Vitamin D, 25-Hydroxy [ser]

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like muscle weakness, bone pain, or if you’re at higher risk for vitamin D deficiency. It’s also used to monitor vitamin D levels in people with conditions like osteoporosis, kidney disease, or those who don’t get enough sunlight.

What to Expect During the Test

A blood sample will be taken from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. The test is quick and doesn’t require special preparation, but fasting may be advised in some cases—always follow your provider’s instructions.

What the Results Mean

Results help determine if your vitamin D levels are within a healthy range. Low levels may indicate deficiency, while higher levels could signal over-supplementation or other conditions. Your provider will interpret results based on your overall health and medical history.

Common Reasons for Low or High Levels

Low vitamin D levels can be caused by limited sun exposure, certain medical conditions, or poor diet. High levels may result from overuse of supplements or certain medications. Both extremes can affect bone health and other body functions.