Vitamin D & Vitamin B12 Tests🧪 Vitamin D & Vitamin B12 Tests
Evaluates levels of essential vitamins that affect energy, immunity, brain function, and bone health.
🔍 What is it?
These blood tests measure the concentration of Vitamin D and Vitamin B12 in your blood — both are crucial nutrients your body needs but cannot produce in sufficient amounts without diet or supplementation.
- Vitamin D supports bone health, immune function, and mood regulation.
- Vitamin B12 is essential for energy production, nerve health, and red blood cell formation.
Deficiencies in either vitamin are very common in the UK, especially during winter months or in people with restricted diets (e.g. vegans).
📊 What does it measure?
| Test | What It Indicates |
| Vitamin D (25-hydroxyvitamin D) | Indicates how much vitamin D is stored in your body |
| Vitamin B12 (Cobalamin) | Shows if you have adequate B12 for blood, nerves, and energy |
| (Sometimes included) Folate (Vitamin B9) | Often tested alongside B12 for fatigue or anaemia |
❓ Why might I need it?
You may be advised to take this test if you:
- 😴 Feel chronically tired or fatigued
- 💪 Have muscle weakness or bone pain
- 😔 Suffer from low mood or depression
- 🥦 Follow a vegan or vegetarian diet (low in B12)
- 🦠 Have gut issues (e.g. coeliac or Crohn’s) that affect absorption
- 🤒 Are frequently ill or have weakened immunity
- 👵 Are aged 65+ or have limited sun exposure
- 🤰 Are pregnant or breastfeeding
🧬 Conditions it can help detect or monitor:
- Vitamin D deficiency (linked to bone loss, immune problems, depression)
- Vitamin B12 deficiency (can lead to anaemia and nerve damage)
- Pernicious anaemia (autoimmune B12 absorption issue)
- Osteomalacia or rickets
- Fatigue-related conditions
- Neurological symptoms (tingling, memory issues)
📈 Normal Ranges (UK NHS guidance):
| Nutrient | Deficiency Threshold | Optimal Range |
| Vitamin D | < 30 nmol/L | 50–125 nmol/L |
| Vitamin B12 | < 200 ng/L (pmol/L) | 200–900 ng/L (varies slightly by lab) |
Interpretation should be done with symptoms and health history in mind.
⏱️ How is it done?
- A small blood sample is taken from a vein in your arm
- The test takes just a few minutes
- Results are usually available within 1–2 working days
💷 Typical private cost in the UK:
- Vitamin D test: £40–£70
- Vitamin B12 test: £30–£60
- Combo panel (B12, D, Folate): £60–£110
Often included in fatigue panels or nutrient deficiency screens.
✅ Commonly combined with:
- Full Blood Count (FBC) – Checks for anaemia
- Iron studies – For tiredness or breathlessness
- Thyroid function tests – For energy and metabolism
- Folate test – Works alongside B12 in red cell formation
- Calcium – For bone health
📚 References:
- NHS UK – Vitamin D
- NHS UK – Vitamin B12 or folate deficiency anaemia
- British Dietetic Association (BDA) – Vitamin D: Food Fact Sheet
- National Institute for Health and Care Excellence (NICE) – Vitamin D deficiency in adults