- low or normal RDW (b/c all the hgb chains are made equally incorrect)
- decreased RBC count
- normal ferritin
What would a RDW in the normal range suggest?
-a homogeneous population of cells, either all normal or all abnormal.
Would you expect high, normal, or low values of RDW and MCV for the following diseases:
- thalassemia
- iron deficiency anemia
T- low MCV and Normal RDW
I- low MCV and high RDW
What is G6PD?
WHat is G6PD deficiency?
How is this aquired?
Triggers
- it is an enzyme that protects RBC from damage
- RBC deficient of G6PD are unable to maintain Hgb in reduced state» hgb becomes nonfunctional and is easily denatured leading to hemolysis. * condition is episodic.
- inherited. Gene for G6PD is X-linked, only males have this
Triggers:
- sulfonamides, ASA, chemo, etc.
- mediterranean descent.
What may be the dx of a young male who has hemolytic anemia just after taking a medication?
G6PD deficiency
**PANCE?
Examples of potential causes of Aquired Hemolytic Anemia
- Membrane destruction or Aby-mediated lysis
- mechanical factors - heart valve
- obstructions: TTP, DIC, glomerulonephritis, microvasculature*
- infections, drugs, chemicals, toxins, venom.
- the cell is fine, its just being tagged or affected by some other source that is causing destruction
Describe CO binding affinity to Hgb compared to that of O2.
CO binds to hgb with a much greater affinity than O2 forming carboxyhgb (COHb) resulting in impaired O2 transport and utilization. it diminishes the ability of the other three O2 binding sits to off load O2 to peripheral tissues.
The degree of COHb is a function of the relative amounts of CO and O2 in the environment, duration of exposure, and minute ventilation.
Sx of someone with CO poisoning?
sleepy, fatigue, HA
wake up in morning w/ horrible HA and fatigued
Lead
- stored where?
- eliminated where?
-85% stored in bone, 5-10% in blood and the rest in soft tissue
Lead Toxicity is related to many biochemical effects, what are these?
- inactivates enzymes
- competes with Ca for incorporation into bone
- interferes with nerve transmission and brain development
What are the major targets of Lead toxicity?
- RBC
- GI tract (will complain of GI sx)
- Kidneys
- Nervous system (long term problems)
What is the cardinal sign of lead toxicity?
- ANEMIA!!!! will look like iron deficiency.
- -lead competes w/ enzymes required for hgb synthesis
- -resulting BRC are MICROCYTIC and HYPOCHROMIC
- -basophilic stippling seen on blood smear
- RBC lifespan decreased
What does the peripheral blood smear of lead toxicity look like?
- RBC smaller than normal (microcytic)
- increased zone of central pallor (hypochromic)
- small dots in periphery that are common for scraps of RNA
When is it important to screen for lead?
1 and 2 years old!!
Lead Toxicity Signs and Symptoms
- GI tract is main source of sx: lead colic= severe poorly localized acute abd pain
- Lead line: metaphysis of long bones of growing children. (caused by disruption of calcium metab)
- Diffuse kidney damage: major route of excertion, lead exposure can lead to renal failure, HTN may be early sign
- gingival margins in adults
- Nervous system: demyelination of cerebral and cerebellar white matter and death of cortical cells, can affect neurobehavioral development in kids (IQ class room performance), peripheral demyelinating neuropathy in adults.
- -Acute encephalopathy: vomiting, ataxia, seizures, papilledema, impaired conciousness, coma.
Normal level of lead in kids?
Normal level is 5ug/dL, if lower than 5 check CBC for sign of anemia, if no sign of anemia than leave it alone.
What are next steps in dx of child with positive lead toxicity?
get blood smear to identiry microcytic hypochromic anemia
- chemistry profile
- capillary blood to measure erythrocyte protoporphryin (EP) – elevated levels result from inhibition by lead of the ezymes require for heme synthesis in RBC.
Tx of Lead toxicity
- remove lead source
- chelating agents, make lead non-toxic and can then be excreted
- Asymptomatic children with blood lead levels of 45-69ug/dL usually treated with:
- D-penicillamine
- succimer
- Dimercaprol
- edetate disodium calcium
How does acidosis affect the RBC?
- it reduces the affinity of Hgb for O2
- results in more deoxygenated hgb
*body pH 7.35-7.45
If thinking anemia what are you some of the first things you will look for in your laboratoryy tests?
look at reticulocyte count, size, shape, and color.
Common places for bone marrow biopsy?
sternum or illiac crest
What is normochromic anemia?
-conc of hgb in cell is normal, there are not enough RBC though.
Aplastic, post hemorrhagic, hemolytic anemias, anemia of chronic disease
What is normocytic anemia?
-most frequent
- MCV isnormal
- Hgb and HCT are decreased: decerased production of RBC, increased HgS, increased destruction, increase in plasma volume, B2 and B6 deficiency
What is Hypochromic Anemia
Red blood cells are pale
increased central pallor
RBC are usually small
- Fe deficient anemia and thalassemia
What is Microcytic Anemia
small RBC
MCV decreased
MCHC decreased
Fe deficiency anemia and Thalassemia
What is Macrocytic Anemia
RBC are large
Hgb low
Folate, B12, Codocytes (target cells)
What is Anisocytosis?
RBC of unequal size
RDW high
Fe deficiency anemia and thalassemia
What is Poikilocytosis?
- abnormal shaped RBC
- flattened disks that are thinner in the middle than the edges
- abnormal if make up >10%
- membrane abnormalities and truama
Polycythemia (Erythrocytosis), what is this?
too many RBC in plasma:
either increased RBC “absolute” or decreased plasma “relative”.
- Bone marrow problem (myeloproliferataive)
- Malignancy
- Low O2 (COPD)
- Polycythemia vera (bone marrow produces too many RBC)
- Secondary: increased EPO (normal adaptation to higher altitudes)
