Quick Facts
- Sample: Blood (serum)
- Fasting: Not required
- Turn-around: 3-4 business days. May take longer based on weather, holiday or lab delays.
Benefits
- Evaluate active vitamin D function in kidney disease and calcium disorders
- Identify causes of hypercalcemia with high diagnostic accuracy
- No fasting required — convenient testing fits your schedule
- Fast turnaround — results typically within days for timely decisions
- Easy online ordering — skip the doctor's office, order directly
Who Is This Test For?
- Individuals with chronic kidney disease affecting vitamin D metabolism
- People experiencing unexplained high calcium levels (hypercalcemia)
- Those with granulomatous diseases like sarcoidosis or tuberculosis
- Patients with suspected vitamin D-dependent rickets
- Individuals with normal 25-hydroxyvitamin D but ongoing symptoms
- People with parathyroid disorders affecting calcium regulation
How It Works – Just 3 Steps
- Order online - Purchase your test without a doctor's visit
- Visit a lab - Get blood drawn at a convenient location near you
- Receive results - Access confidential results online within 3-4 business days.
FAQ
What does this test measure? It measures calcitriol, the hormonally active form of vitamin D that regulates calcium and phosphate metabolism in your body (Mayo Clinic 2024).
Is this different from the regular vitamin D test? Yes. The standard test measures 25-hydroxyvitamin D (vitamin D stores), while this test measures active vitamin D function, especially important in kidney disease (NIH 2024).
Do I need to fast before this test? No fasting is necessary for this test.
How long until I get results? Results are typically available within 3-4 business days depending on lab processing time.
Can this test diagnose vitamin D deficiency? Not reliably. The 25-hydroxyvitamin D test is better for assessing vitamin D deficiency; this test evaluates active vitamin D function (CDC 2025).
More Details
What is the purpose of this test?
The Vitamin D 1,25 Dihydroxy (Calcitriol) Blood Test measures calcitriol, the active hormonal form of vitamin D produced primarily in the kidneys. Calcitriol plays a critical role in regulating calcium and phosphate metabolism, which directly impacts bone health and mineral balance throughout your body (Mayo Clinic 2024).
Unlike the standard 25-hydroxyvitamin D test that measures vitamin D stores, this test evaluates how well your body is converting and utilizing vitamin D in its active form. This distinction is particularly important for patients with kidney disease, as the kidneys perform the final conversion step to produce calcitriol. The test uses sensitive chemiluminescent immunoassay or mass spectrometry methods to quantify calcitriol levels in your blood.
Who would benefit from this test?
This test is particularly valuable for patients with chronic kidney disease (CKD), where approximately 15% exhibit altered calcitriol levels affecting bone and mineral metabolism (NIH 2024). People with unexplained high calcium levels (hypercalcemia) benefit significantly, as calcitriol testing correctly identifies vitamin D-mediated causes in up to 90% of cases (American Society of Nephrology 2023).
Individuals with granulomatous diseases such as sarcoidosis or tuberculosis should consider this test, as these conditions can cause abnormal calcitriol production. Patients with vitamin D-dependent rickets, parathyroid disorders, or calcium absorption problems also benefit from understanding their active vitamin D function. Additionally, if your 25-hydroxyvitamin D levels are normal but you still experience symptoms, this test provides deeper insight into vitamin D metabolism.
When should I order the Vitamin D 1,25 Dihydroxy (Calcitriol) Blood Test?
Order this test when your standard 25-hydroxyvitamin D measurement is normal or inconclusive but clinical suspicion of vitamin D metabolic problems remains. This is especially important when evaluating hypercalcemia or when kidney disease is present (University Hospitals Oxford 2024).
Consider testing if you experience persistent bone pain, muscle weakness, or unexplained fractures despite normal vitamin D supplementation. Patients with chronic kidney disease should monitor calcitriol levels as part of comprehensive mineral metabolism assessment. If you have granulomatous diseases or unexplained changes in calcium levels, this test provides essential diagnostic information that standard vitamin D testing cannot reveal.
How do I interpret the results?
Calcitriol Level 18–72 pg/mL
- What it means: Normal active vitamin D function
- Typical action: Continue current regimen; routine monitoring
Calcitriol Level below 18 pg/mL
- What it means: Low calcitriol; may indicate kidney dysfunction
- Typical action: Evaluate kidney function; consider calcitriol supplementation
Calcitriol Level above 72 pg/mL
- What it means: Elevated calcitriol; possible granulomatous disease
- Typical action: Investigate underlying causes; monitor calcium levels
Early detection of calcitriol imbalance in kidney disease reduces morbidity and guides appropriate supplementation, reducing fracture risk (Mayo Clinic 2024).
Interpretation must always consider your clinical context, including kidney function, calcium levels, and parathyroid hormone status. Low calcitriol commonly occurs in renal failure when kidneys cannot adequately convert vitamin D to its active form. Elevated levels may indicate granulomatous diseases, certain lymphomas, or excessive vitamin D supplementation. Always discuss your results with a healthcare provider who can evaluate them alongside your complete medical picture and other relevant test results.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
No fasting is required for this test, making it convenient to schedule at any time. The test requires approximately 5 mL of blood collected in serum tubes, which are protected from light to preserve sample integrity. You can continue taking your regular medications and supplements unless specifically instructed otherwise by your healthcare provider.
Bring your lab order to any participating collection facility. The specimen is collected through a standard blood draw and transported promptly at ambient temperature to ensure accurate results. Drink water normally before your appointment to make the blood draw easier.
How often should I get tested?
Chronic kidney disease monitoring
- Suggested interval: Every 3–6 months as directed by physician
Hypercalcemia evaluation
- Suggested interval: As needed during diagnostic workup; then annually
Granulomatous disease management
- Suggested interval: Every 6–12 months or with symptom changes
After starting calcitriol therapy
- Suggested interval: 4–8 weeks after adjustment, then every 3–6 months
Testing frequency should be individualized based on your specific condition, treatment response, and physician recommendations. Patients with stable chronic kidney disease typically test every 3–6 months to monitor progression and guide therapy adjustments. If you're undergoing treatment for vitamin D-related disorders, more frequent testing helps ensure therapeutic effectiveness and prevents complications. Always follow your healthcare provider's specific recommendations for your situation.
Why early detection matters
Early detection of calcitriol imbalances significantly improves outcomes in kidney disease and calcium metabolism disorders. In CKD patients, identifying altered calcitriol levels early allows for timely intervention, reducing fracture risk and preventing secondary bone disease (NIH 2024).
For hypercalcemia cases, accurate diagnosis through calcitriol testing prevents unnecessary treatments and identifies the true underlying cause with 90% accuracy (American Society of Nephrology 2023). Early intervention in vitamin D metabolic disorders preserves bone health, prevents muscle weakness, and maintains overall quality of life. Timely diagnosis also helps avoid complications from untreated calcium imbalances, including kidney stones and cardiovascular issues.
Related tests you may consider
Vitamin D 25-Hydroxy Blood Test- Checks if you have enough vitamin D, helping to ensure your bones stay healthy and reducing the risk of various health issues associated with vitamin D deficiency.
Parathyroid Hormone (PTH) Intact without Calcium Blood Test- Measures the level of PTH in the blood to help screen for osteoporosis and other underlying health conditions.
Calcium Serum Test- Checks the amount of calcium in your blood to help find problems with your bones, muscles, nerves, or kidneys and make sure your calcium levels stay healthy.
Phosphorus Serum Test - Measures the blood's phosphorus (phosphate) levels to help screen for an imbalance.
Comprehensive Metabolic Panel - Evaluates nutrient levels, liver, and kidney function.
