Wellness . Symptoms guide
Vitamin D Deficiency: Symptoms and Testing
Vitamin D deficiency is very common in the UK because of limited sunlight exposure for much of the year. Low vitamin D affects bone health, immune function, mood, hair cycling and muscle strength. A blood test for 25-hydroxyvitamin D gives a definitive answer in minutes.
This patient information is being clinically reviewed by our team. The factual content draws on UK guidance (NHS, NICE, British Association of Dermatologists, British Society for Sexual Medicine where cited).
What this might be
- Insufficient sunlight exposure. Most common cause in the UK.
- Darker skin. Requires longer sun exposure to make the same amount.
- Obesity. Vitamin D is fat-soluble; obesity reduces availability.
- Malabsorption. Coeliac disease, IBD, gastric surgery.
Common features that suggest this
- Persistent fatigue
- Low mood
- Bone or muscle ache
- Hair thinning
- Frequent infections
Recommended tests
Same-day appointments at our Harley Street clinic, results clinician-reviewed.
Need a marker not in these panels? Build a custom panel and a GMC-registered clinician will design one for you.
Testing advice
No fasting. If you are already taking a vitamin D supplement, the result reflects supplemented status; helpful for adjusting dose.
Common questions
What should my vitamin D level be?
NHS classifies under 25 nmol/L as deficient and 25 to 50 nmol/L as insufficient. Most clinicians aim for 75 to 125 nmol/L for symptomatic patients.
Should everyone in the UK supplement?
NHS advice is that all adults consider 10 micrograms (400 IU) daily in winter. Testing tailors the dose to the individual.
Related symptoms
Sources and further reading
This page provides general information only and is not a substitute for medical advice. A GMC-registered clinician will review your results and tailor any recommendations to you personally.