South College AVL Lab Med: Hgb/Hct, RBC - Lecture 2

Hematopoiesis

formation of blood cells

production and turnover of blood cells is coordinated

what happens to hematopoiesis under normal conditions?

increased production of blood cells (illness, altitude, exercise, bleeding)

what happens to hematopoiesis under stress?

Erythropoiesis

production of red blood cells

hematopoieitic stem cell - myeloid stem cell - early erythroblast - late erythroblast - normoblasts - reticulocyte - erythrocyte

what is the pathway of erythropoiesis?

EPO

promotes growth of red blood cells (myeloid stem cell - early erythroblast)

B12 and folate

condenses nucleus during the late erythroblast state to the normoblasts stage

during normoblast stage

when does iron come in for hemoglobin synthesis?

looses most organelles (ex: mitochondria) and nucleus (make room for hemoglobin), flexible, biconcave, contains hemoglobin (contains iron and carries O2)

what are some key characteristics of a healthy, mature erythrocyte?

several hundred million

how much hemoglobin does one RBC contain?

heme

what specifically does oxygen bind to on hemoglobin?

100-120 days, 6-8 hrs, 7-10 days

what is the life cycle of an RBC? WBC? Platelet?

liver and spleen

where are 90% of old/damaged RBCs removed from circulation?

hemolysis in circulation

where are 10% of old/damaged RBCs removed from circulation?

contents are recycled and used again (globin, heme, iron)

what happens when old/damaged RBCs are removed from circulation?

Hemoglobin (Hgb), Hematocrit (HCT), Red blood cells (RBC - count), Mean corpuscular volume (MCV), Red blood cell distribution width (RDW)

When obtaining a CBC, what categories are we looking for?

classifications of anemia

Why is Mean corpuscular volume (MCV) and Red blood cell distribution width (RDW) important, or what do these help us diagnose?

Hematocrit (Hct)

percentage of erythrocytes in total volume of blood (Approx: 3 x Hgb (g/dL) if RBCs are normal size and normal Hgb)

RBC, Hgb, Hct

what are we following SERIALLY if we suspect bleeding and are INTEGRAL for anemia work up>

adrenal/brain/kidney/liver cancer, anabolic steroids, congenital heart disease, dehydration (severe diarrhea/burns), high altitudes, lung disease (COPD/smoking), certain meds, sleep apnea (more EPO production due to lack of O2 due to snoring)

What are some reasons as to why RBC, Hgb, and Hct values might be increased (erythrocytosis/polycythemia)?

Erythrocytosis/Polycythemia

increase in the number of red blood cells

Anemia

A condition in which the blood is deficient in oxygen carrying capacity of red blood cells, specifically hemoglobin, and/or hematocrit.

bone marrow failure, bleeding, cancer, cirrhosis, hemoglobinopathy, certain meds, pregnancy, prosthetic valves, renal disease, rheumatoid/collagen vascular disease, splenomegaly, vitamin deficiencies

What are some reasons as to why RBC, Hgb, and Hct values might be decreased (anemia)?

diuretics, gentamicin, methyldopa

what meds increase RBC, Hgb, and Hct values?

antibiotics, chemo, aspirin, indomethacin, rifampin, sulfonamides

what meds decrease RBC, Hgb, and Hct values?

underlying disease (rather than specific diagnosis)

what is anemia a sign of?

left = normal, right = abnormal

which side is normal? abnormal?

hollow - missing hemoglobin, and they are light in color

what is wrong with the RBCs on the right?

decreased production and destruction of RBCs

What are the two main reasons for anemia (pathophys)?

bone marrow damage (fibrosis/drugs), decreased marrow stimulation (renal disease/inflammation), Iron/folate/B12 deficiencies

what are three causes of decreased RBC production?

Healthy bone marrow cant keep up with blood loss or hemolysis

What causes the destruction of RBCs?

