Imperial Collage Healthcare

Vitamin D 25-hydroxy

Test Background
25-hydroxy vitamin D3 is the storage form of vitamin D3 from which 1,25-dihydroxy vitamin D3 is synthesised. 1,25-dihydroxy vitamin D acts as a hormone and stimulates intestinal calcium/phosphate absorption and increased bone resorption.

Clinical Indications
Investigation of vitamin D deficiency 25-hydroxy vitamin D3 and 25-hydroxy vitamin D2 concentrations to assess treatment efficacy in established vitamin D deficiency Differential diagnosis of bone disease Investigations of hyperparathyroidism secondary to chronic kidney disease

Reference Range
Replete: 70-150 nmol/L Insufficient: 40-70 nmol/L Deficient: <40 nmol/L

Sample Required
Serum (red top)

Sample Volume
0.5 mL


For referred samples:

Stable at 2-8oC for 72 hours. Please freeze pending dispatch for analysis.

Sample can be sent by first class post.

Turnaround Time
1 week


Grossly haemolysed samples are unsuitable for this assay.

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