VITAMIN D3(25-OH-HYDROXY)

Vitamin D 25-Hydroxy Test (25-OH Vitamin D)

The Vitamin D 25-Hydroxy test measures the level of 25-hydroxyvitamin D [25(OH)D] in your blood.
This is the best test to assess your overall vitamin D status.

🧬 What Is 25-Hydroxy Vitamin D?

When you get vitamin D from:

• Sunlight (UVB exposure)

• Food (fish, fortified milk, egg yolk)

• Supplements

Your body converts it in the liver into 25-hydroxyvitamin D, the main circulating form in blood.

This form reflects:
✔ Vitamin D produced in skin
✔ Vitamin D taken from diet or supplements

🧪 Why Is the Test Done?

Doctors order it to:

• Check vitamin D deficiency

• Evaluate bone pain or weakness

• Investigate osteoporosis

• Monitor vitamin D supplementation

• Assess risk of fractures

• Evaluate certain parathyroid disorders

📊 Normal Levels (Adults)

(Ranges may slightly vary by lab.)

⚠️ Symptoms of Vitamin D Deficiency

• Bone pain

• Muscle weakness

• Fatigue

• Frequent infections

• In children → rickets

• In adults → osteomalacia

🌞 Causes of Low Vitamin D

• Limited sun exposure

• Darker skin

• Obesity

• Kidney or liver disease

• Malabsorption disorders

• Strict indoor lifestyle

⚠️ High Vitamin D (Toxicity)

Usually due to excessive supplements.
May cause:

• High calcium levels

• Nausea

• Kidney stones

• Confusion

💡 Important Note

The 25-OH test is preferred over the 1,25-dihydroxy vitamin D test, which is used only in special conditions.