Vitamin D deficiency can easily be identified or detected by a simple Vitamin D blood test.
Vitamin D Test measures the levels of Vitamin D in the blood. Two forms of vitamin D can be measured in the blood, 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D. The 25-hydroxyvitamin D (Vitamin D 25-OH) is the major form found in the blood and is the relatively inactive precursor to the active hormone, 1,25-dihydroxyvitamin D. Because of its long half-life and higher concentration, 25-hydroxyvitamin D is commonly measured to assess and monitor vitamin D status in individuals. Vitamin D Total blood test is also available which measures the total combined levels of both forms of Vitamin D.
The normal range of Vitamin D 25-OH is measured as nanograms per milliliter (ng/mL) or nmol/L and can vary from lab to lab.
|Level||Reference range (ng/mL)|
|Severe deficiency||<10 ng/mL|
|Mild to moderate deficiency||10-24|
· There can be seasonal variation in 25 (OH) vitamin D level, with values being 40-50% lower in winter than in summer. It is also influenced by sunlight, latitude, skin pigmentation, sunscreen use, and hepatic function.
· 25 (OH) vitamin D levels can vary with age
· 25 (OH) vitamin D level is increased during pregnancy.
Low vitamin D level than normal reference range indicates vitamin D deficiency which can be because of less sun exposure, dietary deficiency or due to decreased absorption from the intestine. Sometimes, medicines used to treat seizure (Phenytoin) can cause Vitamin D deficiency by interfering with transformation to 25-hydroxyvitamin D in the liver. Severe liver and kidney diseases can also cause vitamin D deficiency.
High vitamin D level than normal reference range indicates vitamin D intoxication and is usually due to excess supplementation of the vitamin.
You can easily beat Vitamin D deficiency by getting more Vitamin D through diet and supplements. Increased exposure to sunlight also helps as Vitamin D is produced in our body on exposure of skin to sunlight.
Vitamin D requirements depend on a number of factors like age, race, geographical location, season, sun exposure etc. A daily Vitamin D intake of 1000–4000 IU, or 25–100 micrograms, should be enough to ensure optimal blood levels in most people.