G6PD Deficiency

Overview

G6PD deficiency is an X-linked inherited disorder affecting red blood cell protection against oxidative stress. It can cause neonatal jaundice and acute hemolytic anemia triggered by oxidant stressors.

Because it is X-linked, males are almost always clinically affected. Screen males only from endemic regions.

Important: Screen ALL patients (male or female) with Plasmodium vivax or P. ovale malaria before prescribing primaquine.

Who to Screen

Screen male patients who were born in Africa, Asia, or the Middle East.

How to Order in Calgary

On the CLS Community General Requisition, write 'G6PD levels' under 'Other Tests Not Listed.' If the screening test is positive, the laboratory will automatically perform a quantitative confirmatory test.

Interpreting Results

*     Clinically significant deficiency: enzyme activity below 30% (less than 3 U/g Hb)

*     Mild deficiency: 3-8 U/g Hb. Lower risk but still requires counselling.

*     Normal: above 8 U/g Hb

Patient Education

Foods and substances to avoid:

*     Fava beans

*     Henna

*     Mothballs (naphthalene)

Medications to avoid:

*     Primaquine and tafenoquine (malaria treatment)

*     Dapsone

*     Nitrofurantoin

*     Rasburicase

*     High-dose aspirin (greater than 3g/day)

*     Certain sulfonamides

Symptoms of acute hemolysis (seek care immediately):

*     Jaundice or yellowing of eyes/skin

*     Pallor

*     Dark or brown urine

*     Fatigue and rapid heart rate

Provide patients with a wallet-sized information card listing substances to avoid, to show at medical appointments.