G6PD test

1. Expanding access to safe radical cure: a study to assess the
operational feasibility of integrating point of care G6PD testing into P.
vivax malaria management in Vietnam
Training workshop
Session 2.1: How to perform a quantitative
G6PD test
By the end of this session you should be able to:
- Set up the G6PD analyzer
- Prepare all components you need for testing
- Explain the test procedure for measuring patients G6PD activity
- Interpret the results of the G6PD test

2. 2
Introduction - a new tool: Quantitative G6PD
test by SD Biosensor
G6PD
activity
(U/g Hb)
Hb
(g/dL)
• Measures G6PD enzyme activity (U/g Hb*) and
total Haemoglobin (g/dL)
• You can use either capillary (finger prick) or
venous whole blood
• A small sample of blood - 10 µl - is needed for the
test
• It takes 2 minutes to get the test results
• Test device should be stored between:
2°- 30°C
• Analyzer should be stored between: 20°- 50°C
*U/g Hb: Units of G6PD enzyme activity per gram of haemoglobin /**
Analyzer
Test device
S2.1
S2(i).1

3. Setting up the G6PD analyzer
• Insert 4 AAA 1.5 V alkaline batteries into the battery
compartment of the analyzer
• Perform “Check Strip”
⁻ Switch on the analyzer and press the left and right button at
the same time for 3 seconds to enter the “check strip” test
mode
⁻ When the ‘CHE’ appears on the screen, insert the strip
⁻ Wait 10 seconds. ‘OK’ message will appear on the screen to
proceed for testing
⁻ If there is a problem ‘EEE’ error message will appear
S2.1
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4. For each new box of test devices
1. Check the expiry date of the test device (printed on
the foil pouch of the test device “EXP”
2. There is one code chip in every box of test devices
(25 devices).
3. Check that the code chip number matches the code
chip (printed on the foil pouch of the test device
“CODE”)
Code chip
S2.1 Setting up the G6PD analyzer
S2(i).1

5. 5
Test procedure steps
S2.1
S2(i).1

6. 6
Test Device
2 x sample
collector
(STANDARD™
Ezi Tube+)
Extraction
Buffer
Code
Chip Analyzer
Lancet
Sharps and
waste bins
Gloves
Step 1: Prepare all components needed for testing
S2.1 Setting up the G6PD analyzer
S2(i).1

7. • Switch the analyzer on and check the battery. Replace
batteries if low.
• Check the expiry date of the test device (printed on the
foil pouch of the test device “EXP”).
• Check that the code chip number (printed on the foil
pouch of the test device “CODE”) matches the number
on the Analyzer screen. (“CODE”).
• Always replace the code chip when you open a new
box of test devices. Each box has a specific code chip.
Step 2: Prepare the analyzer
S2.1 Test procedure steps
S2(i).1

8. Step 3: Prepare the test device
• Put on new gloves for each patient
• If the test device is refrigerated, remove from the fridge one hour before
so it reaches room temperature before use
• Open the foil pouch with test device and take a test device out
• Hold the test device with thumb and index finger so that the upper test
device is facing upwards.
• Insert the test device into the test device slot until it will go no further.
• Open the measurement chamber flap
S2.1 Test procedure steps
S2(i).1

9. Step 4: Prepare blood specimen
(finger prick)
• Clean the side of the finger of the patient’s non-
dominant hand with an alcohol swab and allow to dry
• Prick finger on the side of the finger pad
• Discard used lancet immediately in the sharps box.
S2.1 Test procedure steps
S2(i).1

10. Step 5: Collect blood specimen
• All supplies needed for the test should be prepared and
ready before taking the fingerprick sample
• Open the Ezi Tube+ pouch and take out two new Ezi
Tube+’s
• Gently hold the stem of the Ezi Tube+ horizontally, and
touch the tip of sample collector to the blood drop.
• The blood will automatically fill the Ezi Tube+ until the black
line. Stop when the blood reaches the black line (10 μl). It is
very important to collect the right amount of blood.
**Do not remove the sample collector too early. When held correctly, it will
not collect more blood than needed.
S2.1 Test procedure steps
S2(i).1

