red cell disorders (clinical)

Question 1

anemia

Answer 1

• total # of RBCs are reduced –> lower O2 carrying capacity
• measured with Hb, hematocrit, MCV, RBC count etc.
• SYMPTOM of a disease, need to find the underlying cause**

Question 2

values

Answer 2

• Hb concentration - men (15.8), women (13.8)
• hematocrit % - men (46), women (40)
• MCV (average size of RBC) - men/women (88)
• MCH, MCHC (how much Hb in cell) - men/women (30 MCH), (34 MCHC)
• RDW (variety in size) - men/women (13)

Question 3

erythropoiesis

Answer 3

• RBC production that takes 3 weeks
• EPO from the kidney –> stimulate bone marrow to produce RBCs
• EPO dependent 1st 2 weeks
• Fe dependent last week

Question 4

RBC recycling

Answer 4

• degrading RBCs by macrophages in spleen after 120 days
• RBC components like Hb recycled
• Fe transported to liver by transferrin, stored as ferritin (hemosiderin in excess)
• bilirubin further metabolized

Question 5

Hb molecule

Answer 5

-porphyrin ring, Fe, 2 alpha and beta chains

Question 6

Fe metabolism

Answer 6

• 10mg absorbed every day by duodenum, 1-2mg are lost due to skin exfoliation
• most Fe in circulation –> bone marrow to make RBCs
• rest of Fe stored in liver as ferritin
• EPO increases Fe absorption

Question 7

hypovolemia and hypervolemia

Answer 7

• can change the parameters since most are measured on [] (Hb changes with changing volume)
• may look anemic on #s, but may not be and vice versa

Question 8

mechanisms to compensate for anemia and low O2

Answer 8

• increase CO (can lead to heart failure)

- increase O2 unloading at the tissues

Question 9

3 ways anemia can develop

Answer 9

• blood loss
• underproduction of RBC
• increased destruction of RBC

Question 10

blood loss

Answer 10

• not always obvious –> could be slow as in gastric ulcer or prolonged menstrual bleeding
• blood loss = Hb loss = Fe loss –> leads to decreased RBC production when stores depleted

Question 11

decreased RBC production

Answer 11

• production is lower than loss (bone marrow cannot compensate)
• measure reticulocyte count (>3% with healthy marrow)
• cause: low Fe, B12, marrow disorders or suppression, low levels of EPO or thyroid hormone

Question 12

ineffective erythropoiesis

Answer 12

• hyperactive marrow but immature production of RBCs

- cause: B12/folate deficiency, myelodysplastic syndromes, thalessemias, sideroblastic anemia

Question 13

increased RBC destruction

Answer 13

• destruction of RBC earlier than 100 days –> hemolysis
• enlarged liver or spleen
• due to hypersplenism or hemolytic anemia (inherited or acquired)
• high LDH and bilirubin (jaundice), reduced haptoglobin, hemoglobinuria (dark urine due to indirect Hb)
• heme –> biliverdin –> Fe

Question 14

haptoglobin**

Answer 14

• protein produced by liver –> binds free Hb in circulation
• prevents loss of Fe and toxic effects of Fe
• low in anemia bc it is binding all the free Hb (<25mg/dL)**

Question 15

what does low Hb/HCT with minimal to no symptoms mean?

Answer 15

anemia is slow and chronic

-want a reticulocyte count

Question 16

low WBC count

Answer 16

-aplastic anemia or marrow replacement with fibrosis

Question 17

high WBC count

Answer 17

-infectious process, leukemia

Question 18

low platelet count

Answer 18

-aplastic anemia, hypersplenism, TMA

Question 19

high platelet count

Answer 19

-Fe deficiency, inflammation, infection

Question 20

WBC with B12/folate deficiency

Answer 20

-hypersegmented neutrophils with impaired DNA synthesis

Question 21

reticulocyte production index (RPI)**

Answer 21

• index adjusts for level of anemia and reticulocyte maturation time**
• cannot judge the function of bone marrow by looking at absolute or % of reticulocyte count
• sever anemia –> reticulocyte count high with marrow trying to compensate**

Question 22

Fe deficiency anemia

Answer 22

• cause: reduced absorption, blood loss, hemosiderosis (Fe stored elsewhere)
• microcytic anemia, pica/ice craving, restless leg, glossitis

Question 23

anemia of chronic disease

Answer 23

• infection, inflammation (cytokines), malignancy
• increase production of hepcidin levels from liver –> decrease Fe absorption from GI and release from Macs
• normocytic, hypoproliferative
• shortened survival
• low serum Fe and TIBC, high ferritin, high inflammatory markers (ESR and CRP)
• treat: give EPO after treating Fe deficiency

Question 24

hereditary spherocytosis

Answer 24

• mutations of genes encoding RBC membrane proteins (ankrin and spectrin) –> damaged cytoskeleton membrane and loss shape
• microcytic, hyperchromic** (no loss of Hb)
• most common RBC membrane disease**

Question 25

sideroblastic anemia

Answer 25

• ring sideroblasts on Prussian blue stain**
• deficient in porphyrin ring**
• cause: genetics, EtOH, B6 deficient, lead poison, meds
• microcytic, normochromic
• high Fe, ferritin, and RDW; low transferrin

Question 26

B12 and folate deficiency

Answer 26

• macrocytic (megaloblastic anemia)
• neurologic symptoms with B12 deficiency (not folate)**
• folate deficiency is acute, B12 is chronic**
• give methotrexate without folate –> folate deficient quickly