Test guide
25-OH Vitamin D
The main circulating form of vitamin D and the standard measure of vitamin D status.
What it is for
Assesses vitamin D status in patients with bone disease, malabsorption, chronic kidney disease, or suspected deficiency, and monitors supplementation in treated patients.
Limitations
Results differ measurably between assay platforms and between immunoassay and LC-MS/MS; serial monitoring should use the same method. Interpretation thresholds vary between guidelines and are debated. Season, skin pigmentation, and supplementation timing all influence values.
Before you test
Note supplement use and the dose. No fasting is generally required.
Health information only. This guide does not diagnose or replace advice from a healthcare professional.
Also known as
- 25-hydroxyvitamin D
- calcidiol
- vitamin D test
Reviewed products
Curated product links for this test are still under editorial review. Meanwhile, browse the product directory or request a supplier match below.