11. Step 5: Prepare blood specimen
(venous blood)
• If venous blood is refrigerated, ensure that you take it out of the
fridge to warm to room temperature before testing
• Ensure the blood vial is mixed before testing
• Use EZI Tube+ to draw blood to black line
S2.1 Test procedure steps
S2(i).1

12. Step 6: Mix the blood specimen with the
extraction buffer
• Place the Ezi Tube+ into the extraction buffer.
• Press and release the bulb of the Ezi Tube+ 8-10
times to mix the collected specimen with extraction
buffer.
• Discard used Ezi Tube+ in the biohazard waste or
sharps box.
S2.1 Test procedure steps
S2(i).1

13. VivAccess Tips on how to use to sample collector tube
• Collecting the right amount of blood and the right amount of mix is very important in order to have
a correct result
• When you touch the Ezi Tube+ to the blood drop or mix, the liquid will automatically fill the Ezi
Tube+ up to the black line
• Do not remove the sample collector tube too early.
• When you need to push out the blood or mix, squeeze the bulb of the Ezi Tube+. If bubbles are
present, discard the Ezi Tube+ and try again
S2.1 Test procedure steps
S2(i).1
To push out
To draw up

14. Step 7: Extract the mixed specimen
• Pick up the second new Ezi Tube+ you took out of the sample
collector pouch previously
• Hold the stem of the SECOND Ezi Tube+ at a 25-30 degree
angle and touch the tip of sample collector to the mixed
specimen (the mix).
• The mix will automatically fill the Ezi Tube+ to the black line.
Stop when it reaches the black line. It is very important to
collect the right amount of the mix.
**Do not remove the sample collector too early. When held correctly, it will
not collect more than needed.
S2.1 Test procedure steps
S2(i).1

15. Step 8: Place the mixed specimen on the
test device
• Press the bulb of the Ezi Tube+ fully (cover the small hole on the
bulb). Apply the mixed specimen to the specimen application
hole of the test device.
• Close the measurement chamber flap immediately after
applying.
• Discard used Ezi Tube+ in the biohazard waste or sharps box.
• Wait for 2 minutes for the test result automatically to appear on
the screen.
S2.1 Test procedure steps
S2(i).1

16. Step 9: Read and record the results as
appropriate
Number of the code chip
used in testing. This is
not the patient ID
Measurement of Hb in
grams per dL
G6PD enzyme activity
measured in
international units per
gram of haemoglobin
S2.1 Test procedure steps
S2(i).1

17. Step 10: Interpret the G6PD test results
G6PD enzymatic activity
IU/ g Hb
Classification
Greater than 6.0 Normal
4.0 to 6.0 Medium (intermediate)
Less than 4 Low (deficient)
S2.1
S2(i).1

18. Default Analyzer Settings
The analyzer manual provides
instructions on how to
• Modify default settings
• Connect to PC and printer
• Interpret various error codes
S2.1 Setting up the G6PD device
S2(i).1

19. Analyzer Display
S2.1 Setting up the G6PD analyzer
S2(i).1

20. 20
• Forgot to calibrate the analyzer.
• Make sure to calibrate the analyzer if using a new
analyzer or a new lot of test devices, or if the
analyzer has been dropped.
• Did not collect a large enough sample.
• Ensure you collect sufficient volume of blood and
buffer. Fill the sample collector to the black line.
• Used the same sample collector for
collecting both blood and buffer.
• Dispose of sample collector after blood collection and
use NEW sample collector for buffer collection.
Common User Mistakes

21. 21
• Waited too long to close
measurement chamber and test
timed out.
• Close measurement chamber flap immediately
after applying specimen.
• Read hemoglobin results incorrectly.
• The top right 13.1 U/g Hb indicates units for
G6PD measurement. The bottom left 15.7 T-Hb
g/dL indicates hemoglobin measurement.
Common User Mistakes (cont.)

22. Any questions?
• When using the quantitative G6PD test - check that the code number printed on the foil pouch matches
the code chip number on the code chip / G6PD analyzer.
• Always use a NEW sample collector to transfer the blood mixed with buffer to the G6PD test
• Ensure you categorise patients according to the thresholds set out for the quantitative G6PD device
Key points to remember:
M4
S2.2