Lab diagnosis of sickle cell anemia is important for confirmation. For this purpose sickling test is performed.
Sickling test principle (Sick cell anemia test)
The principle of Sicking test is quite simple. In the presence of a reducing agent (Sodium dithionite), the solubility of sickle cell hemoglobin (HbS) decreases at low oxygen tension.
Sickling test procedure (sodium metabisulphite test)
- First, add 4 to 5 drops of reducing agents (Sodium metabisulphite) to one drop of EDTA mixed blood (1:4 ratio) in a test tube and mix.
- Drop a drop from the test tube mixture on the slide.
- Cover the mixture with a coverslip.
- Seal the mixture and coverslip with wax or petroleum jelly, so that it prevents the entering of air.
- After sealing, look for sickling if negative look again for 1 to 2 hours and after 12 hours.
Sickling test Requirements
- Reducing agents: Sodium metabisulphite
- Glass slide
- Wax or petroleum jelly
Result interpretation of Sickling Test
Immediate sickling positive is an indication of HbS (Sick cell Hemoglobin).
But If sickling occurs after 1 to 2 hours or after 12 hours. It is suggestive of Sickle cell Hemoglobin Traits.