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Test Code LAB535 Vitamin D, 25-Hydroxy

Performing Laboratory

St. Louis Children's Hospital Laboratory - Chemistry

Specimen Requirements

Patient Preparation: Samples should not be taken from patients receiving therapy with high biotin doses (i.e., >5 mg/day) until at least 8 hours following the last biotin administration

Collection Container/Tube:

Preferred: Mint green-top Lithium Heparin (MNTGRN LiHep) tube

Acceptable: plain red-top tube, Gold SST gel tube, or Lavender-top (EDTA) tube

Submission Container/Tube: If specimen is coming from outside facility and collected in a plain red-top tube or lavender-top tube aliquot processed sample into a plastic vial for transport (labeling with specimen type).

Specimen Volume: 1.0 mL (minimum 0.6 mL)

Special Collection Instructions: None

NOTE: Patients taking >20 mg biotin per day may need to discontinue biotin intake for longer than 8 hours prior to collection.

Sample Rejection

Mislabled or unlabeled specimens

Specimens that are grossly hemolyzed

Logistics

Test Availability: Monday-Sunday

Cut-off time: None, performed as received

Turnaround Time: Same Day; 2 hours from receipt in performing lab

Reference Values

Reference Interval: 

<18 years: 20-100 ng/dL
≥ 18 years: 30-80 ng/dL                                                                              

Critical Value: none established

 

Methodology

Electrochemiluminescence binding assay - competition principle

Limitations

  • In rare cases, interference due to extremely high titers of antibodies to analyte-specific antibodies, streptavidin or ruthenium can occur.

Additional Information

FOR SLCH CORE LABORATORY USE ONLY

Lab Processing Instructions: Centrifuge to separate. If specimen is collected in a plain red-top tube or lavender-top tube aliquot sample into a Roche false-bottom tube for testing (labeling aliquot with specimen type).

   Note: specimen do NOT need to be protected from light.

Processed Volume: 0.5 mL (minimum 0.3 mL) plasma/serum

Analyte Stability:

Specimen Type Temperature Time
Whole Blood (unprocessed)  Ambient NA
Plasma/Serum (processed) Refrigerated (preferred) 12 days
  Ambient  72 hours    
  Frozen  NA      
Avoid repeated (>4) Freeze /thaw cycles

Test Classification and CPT Code

82306

LOINC

1989-3

Last Reviewed

06/2025