Optimal Levels for Vitamin D

January 7, 2011 Leave your thoughts

In 2010 the “Optimal” level most often quoted at National Osteoporosis Foundation and at American Society for Bone Mineral Research was 32 to 100ng/ml.  This is markedly different from the original “normal” range of 15 to 40ng/ml. Not all testing laboratories have adjusted their standard values.  Some labs still report 30 or 25 or even 20 ng/ml as “normal”.

In individuals with less than 32 ng/ml of 25-hydroxy Vitamin D, the Bone Mineral Density drops rapidly and the Risk of Fracture rises rapidly.  Less than 32ng/ml is considered “Insufficient”.

Less than 20 ng/ml is called Deficient and is associated with high Risk of Fracture.  The result <6 ng/ml indicates a level too low to even detect.

Individuals with all day, year round exposure to tropical sun usually have 25-hydroxy vitamin D levels between 90 and 100 ng/ml.  This strongly suggests that more than 100ng/ml is not needed.

We now aim for between 40 and 70 ng/ml when we Test for Vitamin D Level.  We also take into account the time of year of the test since most individuals get some Vitamin D from the sunshine in the summer and drop their values by 10 or 20 ng/ml between September and March.

Vitamin D toxicity in an adult is extremely rare, even at levels far above 100ng/ml.  Possible toxicity has been reported in individuals with blood levels above 500 ng/ml.  The lowest dose reported to have resulted in toxicity in an adult was 10,000 IU daily for well past 6 months.

Jay Ginther, MD

2008 / Revised November 2010

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