Vitamin D

Keywords: Vitamin D 25 hydroxy, Vitamin D 25 OH, 25 hydroxycholecalciferol, 25 OH Vitamin D, Cholecalciferol, Vitamin D3

Specimen:

5 mL blood in plain tube.

Method:

Immunoassay.

Reference Interval:

50-200 nmol/L.

Application:

Investigation of suspected rickets and osteomalacia (eg, Malabsorption, dietary deficiency).

Investigation of Osteoporosis.

Investigation of suspected vitamin D toxicity.

Interpretation:

Vitamin D adequacy: ≥ 50 nmol/L at the end of winter (level may need to be 10–20 nmol/L higher at the end of summer, to allow for seasonal decrease).

Mild vitamin D deficiency: 30–49 nmol/L

Moderate vitamin deficiency: 12.5–29 nmol/L

Severe vitamin D deficiency: < 12.5 nmol/L

Toxicity: (Hypercalcaemia, hypercalciuria and nephrocalcinosis). Hypercalcaemia is not seen until serum 25-OHD levels reach 220 nmol/L and is generally not reported until levels reach 500 nmol/L

Reference:

Nowson C et al. Med J Aust. 2012 Jun 18;196(11):686-7.