25-hydroxyvitamin D (25-OHD)
Private 25-hydroxyvitamin D testing in London for £45, measuring one vitamin D status marker with results expected in around 1 day.
Turnaround time
1 business day
Biomarkers count
1
Book your test
Choose Service Type
Professional phlebotomist comes to you
+ £{{ home_visit_fee }}
Visit our clinic for your test
{{ clinic_visit_fee > 0 ? '+ £' + clinic_visit_fee : 'Free' }}
Home Visit Details
Home visits require at least 24 hours notice.
Select a clinic: Sorting by distance…
{{ clinicAddress(clinic) }}
{{ clinicAddress(selectedClinic) }}
Select a date
Select an hour
Available time slots: {{ timeSlots.length}}
Overview of the 25-hydroxyvitamin D (25-OHD) Test
The 25-hydroxyvitamin D blood test measures 25-OHD, the principal circulating storage form of Vitamin D and the standard laboratory marker used to assess overall Vitamin D status.
The test assesses 1 nutritional biomarker: 25-hydroxyvitamin D (25-OHD).
Vitamin D can be obtained through skin production following ultraviolet-B sunlight exposure, food and supplements.
Vitamin D3 is converted in the liver into 25-hydroxyvitamin D.
This circulating form has a substantially longer half-life than the active hormone 1,25-dihydroxyvitamin D.
For this reason, 25-OHD is the preferred marker for assessing Vitamin D stores.
Vitamin D plays an important role in calcium and phosphate regulation.
It is essential for normal bone mineralisation and also contributes to muscle function.
Severe deficiency can cause osteomalacia in adults and rickets in children.
Low concentrations are common in the UK, particularly during months with limited sunlight.
Risk is also increased in people with darker skin, limited outdoor exposure, extensive skin covering, obesity, malabsorption and selected liver or kidney conditions.
Vitamin D supplementation can correct deficiency but excessive dosing can also be harmful.
Very high Vitamin D intake can cause hypercalcaemia and associated kidney or other complications.
Testing can therefore help guide an appropriate supplementation dose rather than relying on symptoms alone.
The 25-OHD result should not be confused with 1,25-dihydroxyvitamin D, which is the hormonally active form and is used for different specialist clinical questions.
What Does the 25-hydroxyvitamin D (25-OHD) Test Check?
The test measures circulating 25-hydroxyvitamin D as the principal marker of Vitamin D stores. This test measures 1 biomarker.
25-hydroxyvitamin D (25-OHD)
Measures the principal circulating storage form of Vitamin D, providing the standard laboratory assessment of overall Vitamin D status.
Who May Benefit From the 25-hydroxyvitamin D (25-OHD) Test?
Vitamin D testing can be useful where deficiency risk, bone health or supplementation requires assessment.
People with limited sunlight exposure - Reduced UVB exposure can reduce Vitamin D production in the skin.
People with darker skin living in the UK - Higher melanin content reduces cutaneous Vitamin D synthesis from a given amount of sunlight.
People with bone pain or suspected osteomalacia - Severe deficiency can impair bone mineralisation.
People with muscle weakness and recognised deficiency risk - Vitamin D is important for normal musculoskeletal function.
People with malabsorption - Gastrointestinal disease can reduce absorption of supplemental or dietary Vitamin D.
People taking Vitamin D supplements - Testing can guide whether supplementation is adequate or excessive.
People with a previous low Vitamin D result - Repeat testing can assess response to supplementation.
People undergoing broader bone-health assessment - Calcium, Phosphate, Parathyroid Hormone and other markers may be relevant alongside Vitamin D.
How to Prepare
Do not take additional Vitamin D immediately before testing simply to improve the result.
Supplementation should reflect measured status and appropriate clinical guidance.
Symptoms and Reasons to Consider the 25-hydroxyvitamin D (25-OHD) Test
Mild Vitamin D deficiency is often asymptomatic, while more significant deficiency can affect bones and muscles.
Bone or diffuse musculoskeletal pain - Severe deficiency can impair bone mineralisation.
Muscle weakness - Vitamin D deficiency can contribute to proximal muscle weakness.
Limited sun exposure - Reduced cutaneous synthesis increases deficiency risk.
Known malabsorption - Reduced nutrient absorption can lower Vitamin D.
Previous Vitamin D deficiency - Repeat measurement can guide supplementation.
Long-term high-dose supplementation - Testing can help identify excessive exposure.
Bone-health concerns or osteomalacia risk - Vitamin D is central to calcium and phosphate homeostasis.
Fatigue and low mood are non-specific and should not be assumed to result from Vitamin D deficiency without measurement and broader clinical assessment.
Excessive Vitamin D supplementation can cause hypercalcaemia and should be avoided.
How to Book Your 25-hydroxyvitamin D (25-OHD) Test
The 25-hydroxyvitamin D test can be booked privately for focused assessment of Vitamin D stores.
Choose the 25-hydroxyvitamin D (25-OHD)
Select the individual 25-OHD blood test online.
Select your sample collection option
Choose an in-clinic blood draw or professional home or hotel phlebotomy where suitable.
Attend your appointment
A trained healthcare professional collects the required venous blood sample.
Laboratory analysis
Your serum undergoes measurement of 25-hydroxyvitamin D (25-OHD).
Receive your results securely
Your authorised result is delivered securely and can be interpreted alongside supplementation, Calcium and other bone-health markers.
When Will I Receive My Results?
The specialist laboratory turnaround for 25-hydroxyvitamin D is approximately 1 day after laboratory receipt.
The assay is routinely processed and undergoes laboratory quality control and result authorisation before release.
The current London Blood Tests catalogue lists this specific 25-hydroxyvitamin D (25-OHD) test at £45.
Understanding Your Results
A low 25-OHD result indicates reduced Vitamin D stores.
The degree of deficiency should be interpreted according to the laboratory and current clinical guidance.
A result within the laboratory's adequate range suggests sufficient circulating Vitamin D stores for the assessed threshold.
A high result commonly reflects supplementation.
Markedly excessive Vitamin D can increase Calcium absorption and cause hypercalcaemia.
This can produce thirst, increased urination, nausea, weakness and kidney complications.
The result should therefore be used to guide appropriate dosing rather than assuming more Vitamin D is always better.
25-OHD is different from active 1,25-dihydroxyvitamin D and the two tests should not be interpreted interchangeably.
Why Book With London Blood Tests?
London Blood Tests provides private 25-OHD testing for direct assessment of Vitamin D stores.
Measures the standard Vitamin D status marker - 25-OHD is the principal circulating form used to assess body stores.
Relevant to bone and muscle health - Vitamin D supports calcium regulation and bone mineralisation.
Useful in limited sunlight exposure - Deficiency risk increases when UVB exposure is low.
Can monitor supplementation - Testing helps determine whether treatment has corrected deficiency.
Can identify excessive supplementation - Very high Vitamin D can cause clinically important hypercalcaemia.
Rapid specialist turnaround - Results are expected approximately 1 day after laboratory receipt.
Professional blood collection - Clinic and suitable home or hotel appointments are available.
Clear pricing - The 25-hydroxyvitamin D (25-OHD) test costs £45.
Private 25-hydroxyvitamin D (25-OHD) Blood Test in London
London Blood Tests provides private 25-hydroxyvitamin D testing for people requiring direct assessment of Vitamin D stores.
The test costs £45 and measures 1 nutritional biomarker.
Results are expected approximately 1 day after laboratory receipt.
25-OHD is the standard laboratory marker for Vitamin D status and is distinct from active 1,25-dihydroxyvitamin D.