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


Turnaround Time
1 week


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