Glucose 6-phosphate dehydrogenase (G6PD), quantitative, blood and RBC

Alphabetical Test listing

Glucose 6-phosphate dehydrogenase (G6PD), quantitative, blood and RBC-13506

Test name:

Test number:

13506

Excellian order number:

LAB13506

Abbreviation:

G6P

Alternate names:

Glucose 6-phosphate dehydrogenase (G6PD), quant, whole blood and RBC
G6PD, quant, blood
G6PD, quantitative, blood and RBC
G6PDH
G6PD

Useful for:

Evaluate glucose 6-phosphate dehydrogenase (G6PD) deficiency.

Limitations:

This test may be collected M-Th only.

Specimen type:

EDTA whole blood

Collection container:

Lavender (EDTA), 4mL (2 tubes)

Volume:

8 mL (4 mL in each of two tubes)

Minimum volume:

RBC: Two 500 µL Microtainer - Lavender (EDTA)
G6P: 1 Lavender (EDTA) or Dk green heparin (Li or Na) or 1 Yellow ACD 1(A or B)

Collection instructions:

Collect M - Th only
Immediately following collection, mix samples thoroughly by gentle inverting 8 - 10 times to prevent clotting

Transport container:

Lavender (EDTA), 4mL

Alternate specimen type:

Heparin whole blood and EDTA whole blood
ACD whole blood and EDTA whole blood

Alternate collection container:

Dk green heparin (Li or Na), no gel and Lavender (EDTA), 4mL

or AND

Yellow ACD (A or B) and Lavender (EDTA), 4mL

or AND

Alternate specimen volume:

Heparin and EDTA or ACD and EDTA - 4 mL each

Alternate collection instructions:

Immediately following collection, mix samples thoroughly by gentle inverting 8 - 10 times to prevent clotting

Alternate transport container:

Heparin whole blood and one EDTA whole blood

ACD whole blood and EDTA whole blood

Transport and stability:

RBC:

Refrigerated - 72 hours

G6PD:

Refrigerated - 7 days

Reason for rejection:

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

Performing lab:

LabCorp Burlington (001917): R-LC

Days set up:

Mo - Sa

TAT:

2 - 4 days

Method:

Kinetic - 340 nm

Reference ranges:

Age	Male Unit/trillion RBC's	Female Unit/trillion RBC's
0 - 30 days	229-708	239-732
31 days - 6 months	186-525	177-497
7 months - 5 years	182-363	111-371
6 - 17 years	184-364	158-357
18 - 30 years	156 - 397	155 - 399
>30 years	127 - 427	127 - 427

Clinical information:

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.

G6PD deficiency 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.

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. A partial list of safe and unsafe drugs is given in following table.

Partial List of Drugs and Chemicals in Glucose-6-Phosphate Dehydrogenase Deficiency

**Note: This is a partial list only.

Source: Beutler E. G6PD deficiency. Blood. 1994 Dec 1; 84(11):3613-3636.

Unsafe for Class I, II, and III Variants Safe for Class II and III Variants

Acetanilid Acetaminophen

Dapsone Aminopyrine

Furazolidone Ascorbic acid (except in very high doses)

Methylene blue Aspirin

Nalidixic acid Chloramphenicol

Naphthalene (mothballs, henna) Chloroquine

Niridazole Colchicine

Nitrofurantoin Diphenhydramine

Phenazopyridine Isoniazid

Phenylhydrazine L-Dopa

Primaquine Menadione

Sulfacetamide Para-aminobenzoic acid

Sulfamethoxazole (Δ) Phenacetin

Sulfanilamide Phenytoin

Sulfapyridine Probenecid

Thiazolesulfone Procainamide

Toluidine blue Pyrimethamine

Trinitrotoluene Quinidine

Uricase (rasburicase, pegloticase) Quinine

Streptomycin

Sulfamethoxypyridazine

Sulfisoxazole

Trimethoprim

Tripelennamine

Vitamin K

CPT codes:

82955
85041

LOINC code:

Result 49502-8

Date created:

04/05/2019

Revised date:

02/16/2024

Review date:

09/21/2023