Key Points Previously, the Endocrine Society had labeled vitamin D status as “deficient” when serum hydroxyvitamin D (25[OH]D) was lower than 20 ng/mL, and “insufficient” when serum 25(OH)D was 20 ng/mL to 29 ng/mL. Now, the Society “no longer endorses specific 25(OH)D levels to define vitamin D sufficiency, insufficiency, and deficiency.” The rationale is that clinical research has not established distinct thresholds of serum levels that can be tied confidently to specific clinical outcomes. In a separate essay accompanying the guideline, authors (McCartney CR et al.) discuss this move in more detail. In the general population of adults (age range, 19–74), neither routine vitamin D supplementation nor routine testing of 25(OH)D levels are recommended. However, adults in this age group should follow the U.S. National Academy of Medicine's recommended daily allowance for vitamin D intake — 600 IU daily until age 70, and 800 IU daily for people 70 or older. For older people (age, ≥75), routine testing of 25(OH)D levels is not recommended. However, empirical vitamin D supplementation is recommended because of its “potential to lower mortality.” The authors do acknowledge that a mortality effect was small and of borderline statistical significance in meta-analysis of clinical trials (relative risk, 0.96; 95% confidence interval, 0.93–1.00). An evidence review showed no conclusive evidence that supplementation lowered risks for fractures, falls, or infections in this age group. Supplementation in older adults can be accomplished through either dietary intake or vitamin D preparations. Because natural food sources of vitamin D are limited, vitamin D–fortified foods often are needed to ensure adequate intake through diet alone. The authors indirectly suggest that supplementation with ≈1000 IU daily is reasonable. Empirical vitamin D supplementation is recommended during pregnancy (through foods or vitamin preparations). Empirical supplementation is recommended for adults with “high-risk prediabetes,” based on meta-analyses suggesting that supplementation might lower risk for progression to diabetes (relative risk, 0.90; borderline statistical significance). The guideline doesn't clearly state the difference between “high-risk prediabetes” and simple “prediabetes” (as defined by the American Diabetes Association). When supplementation is given, low daily doses are recommended (rather than high doses given at intervals such as weekly or monthly), because evidence suggests some adverse effects with intermittent high dosing. Routine screening for low vitamin D levels in adults with obesity and adults with dark complexion is not recommended. LINK
