Vitamin D (25-OH)
What Is This Test?
The Vitamin D (25-OH) test is a blood test that measures the level of 25-hydroxyvitamin D, the main circulating form of Vitamin D in the body. It is considered the best test for assessing your overall Vitamin D status.
Vitamin D plays a vital role in calcium absorption, bone strength, muscle function, immune health, and overall well-being. This test helps diagnose Vitamin D deficiency or excess and monitor response to Vitamin D supplementation.
Why this test is performed?
Doctors may recommend the Vitamin D (25-OH) test to:
- Diagnose Vitamin D deficiency
- Evaluate bone pain or muscle weakness
- Assess osteoporosis or osteopenia
- Investigate frequent bone fractures
- Monitor Vitamin D supplementation
- Evaluate calcium and phosphorus disorders
- Assess patients with kidney or liver disease
- Investigate unexplained fatigue
- Evaluate conditions affecting Vitamin D absorption
- Monitor individuals at high risk of deficiency
Test Preparation
- No fasting is generally required.
- You may eat and drink normally unless instructed otherwise.
- Inform your healthcare provider about Vitamin D supplements, calcium supplements, or medications such as anticonvulsants or corticosteroids.
- If you are taking high-dose Vitamin D therapy, tell your doctor before the test.
Medical disclaimer
This article is for general information and education only. It is not medical advice, does not create a doctor–patient relationship, and is not a substitute for consultation with a qualified doctor who has assessed your individual situation. Never delay seeking medical advice because of something you have read here.
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