1,25-dihydroxyvitamin D (Calcitriol)
Private 1,25-dihydroxyvitamin D blood test in London for £195, measuring one active vitamin D marker with results in 5–8 business days.
Turnaround time
5-8 business days
Biomarkers count
1
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Overview of the 1,25-dihydroxyvitamin D (Calcitriol)
The 1,25-dihydroxyvitamin D (Calcitriol) blood test is a specialist investigation that measures the biologically active hormonal form of vitamin D.
Vitamin D undergoes several stages of metabolism before becoming active. It is first converted mainly in the liver into 25-hydroxyvitamin D and is then converted predominantly by the kidneys into 1,25-dihydroxyvitamin D, also known as calcitriol.
Calcitriol plays an important role in regulating calcium and phosphate balance and works closely with parathyroid hormone, kidney function and bone metabolism.
The test contains 1 biomarker: 1,25-dihydroxyvitamin D (Calcitriol).
This is not the routine test used to assess whether someone has sufficient vitamin D stores. For routine vitamin D deficiency assessment, 25-hydroxyvitamin D (25-OHD) is generally the more appropriate marker.
Calcitriol can remain normal or even become elevated despite low vitamin D stores because its production is tightly regulated by calcium, phosphate, PTH and kidney function.
Measurement is therefore most useful in specific clinical situations, including unexplained calcium abnormalities, chronic kidney disease, selected disorders of vitamin D metabolism and some granulomatous conditions.
What Does the 1,25-dihydroxyvitamin D (Calcitriol) Test Check?
This test measures 1 biomarker.
1,25-dihydroxyvitamin D (Calcitriol)
Measures the biologically active form of vitamin D involved in calcium and phosphate regulation. The result can provide supporting information when investigating abnormalities in vitamin D activation, kidney-related mineral metabolism and selected calcium, endocrine or granulomatous conditions.
Who May Benefit From the 1,25-dihydroxyvitamin D (Calcitriol) Test?
This test may be suitable for people requiring specialist assessment of active vitamin D metabolism rather than routine measurement of vitamin D stores.
Unexplained high calcium levels - Increased calcitriol production can contribute to hypercalcaemia in selected granulomatous diseases, lymphomas and uncommon disorders of vitamin D metabolism.
Unexplained low calcium levels - Measurement may form part of a wider investigation when calcium regulation remains abnormal despite routine testing.
Chronic kidney disease - The kidneys are a major site where 25-hydroxyvitamin D is converted into active calcitriol, so impaired renal function can alter this process.
Abnormal parathyroid hormone results - Calcitriol, calcium, phosphate and PTH interact closely and may need to be interpreted together.
Possible sarcoidosis or another granulomatous disease - Activated immune cells within granulomas can produce calcitriol outside normal kidney regulation.
Suspected inherited vitamin D metabolism disorder - Specialist testing may be useful where vitamin D activation or response is thought to be abnormal.
Possible vitamin D-dependent rickets - Calcitriol measurement can contribute to specialist investigation of selected disorders affecting vitamin D metabolism.
Complex calcium or phosphate abnormalities - Testing may provide additional information when routine mineral investigations do not fully explain the findings.
Specialist-requested active vitamin D testing - The test can be arranged privately where an endocrinologist, nephrologist, metabolic bone specialist or GP has specifically requested calcitriol measurement.
How to Prepare
Do not stop prescribed vitamin D treatment or substantially alter supplements simply to influence a calcitriol result unless specifically instructed by the clinician responsible for your care.
Providing previous calcium, PTH, kidney-function and standard vitamin D results can be particularly useful because calcitriol is interpreted as part of a wider mineral-metabolism assessment.
Symptoms and Reasons to Consider the 1,25-dihydroxyvitamin D (Calcitriol) Test
You may wish to consider the 1,25-dihydroxyvitamin D (Calcitriol) test when active vitamin D metabolism is being investigated because of calcium, phosphate, kidney or parathyroid abnormalities.
Unexplained high calcium levels - Hypercalcaemia can have many causes and may occasionally involve excessive calcitriol production.
Unexplained low calcium levels - Persistently reduced calcium may prompt assessment of vitamin D metabolism, PTH and kidney function.
Abnormal phosphate levels - Calcium and phosphate regulation is closely linked to vitamin D activity.
Abnormal parathyroid hormone results - PTH influences renal production of calcitriol and forms part of the same mineral-regulating pathway.
Known or suspected chronic kidney disease - Reduced renal function can impair conversion of 25-hydroxyvitamin D into calcitriol.
Recurrent calcium-containing kidney stones - Selected patients may require more detailed investigation of calcium and vitamin D metabolism.
Bone abnormalities or suspected metabolic bone disease - Specialist assessment may include calcitriol when routine vitamin D, calcium and phosphate testing does not adequately explain the findings.
Suspected granulomatous disease - Conditions such as sarcoidosis can sometimes cause abnormal production of active vitamin D.
