LAB 16 - Total RBC count, hematocrit, MCV, hemoglobin, MCHC

What are the basic characteristics of RBC?

As a result their shape is a biconcave disc, which increases SA to volume ratio, speeding up the diffusion of gases (O2 + CO2). Additionally being anucleate + their shape allows RBCs to be flexible and squeeze through capillaries. Their primary function is to transport oxygen and carbon dioxide throughout the body.

How did we measure total RBC count? What tool did we use? What was the basic procedure? What is the normal value for total RBC count?

Total RBC count is measured using a hemocytometer. The procedure involves filling a small capillary tube with blood, isolating the RBCs with a lysis solution (WBCs), and adding the sample to the hemocytometer. Cells are counted in five small squares, expecting to see 80-120/square. Calculation: the total count from each square is added and multiplied by 10,000, a factor that adjusts for dilution and volume. The normal value for total RBC count is 5million/microliter. For women its normal to be lower and for men higher. Once its bellow 4million/microliter the person has anemia.

What may have influenced accuracy in total RBC count?

Influenced by dilution accuracy and sample homogeneity.

• Incorrect sample size in capillary tube

• Not mixing sample after letting it sit in lysis solution after a minute because cells settle

• Inaccurate counting

What is hematocrit? What is it a measure of? What was the procedure? What is the relationship of Hct to plasma? What is the ratio of Hct to Hemoglobin? What is the normal value?

Hct is the total packed red cell volume, representing the ratio of red cells to the total volume of blood in the container. Get the Hct value after centrifuging blood in a capillary tube and reading it with a microcapillary reader. Plasma and Hct together make up 100% of the blood volume. The ratio of Hct to hemoglobin concentration is 3:1. The normal value is 42; it’s normal for women to be lower and men to be higher. Anything below 37 is considered anemia.

What is hemoglobin? What is its basic structure and function?

Hemoglobin is a protein found in RBCs. It is a tetramer composed of 4 subunits (2 alpha and 2 beta) an each subunit contains a heme group (within that heme group is Fe where O2 binds). So for one hemoglobin protein it can bind to 4 O2 molecules.

What molecules can hemoglobin transport? What are the names for hemoglobin bound to the various molecules discussed?

Oxyhemoglobin - O2 is bound to heme, so Fe3+ is oxidized, giving the red color to blood

Deoxyhemoglobin - Hb without O2, Fe2+ is reduced, giving a blue color (cyanosis)

Carbaminohemoglobin - CO2 is bound to the protein portion (amino acids) of Hb

Carboxyhemoglobin - CO is bound to heme. CO is a competitive inhibitor to O2 that has 200x greater affinity.

Hb: What is oxygen saturation a measure of? How does it change throughout circulation

The ratio of oxygenated hemoglobin (oxyhemoglobin) to the total amount of hemoglobin in the arterial blood (lungs →tissues). Hb is 99% saturated with O2. In venous blood (tissues → lungs) 70% of Hb is saturated with O2, those not are deoxyhemoglobin.

Throughout circulation oxygen saturation changes as Hb transitions between different states based on the presence of O2.

How was Hb measured? What is the normal value?

Tallquist method using a color chart and dried blood on a strip of paper. Hb is then estimated from the closets color match. Normal concentration of Hb is 14g/dL, its normal for women to be lower and men to be higher. Hb concentration less than 12g/dL is considered anemia.,

What is MCV? What is it a measure of? What is the normal range? What are the ranges for microcytic, normocytic, and macrocytic?

Mean corpuscular volume (MCV) is a measure of the average RBC size; MCV = Hct x 10 / RBC (millions). The normal range of MCV is 82-92.

Microcytic: below 82

Normocytic: 82-92

Macrocytic: above 92

What is MCHC? What is it a measure of? What is the normal range? What are the ranges of hypochromic, normochromic, and hyperchromic?

Mean corpuscular hemoglobin concentration is a measure of the average concentration of Hb/RBC. The normal range is 32-36

• Hypochromic: below 32

• Normochromic: 32-36

• Hyperchromic: above 36

What is anemia? How can it be diagnosed?

Anemia is the compromised ability to carry O2, it is diagnosed using indicators like low RBC count (less than 4 million/microliter), low hemoglobin concentration (less than 12g/dL) or inadequate hemoglobin (quality problem)

What are the potential causes of anemia?

Low RBC count

• Decrease in production

  • Dietary deficiencies

    • Fe: Not eating enough Fe or absorbing enough due to increase of Hepcidin production.

    • B12: Not enough enough V B12 or cannot produce intrinsic factor to absorb, leading to a decrease in RBC production

    • Folic acid: an important vitamin essential for RBC production

  • Bone marrow disease

  • Inadequate EPO, potential damage to kidney

• Increase in destruction

  • Weakened RBC: hereditary spherocytosis, a genetic disorder where RBCs break easily

  • Increase of blood loss: menstruation, bleeding ulcer, or acute blood loss

Insufficient Hb

• Generally a Fe deficiency and not producing enough Hb

Inadequate Hb

• ex) sickle cell anemia where there is a mutation in Hb gene and it does not fold correctly. The misshapen Hb results is misshapen RBC that cannot efficiently carry O2

What parameters are used to characterized/distinguish/describe the different types of anemia?

Anemia can be characterized/assessed using the calculations obtained from MCV and MCHC

MCV = Hct x 10 / RBC (millions)

MCHC = Hb x 100 / Hct

What is the most prevalent cause of anemia? What type of anemia is this?

The most common anemia is microcytic, hypochromic anemia, aka Fe deficiency anemia. It can be caused by dietary lack, poor absorption, or in chronic infections where the liver sequesters Fe to hide from pathogens as most use Fe for survival.

Microcytic, hypochromic anemia in women, men, children, and pregnancies

Women: 20%

Men: 3%

Children: 20%, because kids grow fast and many times they do not consume enough Fe as they increase their production of BC

Pregnancies: 50%, mother is sharing Fe with baby and its easy to not eat enough

What is the second most prevalent cause of anemia? What type of anemia is this?

Macrocytic, normochromic anemia aka Pernicious anemia. B12 deficiency by either not eating enough or unable to produce intrinsic factor

Erythrocytes diseases

Polycythemia vera (PV) : Increases blood viscosity “many cells in the blood”

• Ok in athletes that train in high altitudes because they are healthy

• Abnormal in smokers they inhale less O2. Their kidneys detect this, secrete EPO, stimulating erythropoiesis. So more RBC are made but their body does NOT carry more O2, but a smoker has more RBC, increasing blood viscosity.

Anemia: compromised ability to carry O2. The indicators are reduced RBC count, insufficient Hb, and inadequate Hb.