What is the Vitamin D3 (25-OH) Test?

The Vitamin D3 (25-hydroxy Vitamin D) test measures the level of Vitamin D stored in your body.

It is the most accurate test to check Vitamin D levels.

Vitamin D is essential for:

• Healthy bones
• Calcium absorption
• Nerve & muscle function
• Immunity

This test helps detect deficiency, insufficiency, or excess Vitamin D.

What Is Purpose of the Vitamin D3 (25-OH) Test

This test is done to:

• Check for Vitamin D deficiency
• Evaluate bone health
• Identify causes of bone pain or muscle weakness
• Monitor people taking Vitamin D supplements
• Diagnose osteoporosis, osteomalacia, or rickets
• Evaluate absorption issues (Crohn’s, Celiac, Gastritis)

When is the Vitamin D3 Test Recommended?

✔ Symptoms of Low Vitamin D

• Fatigue, low energy
• Muscle cramps, weakness
• Bone or back pain
• Hair fall
• Frequent colds/infections
• Mood changes, depression
• Slow wound healing

✔ Medical Reasons

• Thyroid disorders
• Kidney disease
• Liver disease
• Diabetes
• Autoimmune diseases
• Osteoporosis

✔ Lifestyle Reasons

• Low sunlight exposure
• Indoor work
• Darker skin (needs more sunlight)
• Vegetarian/vegan diet

What Is Preparation for Vitamin D3 Test

Usually no special preparation is needed.

But for accuracy:

• Avoid supplements 24 hours before testing.
• No fasting needed unless combined with other tests.

How is the Vitamin D3 Test Done?

Simple process:

1. A blood sample is taken from your arm.
2. Lab measures the level of 25-hydroxy Vitamin D.
3. Report comes in a few hours to 1 day.

Understanding Vitamin D3 Test Results

Vitamin D Level Interpretation

< 10 ng/mL Severe deficiency

10–20 ng/mL Deficiency

20–30 ng/mL Insufficient

30–50 ng/mL Normal / Optimal

> 50–100 ng/mL High (monitor)

> 100 ng/mL Toxicity (very rare)

Best Range:

👉 30–50 ng/mL (Healthy & safe range)