In 2024, the Endocrine Society issued updated guidelines on the evaluation, treatment, and prevention of vitamin D deficiency in adults, reflecting recent research. The new recommendations, which replace a 2011 guideline, aim to simplify the approach to vitamin D testing and supplementation.

Key changes in vitamin D guidelines

Previously, the Endocrine Society defined vitamin D levels in terms of "deficiency" and "insufficiency" based on serum 25-hydroxyvitamin D (25[OH]D) levels. However, the new guidelines no longer categorise vitamin D status in this way. Research has not confirmed a clear connection between specific vitamin D levels and clinical outcomes, leading to this shift.

For most adults aged 19 to 74, the guideline advises against routine vitamin D testing or supplementation. Instead, it recommends following the U.S. National Academy of Medicine's daily intake guidelines: 600 IU until age 70 and 800 IU daily for those over 70.

Special recommendations for older adults and pregnant women

While routine testing is not advised for people aged 75 and older, empirical vitamin D supplementation is recommended due to its potential to lower mortality, although the evidence is modest. Supplementation in older adults should focus on low daily doses (about 1,000 IU), either through fortified foods or supplements.

Pregnant women are also advised to take vitamin D, either from fortified foods or supplements, to ensure sufficient intake.

Other key considerations

The guideline also recommends vitamin D supplementation for adults with high-risk prediabetes, as research suggests it may help lower the risk of progressing to type 2 diabetes. However, there is no clear definition of "high-risk prediabetes" compared to regular prediabetes.

In contrast, the guideline advises against routine testing for vitamin D levels in individuals with obesity or darker skin tones, as no evidence supports the need for routine screening in these populations.

Impact on clinical practice

The new guideline could significantly change how clinicians approach vitamin D testing and supplementation. The practice of routinely testing vitamin D levels and prescribing supplements to raise levels to 30 ng/mL or higher is no longer recommended. However, this guideline does not apply to people with conditions affecting vitamin D metabolism, such as malabsorption, chronic kidney disease, or bone disorders like osteomalacia, for whom testing and treatment remain necessary.

Clinicians should also be aware that while diet and sunlight contribute to vitamin D intake, it is challenging to accurately assess vitamin D status through routine history-taking during office visits. Despite these challenges, familiarity with these updated guidelines is essential for primary care providers to ensure effective care and avoid unnecessary testing and supplementation.

Source: The Journal of Clinical Endocrinology & Metabolism