From the Research
After reducing your vitamin D dose due to high levels, you should typically wait about 2-3 months before rechecking your levels. This timeframe allows your body sufficient time to adjust to the lower dose and for vitamin D levels to stabilize in your bloodstream. Vitamin D has a relatively long half-life in the body (about 2-3 weeks), so changes in supplementation don't show up immediately in blood tests 1. When you retest, the standard blood test measures 25-hydroxyvitamin D, which is the main circulating form of vitamin D. If your levels were significantly elevated (above 100 ng/mL or 250 nmol/L), your healthcare provider might recommend testing sooner, perhaps at 4-6 weeks.
Some key points to consider when rechecking vitamin D levels include:
- The optimal range for vitamin D levels is generally considered to be 30-50 ng/mL (75-125 nmol/L) 1
- Factors like seasonal changes in sun exposure can also affect your vitamin D levels, so consistent timing of tests can provide more reliable comparisons
- Long-term vitamin D supplementation can result in increased risks of hypercalcemia and hypercalciuria, but does not increase the risk of kidney stones 2
- Cholecalciferol is the preferred form of vitamin D for supplementation, as it is more stable and potent than ergocalciferol 3
After this initial recheck, if your levels have improved but aren't yet optimal, continue with the adjusted dose and retest in another 3 months. It's essential to work closely with your healthcare provider to determine the best approach for your individual situation, as the risks and benefits of vitamin D supplementation can vary depending on your specific health needs and circumstances 4.