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 ascls.119.002030
DO 10.29074/ascls.119.002030
A1 Tim R. Randolph
A1 Austin Le
A1 Jeffrey DeMond
YR 2019
UL http://hwmaint.clsjournal.ascls.org/content/early/2019/10/09/ascls.119.002030.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 testing positive 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/200 RBCs under 100x oil immersion and placed into 4 Likert categories (1+-4+) based on degree of sickling. In AS samples, 2+ and 3+ sickle cells rose most rapidly while 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 degrees Celsius. Mean number of 4+ sickle cells in AS samples were 4.75/200 at 2 hours and 17.75/200 at 3 hours whereas SS samples yielded 78.29/200 at 2 hours and 115.43/200 at 3 hours. Two-hour incubation showed a statistical difference (P=0.00024) between groups in the shortest time and may be used to distinguish SS from AS genotypes. More testing is needed to determine cutpoints to distinguish genotype.