Red Blood Cell Disorders: Background

Question 1

What do RBCs do?

Answer 1

Transport oxygen, CO2, CO, and HN03 (nitric acid) gases for exchange

Via the protein hemoglobin

Question 2

Anemia definition

Answer 2

Low hemoglobin, RBC count, or hematocrit

Question 3

Hematocrit definition

Answer 3

the % of RBCs

total blood volume

Question 4

Polycythemia definition

Answer 4

elevated Hbg, RBC count, or hematocrit

Question 5

What tests do you first use to assess for RBC disorders?

Answer 5

CBC

peripheral smear

Question 6

What does a peripheral smear test?

Answer 6

morphology of RBCs

Question 7

Where are RBCs made?

Answer 7

bone marrow stem cells

Question 8

what hormone drives RBC production?

Answer 8

erythropoeitin (epo)

Question 9

What organ secretes epo?

Answer 9

kidney

Question 10

What items in our diet are needed to supply the bone marrow?

Answer 10

iron

folic acid

vitamin B12

protein

Question 11

Life cycle of a RBC

Answer 11

1. In bone marrow w/ nuclei
2. Nuclei get extruded after all the Hgb is made
3. RBC leaves the bone marrow w/ some RNA (this RNA stains as a reticulocyte)
4. The reticulocyte matures into an RBC in 2 days
5. This RBC circulates in the blood for 120 days

Question 12

What does the reticulocyte count measure?

Answer 12

how the bone marrow is responding to a decrease in RBCs

Question 13

How is reticulocyte count measured? (fraction)

Answer 13

raw reticulocyte count x patient Hgb

normal Hgb

Question 14

What percentage of reticulocyte count indicates the bone marrow is working?

Answer 14

greater than 3%

Question 15

What happens to RBCs after 120 days?

Answer 15

They are hemolyzed in the spleen, and Hgb is degraded into heme and globin.

Heme –> indirect bilirubin; transported to liver to become direct bilirubin

This gets stored in the gall bladder

Question 16

What could high levels of indirect bilirubin indicate?

Answer 16

hemolysis or hereditary Gilbert syndrome

Question 17

What could high indirect bilirubin PLUS high corrected reticulocyte, high LDH, and hemoglobinuria point to?

Answer 17

hemolysis

Question 18

Hemoglobin definition

Answer 18

protein composed of different amino acid chains (alpha, beta, delta, gamma)

has 4 iron-containing heme groups

Question 19

What types of Hgb are in everyone’s RBCs?

Answer 19

Hgb A, F, and A₂

Question 20

What Hgb is predominant in utero?

Answer 20

F

Question 21

What Hgb is most dominant after birth?

Answer 21

A

Question 22

What can decreased alpha- or beta-chain production cause?

Answer 22

thalassemia (alpha and beta types)

Question 23

What is the most common hemoglobinopathy?

Answer 23

sickle hemoglobin (Hgb S)

Question 24

What lab tests can be used to identify hemoglobinopathies?

Answer 24

hemoglobin electrophoresis

isoelectric focusing (IEF)

high-performance liquid chromatography (HPLC)

capillary zone electrophoresis (CZE)

Question 25

What causes a hypocoagulable state?

Answer 25

platelet deficiency factor deficiency (clotting factors, vWF, Vit K)

Question 26

What causes a hypercoagulable state?

Answer 26

excess platelets deficiency of anti-thrombotic proteins (protein C, protein S)

Question 27

How do platelet problems usually manifest?

Answer 27

excessive/repetitive bleeding, bruising, or bleeding @ unusual sites

Question 28

How do platelet problems & vWD present?

Answer 28

skin petechiae, bruising, increased mucosal bleeding (epistaxis, gums, menorrhagia)

Question 29

How do coagulation defects typically present?

Answer 29

(e.g. hemophilia) hemarthroses and deep tissue hematomas

Question 30

What diagnostic studies are usually used for coagulation disorders?

Answer 30

CBC with platelet count, peripheral smear, and PFA (for ID and quantifying cellular changes) PT (extrinsic clotting pathway) or INR PTT (intrinsic clotting pathway) TT (if either PT or PTT is prolonged) metabolic profile (liver and kidney fn) D-dimer (detects thrombosis)

Question 31

What is the intrinsic clotting pathway?

Answer 31

indicates when there is damage **inside** a blood vessel feeds into the common pathway (factors X, V, II)

Question 32

What is the extrinsic clotting pathway?

Answer 32

indicates there is a **tissue injury** (outside the blood vessel) feeds into the common pathway (X, V, II)

Question 33

What does PT tell?

Answer 33

examines how long clotting takes in the **ex****trinsic** pathway, or common pathway (Factors **VII**, X, V, II)

Question 34

What does PTT tell?

Answer 34

examines how long clotting takes in the **in****trinsic** pathway, or common pathway (Factors XII, XI, **IX**, **VIII**, X, V II)

Question 35

Which clotting factors work with Vitamin K?

Answer 35

II, **VII, IX,** X

Question 36

Which lab value measures the effect of Coumadin? (which affects the Vit. K dependent factors)

Answer 36

PT

Question 37

Which lab values tell you about Heparin's effect? (which increases antithrombin III activity)

Answer 37

PPT