1,25-dihydroxyvitamin D (calcitriol)
This test measures 1,25-dihydroxyvitamin D, the biologically active form of vitamin D. It is used to investigate calcium imbalance, kidney disease and...
Vitamin C
108.00
This test measures Vitamin C levels to assess antioxidant and immune support. Vitamin C is essential for skin, healing, and cellular protection.
Turnaround time
8 days
Biomarkers count
1
Same-Day Appointments
UKAS Accredited Labs
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Under 18? Patients under 18 can only be seen at GB Medlabs and Clinilabs, Monday to Friday only.
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Details about Vitamin C
What is a Vitamin C test?
A Vitamin C test measures the level of ascorbic acid in your blood, a powerful antioxidant required for immune defence, collagen production, wound healing, and iron absorption.
Because Vitamin C is water-soluble and not stored in large amounts, levels can drop quickly with poor diet, stress, illness, or smoking.
Why do I need a Vitamin C test?
Low Vitamin C can affect immunity, skin quality, gum health, and recovery from illness.
Reasons for testing include:
• Frequent infections
• Slow wound healing
• Bleeding gums
• Easy bruising
• Fatigue
• Poor skin quality
• Restricted diet or poor fruit/vegetable intake
• Smoking or high stress levels
Benefits of the test
1. Assesses antioxidant protection
2. Supports immune system evaluation
3. Helps explain slow healing
4. Important for collagen and skin health
5. Supports iron absorption assessment
6. Detects hidden nutritional deficiency
7. Useful for smokers and high-stress lifestyles
8. Guides targeted supplementation
Expanded benefit explanation
Vitamin C is vital for immunity, tissue repair, and antioxidant defence. Identifying deficiency allows correction before symptoms worsen.
Step-by-step — How testing works
We offer two UK-wide testing options:
Clinic testing
• Choose nearest UK clinic
• Blood sample collected
• Laboratory analysis performed
• Results securely returned
Home visit (+£60)
• Phlebotomist visits you
• Blood sample collected safely
• Sample sent to lab
• Results delivered confidentially
Your results explained
Low levels
May indicate poor diet, stress load, or increased oxidative demand.
Normal levels
Indicates adequate antioxidant and immune support.
High levels
Usually related to supplementation.
How It Works
Simple steps to get your results
1
Book Online
Choose your test online and book in seconds. Select your preferred clinic location or home visit option.
2
Visit or Test at Home
Attend one of our UK or London clinics, arrange a home nurse visit, or use a finger-prick kit where available.
3
Get Your Results
Your sample is analysed by accredited UK laboratories, with secure results delivered directly to you.
Take control of your health with London Blood Tests
WhatsApp UsHow to Prepare for Your Test
Follow these guidelines for accurate results
Sample Timing
Where possible, attend your blood test between 7am and 12pm. Please wait until any short-term illness or infection has fully resolved before testing. Avoid intense exercise for 24–48 hours beforehand, as this can affect certain markers.
Fasting & Hydration
Fasting is not always required, but some tests may recommend it. If fasting is advised, avoid food for 8–12 hours before your appointment and drink water only. Stay well hydrated, as this helps with sample collection and accuracy.
Medications & Supplements
Continue prescribed medications unless advised otherwise by your clinician. Avoid vitamin, mineral, or biotin supplements for at least 24–48 hours before your test, as these can interfere with results. If you are unsure about any medication or supplement, please let us know before your appointment.
Hormones & Menstrual Cycle
For hormone-related tests, timing within your menstrual cycle may be important. If relevant, follow any specific guidance provided on your test page.
If you have any questions or special circumstances, our team is happy to advise before your appointment.
Frequently Asked Questions
It measures plasma ascorbic acid, the most accurate indicator of current vitamin C levels.
No fasting is required, though morning supplements may temporarily elevate results.
Yes — a phlebotomist can come to your home or hotel for a professional venous blood draw.
It supports immunity, collagen production, wound healing, energy levels, and antioxidant protection.
Within 1–3 business days after your sample reaches the lab.
Low intake, stress, smoking, illness, poor absorption, and restrictive diets.
Avoid taking vitamin C on the morning of the test unless medically advised otherwise.
Yes. Deficiency commonly contributes to both symptoms.
Targeted supplementation and dietary changes can restore normal levels quickly. A GP can advise you.
Every 6–12 months, or sooner if you are supplementing, ill, or have absorption issues.
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