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Vitamin D Testing

About Vitamin D
There is some difference of opinion over what are optimal vitamin D levels. At this time there is no consensus in medicine about what blood levels define the categories of deficient, insufficient, adequate, optimal, high and toxic levels of vitamin D in the blood.

The NHS reference range currently suggests that a vitamin D level of greater than 50 nmol/L is adequate. 50 nmol/L is the lowest blood level that may protect most people from osteoporosis.

The functional reference range is 125 to 225 nmol/L. This was developed taking into account the huge body of research showing how maintaining optimal levels of vitamin D also protects against or reduces the risk of cancer, heart disease, infection, multiple sclerosis, acne, eczema, age-related cognitive impairment, diabetes, fibromyalgia and depression.

Vitamin D testing can be done with a simple fingerprick test. The sample is sent to a specialist vitamin D testing laboratory. Vitamin D testing is included in the full functional lab assessment.

It is important to take into account whether you are currently taking a vitamin D supplement, or when you stopped taking a supplement when interpreting the results. Sun exposure and diet will also affect your vitamin D levels.

Medication must also be assessed, as vitamin D supplementation is incompatible with certain forms of medication, and should also be carefully controlled in certain autoimmune diseases.

    1. Hossein-nezhad A, Holick MF. Vitamin D for health: a global perspective. Mayo Clin Proc. 2013 Jul;88(7):720-55. doi: 10.1016/j.mayocp.2013.05.011. PMID: 23790560
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    Fingerprick testing