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Glucose-6-Phosphate Dehydrogenase (G6PD) Activity in Red Blood Cells

Published: August 9, 2026Updated: August 17, 2026

This test measures the activity level of Glucose-6-Phosphate Dehydrogenase (G6PD), an enzyme critical for red blood cell health. It helps identify whether you may be at risk for certain blood disorders.

Quick summary

["G6PD activity helps assess red blood cell function and potential risks for hemolytic anemia or other blood-related conditions."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
110934-7
Short code
G6PD Msmt RBC
Synonyms
G6PD Msmt RBC
Category
glucose
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
true
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test if you have symptoms like fatigue, jaundice (yellowing of skin/eyes), or frequent episodes of anemia. It’s also used to screen for conditions that could affect how your body breaks down certain medications or toxins.

What Does the Test Involve?

A small blood sample is taken from your arm. The lab then analyzes the red blood cells to measure G6PD enzyme activity using an enzymatic method. This helps determine if your red blood cells are functioning normally.

What Are Common Causes or Conditions?

G6PD deficiency is the most common inherited enzyme disorder. It can lead to red blood cells breaking down too easily (hemolysis) when exposed to certain triggers like infections, certain foods, or medications.

How Does This Test Relate to My Health?

High or low G6PD activity may indicate an underlying issue with red blood cell metabolism. For example, low levels could suggest a hereditary condition, while abnormal results may prompt further testing for conditions like hemolytic anemia or drug sensitivity.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

G6PD Activity Test

Frequently asked questions

Why might my doctor recommend this test?
Your doctor may recommend this test if you have symptoms like fatigue, dark urine, or frequent infections, especially if they suspect a red blood cell disorder. It’s also used in prenatal screening or before starting certain medications that could interact with G6PD.
What does a low or high G6PD activity level mean?
Low G6PD activity often means you have a hereditary condition that may cause red blood cells to break down more easily. High activity levels are less common and may not indicate a problem, but further evaluation could be needed to rule out other factors.
Can I prepare for this test?
No special preparation is needed. However, avoid taking certain medications (like some antibiotics or antifungals) that might affect results, as discussed with your healthcare provider.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy