Set up with the test, a negative control (HbAA) and a positive control using blood from a person with sickle cell trait (HbAS).
1. Pipette 2 ml of working reagent into a test tube approximately 13 × 77 mm.
2. Wash in (0.1 ml) of capillary blood or well mixed venous blood.
Note: When the haemoglobin is below 70 g/l (7 g/dl), use twice the volume of blood or if a venous blood sample, use plasma reduced blood (remove about half the plasma).
3. Mix well and filter through a small (5.5 cm diameter) No. 1 filter paper.
4. Note the colour of the solution (pale yellow, pink red, or dark red) and whether there is any red precipitate (insoluble reduced HbS) on the filter paper.
Findings
HbSS . . . . . . Clear pale yellow filtrate. Abundant red precipitate on filter paper
HbAS. . . . . . Clear pink filtrate. Small amount of red precipitate on filter paper
Same result will be obtained with HbSC and HbS with other Hb variant
HbAA (normal) . . . . . . . . Dark red fluid (soluble reduced Hb) with no precipitate on filter paper
Same result will be obtained with HbAC and HbAD
Reporting results
–‘Positive for sickle cell anaemia’ when result shows HbSS appearance.
– ‘Positive for sickle cell haemoglobin’ when result shows HbAS appearance.
– ‘Negative for HbS’ when result shows HbAA appearance.
See also:
Lablink 