Hem 3 - Red Blood Cells Part 2

Question 1

evaluation of erythrocytes - what do we look at

Answer 1

-we examine their numbers, their morphology and specific indices that describe some important characteristics reflecting overall health of the erythron

-morphology = physcial characteristics of the red cells
-size = normo, micro, macro
-staining = hypo, normo, poly, presence of reticulocytes

Question 2

erythrocyte count - what is it, what can levels tell you

Answer 2

-its the number of RBC per volume of blood, and is reported in either millions in a microliter or millions in a liter of blood

-levels of RBCs out of the normal range (higher or lower) is an indication of specific conditions.

Question 3

hemoglobin concentration in blood - trends

Answer 3

when the number of red cells is low, usually the hemoglobin is also low and when when the number of red cells is high, hemoglobin is high

Question 4

packed cell volume/hematocrit - what does it indicate, differnce in them, relatinship between red cells and PCV

Answer 4

indicate the percentage of volume of whole blood composed of red blood cells in a centrifuged sample

terms are interchangable although PCV is actually centrifuged and Hct is a calculated percentage by blood analysis machine

when red cell numbers are low, PCV is low. when red cell numbers are high, PCV is high

Question 5

erythrocyte indices - what is it used for, what is included and what each tell you

Answer 5

a group of measurements/calcuations of erythrocyte characteristics determined as part of a CBC that can be used to determine the causes of abnormal erythrocyte numbers

-mean corpuscular volume (MCV) = average volume of each RBC

-mean corpuscular hemoglobin (MCH) = average total amount of hemoglobin in each RBC

-mean corpuscular hemoglobin concentration (MCHC) = average conccentration of hemoglobin in each RBC

-red cell distribution width (RDW) = difference in size between the largest and smallest RBCs in a sample

Question 6

mean corpuscular volume (MCV) - classifications, what does this help with

Answer 6

if the MCV is within normal range, RBCs = normocytic

if the MCV is high, RBCs = macrocytic

if the MCV is low, RBCs = microcytic

different causes for red cell disorders lead to different sizes of red cells so this helps in the diagnosis of underlying cause

Question 7

mean corpuscular hemoglobin (MCH) + mean corpuscular hemoglobin concentration (MCHC) ; classifications

Answer 7

cells with normal, high or low MHC/MCHC are referred to as normochromic, hyperchromic, and hypochromic

Question 8

red cell distribution width (RDW) - what is high RDW called, what does it indicate

Answer 8

high RDW = anisocytosis
usually RBC are a standard size. certain disorders can cause significant variation in cell size. higher numbers indicate greater variation in size.

often indicates an increase in reticulocytes as these cells are larger, but some smaller mature RBCs are also present so they RANGE of size is INCREASED

may also be seen when increased numbers of microcytic RBCs are present

Question 9

clinical condition: polycythemia. - what is it, when is it observed, what causes it

Answer 9

-increased numbers of RBC per mL of blood

-can be observed with anything that increases erythropoietin levels: hypoxia due to respiraoty and cardiovascular problems, EPO-secreting tumors, high altitude pressure, exposure to EPO as a drug

-can be due to leukemic syndrome called polycythemia vera where the bone marrow simply takes too many red cells

-can be due to dehydration - plasma volume is lost due to dehydration but number of RBCs stay the same. called “relative” polycythemia. plasma protein level will usually be elevated in this case

Question 10

parameters for dehydration and polycythemia

Answer 10

dehydration = loss of plasma with normal number of RBCs. PCV appears higher than normal. PCV = 60%, TP 8.5gm/dL

polycythemia = true increase in total red cell mass with normal plasma volume. PCV = 75%, TP 6.8 gm/dL

Question 11

causes of polycythemia - relative and true and what causes it

Answer 11

elevated red cell numbers, Hb and PCV can be either relative or a true increase in blood cell mass

relative = not an actual increase in mass = physiological (spleen contraction after exercises) or dehydration

true increase in blood cell mass = either increased or decreased EPO
-increased = from hypoxia or tumors
-decreased = polycythemia vera

Question 12

critical condition - anemia: what is it, causes

Answer 12

decreased number of red cells per mL (and decreased PCV and Hb levels)

caused by: blood loss, iron deficiency, immune destruction of RBC (IMHA), bone marrow problem (leukemia, myelofibrosis), chronic diseases/inflammation (kidney disease, cancer, IBD)

