The optimal range of 1,25-dihydroxy vitamin D in adult men and women ranges from 18 to 64 and 18 to 78 picograms per milliliter, respectively, according to Mayo Clinic. The normal range for males and females less than 16... More »

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In most states, individuals can have their vitamin D levels tested by presenting a doctor's order at a laboratory facility, according to Quest Diagnostics. No preparation is necessary prior to testing vitamin D levels, w... More »

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Some symptoms of vitamin D deficiency include muscle weakness, bone pain and muscle aches, as stated by Merck Manuals. Vitamin D deficiency occurs due to inadequate exposure to sunlight and its a common condition worldwi... More »

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The normal range for vitamin B12 levels is from about 110 to 1,500 picograms per milliliter (pg/mL), according to WebMD. Vitamin B12 levels are determined from a standard blood test. More »

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Vitamin D2 and vitamin D3 are the forms of vitamin D most important to human health, according to the Mayo Clinic. Vitamin D2 is manufactured by plants, while vitamin D3 is manufactured in the skin when it's exposed to t... More »

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Too much vitamin D is called "vitamin D toxicity," or hypervitaminosis D. This toxicity can be produced by excessive taking of vitamin D supplements including vitamin D3 supplements, according to Mayo Clinic. More »

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Adult men and women should consume 15 micrograms of vitamin D daily, but a specific amount of D-3 is not given, according to a report on SFGate.com, the online news publication of the San Francisco Chronicle. This can be... More »

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