There are two forms of vitamin D in the blood: 25-hydroxy vitamin D, or calcidiol, and 1,25-dihydroxy vitamin D, or calcitriol. Tests will measure the amount of 25-hydroxy vitamin D in the blood. This ...

Vitamin D is vital for immunity, brain health, strong bones, and overall well-being, but taking in too much from supplements ...

Vitamin D tests certified by the U.S. Centers for Disease Control and Prevention (CDC) Clinical Standardization Programs (CSP) are well calibrated overall, according to a new study presented Sunday at ...

Some vitamin D tests may give misleading results despite progress made in recent years to improve the quality of these assays, according to the US Centers for Disease Control and Prevention (CDC).

Low levels of vitamin D seem to raise your risk of heart attack but scientists are still figuring out why—and whether ...

We tested the best vitamin deficiency tests from LetsGetChecked, Everlywell, and LabCorp, and our testers found them easy to use and informative. Learn more about the best vitamin deficiency tests ...

A doctor explains who truly needs a vitamin D supplement in the winter, how to tell if you're deficient, and when ...

Imagine glancing in the mirror and noticing dull skin, flaky patches, or your hairline looking thinner than before. These might not be mere cosmetic issues — they could be early signals that your body ...

There's not enough evidence that screening the general public for vitamin D deficiency helps reduce the risk of disease, the U.S. Preventive... Should you get a blood test to see if you're deficient ...

Fact checked by Nick Blackmer Your body makes vitamin D from sunlight, but food is also an important source, since deficiency is common.Fish and egg yolks are naturally rich sources, but there are ...

The nation's largest medical lab company says it recently discovered and fixed a problem that led to inaccuracies in a small number of tests for vitamin D deficiency. Quest Diagnostics of Madison, N.J ...

Vitamin D is an essential micronutrient that's an important part of a healthy diet. Learn what types of foods are rich in vitamin D.