G6PD, quantitative; red blood cell count (RBC)
2 - 4 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for
testing to when the result is released to the ordering provider. In some cases, additional time should be
allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
8 mL (4 mL in each of two tubes)
RBC: Two 500-µL lavender-top Microtainer™ tubes filled to at least 50% of tube capacity. (Note:
If any other size lavender tube is used, the tube must be filled to at
least 50% capacity of tube fill volume. Insufficient volume may limit
the extent of procedures performed.) and G6PD: One lavender-top (EDTA) tube, green-top (heparin) tube, or yellow-top (ACD) tube (0.1 mL) whole blood.
Two lavender-top (EDTA) tubes; or one green-top (heparin) tube and one lavender-top (EDTA) tube; or one yellow-top (ACD) tube and one lavender-top (EDTA) tube
RBC: Stable refrigerated for 72 hours. G6PD: stable refrigerated for seven days.
RBC: Hemolysis; tube not filled with
minimum fill volume; specimen drawn in any anticoagulant other than
EDTA; specimens diluted or contaminated with IV fluid; clotted specimen;
improper labeling; transfer tubes with whole blood; lavender-top (EDTA)
tubes received with plasma removed; samples more than 72 hours old. G6PD: Frozen specimen; clotted specimen.
Evaluate glucose 6-phosphate dehydrogenase (G6PD)
deficiency.G6PD deficiency, an X-linked disorder, is the most common
enzymatic disorder of red blood cells in humans, affecting more than 400
million people worldwide. The clinical expression of G6PD variants
encompasses a spectrum of hemolytic syndromes. Affected patients are
most often asymptomatic, but many patients have episodic anemia, while a
few have chronic hemolysis.
With the most prevalent G6PD variants
(G6PD A- and G6PD Mediterranean), hemolysis is induced in children and
adults by the sudden destruction of older, more deficient erythrocytes
after exposure to drugs having a high redox potential (including the
antimalarial drug primaquine and certain sulfa drugs) or to fava beans,
selected infections, or metabolic abnormalities. In the neonate with
G6PD deficiency, however, decreased bilirubin elimination may play an
important role in the development of jaundice.
should be suspected in any subject with an episode of nonimmune
hemolytic anemia, especially if occurring after drug ingestion,
infection, or an episode of diabetic ketoacidosis.
False normal results after hemolysis may occur; vide infra. See Additional Information.
Levels of G6PD are higher in the newborn than they are in the adult.
high levels are seen in older patients, it invariably reflects the
presence of a young red blood cell population with reticulocytosis.
Kinetic - 340 nm
Male (units/trillion RBCs)
Female (units/trillion RBCs)
0 to 30 d
31 d to 6 m
7 m to 12 y
13 to 17 y
18 to 30 y
G6PD hemolysis is associated with formation of Heinz
bodies in peripheral red blood cells. It is the older erythrocytes that
are most G6PD-deficient in affected individuals. These cells are first
eliminated in a hemolytic crisis. The younger cells and reticulocytes
contain more G6PD. For these reasons, after a hemolytic crisis, when
only younger erythrocytes and reticulocytes are present, the G6PD values
may be spuriously normal.
These "false-negative" (ie, spuriously
normal or high) results are a potential concern because the most
severely deficient red cells have already been removed from the
circulation via hemolysis.
This problem is usually not important
when testing male Caucasians but is a concern in some Caucasian females
and blacks of both sexes, especially during the reticulocytosis
following acute hemolysis. When a false-negative test is suspected, the
best approach is to reëvaluate the patient three months after the
hemolytic episode, a time at which the red cell mass will have been
repopulated with red cells of all ages.
To prevent future
hemolytic episodes, subjects with G6PD deficiency should avoid drugs and
chemicals with oxidant potential.