Vitamin D (25-Hydroxy)

Vitamin D level, bone health

This test measures 25-hydroxy vitamin D, the main form of vitamin D stored in the body and the standard measure of your vitamin D status. Vitamin D helps the body absorb calcium and keeps bones and muscles healthy. The body makes it when skin is exposed to sunlight, and smaller amounts come from foods such as oily fish and eggs. Low vitamin D is common, even in sunny countries, among people who spend most of their time indoors or keep most of their skin covered.

• If you have bone pain, muscle weakness or aches
• If you have thin bones (osteoporosis) or have broken a bone after a minor fall
• If you spend little time outdoors or keep most of your skin covered
• To check levels during or after vitamin D treatment
• In conditions that affect absorption from the gut, or in kidney or liver disease

Fasting and special preparation are not necessary. If you take vitamin D or calcium supplements, keep taking them as usual unless your doctor has told you otherwise, and mention them when you discuss the result.

Sample

Blood sample

How it works

During the home visit, the collector takes a small blood sample from a vein in your arm. The draw only takes a few minutes, and you can carry on with your day straight away.

Report

Within 24 hours of collection.

The report shows your vitamin D level next to the laboratory's reference range, which may be split into deficient, insufficient and sufficient. A low level can contribute to weak bones, bone pain and muscle weakness. A very high level is uncommon and is usually linked to taking too much supplement. Your doctor will interpret the result and advise whether any treatment is needed.

One test: Vitamin D (25-Hydroxy), from one blood sample.