In vitamin D deficiency, what lab pattern is typical and what is a common treatment?

• A. Low 25-hydroxyvitamin D; treat with vitamin D supplementation (cholecalciferol or ergocalciferol)
• B. High 25-hydroxyvitamin D; treat with calcium
• C. Normal 25-hydroxyvitamin D; treat with vitamin C
• D. Low 25-hydroxyvitamin D; treat with vitamin B

Answer: (D)

When vitamin D deficiency is present, the key clue is a low level of 25-hydroxyvitamin D in the blood. This is the standard measurement used to assess vitamin D status, with deficient levels typically defined as below about 20 ng/mL. The typical treatment is to replenish vitamin D stores with supplements, most commonly cholecalciferol (vitamin D3) or ergocalciferol (vitamin D2). This repletion helps raise the 25-hydroxyvitamin D level and supports proper calcium and phosphate balance. Options proposing high 25-hydroxyvitamin D or treating with calcium alone don’t address the deficiency, and vitamins C or B aren’t relevant to correcting vitamin D status.