What does a high Vitamin D 25-OH result mean?

A high 25-hydroxyvitamin D level (e.g., >100 ng/mL) typically indicates excessive supplementation. Vitamin D toxicity can cause hypercalcemia, nausea, kidney stones, and long-term renal damage. The toxic threshold is >150 ng/mL, but levels >80 ng/mL warrant medical evaluation. Genetic variants (e.g., in the GC gene) affect vitamin D binding and bioavailability, but evidence for personalized dosing is weak (evidence: marketing/unclear). MyBody-X offers vitamin D testing, but interpretation of high results should always be done by a physician. A DNA-based recommendation of 4000 IU daily is not well-supported and could be dangerous if baseline levels are already high. Causes of high levels (supplements, rare diseases like sarcoidosis) require differential diagnosis.