Intro to Anemia

Question 1

what is a normal range of RBC per CBC? what about reticulocytes?

Answer 1

RBC: 4.5-6 million/uL

reticulocytes: 1-2%

Question 2

what is a normal range of hemoglobin and hematocrit per CBC?

Answer 2

hemoglobin: 12-18 g/100mL

hematocrit: 38-48% (portion of total blood volume that is made of RBCs)

(anemia is 30% hematocrit or less)

Question 3

the flexible biconcave disk of RBC depends on which two structural proteins?

Answer 3

spectrin + ankyrin

Question 4

specialized RBC metabolism generates 2,3BPG via _______ and NADPH via ______

Answer 4

anaerobic glycolysis —> 2,3BPG (regulates hemoglobin-O2 binding)

hexose monophosphate shunt —> NADPH (defends against oxidative stress)

Question 5

iron must be in _____ state to bind oxygen in hemoglobin

Answer 5

reduced state - Fe2+ (ferrous)

ferric (Fe3+) iron cannot bind oxygen and makes methemoglobin

Question 6

how would dehydration affect CBC measurements of hemoglobin and hematocrit?

Answer 6

dehydration or other changes in plasma volume can artificially increase or decrease RBC laboratory measurements - measurements are concentration dependent

Question 7

oxygen delivery to tissues is determined by what 2 factors?

Answer 7

oxygen in arterial blood (1) x cardiac output (2) = O2 delivery

Question 8

oxygen travels through blood in 2 ways:

Answer 8

1. bound to hemoglobin in RBC
   (~19.7mL O2/dL)
2. dissolved in plasma
   (~0.3mL O2/dL)

amount of oxygen dissolved in blood is not enough - need hemoglobin to be functioning

Question 9

explain why anemia causes an increase in cardiac output

Answer 9

O2 delivery = CO x O2 content in blood

anemia is a decrease in O2 delivery due to decreased hemoglobin and/or hematocrit

body compensates by increasing cardiac output —> increase heart rate (tachycardia), contractility of the heart

Question 10

how does anemia affect blood viscosity, and what is the effect of this?

Answer 10

decrease RBC mass (hematocrit) decreases blood viscosity (makes blood “thin”) —> decreased resistance —> blood flow increases

increased blood flow may manifest heart murmur due to turbulence

Question 11

what are the general symptoms of decreased oxygen delivery (no matter the cause) (5)

Answer 11

1. fatigue
2. weakness
3. dyspnea (SOB)
4. light-headed
5. palpitations (can feel their heart beating in their chest)

Question 12

severe anemia can cause this cardiovascular symptom:

Answer 12

angina, due to decreased oxygen delivery to the heart

Question 13

why does anemia cause change in skin tone or conjunctival pallor?

Answer 13

blood is diverted away from the skin (smaller capillary beds)

extremities may feel more cool

Question 14

the first question to ask in determining the cause of anemia is whether ONLY RBC are low or ALL CELL COUNTS are reduced. In the latter, this would be called….

Answer 14

pancytopenia: all cell counts are low

this has a distinct differential than anemia

Question 15

RBC mass is maintained by renal production of _____

Answer 15

erythropoietin (EPO)

cells that make erythropoietin are very sensitive to oxygen levels in blood, and erythropoietin production increases exponentially with drop in tissue oxygen concentration

Question 16

if a patient is anemia, which 2 parameters should BOTH INCREASE

Answer 16

1. erythropoietin levels (cells producing are very sensitive to oxygen in tissues)
2. RBC synthesis (in bone marrow, affected by erythropoietin)

Question 17

an important question to ask in diagnosing anemia is whether new RBC are being made (production or destruction problem?)

how can you detect newly produced RBC?

Answer 17

reticulocyte count - new RBC released from bone marrow, larger than mature RBC, still have visible ribosomes (can be identified by detection of rRNA)

can be absolute number or percentage (1-2%)

note that % reticulocyte must be corrected for anemia so it does not give false appearance of increase

Question 18

if it is determined that a patient has anemia, with a corrected reticulocyte % count, what would the following 2 results mean?
a. 1-2% reticulocytes
b. 3-5 fold increase in reticulocytes

Answer 18

a. 1-2% reticulocytes is normal, so production problem

b. 3-5 fold increase is indicative of RBC destruction problem