Our Vitamin D test gives you a comprehensive overview of your Vitamin D levels. It measures both forms of Vitamin D, namely 25-hydroxyvitamin D3 (cholecalciferol) and 25-hydroxyvitamin D2 (ergocalciferol).
Vitamin D2 (ergocalciferol) is synthetic and is not produced in the human body. It's made by exposing certain plant-derived materials, like yeasts, to ultraviolet light. Most conventional Vitamin D supplements are made from Vitamin D2.
In contrast, Vitamin D3 (cholecalciferol) is produced by the human body when we expose our skin to sunlight and is also available through certain foods including oily fish and fortified dairy. Vitamin D3 is now available in supplement form and is the preferred form to take.
- Optimal Vitamin D levels should be between 60-80 ng/ml
- Some physicians say you can go as high as 100+ ng/ml but that this should only be done under the guidance of a medical practitioner
- Many people in sunny countries have values around 30 ng/ml
Vitamin D deficiency (levels measured below 32 ng/ml) does not manifest obvious symptoms but can increase the risk of several forms of cancer including breast and colon cancers, as well as flu, cardiovascular disease, osteoporosis, osteomalacia, multiple sclerosis, strokes, some autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, Type I Diabetes, Type II Diabetes, certain neurological diseases, depression and even schizophrenia.
Many physicians now advise adding Vitamin D testing to a person's annual blood test panel. Many doctors are also starting to supplement their patients with Vitamin D in response to recent research linking the risk of a variety of diseases as well as general wellness to Vitamin D deficiency.
In the past, it was thought that only people who lived in the regions with little sunlight in winter and summer months could be deficient in vitamin D, but quite recently it was found that people who live in sunny countries can also be grossly deficient. This might be because we're afraid to sit in the sun for risk of skin damage or skin cancer. Suncream and limited time in the sun due to busy schedules prevent us from naturally making enough Vitamin D via our skin.
The likelihood of a Vitamin D insufficiency is increased in malabsorption syndromes, aging (elderly individuals have a reduced capacity for vitamin D3 formation), darker skin (higher concentrations of melanin reduce efficiency in vitamin D3 production), obesity (fat-soluble Vitamin D is stored in adipose, which reduces bioavailability), and minimal sun exposure, such as in winter or at more northern latitudes.
- Get 20 minutes of natural sunlight, no sunglasses, no suncream, twice a day.
- Monitor your vitamin D levels regularly with tests such as this one.
- Supplement with vitamin D3 if your levels are low. NOTE: While Vitamin D has many amazing benefits, it is also a fat-soluble vitamin meaning it is stored in the body and can build up to toxic levels. Retest every 6-12 months to ensure your vitamin D blood levels are not going into the toxic range. Only start supplementation once you've consulted your healthcare practitioner.
- The half-life (how long Vitamin D lasts in the body) of 25(OH)D in the circulation in the body is about 1 month
- Levels generally plateau after about 3 months of vitamin D supplementation or UVB exposure
- When dosing higher than 1000 iu/day, regular monitoring of 25(OH)D (along with serum calcium) is recommended until optimal levels are achieved, above 40 ng/mL
- Persistently low levels may indicate malabsorption or non-compliance
- Levels higher than 80 ng/mL suggest excessive supplementation
Vitamin D, also known as 'The Sunshine Vitamin', is a vital compound responsible for the intestinal absorption of calcium and phosphate. But Vitamin D is actually a prohormone and not technically a vitamin. A vitamin is defined as a substance that is not made naturally by the body but must be supplied in the diet to maintain life processes. But we make most of our Vitamin D by the action of ultraviolet light (sunlight) on the Vitamin D originator that is found in our skin. We only get very small amounts of Vitamin D from our diet from oily fish and fortified dairy, although increasingly it is added to foods eaten by children, in an attempt to prevent rickets.
A major cause of deficiency is not getting enough sun. This is very common in northern climates where people don’t spend much time outdoors and don't expose enough skin area to the sun.
Vitamin D is metabolised by the liver to a storage form of the vitamin, which circulates in the blood until needed. Enzymes in the kidneys metabolise it further to form the highly active hormone that is involved in essential biochemical processes throughout the body.
Who would benefit from this test?
Anyone with the following symptoms and conditions:
- Breastfed infants
- Cardiovascular disease
- Chronic low back pain
- Dark skin
- Diabetes Types 1 & 2
- Increased belly fat
- Multiple sclerosis
- Non-specific musculoskeletal pain
- Rheumatoid arthritis
- The elderly
Who is at risk?
People wanting to prevent cancers should monitor their Vitamin D levels annually and ensure their levels are between the optimal range of 60-80 ng/ml.
Amounts of the Vitamin D originator in the skin decrease with age, therefore elderly people are particularly prone to deficiency, and living in rest homes or becoming home-bound can limit exposure to sunshine. Muscle weakness and osteoporosis associated with Vitamin D deficiency make the elderly more susceptible to falling and fracture risk and studies show that Vitamin D supplementation may decrease the risk of fractures.
Because people with darker skin have higher levels of melanin which can block the action of sunlight on Vitamin D originators in skin, they may require much longer sunlight exposure than people who are fair skinned.
Limited Sun Exposure
People living at northern latitudes, who have limited sunlight exposure because of their working environment, or whose cultural dress rules may prevent sun exposure may have low Vitamin D levels.
Musculoskeletal Pain Suffers
People with symptoms of hypothyroidism, non-specific musculoskeletal pain, chronic low back pain, or fibromyalgia are frequently found to have low vitamin D levels and show clinical improvement after supplementation.
Vitamin D screening is strongly recommended for people with muscle and joint pain.
Overweight or Obese
Vitamin D can be locked up in the fat stores of obese people, who have been found to have lower levels of circulating vitamin D and are at risk of deficiency.
Breastfed Babies & Children with Limited Sun Exposure
All children require adequate circulating vitamin D to prevent rickets. Dark-skinned children and those who spend much of the day inside daycare centres are at risk of deficiency and breastfed children often receive inadequate amounts of vitamin D, particularly when their mothers are deficient. Giving vitamin D supplements to the nursing mother or the use of cod liver oil or other vitamin D supplements in infants and children can reduce the risk of developing Type I Diabetes in childhood. Vitamin D screening has been recommended as a routine part of the annual physical examination. Deficiency doesn't always have obvious symptoms but increases your risk for more serious diseases.
- Vitamin D, 25-OH, Total
- Vitamin D, 25-OH, D2
- Vitamin D, 25-OH, D3
- To determine whether your body has insufficient, sufficient, or excessive levels of Vitamin D
- To assess Vitamin D levels in your body related to bone health, cancer risk, cardiovascular health, cardiovascular disease
Test Sample Type
Dried blood spot (dried blood)
Sample Type Advantages
- No phlebotomist or centrifuging required
- Nearly painless finger prick, simple and safe
- Private (home collection) and convenient
- Hormones are stable in dried bloodspot at room temperature for weeks allowing for worldwide shipment
- Less expensive than conventional blood draws (no phlebotomist, centrifuge, or expensive shipment)
- Ease of collection allows for routine monitoring and adjustment of hormone supplementation as needed
Average Lab Processing Time