Simultaneous automated determination of glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities in whole blood.
We report a potentiometric fully automated method for determining red cell glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase activities and the glucose 6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase index using 25 microliters of whole blood. No sample pre-treatment (e.g., preparation of the haemolysate) is needed and the measurements are performed at pH 8.0 and 37 degrees C under the conditions recommended by the ICSH committee. The reproducibility was constantly good, with within-run CV of 1.0% (glucose 6-phosphate dehydrogenase) and 5.9% (glucose 6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase) for activities in glucose 6-phosphate dehydrogenase non-deficient adults, and of 2.3% (glucose 6-phosphate dehydrogenase, G6PD) and 2.5% (glucose 6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase) for G6PDMediterranean heterozygotes. Linearity was observed up to an activity of 2800 U/l of glucose 6-phosphate dehydrogenase. Results of glucose 6-phosphate dehydrogenase activity (U/l) in whole blood (y) correlated well with those obtained with the previously described monostarter assay, performed at pH 9.2 (y = 0.60x + 37; n = 80; r = 0.991). Results of 6-phosphogluconate dehydrogenase (U/l) in whole blood (y) correlated well with those obtained by the ICSH recommended method (x) (y = 0.779x - 44; n = 23; r = 0.991). Reference intervals are reported for glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and glucose 6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase index relatively to normal, beta- and alpha-thalassaemic glucose 6-phosphate dehydrogenase non-deficient adults, to glucose 6-phosphate dehydrogenase deficient adult males and to G6PDMediterranean non-thalassaemic heterozygotes. We demonstrate that the diagnostic sensitivity of the glucose 6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase index in detecting the G6PDMediterranean heterozygotes is superior to that of the glucose 6-phosphate dehydrogenase activity alone.
Mosca
A
A
Dipartimento di Scienze e Tecnologie Biomediche, Università degli Studi, Milano, Italy.
Paleari
R
R
Rosti
E
E
Luzzana
M
M
Barella
S
S
Sollaino
C
C
Galanello
R
R
D000293:Adolescent; D000328:Adult; D001483:Base Sequence; D001774:Blood Chemical Analysis / Q000379:methods* / Q000706:statistics & numerical data; D004247:DNA / Q000235:genetics; D005069:Evaluation Studies as Topic; D005260:Female; D014644:Genetic Variation; D005954:Glucosephosphate Dehydrogenase / Q000097:blood* / Q000235:genetics; D005955:Glucosephosphate Dehydrogenase Deficiency / Q000201:enzymology / Q000235:genetics; D006579:Heterozygote; D006801:Humans; D008297:Male; D010734:Phosphogluconate Dehydrogenase / Q000097:blood*; D011199:Potentiometry / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017085:alpha-Thalassemia / Q000201:enzymology; D017086:beta-Thalassemia / Q000201:enzymology
D004247:DNA; D010734:Phosphogluconate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase