Vitamin D deficiency: when to get tested and how it is treated

Vitamin D helps your body absorb calcium, which keeps bones strong. Your muscles, nerves and immune system need it too. The body makes it when your skin gets sun, and it also comes from some foods: fatty fish such as tuna, salmon and mackerel, egg yolks, beef liver, and fortified foods such as milk and some cereals.

When vitamin D stays low for a long time, bones weaken. In adults it can cause osteomalacia (soft bones) and contribute to osteoporosis; in children, rickets, which affects how bones grow.

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The evaluation is a US$79 doctor visit, the same price for every age, with no membership. When you have the result of the test the doctor ordered, we go over it with you in a US$49 follow-up visit, which is for existing patients only.

You pay by card when you request the visit, and you get a full refund if the visit can’t take place. We do not bill insurance; the lab charges separately. See all prices. The service is run by The Health Initiative, a nonprofit.

Many people with low vitamin D have no symptoms. When they appear, MedlinePlus lists these in adults:

• Bone pain
• Muscle weakness or aches
• Soft or deformed bones
• Weak bones and fractures

The test is not for everyone. In 2021 the U.S. Preventive Services Task Force (USPSTF) concluded that the evidence is insufficient to recommend routine testing in adults without symptoms. So the doctor orders it when there are symptoms, a bone condition or risk factors, such as:

• Being an older adult
• Having darker skin
• Getting little sun
• A condition that affects fat absorption, such as Crohn’s or celiac disease
• Obesity or gastric bypass surgery
• Kidney or liver disease
• Babies fed mostly breast milk, and children whose diet is low in vitamin D

Treatment is usually a vitamin D supplement, at the dose and for the time the doctor sets based on your result, along with eating more foods that contain it. The recommended daily amount for most children and adults aged 1 to 70 is 600 IU, and 800 IU after 70.

More is not better. For anyone over 9, the safe upper limit is 4,000 IU a day. Too much vitamin D, almost always from taking too many supplements, raises blood calcium and can cause nausea, vomiting, constipation, weakness, confusion and kidney stones. Don’t take high doses on your own. If you already take a prescribed supplement and only need a refill, see prescription refills.

For your safety, go to the emergency room or call 911 if any of these happen. See when to go to the ER.

• Confusion, vomiting that won’t stop or severe weakness, especially after taking high doses of vitamin D
• Severe pain, a deformity or being unable to bear weight after a fall or a blow
• Severe pain in your side or back with blood in your urine