Red Blood Cell Disorders

Question 1

What is hematopoiesis - and what sites produce RBC

Answer 1

Creation of RBCs and as a fetus occurs in the the spleen, LNs and liver, moves into bone marrow and is produced there from birth and in adulthood.

Question 2

Approach to anemia

Answer 2

Macrocyctic (High MCV) - B12/folate deficiency, drug induced, liver disease, hypothyroidism
Microcytic (Low MCV) - Thalassemia, chronic disease, iron deficiency, lead pointing, sideroblastic
Normocytic (normal MCV) - bleeding/ hemolysis (high reticulocytes), aplastic, renal disease, leukaemia (low reticulocytes)

Question 3

How do the kidneys regulate RBCs?

Answer 3

EPO - kidney senses low O2 and releases EPO from HIF2Alpha, if kidney damage will have anemia

Question 4

Mechanism of coagulation

Answer 4

Vasoconstriction, Primary hemostasis - platelet aggregation (VWF), secondary hemostasis (formation for platelet clot - fibrin clot formation - cross linking), fibrinolysis

Question 5

Order of the clotting cascade?

Answer 5

12.
   11. 
      9.      7 
        8.   3
        10 
          5
          2
          1

7 is the extrinsic pathway, 12 is the intrinsic, Fibrin is activated factor 13 which is activated by the common pathway, and factor 10 activates thrombin

Question 6

Mechanism of clot break down

Answer 6

TPA converts plain which cuts up the fibrin mesh, and healthy cells actually secrete things to prevent breakdown
D- dimer is the breakdown products

Question 7

Vitamin K dependant clotting factors?

Answer 7

2, 7, 9, 10 - needed to convert to functional form, produced by gut bacteria and found in diet. Warfarin stops recycling vitamin K

Question 8

When to transfuse blood

Answer 8

Hbg <70 and symptomatic, consider if hemodynamically stable

Question 9

Iron supplementation?

Answer 9

Ferrous gluconate is the preferred supplementation - ideally three times a day. But it not tolerated very well.

IV - people will get a reaction, just order Benadryl in advance.

Question 10

What does ferritin indicate? What is the TIBC?

Answer 10

Serum ferritin - indicated level of iron stores - low = iron deficiency, high can be an inflammatory marker

TIBC - indirect measure of transferrin (transporter that allows for cellular storage)

Question 11

Reason for anemia in CKD?

Answer 11

Decreased EPO.

Question 12

Signs and Sx of anemia

Answer 12

Pallor, fatigue, tachycardia, nail changes, glossitis

Question 13

How do you test for hemolytic disease of the newborn?

Answer 13

direct coombs

Question 14

What is HUS? And what is it caused by?

Answer 14

Hemolysis due to shiga toxin (e.coli) - most common cause

Will present with AKI, bloody diarrhea, weakness, fatigue

Question 15

What causes TTP?

Answer 15

Deficiency of ADAMTS13, clotting in small vessels leading to low platelet count. Results from excessive vWF on platelets

Question 16

Abnormally high Hb?

Answer 16

Consider polycythemia Vera, could be secondary to COPD/ pulmonary fibrosis, kidney disease, dehydration, smoking (CO exposure), hypoxia (adaptive response to high altitudes), EPO/ synthetic supplementation.

Question 17

Hemochromatosis?

Answer 17

Too much iron in body.

Question 18

Risk of transfusions?

Answer 18

Autoimmune rxn, possible infection from blood borne illness, volume overload, hyperkalemia, iron overload

Question 19

How does endothelial injury trigger clotting?

Answer 19

Exposure of of VWF and collagen, combined with decreased release of NO and PG will trigger platelet and immune recruitment. VWF will trigger platelet binding. Fibrogen will bind the platelets together and get cleaved to fibrin to form a mesh. This process is mediated by the clotting cascade.

Question 20

Microcytic anemia?

Answer 20

TAILS

Thalassemia, Anemia of chronic disease, Iron deficiency, Lead intoxication and Sideroblastic anemia

Question 21

Normocytic anemia

Answer 21

Hemorrhage
Hypoxia
Hemolysis

Question 22

Macrocytic anemia?

Answer 22

B12 and folate, liver disease, thyroid dysfunction, aplastic anemia