If you walked into my clinic tomorrow and peeked at my lab orders, you’d likely see a familiar trend from the last decade: Vitamin D, Vitamin D, and more Vitamin D. It has been on everyone’s radar for years. Patients ask for it, we order it, and many of us probably take a supplement ourselves, especially during those gray winter months. However, you may have recently noticed insurance companies denying coverage for routine 25(OH)D screenings. In 2024, the Endocrine Society released updated clinical practice guidelines that significantly changed the landscape of Vitamin D management.
Change in medicine can be frustrating, especially when it involves unlearning a routine we’ve performed thousands of times. However, these updates aim to simplify our practice, minimize unnecessary costs, and reduce health disparities. Let’s break down what has changed and how to apply it when you’re face-to-face with a patient in the exam room.
Vitamin D isn’t technically a true vitamin because we can synthesize it ourselves through sun exposure. It’s a fat-soluble powerhouse that undergoes two hydroxylations — one in the liver and one in the kidneys — to become its active form. Its primary job is promoting calcium absorption in the gut and maintaining bone mineralization.
For years, we’ve operated under the 2011 guidelines, which suggested routine screening for anyone at risk for deficiency. This led to a massive surge in testing. However, the 2024 panel looked at the data and found that, for most healthy adults, routine screening doesn't actually lead to better health outcomes.
The biggest takeaway from the new guidelines is the recommendation against routine 25(OH)D screening in healthy adults. Instead of spending $25 to $100 on a lab test that may lead to more testing, we can move straight to empiric, low-dose supplementation if indicated.
We should now reserve testing for very specific clinical scenarios:
If we aren’t testing everyone, who are we treating? The 2024 guidelines have identified four specific groups. For these patients, the benefit of taking a supplement outweighs the need for a baseline lab.
1. Children and Adolescents (Ages 1–18): Beyond the well-established need for Vitamin D in infants to prevent rickets, the new guidelines suggest empiric supplementation in older children to continue preventing rickets and potentially reduce the risk of respiratory tract infections.
2. Adults Aged 75 and Older: This group carries a higher risk of falls and fractures. The guidelines suggest empiric supplementation here due to its potential to lower overall mortality risk in this demographic.
3. Pregnant Individuals: Supplementation is suggested to help reduce the risks of preeclampsia, preterm birth, and neonatal mortality.
4. Adults with High-Risk Prediabetes: This is perhaps the most debated group. The Endocrine Society suggests supplementation alongside lifestyle changes to reduce the risk of progression to Type 2 Diabetes. However, it’s worth noting that the NIH remains skeptical, stating that supplementation may not offer much benefit to those who are already Vitamin D-replete.
If your patient is a healthy 45-year-old, the guidelines suggest against routine empiric supplementation beyond the Recommended Dietary Allowance (RDA). However, the RDA is 600 IU daily for those under 70, and getting that through diet alone is incredibly difficult.
To put it in perspective, 8 ounces of cow’s milk only has about 100 IU. Unless your patient is eating fatty fish or liver every single day, they are likely falling short. While the guidelines say "don't supplement," they also say "get the RDA." It’s no wonder our patients are confused. A practical middle ground is a daily multivitamin, which typically contains 800 to 1,000 IU — enough to hit the goal without overthinking it.
When it comes to the amount, the 2024 guidelines are a bit vague, noting that "optimal doses remain unclear." However, we can look to the safe limits established previously. A daily dose of 600–800 IU is the baseline, but 1,000–2,000 IU is generally considered a safe and reasonable maintenance range for most adults.
We are also moving away from the era of the bolus dose. You may remember prescribing 50,000 IU once a week; the new panel suggests that daily, lower-dose Vitamin D is preferable to these high-dose intermittent treatments. As for the form, both D2 (ergocalciferol) and D3 (cholecalciferol) are well-absorbed. D3 is often preferred for its slightly superior efficacy in raising levels, though vegan patients may prefer D2 or a lichen-based D3.
We should caution patients against taking high doses of Vitamin D supplements. Toxicity can lead to hypercalcemia, renal failure, and cardiac arrhythmias. If a patient is taking more than 5,000 IU daily, it’s reasonable to check a level to ensure they aren't drifting into the danger zone.
Also, keep an eye on those drug-drug interactions. High doses of Vitamin D can compete with the enzymes used by common statins (atorvastatin, lovastatin, and simvastatin), potentially reducing their potency. Additionally, thiazide diuretics decrease calcium excretion; combining them with Vitamin D supplements can increase the risk of hypercalcemia, especially in our older patients.
The 2024 Vitamin D update is an invitation to stop over-testing and start being more intentional. We can save our patients the sticker shock of an uncovered lab bill and instead focus on meaningful conversations about bone health, nutrition, and targeted supplementation for those who truly benefit.
Remember, no more routine testing for healthy adults (and kids!). Supplementation is recommended in children up to 18, adults 75 and over, and pregnant people. 1,000-2,000 IU per day is a typical dose for supplementation, in either D2 or D3 formulations. Everyone else should aim to consume the recommended dietary allowance of 600 IU per day.
You can hear more on this topic on the Primary Care Reviews and Perspectives segment, "Vitamin D Guideline Update."