Vitamin D3 (25-OH Cholecalciferol)

Clinical definition of the 25-OH Vitamin D3 test
Vitamin D comes from two sources: endogenous, which is produced in the skin on exposure to sunlight, and exogenous, which is ingested in foods and supplements. Vitamin D exists in two forms in the blood, 25- hydroxyl D [25(OH) D] and 1, 25-dihydroxy vitamin D [1, 25 (OH) (2) D]. 25- Hydroxy vitamin D is the major form of the hormone found in the blood and is vital for the growth and health of the bone. Without it bones turn soft resulting in various diseases such as rickets and osteomalacia. It also regulates the absorption of calcium, phosphorus, and to a lesser extent, magnesium.

Why is the 25-OH Vitamin D3 test done?
25-OH vitamin D3 is a blood test that measures a person’s vitamin D levels in the blood. Vitamin D deficiency leads to bone malformation, softness or fracture of the bone and abnormal levels of calcium. 25- OH vitamin D3 test is carried out to determine vitamin D deficiency and vitamin D supplementation level.

What are the common signs/symptoms when the 25-OH Vitamin D3 test is done?

  • Poor mineralization of bones
  • Fractures, teeth problems
  • Bone pain and tenderness
  • Bow legs or knock knees
  • Curvature of the spine
  • Poor muscle development and tone
  • Impaired growth and delayed walking in children
  • Lower than normal bone mass

Who should do the 25-OH Vitamin D3 test (Target population)?
Persons showing the above signs & symptoms and abnormal levels of calcium and phosphorus in the blood.

What should I do before the 25-OH Vitamin D3 test?

Specimen type

Specimen collection procedure

Preparatory instructions before the test *

Serum (Blood Sample)


Collection of blood from a vein, usually from the arm.

No Fasting Required.

No other special preparations required.

*Subjects suffering from any illness or on oral or injectable medications are advised to consult their physician prior to requesting any tests or procedures.

How do I interpret my 25-OH Vitamin D3 test results?

Reference Range*


30 to 100 ng/ml


10 to 30 ng/ml


Above 100 ng/ml


Below 10 ng/ml


‘*A Reference range is a set of values which helps the healthcare professional to interpret a medical test. It may vary with age, gender, and other factors. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’

Diseases/conditions related to the 25-OH Vitamin D3 test

  • Vitamin D deficiency
  • Hypervitaminosis D
  • Sarcoidosis
  • Rickets
  • Osteomalacia
  • Multiple sclerosis
  • Arthritis
  • Osteoporosis

Other tests related to the 25-OH Vitamin D3 test

  • Calcium
  • Phosphorus
  • Parathyroid Hormone (PTH)
  • Magnesium

Synonyms : Calcidiol, 25-OH Cholecalciferol
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Vitamin D3(25-OH Cholecalciferol) Serum