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1,25-dihydroxy Vitamin D
(a.k.a Calcitriol)
minimum sample volume required ~ 5ml
Test Code: VI2
Tube type: SST
Special instructions
Must be discussed with the duty biochemist before requesting.
Age ........ Reference range
0 - <1 year ...... 77 - 471
1 - <3 years ..... 113 - 363
3 - <19 years .... 108 - 246
19+ years ........ 55 - 139
Sent away
to Norfolk & Norwich University Hospital
Contact Laboratory before requesting
Units
pmol/L
Turnaround Time
21
days
Department: Biochemistry
Clinical Application
NB: Measurement of total vitamin D (25-hydroxyvitamin D) is the first-line test for investigation of suspected Vitamin D deficiency.
1,25 dihydroxyvitamin D (calcitriol; 1,25 D3) is the most active form of vitamin D. It is formed in the kidney by the action of 1-α hydroxylase on 25-hydroxyvitamin D, but may also be produced extra-renally in sarcoidosis, TB, lymphoma and other granulomatous disease.
1,25 D3 is not a good indicator of vitamin D status in most patients. The preferred test for this is 25-hydroxyvitamin D (total vitamin D).
1,25 D3 may have limited use in the differential diagnosis of hypercalcaemia, or in the investigation of possible vitamin D-dependent rickets due to hereditary deficiency of renal 1-alpha hydroxylase or end-organ resistance to 1,25-dihydroxyvitamin D.
Prior discussion with the duty biochemist is essential for this test (ext 4050).
Webpage updated: December 2024
