A private Vitamin D (25-OH) Blood Test at 117a Harley Street, London costs £108.75, with results usually in 1 day. Sample collection £50. This test measures 25-hydroxyvitamin D, the main circulating form of vitamin D and the standard way to assess your vitamin D status.
Low levels are common in the UK, especially between October and March when sunlight is too weak for the skin to make enough.
No fasting is needed. If you already take a vitamin D supplement, keep taking it as usual unless a clinician has told you otherwise, so the result reflects your normal level.
Written by Mr Stephen Lingam. Reviewed by Dr Mohammad Bakhtiar (GMC 4694470) on 06/09/2026.
People with tiredness, bone or muscle aches, limited sun exposure, darker skin, or conditions that affect absorption, and anyone checking whether a supplement is working.
No. There is no fasting or special preparation for a vitamin D test.
The result is given in nmol/L. In the UK, levels below 25 nmol/L are generally considered deficient and 50 nmol/L or above adequate for most people.
Results are usually available in 1 day by email.