Indicator Explainer
25-OH Vitamin D
The main circulating vitamin D metabolite — the standard measure of vitamin D status.
This page explains what the indicator is and how results are interpreted in general terms. Reference ranges depend on the laboratory, the method, and your own situation — no single “normal value” applies to everyone. This page is health information, not a diagnosis. For symptoms, treatment, or urgent concerns, contact a healthcare professional.
When it is tested
Measured in bone-health assessments, in malabsorption and chronic kidney disease follow-up, and before and during high-dose supplementation.
Reading results
Values depend on season, latitude, skin tone, body weight, and supplementation timing, and fluctuate across the year. Assays differ measurably — immunoassay and LC-MS/MS results are not interchangeable — so serial monitoring should stay on one method and one laboratory. What counts as deficient versus insufficient varies between guidelines and remains actively debated.
Questions to ask a professional
- Which assay and laboratory was used — will monitoring stay on the same method?
- What season and supplementation pattern applies to this value?
- Which guideline’s thresholds is this report using?
References
- Lab Tests Online — Vitamin D Test
- Risk of Infertility Due to Vitamin D Deficiency among Women with Polycystic Ovarian Syndrome. — Mymensingh Med J, 2026-10-01 (PMID 42811862; literature)
- Evaluation of a new non-competitive chemiluminescent immunoassay for 25-OH vitamin D measurement. — Diagnosis (Berl), 2026-09-21 (PMID 42763789; literature)
- The causal associations between 25(OH) vitamin D levels and ectopic pregnancy: A 2-sample Mendelian randomization study. — Medicine (Baltimore), 2026-09-01 (PMID 42760711; literature)
- Prevalence of Vitamin D Deficiency and Nutrition Knowledge Among University Students in Durres, Albania. — Clin Lab, 2026-09-01 (PMID 42733986; literature)
- Effect of Vitamin D Supplementation in Rheumatoid Arthritis. — Adv Ther, 2026-08-22 (PMID 42631800; literature)
- Serum 25(OH) vitamin D and SIRT1- VDR- miR-124 expression: A controlled interventional study in a vitamin D-deficient male rat model. — Exp Gerontol, 2026-07-27 (PMID 42508623; literature)
- Vegan multinutrient supplementation significantly increases Omega-3 index and 25-OH-vitamin D status: a randomized, double-blind, placebo-controlled trial in healthy young vegans. — Prostaglandins Leukot Essent Fatty Acids, 2026-07-12 (PMID 42480243; literature)
- Clinical Reclassification of Vitamin D Status Across Three Automated Immunoassays After Comparability Study. — Nutrients, 2026-07-10 (PMID 42514336; literature)
- [Lipid, protein oxidation and antioxidant status in menopausal women with different levels of vitamin D in blood]. — Vopr Pitan, 2026-06-30 (PMID 42572215; literature)
- Low 25(OH)Vitamin D levels are associated with nutritional risk and disease severity in outpatient individuals with advanced chronic liver disease. — J Nutr Sci, 2026-06-16 (PMID 42325731; literature)
- [Reducing inappropriate vitamin D testing: an overview]. — Rev Med Suisse, 2026-10-01 (PMID 42899624; literature)