LabInformationLab tests, explained

Vitamin D 25-Dihydroxy (Calcitriol) Test in California

Below is a plain-language overview of the vitamin d 25-dihydroxy (calcitriol) test. The Vitamin D 25-Dihydroxy (Calcitriol) Test measures the active form of vitamin D in your blood. It is usually ordered when a clinician suspects a problem with calcium regulation, parathyroid function, or kidney activation of vitamin D, rather than to check for a simple vitamin D deficiency. Across California, part of Pacific, the vitamin d 25-dihydroxy (calcitriol) test can be ordered directly and collected at a certified site — no referral required.

Sample type
blood
Category
Vitamin & Mineral
Turnaround
1-3 business days
Price
$170
Referral
Not required

The Vitamin D 25-Dihydroxy (Calcitriol) Test measures the active form of vitamin D in your blood. It is usually ordered when a clinician suspects a problem with calcium regulation, parathyroid function, or kidney activation of vitamin D, rather than to check for a simple vitamin D deficiency.

What it measures

  • 25-dihydroxyvitamin D (calcitriol) — The active hormone form of vitamin D that helps control calcium and phosphate levels.
  • Calcium — A mineral that works closely with vitamin D and parathyroid hormone.
  • Phosphorus — Another mineral affected by vitamin D activity.
  • Parathyroid hormone (PTH) — A hormone that rises or falls in response to calcium and vitamin D levels.

Who it is for

This test is typically ordered by endocrinologists, nephrologists, or other clinicians evaluating calcium disorders, kidney disease, or unusual vitamin D metabolism. It is not a routine screening test for most adults.

Preparation

No fasting is usually required. Tell your clinician about any vitamin D, calcium, or steroid supplements you take, because timing and recent doses can affect the result.

Results and what they mean

Results are reported as a number with a reference range, and your clinician interprets them alongside calcium, phosphorus, and PTH. A single value is rarely enough to make a decision. This is general information only and is not medical advice; discuss your results with a qualified clinician.

Requesting the Vitamin D 25-Dihydroxy (Calcitriol) Test in California

Order online, choose a certified collection site in California, and review results through a secure portal. No referral is required, and orders are processed confidentially. Because the region is uneven, coastal metros, inland towns, and rural counties with very different access to testing — worth planning around when you book.

Frequently asked questions

How is this different from a regular vitamin D test?

A regular vitamin D test measures 25-hydroxyvitamin D, the storage form. This test measures calcitriol, the active hormone form, which is used in more specific situations.

Do I need to stop my vitamin D supplement?

Ask your clinician. Do not stop or change any supplement or medication on your own before testing.

Can I eat before this test?

Yes, fasting is usually not required unless your clinician gives other instructions.

What if my result is outside the reference range?

Your clinician will consider your symptoms, other lab values, and medications before deciding what it means. Do not adjust treatment based on the number alone.

Vitamin D 25-Dihydroxy (Calcitriol) Test by city in California

All testing in California →   Full Vitamin D 25-Dihydroxy (Calcitriol) Test guide →