25-hydroxyvitamin D

Alternative names, keywords

Vitamin D, 25-hydroxy vitamin D, 25-OH vitamin D, 25 OHD

Samples required

● 5 mL clotted blood. Smaller tubes are available for paediatric samples.

Avoid haemolysis.

Test indications

For investigation of suspected vitamin D deficiency or toxicity.

For suspected deficiency in adults measurement is only indicated for:

  • Musculoskeletal symptoms that may be due to vitamin D deficiency.
  • Suspected bone disease that may be improved with vitamin D treatment.
  • Known bone disease where correction of vitamin D deficiency is needed prior to specific treatment.

See NICE Clinical Knowledge Summary: Vitamin D deficiency in adults

Test information

Assay detects both D3 (cholecalciferol) and D2 (ergocalciferol) forms.

Factors affecting test performance/ results

Haemolysis may cause interference - potentially affected results (serum Hb > 2g/L) will be blocked..

Very high dose biotin (>20 mg/day) may interfere - please contact lab if further information required.

In rare cases, interference due to extremely high titres of antibodies to analyte-specific antibodies, streptavidin or ruthenium can occur.

Results should always be assessed in conjunction with the patient’s medical history, clinical examination and other findings.

Reference range

> 50 nmol/L

Source: local consensus

Turnaround time

RSCH same day*, PRH one working day.

*analysis not available at weekends.

Enquiries

Biochemistry (Automation)

 

Details