Vitamin D Determination

D, a fat-soluble vitamin, is more appropriately categorized as a prohormone which is a collective term for a group of seco-steroids. Vitamin D is metabolised by hepatic 25-hydroxylase into 25-hydroxyvitamin D and by renal 1α- hydroxylase into the active form 1, 25- dihyroxyvitamin D. Essentially, vitamin D maintains the levels of calcium and phosphate which in turn is needed for normal bone mineralization, muscle contraction, nerve conduction and general cellular function. More specifically 1, 25-dihydroxyvitamin D is a strong steroid hormone that has a crucial role in calcium homeostasis, bone metabolism, cell growth and replication.

Why do I need vitamin D?

Your body must have vitamin D to absorb calcium and promote bone growth. Too little vitamin D results in soft bones in children (rickets) and fragile, misshapen bones in adults (osteomalacia). You also need vitamin D for other important body functions.

Vitamin D deficiency has now been linked to breast cancer, colon cancer, prostate cancer, heart disease, depression, weight gain, and other maladies. These studies show that people with higher levels of vitamin D have a lower risk of disease, although they do not definitively prove that lack of vitamin D causes disease -- or that vitamin D supplements would lower risk.

Causes Vitamin D deficiency

There are a number of factors which can cause a vitamin D deficiency:

  • Deficient production
  • Decreased input due to seasonal lack of exposure to sunlight
  • Anything that interferes with the penetration of solar ultraviolet radiation into the skin will diminish the cutaneous production of Vitamin D3
  • Dietary intake is low
  • Marked decrease in the capacity of the human skin to produce vitamin D in the elderly
  • Impaired absorption due to kidney or digestive diseases
  • Inherited polymorphisms which affect vitamin D absorption.
Test for Vitamin D deficiency

Vitamin D deficiency can be a serious problem and does not have very obvious symptoms. It increases susceptibility to other more serious conditions.

Maintaining Vitamin D levels protects the body from a wide range of diseases including viruses, cardiovascular disease, bone disease including osteoporosis, rickets and osteomalacia, autoimmune disease (such as multiple sclerosis and rheumatoid arthritis), strokes, nervous system disorders (such as Parkinson’s Disease) and type 1 and 2 diabetes. Depression and breast, prostate and colon cancer have also been linked to Vitamin D deficiency.

How does the test work?

CNS uses a conventional ELISA based technology to determine the total concentration of both 25- hydroxyvitamin D2 and 25-hydroxyvitamin D3 (25(OH)D). The method has been calibrated against the gold standard LC-MS/MS method, demonstrating excellent agreement with external quality assurance.

As part of your regular blood test, your health practitioner should order a test for 25-hydroxyvitamin D (25-OHD). It is commonly accepted that adults with a 25-OHD level of less than 15 ng/mL or 37.5 nmol/L (depending on the units reported by a lab) need more vitamin D. A 2002 study found that 42% of African-American women of childbearing age had vitamin D levels below 15 ng/ml. The U.S. National Institutes of health notes that 25-OHD levels over 30 ng/mL are optimal, and that there is insufficient data to support recommendations for higher levels. The Vitamin D Council considers the ideal 25-OHD level to be between 40 ng/mL and 70 ng/mL.

Sample requirements & Test turnaround

Simply collect a finger-prick blood sample using the components provided in the Sample Collection Pack and send to the Cambridge Nutritional Sciences Laboratory using the pre-paid envelop supplied. Results are available within 10-15 working days. CNS participates in the DEQAS external quality assessment scheme for Vitamin D testing.

The CNS Vitamin D test has not been verified for use with clients under the age of 18. Although it can still be used in some cases, under 18s may have different blood protein levels which may affect the results of most Vitamin D tests currently available.

Sources Cambridge Nutritional Science