RT Journal Article
SR Electronic
T1 A Modified Sodium Metabisulfite Method to Distinguish Sickle Cell Disease from Sickle Cell Trait for Use in Underdeveloped Countries
JF American Society for Clinical Laboratory Science
JO Clin Lab Sci
FD American Society of Chemistry and Laboratory Science
SP 93
OP 93
DO 10.29074/ascls.2019002030
VO 32
IS 3
A1 Randolph, Tim R.
A1 Le, Austin
A1 DeMond, Jeffery
YR 2019
UL http://hwmaint.clsjournal.ascls.org/content/32/3/93.abstract
AB The objective of this study was to develop a simple, inexpensive, and rapid confirmatory test using a sodium metabisulfite microscopic method to distinguish AS from SS genotype in patients with positive test results for hemoglobin S. Equal volumes of de-identified EDTA blood and 2% sodium metabisulfite were mixed, placed on a microscope slide with coverslip, and observed for sickling at 30-minute intervals over 3 hours. Sickle cells were enumerated per 200 red blood cells (RBCs) under 100x oil immersion and placed into 4 Likert categories (1+ to 4+) based on degree of sickling. In AS samples, 2+ and 3+ sickle cells rose most rapidly, and 4+ sickle cells showed the steepest rise in the SS samples. Based on these data, the number of 4+ sickle cells were counted every 30-minutes over 3 hours in 5 AS and 28 SS samples at 37°C. The mean numbers of 4+ sickle cells in AS samples were 4.75 per 200 RBCs at 2 hours and 17.75 per 200 RBCs at 3 hours. SS samples yielded 78.29 per 200 RBCs at 2 hours and 115.43 per 200 RBCs at 3 hours. Two-hour incubation showed a statistical difference (P = 0.00024) among groups in the shortest time and may be used to distinguish SS from AS genotypes. More testing is needed to determine cut points to distinguish genotype.