1. Sickle Cell

2. Genetics Review
Chromosomes
Genes
Loci
Genotype

3. Normal Adult Hemoglobin (Hgb A)
Heme molecule composed of iron in the ferrous state (Fe++)
Globin is the protein portion
95-98% of adult Hgb is Hgb A
Remaining amount is A2 and A3

4. Sickle Cell Hemoglobin (Hgb S)
The amino acid glutamic acid is replaced by amino acid valine
Ability of RBCs oxygen carrying capability is impaired
Two possible genotype
AS (sickle cell trait)
SS (sickle cell disease)

5. Pathophysiology of Sickle Cell
Sickle Cell trait
Clinical manifestation
Sickle Cell disease

6. Peripheral Blood Picture
Varying number of sickled forms
Marked anisocytosis, poikilocytosis,
and polychromasia
Target cells, nucleated RBCs,
increased WBCs and platelets
Reticulocyte count is elevated:
(5-25%)

7. Sodium metabisulfite Principle
Cells containing Hgb S will “sickle” when placed under a condition of reduced oxygen tension
Sodium
Metabisulfate
15 minutes
&
30 minutes

8. Dithionite tube test Principle
Hgb S is insoluble in a phosphate buffer
Results in turbidity
Hgb A is soluble
Results in clear appearance
Other abnormal hemoglobins
may result in turbidity

9. ESR Clinical Significance
The ESR is a nonspecific test that
suggests the possibility of an inflammatory
process or tissue damage in the body
The ESR is not diagnostic but is useful in
following the course of some diseases like
rheumatic fever, arthritis, and Lupus

10. Principle
Based on principle of sedimentation where solids settle to the bottom of a liquid
A known quantity of anticoagulated blood is left undisturbed, the RBCs separate from the plasma and fall to the bottom of the container

11. Procedure
Anticoagulated blood is placed in a calibrated tube of standard dimensions
It is incubated in a vertical position and left undisturbed for a designated period of time (usually 1 hr)
Distance RBCs fall within the given time is measured in millimeters and reported
mm/hr

12. Types of ESR Methods Wintrobe – simplest and mostcost effective
Westergren – more sensitive
Automated methods

13. Factors affecting ESR Plasma factors Abnormal plasma proteins
may lead to rouleaux
formation
(falsely increases ESR)
The single most important
factor in determining
ESR rate

14. RBC Factors Size Shape Number of RBCs
Large erythrocytes settle faster than smaller ones and will increase ESR
Shape
spherocytes settle rapidly while sickle cells settle very slowly
Number of RBCs
In anemia there are less RBCs and more plasma volume which increases ESR

15. Technical Factors Tilting Noise and vibration Temperature
Test set up within 2hrs of blood collection
ESR tube
Well mixed sample
Air bubbles
Accurately timed
This project was funded at $3,000,000 (100% of its total cost) from a grant awarded under the Trade Adjustment Assistance Community College and Career Training Grants, as implemented by the U.S. Department of Labor’s Employment and Training Administration. Rogue Community College is an equal opportunity employer/program. Auxiliary aids and services, alternate form and language services are available to individuals with disabilities and limited English proficiency free of cost upon request.
This work is licensed under a Creative Commons Attribution 4.0 International License.