Vitamin D Low (Deficiency): What Levels Mean, Repletion, and Recheck Timing

The correct test for status is 25-hydroxy vitamin D (25-OH). Searches include “vitamin D level 15”, “how much vitamin D should I take”, “vitamin D and fatigue”. Assays and targets vary by region; decisions are individualized.

Who is at risk for low vitamin D?

• Limited sun exposure, darker skin, northern latitudes, covering clothing.
• Malabsorption (celiac, IBD, bariatric surgery), liver/kidney disease.
• Older adults, pregnancy, some medications (anticonvulsants, glucocorticoids).

Educational repletion notes (not a prescription)

• Food + safe sunlight; supplements discussed with a clinician.
• Common clinician-guided approaches include daily 800–2000 IU or time-limited higher-dose regimens; avoid mega-doses without supervision.
• Calcium intake and resistance exercise support bone health; avoid excess calcium if not indicated.

When to recheck

Often 8–12 weeks after a dose change. Persistently low levels may warrant checking adherence, absorption, or interacting medications.

FAQs

Educational use only. Not medical advice.