A serum 25(OH)D level of 25 ng/mL corresponds to which vitamin D status category?

• A. Insufficiency
• B. Deficiency
• C. Adequacy
• D. Toxicity

Answer: (A)

Vitamin D status is assessed by serum 25(OH)D levels, with specific cutoff ranges used to categorize how much vitamin D is available. Deficiency is usually below about 20 ng/mL, sufficiency (adequacy) is generally 30 ng/mL or higher, and insufficiency falls between roughly 20–29 ng/mL. A value of 25 ng/mL sits in the middle of the insufficiency range, meaning it’s not low enough to be labeled a deficiency but not high enough to be considered adequate. Toxicity would require much higher levels, so 25 ng/mL is not toxic.