The Importance of
a Vitamin D Blood Test

A vitamin D blood test is not considered a routine procedure by most doctors today; in fact, these tests are rarely recommended. However, increasing evidence indicates that this might be one of the most important indicators of your overall health that you could find.

Numerous studies in recent years have shown that the overwhelming majority of the population suffers from vitamin D deficiency. Low vitamin D levels are now known to be at the root of many chronic illnesses. Since most of these health problems are very complex, and take many years to manifest, the connection between them and a vitamin D deficiency has been ignored for a very long time.

You can find specific information at my page on
Symptoms of Vitamin D Deficiency

"We estimate that vitamin D deficiency is the most common medical condition in the world."

Dr. Michael F. Holick,
Vitamin D expert

Why Would You Need a Vitamin D Blood Test?

Unless you practice regular sunbathing in the summertime, and take vitamin D supplements the rest of the year, you almost certainly have low vitamin D levels in your bloodstream. You can't really determine this for sure without a vitamin D blood test.

You can arrange a vitamin D blood test with your health care provider (you can read reviews ahead of time before committing), or order an inexpensive home blood test.

Make sure you get the correct test. There are two vitamin D tests currently being offered: 1,25(OH)D, and 25(OH)D. The correct test to order is 25(OH)D, also called 25-hydroxyvitamin D, which is the better indicator of overall D status.

If you use your doctor, make sure he orders the correct test. If you have insurance, you may be able to save money by going to your doctor. Some insurance companies will pay for a 25(OH)D test, some won't.

Surprising as it may seem, many doctors are unfamiliar with the different vitamin D tests. About 20% of them order the wrong test. They order a 1,25-dihydroxy-vitamin D, which is NOT the test you want.

Even if they order the correct test, few doctors know how to correctly interpret the results! A doctor who is not up to date with current studies might think anywhere from 20–50 ng/ml (nanograms per milliliter) is a normal vitamin D level, but that standard is terribly outdated. Make sure you get the results and interpret them for yourself.

Interpreting Your Vitamin D Blood Test

A normal vitamin D level has traditionally been set at between 20-56ng/ml (nanograms per milliliter). However, more recent studies have indicated that anything less than 50ng/ml could be considered deficient.

Current guidelines for vitamin D blood levels:

Deficient: lower than 50ng/ml
Optimal: between 50-65ng/ml

This range applies for everyone; children, adolescents, adults and seniors.

A normal vitamin D level should never be below 32 ng/ml, and any levels below 20 ng/ml are considered serious deficiency states, increasing your risk of as many as 16 different cancers and autoimmune diseases like multiple sclerosis and rheumatoid arthritis, just to name a few.

The body does not reliably begin storing vitamin D in fat and muscle tissue until blood levels get above 50 ng/ml. So, at levels below 50 ng/ml, the body uses up all its vitamin D, without leaving anything in reserve.

A Game Plan for Optimizing Your
Vitamin D Blood Levels

Start supplementing with vitamin D for a couple of months before you have the vitamin D blood test. Dr. John Cannell of the Vitamin D Council suggests that you take 1,000 IU per 25 pounds of body weight as a starting vitamin D dosage. A person who weighs 150 pounds, for instance, would take 6,000 IU per day.

Once you get the results of your vitamin D blood test, adjust your dose so your blood level is between 50–80 ng/ml, summer and winter.

Some people may feel more comfortable ordering the blood test before they start supplementing vitamin D because of fears of toxicity. Have no fear — no one can get toxic on doses of less than 10,000IU per day. Just keep your dosage below that level until you get tested.

See my page on Vitamin D Toxicity
for more details.

For more information about how much vitamin D to take,
see my page on Vitamin D Dosage

Visit other pages in this website on vitamin D:

Vitamin D Facts

Health Benefits of Vitamin D

Vitamin D Toxicity

Causes of Vitamin D Deficiency

Symptoms of Vitamin D Deficiency

Vitamin D Dosage

Foods That Contain Vitamin D

Vitamin D From Sun Exposure

Other great resources for vitamin D information:

Grassroots Health A consortium committed to solving the worldwide vitamin D deficiency epidemic.

Dr. Mercola's Video Lecture on the latest science on vitamin D.

How Much Vitamin D Do You Need? Also by Dr. Mercola.

Antioxidants Home Page from Vitamin D Blood Test


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