25-hydroxy Vitamin D, Total (D2 + D3)

Message

Performed in the Metabolic Laboratory, x6-7919
10.2018

Test Code

VITD

Alias/See Also

Vitamin D

Includes

25-hydroxy Vitamin D3 (calciferol)
25-hydroxy Vitamin D2 (ergocalciferol)

Preferred Specimen

Plasma from a green top (PST) tube

Minimum Volume

1mL

Transport Container

Green Top (PST) tube

Transport Temperature

Room temperature

Specimen Stability

2 - 8 ^oC: 7 days
-20 ^oC: 1 month

Methodology
LC-MS/MS

Setup Schedule

This assay is run in batches mulitple times per week

Report Available

Usually 2-3 business days

Limitations

d3-epimer is not separated.

Reference Range

For total 25-hydroxyvitamin D:

<20 ng/mL	Inadequate
20-29 ng/mL	Borderline
30-99 ng/mL	Adequate
>100 ng/mL	Potentially toxic

Clinical Significance

Vitamin D is important in bone metabolism and maintaining calcium and phosphate homeostasis. Calciferol (Vitamin D3) is synthesized endogenously upon skin exposure to UV light, and is found in fortified milk, fatty fish (tuna, salmon, etc.), and supplemented in some cereals and juices. Ergocalciferol (Vitamin D2) sources include some plants and vitamin supplementation. Although 1,25-hydroxy Vitamin D is the active metabolite, it's half-life is short compared to 25-hydroxy Vitamin D which has a half-life of 3 weeks, and is therefore thought to be a better indicator of total Vitamin D body stores.

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.