Hypovitaminosis D - Classifications

Classifications

Hypovitaminosis D is typically diagnosed by measuring the concentration in blood of the compound 25-hydroxyvitamin D (calcidiol), which is a precursor to the active form 1,25-dihydroxyvitamin D (calcitriol). One 2008 review has proposed the following four categories for hypovitaminosis D:

• Insufficient 50–100 nmol/L (20–40 ng/mL)
• Mild 25–50 nmol/L (10–20 ng/mL)
• Moderate 12.5–25.0 nmol/L (5–10 ng/mL)
• Severe < 12.5 nmol/L (< 5 ng/mL)

Note that 1.0 nmol/L = 0.4 ng/mL for this compound. Other authors have suggested that a 25-hydroxyvitamin D level of 75–80 nmol/L (30–32 ng/mL) may be sufficient although a majority of healthy young people with comparatively extreme sun exposure did not reach this level in a study done in Hawaii.