Diagnosis of vitamin D deficiency
Investigation of rickets and osteomalacia
Diagnosis of hypervitaminosis D
Paediatric Specimen 600 uL Lithium Heparin or serum Microtainer (200uL plasma/serum required for analysis)
Ambient (8 - 24 degrees Celsius)
Samples may be stored on or off the red blood cells for up to 72 hours. Separated specimens are stable for up to 12 days at 2-8 oC. Outside these timeframes, the separated sample must be stored frozen at -20oC or colder.
This is the preferred test for assessing vitamin D status and most accurately reflects the body’s vitamin D stores.
The main source of vitamin D is the action of sunlight on the skin. Ultraviolet light converts 7-dihydrocholesterol to 25-hydroxyvitamin D3. Vitamin D may also be obtained from the diet from either plant matter as 25-hydroxyvitamin D2 (ergocalciferol or calciferol) or from animal products as 25-hydroxyvitamin D3 (cholecalciferol or calcidiol). Groups at risk of vitamin D deficiency are those with reduced ultraviolet exposure, such as housebound, individuals with darker skin, or wearers of traditional veiled clothing. Vitamin D concentrations are lowest during winter, and low vitamin D tends to recur each winter in susceptible individuals. In such individuals, vitamin D supplementation is reasonable without blood testing.
Most people with low vitamin D are asymptomatic. If prolonged and severe, vitamin D deficiency may lead to rickets in children and osteomalacia in adults; these conditions are uncommon.
The biological half-life of 25-hydroxyvitamin D in plasma is 3 months.
The method used at CHL measures total vitamin D (both D2 or ergocalciferol and D3 or cholecalciferol)
25-OH-Vitamin D levels < 25 nmol/L are consistent with moderate to severe vitamin D deficiency.
25-OH-Vitamin D levels 25 – 50 nmol/L are consistent with vitamin D insufficiency.
25-OH-Vitamin D levels > 250 nmol/L are found in vitamin D toxicity.
Optimum range for bone health: 50 – 150 nmol/L
Chemiluminescent immunoassay (CLIA) performed on Diasorin Liaison XL analysers using Diasorin reagents.
Method measured total vitamn D (25-hydroxyvitamin D2 and 25-hydroxyvitamin D3)
$28.35 (Exclusive of GST)
Vitamin D analysis by HPLC Tandem mass spectrometry (LC-MS/MS) is still available for research testing by arrangement with the Research study coordinator.