Understanding the Glutathione Peroxidase blood test

The Glutathione Peroxidase blood test measures the activity of glutathione peroxidase, a crucial antioxidant enzyme that protects cells from damage caused by free radicals and oxidative stress. This enzyme plays a central role in neutralising harmful peroxides and maintaining cellular health.

Glutathione peroxidase is selenium-dependent, meaning its activity closely reflects selenium status in the body. Low enzyme activity may indicate reduced antioxidant capacity, selenium deficiency, or increased oxidative stress, while adequate levels suggest effective cellular protection.

This test is commonly used in nutritional assessment, functional medicine, longevity screening, and investigation of chronic inflammatory or oxidative stress-related conditions.

When a Glutathione Peroxidase blood test is recommended

This test is recommended when there is a need to assess antioxidant defence, oxidative stress, or selenium-related enzyme activity. Oxidative stress is linked to ageing, inflammation, cardiovascular disease, and metabolic dysfunction.

Testing may be appropriate if you:

• Have chronic fatigue or low resilience to stress
• Are investigating antioxidant or micronutrient status
• Have inflammatory or autoimmune conditions
• Are focused on longevity or preventive health
• Have suspected selenium deficiency
• Are exposed to high oxidative stress (illness, pollution, smoking)
• Are monitoring nutritional or supplement interventions
• Want a deeper insight into cellular protection mechanisms

Benefits of the Glutathione Peroxidase test

• Assesses antioxidant defence capacity
  Measures a key cellular protective enzyme.
• Reflects functional selenium status
  Indicates selenium-dependent enzyme activity.
• Supports investigation of oxidative stress
  Useful in chronic disease and ageing assessments.
• Aids nutritional and micronutrient evaluation
  Complements selenium and antioxidant testing.
• Relevant for longevity and preventive health
  Links cellular protection with long-term health.
• Useful in functional and integrative medicine
  Provides insight beyond standard blood tests.
• Simple blood test with no preparation required
  No fasting or lifestyle changes needed.
• Provides actionable, clinically relevant insight
  Guides dietary or supplement strategies.

How the test is carried out

We offer two convenient UK-wide testing options:

Clinic-based blood testing

• Choose your nearest UK clinic
• A healthcare professional collects a blood sample
• The sample is analysed in a certified laboratory
• Results are issued once testing is complete

Home or hotel blood collection (+£60)

• A qualified phlebotomist visits your home, workplace, or hotel
• Blood is collected at a time convenient for you
• No clinic visit required
• Available nationwide across the UK

Both options provide the same laboratory accuracy and clinical reliability.

Understanding your Glutathione Peroxidase test results

Low Glutathione Peroxidase activity

Low enzyme activity suggests reduced antioxidant capacity, which may be associated with selenium deficiency, increased oxidative stress, or chronic illness.

Typical UK interpretation:

• Below laboratory reference range

Nutritional assessment or further antioxidant testing may be recommended.

Normal Glutathione Peroxidase activity

Normal levels indicate adequate antioxidant enzyme function and effective cellular protection.

Typical UK interpretation:

• Within laboratory reference range

This suggests balanced oxidative stress management.

High Glutathione Peroxidase activity

High activity may reflect strong antioxidant defence, often seen with optimal nutrition or supplementation.

Typical UK interpretation:

• Upper or above reference range

Usually considered beneficial in the absence of symptoms.