1,25-Dihydroxyvitamin D (Calcitriol)
1,25-Dihydroxyvitamin D, also called calcitriol, is the active, hormone form of vitamin D that your kidneys produce. It directly tells your gut to absorb calcium and helps regulate calcium and phosphate in your blood.
This is a specialized test, not the usual way to check vitamin D status. Because your body tightly controls calcitriol, it can look normal even when storage levels are low. Clinicians mostly use it to investigate specific problems with calcium, phosphate, kidney function, or certain rare conditions.
A high active-vitamin-D level can occur with certain conditions such as granulomatous diseases or some parathyroid problems, where the body produces extra calcitriol. Because this may raise blood calcium, a high result is best interpreted alongside your calcium, kidney, and parathyroid tests. It reflects regulation rather than simple intake.
A low level can point toward kidney issues, since the kidneys make this active form, or to disturbances in the hormones that regulate calcium. It is not the standard way to detect ordinary vitamin D deficiency.
There is a normal reference range, but this test is meaningful only in the context of a specific clinical question. A clinician who ordered it will interpret it alongside your calcium, phosphate, and kidney results.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.