Vitamin D
Why do we do this test?
To find out whether you are Vitamin D deficient or if your Vitamin D supplements are adequate.
Vitamin D levels will be requested by a health care practitioner when you have abnormal calcium, phosphorus and/or parathyroid hormone level; when you have evidence of bone diseases or if you are at a high risk of developing vitamin D deficiency.(Elderly or obese people, people without enough sun exposure, dark skinned, institutionalized, small body stature, post-menopausal)
Vitamin D is essential for proper growth and formation of bone and teeth. The deficiency leading to soft malformation of bones known as rickets in children and osteomalacia in adults. Vitamin D also plays a role in the immune system and which is implicated in certain cancers and autoimmune disorders.
Two forms of vitamin D are measured in blood which are 25 hydroxyvitamin D and 1,25- dihydroxyvitamin D. 25 hydroxyvitamin D is the major form found in blood and is the inactive precursor of active 1,25- dihydroxyvitamin D. 25 hydroxyvitamin D is commonly measured in the assessment of vitamin D levels as it is found in higher concentrations and the levels are more stable as it has a longer half-life.
Specimen Type
Serum, Plasma (EDTA), Plasma (Li Heparin)
Instructions for specimen collection & Patient preparation
Specimen transportation & Processing
Separate serum as soon as possible. Transport separated serum/plasma in ice
Specimen storage & stability
For prolonged storage keep frozen at -20C. If analysis with in 5 days stable at
Specimen storage duration
Reference Intervals & Target Values
Vitamin D status
Deficient < 10 ng/mL < 25 nmol/L
Insufficient 10 - 30 ng/mL 25 - 75 nmol/L
Sufficient 30 - 100 ng/mL 75 - 250 nmol/L
Toxicity >100 ng/mL >250 nmol/L
Critical Limits
Possible Pre-analytical Errors
Lipaemia, Haemalysis
Possible Analytical Errors
Insufficient serum/plasma volume, Air bubbles, Fibrin clots.
Available Government Laboratories
Apeksha Hospital,National Hospital Sri Lanka, Medical Research Institute, Colombo South Teaching Hospital, Colombo North Teaching Hospital, Karapitiya Teaching Hospital, National Hospital Kandy, Jaffna Teaching Hospital, Kurunegala Teaching Hospital
Recommended turnaround time
1 to 7 days

Test Method


1. Dawson-Hughes, B., Heaney, R.P.,Holick, M.F.,Lips, P.,Meunier,P .J.,Vieth,R.,Estimates of optimal vitamin D status. 2005 Osteoporosis Int. 16:713-16
2. Enders DB, Rude RK; Mineral and Bone Metabolism. Burtis CA, Ashwood ER. Tietz Text Book of Clinical Chemistry,3rd edition, USA, Elsevier Saunders 1999, 1395-1457.

Last Updated : 2020-09-23 04:38:48






College of Chemical Pathologists of Sri Lanka

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