Vitamin D (25-Hydroxy) (VIT-D)

What is Vitamin D?

Vitamin D (25-hydroxy) is the primary storage form of vitamin D in your body and the best indicator of your vitamin D status. It reflects vitamin D from both sun exposure and dietary sources, playing crucial roles in bone health, immune function, and cellular processes.

Why is it Tested?

Doctors test vitamin D to diagnose deficiency or insufficiency, especially in patients with bone disorders, frequent infections, fatigue, or muscle weakness. It’s also monitored during supplementation to ensure adequate levels without toxicity.

Normal Ranges

Reference ranges for optimal health:

Deficient: <20 ng/mL
Insufficient: 20–29 ng/mL
Normal: 30–100 ng/mL

Many experts recommend maintaining levels between 40–60 ng/mL for optimal health benefits.

Reference ranges vary by authority. Track yours across multiple standards with automatic unit conversions in LabsVault.

What do Abnormal Results Mean?

Abnormal results are not a diagnosis. Always discuss your results with a qualified healthcare provider before making any medical decisions.

Low Vitamin D

Deficiency or insufficiency may cause:

Bone pain and muscle weakness
Increased fracture risk
Compromised immune function
Seasonal depression
Poor calcium absorption

High Vitamin D

Excessive levels (usually >100 ng/mL) can lead to:

Hypercalcemia
Kidney stones
Nausea and vomiting
Usually from oversupplementation

How to Track Over Time

Vitamin D levels fluctuate seasonally, typically lowest in late winter and highest in late summer. Tracking over time helps optimize supplementation strategies and ensures therapeutic levels are maintained, especially during months with limited sun exposure.

Vitamin D (25-Hydroxy)