These findings can occur for many different reasons. An abnormal calcitriol result does not independently diagnose kidney disease, sarcoidosis, lymphoma, parathyroid disease or metabolic bone disease.
The test is also not designed to replace routine 25-hydroxyvitamin D measurement when the clinical question is simply whether vitamin D stores are adequate.
Severe symptoms associated with significantly abnormal calcium, including confusion, marked weakness, persistent vomiting, dehydration or cardiac symptoms, require appropriate medical assessment.
How to Book Your 1,25-dihydroxyvitamin D (Calcitriol) Test
Booking your 1,25-dihydroxyvitamin D (Calcitriol) test with London Blood Tests is simple and designed to fit around your schedule.
Choose the 1,25-dihydroxyvitamin D (Calcitriol)
Select the 1,25-dihydroxyvitamin D (Calcitriol) test online and review the included active vitamin D biomarker before booking.
Select your sample collection option
Choose an in-clinic blood draw (+£35) or a home or hotel phlebotomy visit (+£60) where a qualified phlebotomist collects your sample.
Attend your appointment
A trained professional will collect your blood sample safely and efficiently at the clinic or during your arranged home or hotel visit.
Laboratory analysis
Your sample is sent to the laboratory, where calcitriol is measured using specialist biochemical analysis.
Receive your results securely
Your results are sent securely by email, ready to review yourself or discuss with a GP, endocrinologist, nephrologist, metabolic bone specialist or other suitably qualified healthcare professional.
When Will I Receive My Results?
The expected turnaround time for the 1,25-dihydroxyvitamin D (Calcitriol) test is approximately 5–8 business days after your sample arrives at the laboratory.
Results are sent securely by email once specialist laboratory analysis and authorisation are complete. Turnaround therefore begins when the laboratory receives the sample rather than necessarily from the time your blood is collected.
Specialist biochemical testing may occasionally require repeat analysis, confirmation or additional laboratory review, which can extend the expected turnaround.
Understanding Your Results
Your 1,25-dihydroxyvitamin D (Calcitriol) result shows the concentration of active vitamin D measured in your blood according to the laboratory reference interval and analytical method used.
The result should not be interpreted in the same way as a standard vitamin D result.
A normal calcitriol concentration does not necessarily mean that overall vitamin D stores are adequate. In vitamin D deficiency, increased parathyroid hormone activity can sometimes maintain or increase calcitriol production despite low 25-hydroxyvitamin D stores.
For this reason, 25-hydroxyvitamin D remains the preferred marker when assessing routine vitamin D status.
A low calcitriol result may occur when the kidneys are unable to activate vitamin D normally, including in more advanced chronic kidney disease.
Higher calcitriol concentrations can occur when production is increased. This can be seen in selected granulomatous diseases, certain lymphomas and uncommon disorders affecting vitamin D metabolism.
PTH can also stimulate calcitriol production, making interpretation alongside parathyroid hormone and mineral markers particularly useful.
Results should therefore be interpreted alongside calcium, phosphate, PTH, creatinine, eGFR, 25-hydroxyvitamin D, symptoms and medical history.
Why Book With London Blood Tests?
Private calcitriol testing in London - Access specialist 1,25-dihydroxyvitamin D testing through London Blood Tests.
Targeted active vitamin D measurement - Measure calcitriol without having to book a broad general health profile.
Relevant to calcium metabolism investigation - Calcitriol can provide additional information when unexplained calcium abnormalities are being assessed.
Useful in kidney-related mineral assessment - Kidney function has an important role in converting vitamin D into active calcitriol.
Relevant to selected granulomatous conditions - Excess calcitriol production can occur in conditions such as sarcoidosis.
Specialist laboratory analysis - Your sample is processed using dedicated biochemical methods for active vitamin D measurement.
Clinic and home visit options - Choose an in-clinic blood draw or arrange home or hotel phlebotomy depending on location and availability.
Secure results by email - Receive your authorised laboratory result securely once analysis is complete.
Clear pricing before booking - The 1,25-dihydroxyvitamin D (Calcitriol) test is priced at £195, with sample collection charges shown separately.
Private 1,25-dihydroxyvitamin D (Calcitriol) Blood Test in London
London Blood Tests provides the 1,25-dihydroxyvitamin D (Calcitriol) blood test in London for people requiring specialist investigation of active vitamin D and calcium metabolism.
The test costs £195 and measures one biomarker: 1,25-dihydroxyvitamin D (Calcitriol). This is the biologically active hormonal form of vitamin D produced predominantly by the kidneys.
Clinic appointments are available alongside home and hotel phlebotomy depending on location and availability, providing flexible options for people looking for a private calcitriol blood test in London or specialist active vitamin D testing near them.
Calcitriol results should not be interpreted as routine vitamin D status. A GP, endocrinologist, nephrologist or metabolic bone specialist may recommend interpretation alongside 25-hydroxyvitamin D, calcium, phosphate, PTH and kidney-function results.