Why get tested?
To investigate a problem related to bone metabolism or parathyroid function

When to get tested?
Your doctor may request a Vitamin D measurement if you have an abnormal calcium, phosphate, and/or parathyroid hormone level, as part of the investigation of some forms of bone disease or occasionally if you have kidney failure or disease of the gastrointestinal tract that may result in malabsorption

Sample required?
A blood sample drawn from a vein in your arm