What Is Vitamin D (25-OH)?

What it is

25-hydroxyvitamin D is the main circulating form of vitamin D, reflecting body stores.

Why it matters

Used to screen for vitamin D deficiency.

Specimen

Whole blood / serum / plasma

Interpretation

Low = vitamin D deficiency/insufficiency.

Limitations

Screening aid; confirm borderline results quantitatively.

Related test: Vitamin D Rapid Test — specimen: WB