Question 13

anemia parameters

Answer 13

Loss of RBCs with normal plasma volume. PCV = 20%, TP 7.5 gm/dL. Low RBCs, low Hb

Question 14

clinical approach to anemia (how we classify, production, end step)

Answer 14

we can classify it based on what the cells look like and the RBC indices (size, Hbg content). then we determine the rate of RBC production and whether there is destruction of RBCs. finally w use these classification criteria to help identify specific disease that caused the anemia

Question 15

classification of anemias (3) and what its based on

Answer 15

cytometric = based on morphology of RBCs (normocytic normochromic, macrocytic normochromic, macrocytic hypochromic, microcytic hypochromic, microcytic normochromic)

erythrokinetic = basd on RBC production (regenerative vs non regenerative)

biological/etiologic = based on determination of the etiological agents or causes (iron deficiency anemia or hemolytic anemia)

Question 16

what type of cytometric classification of anemia cant be regenerative

Answer 16

microcytic hypochromic

Question 17

cytometric classification examples

Answer 17

-normochromic normocytic anemias (normal MCHC and MCV)

-microcytic hypochromic or microcytic normochromic anemia (low MCV and normal/low MCHC) = iron deficiency anemias or genetic hemoglobin defects

-macrocytic normochronic anemia (increased MCV, normal MCHC) = immune mediated anemias and those caused by dietary deficiencies

-macrocytic hypochromic anemia (increased MCV, low MCHC) = B12 or folate deficiency

Question 18

additional observations for cytometric classification

Answer 18

presence of unusual cell shapes, sizes or inclusions

once size and Hb concentration are captured in the description, its also useful to describe whether additional features are present

acanthocytes, leptocytes, heinz bodies

Question 19

erythrokinetic classification - what is it based on, when is regenerative anemia seen, how does the marrow respond

Answer 19

-Classification of anemia based on the rate of RBC production. If production is high, regenerative anemia exists.

-Regenerative anemias are seen in hemolysis (excess destruction of RBC with recovery of the iron) or after a single acute hemorrhage (loss of RBC from the vascular compartment without losing too much iron).

• In these cases, the marrow responds appropriately to anemia
  by increasing the production of RBC and releasing them into the bloodstream prematurely as reticulocytes.

Question 20

regenerative vs non regenerative anemia

Answer 20

-Regenerative Anemia = In a regenerative anemia, the bone marrow responds appropriately to the decreased red cell mass by increasing RBC production and releasing reticulocytes. Anisocytosis and polychromasia are present.

• Non-regenerative Anemia = In a non-regenerative anemia, the bone marrow responds inadequately to the increased need for RBC. No increase in reticulocytes or polychromasia is observed, less variation in cell size

Question 21

parameters to determine RBC turn over - lab tests (3) and what they tell you

Answer 21

There are several lab tests that allow you to determine whether increased RBC turnover/production exists:

1. Reticulocyte count – increased juvenile RBCs in circulation
2. Serum unconjugated bilirubin and urine urobilinogen concentration (byproducts of heme metabolism) -
   suggest increased red cell destruction.
3. Bone marrow biopsy – presence of precursors
   If turnover/production is increased, reticulocytes will be increased, bilirubin will be increased and the bone marrow will contain more red cell precursors. If not, the regenerative response is weak, which may suggest that there a is limited
   amount of iron, hormones (EPO), or the cells are not responding properly due to other problems (toxins,
   inflammation etc.).

Question 22

causes of regenerative anemia

Answer 22

hemolytic anemias or hemorrhage (ACUTE recent episode with sufficient time for a marrow response)

Question 23

causes of non regenerative anemia

Answer 23

-very recent hemorrhage (within past 24hr) or chronic blood loss (depletes iron)
-extramarrow disease/deficiencies (iron)
-intramarrow disease (leukemias)

Question 24

etiologic classification -what needs to be known, examples, what we use to determine it

Answer 24

If the cause is known, or the etiologic agent identified, then the classification becomes related to the disease name.

Examples:
* Iron Deficiency Anemia
* Immune Hemolytic Anemia
* Blood loss anemia
* Parasitic anemia – Babesia, etc.

Overall – We use the appearance (cytometric) classification
of the anemia to help determine turnover (erythrokinetic
classification) and ultimately arrive at a biochemical/etiologic diagnosis where possible.