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Vitamin D – Testing Serum Levels

Posted Oct 25 2009 11:04pm

Vitamin D is an extremely vital substance that is formed in your body when ultra violet B radiation, UVB, converts cholesterol in your skin to cholecalciferol (Vitamin D3).  The Vitamin D3 then forms a prehormone,  25(OH)D that converts to a ‘steroid’, calcidiol.  The importance of calcidiol is that it targets over 2000 genes in the human body.  That is about 10  percent of genome or the total amount of genes that directs our biological functions.  It is also implicated in cancer, diabetes, heart disease, autoimmune disease, hypertension, bone diseases, cavities and periodontal disease, pain, muscle strength, birth defects, immune function, and mental health in depression and schizophrenia.  The seriousness of these diseases and the fact that everyone uses vitamin D at a different rate is why you should test and not just guess at what you ‘think’ may be an adequate amount.

The old understanding was that all of the calcitriol was made in the kidney and circulated to all other places in the body where it was used.  The new understanding is that every cell in the body uses the ubiquitous storage form of 25(OH)D to make the calcitriol as it is needed.  This is exciting as genes get turned off and on and cells communicate with each other through the aid of vitamin D.  Please read the physiology at the Vitamin D Council.

As you would imagine it is very important to keep your storage of form vitamin D level high enough so that all of these really good things can happen within your biological functions.  This has been part of the problem as scientists tried to correlate the active form of vitamin D or calcitriol to disease states in your body.  There was no correlation.  However, in the 1970’s the correlation between disease and the storage form of vitamin D, 25(OH)D,  was discovered to be significant.  So what was happening with the active form in your blood was not what was happening with the active form in the rest of your body.

So it is the storage form of the vitamin D that we are most interested in maintaining at a correct level for health.  The amount of the storage form, 25(OH)D, has been found in typical sunny countries to be in the range of 54 ng/ml to 90 ng/ml.  ( Benefits and Requirements for Vitamin D for Optimal Health, Grant and Holick at Sunarc.org )  So is this the correct range for health?  It would seem that this is most likely the case.  The researchers are saying that a significant number of chronic diseases could be eliminated by keeping it within this range.  See chart by Dr. Garland and Carrole Baggerly at GrassrootsHealth disease prevention chart.  (pdf)

When the level of 25(OH)D increases, it appears from the extrapolation of many different studies that disease rates are significantly reduced.  If you look at breast cancer for example from the above chart you see that the incidence rate decreases by 80 percent in the low 50 ng/ml range.  I suspect as more research is done that we can find significant treatment and not just prevention at higher levels.  To think that when you reach the level of a sunny country that rates of breast cancer become extremely low is exciting considering what is happening with this serious disease in the northern latitudes.  Does this bear out in the studies of breast cancer by latitude?  In other words as you get closer to the equator does the breast cancer rate go down.  The answer is yes as you can see from SUNARC Breast Cancer Studies the mortality rate is about half in south Texas of what it is in New England.

So does everyone’s serum level of vitamin D reach the same amount with the same intake of vitamin D3?   The answer is a definite no and much research is needed to better understand why this is the case.  About sixty percent of the variation is due to difference in weight which makes it easier to determine how much to take.  If you are a 150 lb person you could expect your serum 25(OH)D to increase by 1 ng/ml for 100 IU of vitamin D that you take.  If you found that your serum level was 20 ng/ml,  then to get to 60 ng/ml or an increase of 40 ng/ml you would need to take about 4000 IU per day.  This information was obtained from Dr. Heaney’s work at Creighton University and his video presentation through GrassrootsHealth and UCSD public TV is well worth watching even if it is 50 minutes long.  It will answer many of your questions about vitamin D deficiency and how much we need and the levels of safety.

So the thrust of this is that if you weigh more,  then you need to take more to reach the desired level of vitamin D.  Another good method to achieve the desire level is that suggested by Dr. John Cannell of the Vitamin D Council home page.  That is you start out by taking 5000 IU of D3 per day and then have your serum level tested after three months.

For children Dr. Cannell suggest that 1000 IU per 25 lbs of body weight per day will get you to a reasonable level.  If your child has any significant disease state such as asthma or autism then you should have your child tested regularly initially to be sure that you are given them enough for health.  Here is Dr. Cannell’s newsletter on pediatrics.

D3 Test

There are several methods for having your vitamin D tested.  I think that it is best to have a doctor do it so that you can discuss the validity of the data and how it relates to health.  Not only that, if you doctor is not up to speed on the research you may help get him there.  However, if you have read my two most recent posts then you know that not all doctors are on board.  I have taken on the quest of finding the places online that you can use:

Vitamin D Council:   http://www.zrtlab.com/vitamindcouncil /  $65 per test

GrassrootsHealth:  www.grassrootshealth.net here you join the national survey and fill out a short form about your current health at $40 per test.

In the above test you get a test kit in the mail.  You prick your finger and do a blood smear and send the kit back in the mail and receive the test results some time later.

Life Extension: http://www.lef.org/Vitamins-Supplements/ItemLC081950/Vitamin-D-25-Hydroxy-Blood- This test is $63 and you get your serum drawn at a testing facility in your town or the one closest to you.

At your doctor’s office.  The prices vary significantly depending on how much the doctor wants to add to the test for drawing the blood and interpreting the results and advising you.  I have typically seen the number between $150 and $300.  If your insurance does not pay then you may want to use one of the methods above.

Understanding the meaning of the results: Sometimes the test will include both the steroid form or calcitriol and the storage form or calcidiol or 25 hydroxy-vitamin D or 25(OH)D.  It is only the 25(OH)D level that you are interested about.

The typical reference range or some may think ‘normal’ range is 20 ng/ml to 100 ng/ml.  Some people who spend large amounts of time in the sun with their clothes off may have values of 125 ng/ml or higher such as life guards in the summertime.  There is not any case of extremely high values of 25(OH)D with sun exposure.  The NIH fact sheet that says that anything sustained below 200 ng/ml is safe.  See table 1.  NIH Vitamin D Fact Sheet

You know that you are getting enough when your test comes in above 50 ng/ml.  If you are consistently above 80 ng/ml then you may want to consider reducing the amount of vitamin D that you are getting.

D2 Test If you have taken D2.

When you get your 25(OH)D test result it will most likely show only the total of 25(OH)D2 and 25(OH)D3.  If you have not had any vitamin D2, then your result will show the total of 25(OH)D3.  In some cases where the patient is being aggressively treated with the 50,000 IU D2 then it may show both D2 and D3 results.

Keep healthy serum levels between 50 ng/ml to 80 ng/ml or just be a ‘sunny country’.   – Pandemic Survivor

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