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Calcitriol (1,25-Dihydroxyvitamin D₃) in Serum/Plasma

Published: August 9, 2026Updated: August 15, 2026

This test measures the active form of vitamin D, which helps regulate calcium and bone metabolism. It’s important for maintaining healthy bones and supporting immune function.

Quick summary

["Active vitamin D levels help ensure proper calcium balance and bone health."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 15, 2026Editorial policy

Key facts at a glance

LOINC
12509-6
Short code
CALCITONIN5
Synonyms
Calcit sp5 p chal SerPl-mCnc
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top tube without anticoagulant; plasma may be collected in EDTA or heparinized tube per laboratory protocol.
Units
N/A
Ref low
0
Ref high
10
Critical range
— – 1000 N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 18 years
Method
Chemiluminescent Immunoassay (CLIA) or Electrochemiluminescent Immunoassay (ECLIA)
CPT
82308
SNOMED
313219007
Specimen volume
1-2 mL of serum or plasma
Stability
Serum/plasma stable for 8 hours at room temperature, 24 hours at 2-8°C, and up to 3 months at -20°C. Avoid repeated freeze-thaw cycles.
Hemolysis max
50
Lipemia max
100
Icterus max
40
TAT
24–72 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms or conditions linked to vitamin D deficiency or excess, such as bone pain, frequent fractures, muscle weakness, or unexplained fatigue. It may also be checked in patients with kidney disease, malabsorption disorders, or those on long-term vitamin D supplements.

What to Expect Before the Test

No special preparation is needed. You may have a blood sample drawn from a vein in your arm, similar to other routine blood tests. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Results help assess whether your body is producing enough active vitamin D. Low levels may indicate deficiency, while very high levels could suggest over-supplementation or certain medical conditions. Your provider will interpret results in the context of your overall health.

Common Conditions Monitored

This test is often used to diagnose or monitor conditions like rickets (in children), osteoporosis, or hypoparathyroidism. It may also guide treatment for vitamin D deficiency or hypercalcemia (high blood calcium).

Reference range

Fifth specimen post-calcium (pentagastrin or other secretagogue) challenge. Reference ranges vary by stimulation protocol; basal calcitonin typically <10 pg/mL (males) and <5 pg/mL (females) with stimulated peak values generally <100 pg/mL in normal individuals. Peak values >100 pg/mL in males or >50 pg/mL in females may suggest medullary thyroid carcinoma (MTC).N/A

Specimen: serum

Fasting is not required. Patient should be informed of stimulation testing procedure; intravenous calcium gluconate or pentagastrin is administered per protocol, and blood samples are collected at designated time points including the 5th specimen.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal results can signal underlying issues affecting calcium metabolism, bone health, or immune function. For example, low levels may lead to weakened bones or muscle weakness, while high levels could cause kidney stones or excessive calcium deposits in tissues. Regular monitoring helps manage these risks.

Short name

Vitamin D Active Form

Frequently asked questions

How often is this test typically done?
The frequency depends on your health status. Routine adults may not need it unless they have risk factors (e.g., limited sun exposure, certain diets, or kidney disease). Follow your provider’s advice for follow-up testing.
What does a normal range mean for me?
A normal range isn’t a single number but a target based on your health. Your provider will compare your result to your baseline and any symptoms you have. For example, a deficiency might trigger treatment adjustments.
Can diet or supplements affect this test?
Yes. Vitamin D from sunlight, fortified foods, or supplements can influence results. Avoid taking large doses of vitamin D supplements 24 hours before testing unless instructed by your provider.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 15, 2026. · Read our editorial policy