Two forms of Vitamin D can be measured in the blood:
– 25-hydroxyvitamin D; and
– 1,25-dihydroxyvitamin D.
25-hydroxyvitamin D is the principal form of vitamin D and is converted to the more active hormone, 1,25-dihydroxyvitamin D.
Vitamin D helps regulate the absorption of vital nutrients such as calcium, phosphate and magnesium. It is therefore extremely important for bone, teeth and muscle growth and health.
The reference range for 25-hydroxyvitamin D is:
Deficient: <25 nmol/L*
Insufficient: 25 – 49 nmol/L*
Normal: 50 – 200 nmol/L*
* Reference ranges provided by The Doctors Laboratory (TDL) and subject to change if/when methods are re-standardised from time to time.