Vitamin B12 is essential for nerve function, DNA synthesis, red blood cell formation, and energy production. Deficiency is common and often undiagnosed.
Vitamin B12 (cobalamin) is a water-soluble vitamin that plays critical roles throughout your body. It's essential for maintaining healthy nerve cells, producing DNA and RNA, forming red blood cells, and converting food into cellular energy. Unlike other water-soluble vitamins, B12 can be stored in the liver for years, so deficiency develops slowly but can cause serious, sometimes irreversible damage if left untreated.
B12 deficiency is surprisingly common, affecting an estimated 6% of adults under 60 and up to 20% of those over 60. It's particularly prevalent in vegans and vegetarians (B12 is found almost exclusively in animal products), older adults (who may have reduced absorption), people with digestive disorders, those who've had gastric surgery, and people taking certain medications like metformin or proton pump inhibitors.
Early detection is crucial because neurological damage from B12 deficiency can become permanent if not treated promptly. Symptoms often develop gradually and may be mistaken for normal aging or other conditions.
Price
$8
Results
1-2 days
Lab Network
Quest
Fasting
Not Required
What's Measured
What This Test Measures
This test measures the concentration of vitamin B12 in your blood serum. Normal levels typically range from 200-900 pg/mL, though optimal levels are often considered above 400-500 pg/mL. Levels below 200 pg/mL indicate deficiency.
Who Should Consider This Test
Vegans and vegetarians, adults over 50, people with fatigue or neurological symptoms, those with digestive disorders (celiac, Crohn's, gastritis), individuals who've had gastric bypass surgery, people taking metformin or PPIs long-term, and anyone with anemia or elevated MCV on CBC.
Health Insights
Conditions Screened
Related Symptoms
When to Get Tested
No fasting required. B12 supplements should ideally be stopped 24-48 hours before testing for accurate baseline results. Recent B12 injections can elevate levels for weeks.
Understanding Your Results
Normal B12 is typically 200-900 pg/mL. Levels below 200 pg/mL indicate deficiency requiring treatment. "Gray zone" levels (200-400 pg/mL) may warrant further testing with methylmalonic acid (MMA) or homocysteine, which are more sensitive markers. Very high levels (>1000 pg/mL) without supplementation may indicate liver disease or certain blood disorders.
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.
Frequently Asked Questions
$8
Typical hospital cash price: $100–$200
+ $28 in standard lab & physician fees at checkout (no additional bills later)
$18 lab collection + $10 physician order
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