Vitamin D, 25-Hydroxy

Product Description

The Vitamin D, 25-Hydroxy blood test is used to rule out vitamin D deficiency.


  • 25-Hydroxycalciferol
  • 25-OH-D
  • Cholecalciferol Metabolite
  • Vitamin D
  • Vitamin D3 Metabolite

Vitamin D’s metabolic product, calcitriol, is actually a secosteroid hormone that targets over 2000 genes in the human body. Current research has implicated vitamin D deficiency as a major factor in the pathology of at least 17 varieties of cancer as well as heart disease, stroke, hypertension, autoimmune diseases, diabetes, depression, chronic pain, osteoarthritis, osteoporosis, muscle weakness, muscle wasting, birth defects, periodontal disease, and more.

Several factors are associated with an increased risk of developing vitamin D deficiency. At risk populations include:


  • Individuals with low dietary vitamin D
    levels: Infants fed only mother’s milk and children who do not drink
    fortified milk are at risk.

  • Individuals with malabsorption syndromes:
    Patients with pancreatic enzyme deficiency, Crohn disease, cystic
    fibrosis, celiac disease, and surgical resection of stomach or
    intestines are at risk.

  • Individuals with severe liver disease:
    Hepatic disease can reduce the conversion of vitamin D to 25-D and can
    lead to malabsorption of vitamin D.

  • Individuals with kidney disease: Nephrotic syndrome can increase the urinary loss of vitamin D.

  • Individuals taking certain drugs: Several
    medications, including phenytoin, phenobarbital, and rifampin accelerate
    the breakdown of vitamin D by the liver.

  • Individuals who live at higher latitudes:
    Individuals who live in northern climates are at increased risk of
    deficiency, especially in winter months due to diminished exposure to
    UVB radiation.

  • Individuals who spend little time outside:
    Individuals who are home-bound or simply choose to remain inside are at
    increased risk.

  • Older adults: The skin becomes less
    efficient at producing vitamin D as one ages because of diminished
    levels of vitamin D precursors in the skin.

  • Individuals with decreased sun exposure for
    cultural reasons: Women in some societies are required to cover
    themselves with heavy clothing, reducing exposure to the sun’s rays.

  • Races with high melanin levels: Increased
    skin pigmentation can reduce the efficiency of vitamin D conversion in
    the skin as much as 50-fold. Individuals with dark complexions living at
    higher latitudes are at increased risk.