Alterations of Erythrocyte Function Flashcards
anemia =
a reduction in the total circulating red cell mass or a decrease in the quality or quantity of hemoglobin
too many RBCs is called
polycythemia
normal RBC count; normal HGB
HGB: 12-18g/dL
RBCs: 4.2-6.1 x 10^6 /mcl
Excessive destruction of RBCs caused by two types of hemolysis…
HEREDITARY HEMOLYSIS - sickle cell trait or disease
ACQUIRED HEMOLYSIS :
- immune reaction (blood transfusion)
- infection (malaria, clostridial)
- drugs (quinidine, PCN, methyldopa)
- liver or kidney disease
- toxins (chemical, venoms)
Classifications of anemia include 3 things?
-ETIOLOGIC FACTOR (cause) - ex. iron-deficient
-SIZE:
.Identified by terms that end in -CYTIC
.macrocytic (large), microcytic (small), normocytic (normal)
-HEMOGLOBIN CONTENT
.identified by terms that end in -CHROMIC
.normochromic (normal amount), hypochromic (decreased amount)
RBCs are present in various sizes
ANISOCYTOSIS
RBCs are present in various shapes
POIKILOCYTOSIS
Classic symptoms of anemia?
fatigue, weakness, dyspnea, elevated HR, pallor - remember organ dysfunction can also occur
Normal hgb males; normal hgb females
M = 13-17 F= 12-15
HCT levels M & F?
M - 41-50%
F - 35-46%
characterized by RBCs that are abnormally small and contain reduced amounts of Hgb
microcytic-hypochromic anemias
Most common microcytic-hypochromic anemia worldwide?
iron-deficiency anemia (IDA)
Highest risk for IDA? Associated with what in children? Causes?
Risk: older adults, women, infants, and those living in poverty
Children: cognitive impairment
Causes: inadequate diet, blood loss, chronic parasite infection, metabolic or functional iron deficiency, menorrhagia
Most common PHYSIOLOGIC CAUSE of IDA?
menstruation - normal menstrual flow = 50mL but can vary by 5x
Woman with increased menstrual loss require increased intake _________/day which equals dietary consumption of _______
3-4mg/day which equals dietary consumption of 30-40mg/day
For MEN AND POSTMENOPAUSAL WOMEN, IRON DEFICIENT ANEMIA IS A GOOD INDICATOR of what?
MALIGNANCY
10-17% will be from malignancy
*older age, male, elevated LDH, low ferritin
(LDH indicates tissue damage)
Most common pathophysiologic cause of IDA?
GI bleed
Protein that STORES IRON. Where is it produced? Where is most of it found? Small amounts where?
FERRITIN - produced in the intestines, but found mostly in the liver, spleen, and bone. Small amount circulates in the blood.
What is the MOST SENSITIVE TEST FOR IDA?
ferritin levels
TRANSPORTS IRON IN THE BLOOD
TRANSFERRIN
*delivers iron from absorption centers (duodenum, macrophages) to tissues
How is iron saturation of transferrin measured? Direct or indirect?
TYPICALLY MEASURED INDIRECTLY BY ASSESSING THE TOTAL IRON BINDING CAPACITY (TIBC)
MEASURE OF AVAILABLE TRANSFERRIN THAT IS LEFT UNBOUND TO IRON
WHAT IS CONSIDERED HIGH?
*see slide 12-13
TOTAL IRON BINDING CAPACITY (TIBC)
LOW TRANSFERRIN THAT IS ACTUALLY SATURATED WITH IRON = HIGH TIBC (meaning that not much transferrin is actually saturated)
*THIS MEANS THERE IS MORE CAPACITY TO BIND OR HIGH TOTAL IRON BINDING CAPACITY
In iron deficiency anemia is the ferritin high or low?
What would happen to the total iron binding capacity in iron deficiency?
ferritin is low (classic test for IDA)
TIBC is high or increased b/c the liver produces more transferrin b/c it’s trying to maximize whatever iron is there to be delivered to the tissues that need it.
This means there are more binding sites for iron
Increased transferrin total, but decreased transferrin saturation = high TIBC
Diagnostic manifestations of IDA?
VALUES: MCV, MCH, RDW, FERRITIN, NORMAL SERUM IRON?, TIBC?
Reticulocyte count?
- low MCV = microcytic
- low MCH = hypochromic
- high RDW >15
- Low INITIAL reticulocyte count
- Elevated reticulocyte count once tx and supplementation with iron begins (can be high after tx)
- FERRITIN LOW
- LOW SERUM IRON (NORMAL 50-75MCG/DL)
- TIBC HIGH (MEANING THAT TRANSFERRIN SATURATION IS DECREASED)
Moderate anemia hgb level is?
7-11: mod s/s
s/s of IDA
palpitations, dyspnea, exercise intolerance, angular stomatitis, pallor, Koilonychia (spoon nails), pica
severe IDA hgb less than and s/s
7 - s/s postural hypotension, dizziness, weak, gastritis, paresthesias, lethargy
caused by a DEFECT IN MITOCHONDRIAL HEME SYNTHESIS - what type of anemia? and what does it show on smear - type of RBCs?