Mean corpuscular hemoglobin (MCH) and Mean corpuscular hemoglobin concentration (MCHC)

while still included on a CBC, which categories are we NOT too concerned about?

Mean Corpuscular Volume (MCV)

(Hct % x 10)/RBC (million/mm3) = ?

Alcohol (EtOH) use disorder, folate deficiency, hypothyroidism, chronic liver disease, certain meds, multiple myeloma, myelodysplastic syndrome, pernicious anemia, B12 deficiency

What are some reasons as to why Mean Corpuscular Volume (MCV) values might be high > 96 (macrocytic)?

methotrexate, imuran, hydroxyurea

What meds lead to a high Mean Corpuscular Volume (MCV) value >96?

Alcohol use disorder and certain meds (methotrexate, imuran, hydroxyurea)

Of the problems listed for high MCV values, which have normal RBC distribution width (RDW)?

folate deficiency, chronic liver disease, multiple myeloma, myelodysplastic syndrome, B12 deficiency

Of the problems listed for low MCV values, which have elevated RBC distribution width (RDW)?

chronic disease, early B12/iron deficiency OR mixed deficiencies anemia, renal failure, sickle cell anemia

ALL elevated RDW

What are some reasons as to why Mean Corpuscular Volume (MCV) might be normal = 80-96 (normocytic)? RDW values?

iron deficiency anemia (most common cause of anemia), toxins/drugs, thalassemia, myelodysplastic syndrome

ALL elevated RDW

What are some reasons as to why Mean Corpuscular Volume (MCV) values might be low > 80 (microcytic)?

RDW values?

Mean Corpuscular Hemoglobin Concentration (MCHC)

(Hgb (g/dL) x 100)/ hematocrit (%) = ?

decreased and normal MCHC

What are the two classifications of anemia in terms of MCHC?

hypochromic anemia

reduced hemoglobin content (lighter in color)

normochromic anemia

normal hemoglobin content (normal color)

iron deficiency and thalassemia

what are two examples of hypochromic anemia?

hemolytic anemia

what is an example of normochromic anemia?

RBC distribution width (RDW)

indicates the variation in size of an RBC, the degree of anisocystosis

calculated by machine using MCV and RBC values

anisocytosis

variation/unequal RBC size (can be abnormal)

results in macrocytosis and microcytosis

RDW measures this

iron deficiency anemia B12/folate deficiency anemia, hemoglobinpathies (sickle cell disease), hemolytic anemia, post-hemorrhagic anemia

What are some reasons RDW would be increased?

poikilocytosis

increase in abnormal RBCs of ANY shape where they make up 10% or more of total population

diagnosed via blood smears

flat, elongated, crescent shaped, tear-drop shaped, pointy shaped projections, etc.

poikilocystosis results in what kind of shaped RBCs?

poikilocytosis

what would these cells be an example of?

anisocytosis

what would these cells be an example of?

teardrop - thalassemia, anemia, marrow infiltration, splenic abnormalities

what type of abnormal RBC morphology is this?what is it indicative of?

- Hgb - slight diurnal variation (highest 8am, lowest 8pm)

- heavy smokers

- Hgb/Hct - hemodilution (overhydration)/dehydration

- pregnancy - hemodilution (Hgb/Hct decrease)

- high altitudes - Hgb/Hct increase (more O2 available)

- Abnormal RBC size - higher Hct w/ larger RBCs take up greater % of total blood volume (RBC affectd MCH and MCHC)

- WBC extremely elevated (decrease Hct - false indicate anemia - increase MCV and MCH)

- unreliable labs immediately after hemorrhaging (total blood volume of RBC will not change until replaced w/ fluids)

- extreme elevation in lipid levels (Hgb, MCV, MCHC, and MCH falsely high)

- MEDICATIONS CAN CAUSE INCREASE OR DECREASE IN ALL!!

What are some interfering factors of Hgb, Hct, and RBC?