What this marker measures
This test is usually ordered for specific clinical questions, not for general vitamin D status. Most people should be checked with 25-Hydroxyvitamin D instead. When 1,25-Dihydroxy Vitamin D is ordered, it is typically interpreted alongside calcium, PTH, and kidney markers.
High or low: what it can mean
High 1,25-Dihydroxy Vitamin D
Elevated 1,25-Dihydroxy Vitamin D is uncommon and is most often discussed in specific clinical contexts (for example, certain granulomatous conditions or specific calcium-regulation questions). It is interpreted together with calcium, PTH, phosphorus, magnesium, kidney markers, and clinical context — diagnosis usually requires confirmation and clinical context.
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Low 1,25-Dihydroxy Vitamin D
Low 1,25-Dihydroxy Vitamin D can be seen in advanced kidney patterns (the kidney is the main site of conversion from the storage form) and in specific clinical contexts. As with the high direction, it is reviewed with the broader mineral and kidney picture.
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Frequently asked questions
What is 1,25-Dihydroxy Vitamin D?
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1,25-Dihydroxy Vitamin D is the active hormonal form of vitamin D, produced mainly in the kidneys from the storage form (25-Hydroxyvitamin D). It is NOT the standard vitamin D screening test — that role belongs to 25-Hydroxyvitamin D (the "Vitamin D" entry above).
What does 1,25-Dihydroxy Vitamin D measure?
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This test is usually ordered for specific clinical questions, not for general vitamin D status. Most people should be checked with 25-Hydroxyvitamin D instead. When 1,25-Dihydroxy Vitamin D is ordered, it is typically interpreted alongside calcium, PTH, and kidney markers.
What does high 1,25-Dihydroxy Vitamin D mean?
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Elevated 1,25-Dihydroxy Vitamin D is uncommon and is most often discussed in specific clinical contexts (for example, certain granulomatous conditions or specific calcium-regulation questions). It is interpreted together with calcium, PTH, phosphorus, magnesium, kidney markers, and clinical context — diagnosis usually requires confirmation and clinical context.
What does low 1,25-Dihydroxy Vitamin D mean?
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Low 1,25-Dihydroxy Vitamin D can be seen in advanced kidney patterns (the kidney is the main site of conversion from the storage form) and in specific clinical contexts. As with the high direction, it is reviewed with the broader mineral and kidney picture.
Related biomarkers
Editorial note
LabTestly explains lab markers using plain-English educational content. Reference ranges may vary by laboratory and should be interpreted with a clinician.
Educational content · Editorially reviewed for clarity · Last updated
Common sources used for lab-test education
Not medical advice
This page is for general understanding only and does not replace medical advice from your clinician. Reference ranges can vary by laboratory, age, sex, pregnancy status, medications, and clinical context.