SIDEROBLASTIC ANEMIA, which is a microcytic-hypochromic anemia
what causes sideroblastic anemia? how is it diagnosed?
altered mitochondrial metabolism causes ineffective iron uptake and results in DYSFUNCTIONAL HEMOGLOBIN SYNTHESIS
- intracellular iron accumulates
- can be d/t ETOH abuse, lead poisoning
- ringed sideroblasts found in the BM are diagnostic (RBC w/iron granules that have not be synthesized into hgb)
Autosomal recessive blood disorder that causes MICROCYTIC HYPOCHROMIC anemia
THALASSEMIA
what diagnostic test tests for thalassemia?
diagnostic test is hgb electrophoresis
what is thalassemia characterized by? and what does it result from?
what does this cause?
characterized by ABNORMAL FORMATION OF HGB
results from a MUTATION THAT CAUSES LOSS OF ONE OR BOTH OF ALPHA GLOBIN CHAINS OR ONE OR BOTH OF BETA GLOBIN CHAINS
abnormal hgb formed results in IMPROPER OXYGEN TRANSPORT AND DESTRUCTION OF RBCS; RESULT IN ANEMIA
what kind of anemia results from thalassemia? what does it look like? what kind of complications? what might be seen?
MICROCYTIC HYPOCHROMIC (low MCV, low MCHC)
TARGET CELLS may be seen
complications include iron overload - bone deformities, and CV illness.
*possible protection from malaria
see chart slide 20 - IDA vs thalassemia
ferritin level? serum iron? TIBC? MCHC? hgb electrophoresis? ethnic background?
…
clinical features of sideroblastic anemia? hct? MCV? serum iron? transferrin saturation high or low?
- hct - 20-30%
- MCV usually normal, can be increased or decreased
- serum iron is elevated
- transferrin saturation is high - meaning that TIBC is lower (normal or borderline is what chart says)
can cause iron overload (hemochromatosis) or enlarged spleen and liver
what are the megaloblastic anemias? Macrocytic-normochromic
folate, B12 deficiency, poisons, some antiviral drugs and some chemo
What causes macrocytic-normochromic (megaloblastic) anemias?
PATHO: DEOXYRIBONUCLEIC ACID (DNA) SYNTHESIS IS DEFECTIVE DUE TO DEFICIENCIES IN VITAMIN B12 OR FOLATE
RBCs do not form sufficiently and are released prematurely
Vitamin B12 (cobalamin) comes from? And what does it do in the body - 3 things?
-all b12 comes from diet: flies, walks, swims
FUNCTIONS:
- KEEPS NERVOUS SYSTEM FUNCTIONING PROPERLY
- NECESSARY IN THE FORMATION OF BLOOD
- INVOLVED IN METABOLISM OF EVERY CELL BUT ESPECIALLY AFFECTING DNA SYNTHESIS AND REGULATION
Where is B12 stored?
stored in liver - 2000 to 5000mcg and can take up to 3 years to deplete
very unusual to develop B12 deficiency due to diet except if a strict vegetarian
Lab findings in B12 cabalamin deficiency?
MCV? MCH? Peripheral blood smear? Reticulocyte count? BM?
- MCV is usually very high
- MCH is normal
- Peripheral blood smear: anisocytosis (RBCs are unequal in size), poikilocytosis (RBCs are different shapes), macro-ovalocyte (enlarged, oval shape RBC), HYPERSEGMENTED NEUTROPHILS
- low reticulocyte count initially, and then increases after supplementation occurs
- can see pancytopenia if severe
The most common type of macrocytic normochromic anemia that is CAUSED BY A VITAMIN B12 DEFICIENCY? what causes this?
PERNICIOUS ANEMIA
LACKS INTRINSIC FACTOR FROM THE GASTRIC PARIETAL CELLS
REQUIRED FOR VITAMIN B12 ABSORPTION
PERNICIOUS ANEMIA COULD BE D/T A ________ OR _______ DISORDER
CONGENITAL OR AUTOIMMUNE
*AUTOANTIBODIES AGAINST INTRINSIC FACTOR WHICH IS RELEASED FROM PARIETAL CELLS in the fundus of the stomach (antiparietal antibodies)
clinical manifestations of pernicious anemia
THREE MOST IMPORTANT?
weakness, fatigue, PARESTHESIAS of the feet and fingers, loss of appetite, abdominal pains, wt loss, sore tongue that is smooth and beefy red secondary to ATROPHIC GLOSSITIS, “LEMON YELLOW” SALLOW skin as a result of a combination of pallor and icterus…
*yellow skin d/t weak RBCs that break down more quickly which causes release of bilirubin by the liver
neurologic symptoms from nerve demyelination - ataxia, decreased or lack of DTRs, pathological reflexes; babinski’s, severe paresis (NOT reversible even with tx)
Schilling Test
Testing:
▪ Schilling test: localized site of pathology of the B12 deficiency
▪ Give IM B12, PO radioactive B12 – normal pt’s with extrinsic factor should absorb radioactive B12 and excrete in urine because the receptors would be saturated with IM B12; if there is a problem with the intrinsic factor then it will not be present in the urine; test is repeated and exogenous intrinsic factor is given
*remember that without intrinsic factor B12 can not be absorbed into the bloodstream, hence it would never make it to the kidneys to be excreted
Folate (folic acid) deficiency anemia
What is folate required for?
Where does absorption occur?
Common in what population?
Associated with?
- Folate is an essential vitamin for RNA & DNA synthesis
- absorption of folate occurs in the upper SI, and is not dependent on any other factor
- is common in alcoholics and people with chronic malnourishment
- associated with neural tube defects of the fetus
In what foods do you find folic acid? What is the daily requirement? Most common cause of deficiency?
fruits & veggies (esp citrus fruits + leafy greens)
Daily requirement 50-100mcg
Most common cause of deficiency = diet
-alcoholics, anorexics, overcooked foods, diets that exclude fruits/veg