What causes vitamin D deficiency?

Limited sun exposure (especially in winter or northern climates), darker skin, older age, obesity, digestive conditions, and not eating vitamin D-rich foods all contribute to deficiency.

How much vitamin D should I take?

It depends on your level. Many adults need 2,000-5,000 IU daily to maintain optimal levels. Those who are deficient may need higher doses initially. Always retest after 2-3 months.

Can I get enough vitamin D from food?

It's difficult. Few foods contain significant vitamin D - mainly fatty fish, egg yolks, and fortified foods. Most people need sunlight or supplements.

Is there such thing as too much vitamin D?

Yes, levels above 100 ng/mL can cause toxicity, leading to high calcium levels. This is rare and usually only happens with excessive supplementation.

💊 Vitamins & MineralsPopular

Vitamin D Blood Test (25-Hydroxy)

Name: Vitamin D Blood Test (25-Hydroxy)
Brand: Justlabs
SKU: 0017306
Price: 22 USD
Availability: InStock

Vitamin D

Vitamin D deficiency affects over 40% of Americans. This test measures your vitamin D status, essential for bone health, immune function, mood, and much more.

Vitamin D is more than just a vitamin - it's a hormone that affects nearly every cell in your body. Yet most people don't get enough from sunlight and food alone.

Deficiency is linked to: • Weak bones and osteoporosis • Increased infection risk • Depression and mood issues • Fatigue and muscle weakness • Autoimmune conditions

This test measures 25-hydroxyvitamin D, the main circulating form that best reflects your overall vitamin D status.

Price

$22

Results

1-2 days

Lab Network

Quest

Fasting

Not Required

What's Measured

Vitamin D, 25-OH

What This Test Measures

This test measures 25-hydroxyvitamin D in your blood, reported in ng/mL. Optimal levels are 40-60 ng/mL. Levels below 30 ng/mL indicate insufficiency, and below 20 ng/mL indicates deficiency. Some experts suggest levels of 50-80 ng/mL for optimal health.

Who Should Consider This Test

Everyone! Especially those with limited sun exposure, darker skin, older adults, people who are overweight, those with digestive conditions, and anyone experiencing fatigue, bone pain, muscle weakness, or frequent illness.

Health Insights

Conditions Screened

Vitamin D deficiencyOsteoporosis riskRicketsOsteomalaciaSeasonal affective disorder

Related Symptoms

FatigueBone painMuscle weaknessFrequent infectionsDepressionHair lossSlow wound healingBrain fog

When to Get Tested

Test anytime - no fasting required. Best times to check: late winter (when levels are lowest), before starting supplementation, and 2-3 months after changing your supplement dose.

Understanding Your Results

Deficient: <20 ng/mL | Insufficient: 20-29 ng/mL | Sufficient: 30-100 ng/mL | Optimal: 40-60 ng/mL. If deficient, your doctor may recommend 2,000-5,000 IU daily, or higher doses initially. Retest in 2-3 months.

What to Expect

After placing your order, you'll receive an email from Rupa Health (our lab order partner) within 24 business hours to sign a consent form and schedule your blood draw at a Quest Diagnostics location.

The blood draw typically takes just a few minutes. Results are usually available within 1-2 business days and will appear in your secure Justlabs dashboard.

Our results include reference ranges and easy-to-understand indicators showing whether your values are within normal limits.