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Vitamin D (25 Hydroxy), UW

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Updated Test Information:

Test Description
Vitamin D (25 Hydroxy), UW
Synonym(s)

25-Hydroxycholecalciferol, VITDG, UOW1860
Test ID
VITDG2
General Information

The concentration of 25-hydroxyvitamin D2 and D3 in serum/plasma are determined by heptane liquid-liquid extraction and liquid chromatography-tandem mass spectrometry. The reportable range is 1 - 200 ng/mL with imprecision between 7.7 and 11.5 %CV.


This is the preferred initial test for assessing vitamin D status in patients without renal disease. See Vitamin D Testing Recommendations for an overview of Vitamin D testing.


There is considerable debate over the range of total 25-hydroxy vitamin D concentrations in serum or plasma that is consistent with optimal health. Currently, there are no consensus guidelines for targeting plasma 25-hydroxy vitamin D concentrations and no studies addressing the outcomes of long-term vitamin D supplementation in general populations. 
Container Type

Preferred: 4 mL blood in Gold SST tube
Also Acceptable: 4 mL blood in one of - Orange RST, Lavender (EDTA), Lime Green PST, Red Top tube
Specimen Type

Blood
Specimen Requirements

1 mL plasma/serum
Specimen Collection / Processing Instructions

PST or Gold SST: centrifuge and refrigerate plasma/serum in original container


Lavender or Red Top: centrifuge, remove plasma/serum from red cells and refrigerate.
Minimum Sample Volume

0.5 mL plasma/serum
Pediatric Min. Volume (if applicable)

1 full Lime Green Microtainer
Stability

 Refrigerated - 7 days. If samples can’t be analyzed within 7 days: aliquot serum/plasma from spun tube and store at -20C.
Department (code)

Chemistry, Harborview(CHH)
Methodology

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Estimated TAT

2 Days
Testing Schedule

Monday - Friday
Test Includes

Code               Name
VITD2           Vitamin D2 (25_Hydroxy)
VITD3           Vitamin D3 (25_Hydroxy)
VITDT           Vit D (25_Hydroxy) Total
VTDINF       Vit D (25_Hydroxy) Interp
CPT Code(s)

82306
Reference Range

Concentration range (ng/mL)          Interpretation
less than 8                                                    severe deficiency
8 - 20                                                              deficiency
20.1 - 50                                                       normal
50.1 - 80                                                       high indicates supplementation
greater than 80                                        possible toxicity
STAT Orderable (Y/N)

No
Performing Lab

UW
LOINC Code(s)