Vitamin D (25-OH Vitamin D) Test

The Vitamin D test measures 25-hydroxyvitamin D, the main form of vitamin D that circulates in your blood and the best indicator of your body's overall vitamin D status.

Vitamin D plays a crucial role well beyond bone health — it supports calcium absorption, immune system regulation, muscle function, and has been linked in research to mood and overall well-being.

Your body produces vitamin D naturally when skin is exposed to sunlight, but factors like indoor lifestyles, use of sunscreen, darker skin tone, living at higher latitudes, and certain medical conditions can all significantly reduce natural production, making deficiency extremely common worldwide.

Because symptoms of mild-to-moderate deficiency are often vague or absent altogether, blood testing is the only reliable way to know your actual vitamin D level.