Wellness . Symptoms guide
Vitamin D Deficiency: Symptoms and Testing
Quick answer
Vitamin D deficiency is very common in the UK because of limited sunlight exposure for much of the year. Low vitamin D is linked to poorer bone health and muscle function, with possible effects on immune function, mood and hair cycling. A blood test for 25-hydroxyvitamin D is the gold standard for quantifying your stored reserves. However, because vitamin D works in tandem with minerals to maintain skeletal integrity, a comprehensive evaluation pairs this marker with corrected calcium, serum phosphate, and alkaline phosphatase (ALP) to fully assess bone turnover and rule out secondary metabolic imbalances.
This patient information is being clinically reviewed by our team. The factual content aligns with UK diagnostic frameworks, drawing on NHS primary care pathways, NICE guidelines on vitamin D, and clinical consensus from the National Osteoporosis Guideline Group (NOGG).
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.
Markers your clinician will commonly look at
These are the individual blood markers in the recommended panels above. Click any to read what it measures, its UK reference range, and what high or low values mean.
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?
NICE and SACN classify under 25 nmol/L as deficient, 25 to 50 nmol/L as insufficient and above 50 nmol/L as sufficient for musculoskeletal health. Some clinicians prefer a higher level (often around 75 nmol/L or more) for symptomatic patients, although this is not a formal NHS target.
Should everyone in the UK supplement?
NHS advice is that all adults consider a daily 10 microgram (400 IU) vitamin D supplement during autumn and 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.