Test Description

This assay is intended to measure the quantitative determination of total 25-hydroxyvitamin D. It is used as an aid in the assessment of vitamin D sufficiency in adults.

The vascular effects of vitamin D include modulation of smooth muscle cell proliferation, inhibition of cytokine release, suppression of renin gene expression, and regulation of thrombosis. Low levels of vitamin D are associated with endothelial dysfunction, inflammation, hypertension and left ventricular hypertrophy, elevated parathyroid hormone (PTH), insulin resistance and type 2 diabetes, and risk for cardiovascular events.

When should this test be ordered?
Vitamin D is a fat-soluble steroid hormone precursor that is mainly produced in the skin by exposure to sunlight. It is essential for bone health. Severe deficiency in children can lead to bone malformation, or rickets. Milder degrees of insufficiency are believed to cause muscle weakness and is a common cause of secondary hyperparathyroidism. Elevation of PTH in elderly Vitamin D deficient adults result in osteomalacia, bone turnover, reduced bone mass and risk of fractures.
High Risk · <= 29 (ng/mL)
Manage deficiencies with supplementation according to your physician, and increase exposure to the sun daily. Toxic levels are usually seen with excessive supplement uptake.
Adequate sun exposure, high vitamin D containing foods (such as salmon or fortified milk), and vitamin D supplementation have all been shown to increase vitamin D levels.
Borderline Risk ·
None determined for these assays.
Low Risk · >= 30 (ng/mL)
Within reference range
Testing Method Used
Electrochemilluminescence immunoassays.

Sample is stable for 4 days at 2-8°C.

Please ship samples daily.
Improvements and Prevention
Your medical provider may prescribe over-the-counter or prescription Vitamin D supplementation. Try to find more time to be in direct sunlight for a minimum of 20 minutes per day.
Foods high in vitamin D include: herring, sardines, trout, flounder, cod and cod liver oil, eggs, milk and dairy products, and portabello mushrooms.
Specimen Type
Serum
Fasting Required
No, but may be done with other tests that requires fasting.
Drawing and Processing

tube1

  1. Draw from a vein into a SST tube
  2. Invert tube (do not shake) 1-2 times to mix adequately
  3. Let stand upright in tube rack for 30 minutes
  4. Centrifuge for 15 minutes at 3300rpm
  5. Do not leave at room temperature for more than 1 hour
  6. Keep cold in a refrigerator to maintain stability, until ready to ship
Shipping Instructions
  1. Freeze ice packs 24 hours prior to use
  2. Place ice packs inside the Styrofoam insulated kit
  3. Place processed tubes inside biohazard bag, place inside kit
  4. Seal box, print airbill and adhere to box and wait for courier to pick up
Rejection Criteria
QNS; temperature out of range upon receipt; grossly hemolyzed or lipemic; wrong specimen type; sample stability exceeded for this analyte; unlabeled or mislabeled specimen
References
1. Hollis BW. Comparison of commercially available 125I-based RIA methods for the determination of circulating 25-hydroxyvitamin D. Clin Chem. 2000;46:1657-1661.

2. Malabanan A, Veronikis IE, Holick MF. Redefining vitamin D insufficiency. Lancet. 1998;351:805-806.

The information provided here is intended for educational purposes only and should not be used or substituted as medical advice. You should consult a healthcare practitioner regarding medical diagnosis or treatment.