Podcast: Play in new window | Download

Red Blood Cells

Priming Questions

• What are the four polypeptide chains that make up hemoglobin?
• Define polycythemia
• What does MCV stand for and what does it mean?
• Define hemolysis.

Red Blood Cells Simplified

• The specific shape of a RBC gives it an increased surface area for better gas exchange and flexibility for fitting into tiny places.
• The main job of the RBC is to carry oxygen to the cells of the body and CO2 out from the cells to the lungs.
• Hemoglobin is the protein structure within the RBC that has an affinity for Oxygen.
• Hemoglobin is made up of four heme iron complexes and four polypeptide chains two alpha and two beta chains.

There are two basic problems red blood cells can have

• Polycythemia – To many red blood cells
• Anemia – There are not enough functioning red blood cells
• Due to lack of production or destruction/loss of RBCs
• Due to production of poorly or non functioning RBCs

Clinical Presentation

• Patients with red blood cell disorders typically do not exhibit any symptoms, and when they do they are vague and overlapping.

For example:

• Headaches
• Fatigue
• Exertional dyspnea
• Dizziness
• Tachycardia
• Blurred vision

Physical exam may show

• Pallor of the nail beds
• Pallor of conjunctiva
• Pallor of the palmar creases

Vocabulary

• Reticulocytes – Immature red blood cells
• Mean corpuscular volume (MCV) – Volume of an average red blood cell in the sample
• Microcytosis – MCV< 80 (small cells)
• Microcytosis – MCV>100 (big cells)
• Hypochromic – RBCs a more pale than usual (decreased color)
• Hemolysis – Destruction of RBCs

Important Labs

• CBC
• Hemoglobin (Hgb) – Measures the amount of hemoglobin in the blood
• Male 13.5 – 17.5 g/dL
• Female 12.0 – 15.5 g/dL
• Hematocrit (Hct) – The volume percentage of red blood cells in blood
• Male 41-51%
• Female 36-44%
• Reticulocyte count
• Mean corpuscular volume (MCV)
• Peripheral blood smear will give you cell morphology (shape)

Polycythemia

• Elevated hematocrit or hemoglobin

Causes

• Myeloproliferative syndrome
• Chronic low oxygen
• Malignancy
• Over transfusion

Clinical Presentation

• Most likely asymptomatic
• Weakness
• Headaches
• Lightheadedness
• blurred vision
• Pruritus
• GI bleeding

Labs & Studies

• Hct > 55% (normal is 36-50%)

Treatment

• Phlebotomy
• Hydroxyurea – this is a myelosuppressive medication

Study tip

• Use multiple passes to judge depth

Priming Questions

• What are the four polypeptide chains that make up hemoglobin? 2 alpha and 2 beta polypeptide chains
• Define polycythemia – too many RBCs
• What does MCV stand for and what does it mean? Mean corpuscular volume (MCV) – Volume of an average red blood cell in the sample
• Define hemolysis. Destruction of RBCs