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Vitamin D 25-hydroxy

Category Biochemistry
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: 50-150 nmol/L
Insufficient: 25-50 nmol/L
Deficient: <25 nmol/L



Sample & container required Serum (red top)
Sample volume 0.5 mL
Transport storage For referred samples:
Stable at 2-8°C 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.