What it measures
Vitamin D supports bone health and muscle function. Low levels are common in people with limited sun exposure, darker skin, obesity, or certain gut conditions. Experts disagree about the ideal target, so context matters.
Who should consider it
- People with bone pain, frequent fractures, or osteoporosis risk
- Adults with little sun exposure or darker skin at northern latitudes
- Anyone on long-term steroids or with malabsorption
How to read your result
The National Academy of Medicine treats 20 ng/mL as adequate for most people. The Endocrine Society suggests 30 ng/mL or higher for some groups. Both views are in use.
- Levels above 100 ng/mL raise the risk of toxicity from supplements.
- Retest 8 to 12 weeks after changing your dose.
Reference ranges differ between labs. Use the range printed on your own report.
What to do next
Ask a clinician before taking high-dose vitamin D, especially if you have kidney disease or high calcium.
Where to order Vitamin D, 25-hydroxy
These sellers include an independent physician order. You pay online and visit a partner lab. Availability, price, and lab network vary, so confirm at checkout.
Private MD Labs
Online lab seller- Says 4,500+ Quest and Labcorp locations
- Every order reviewed by a physician. Says you pay $1 to start and the rest after results.
- Secure online portal with plain-English explanations. Says many results arrive overnight.
HealthLabs
Online lab seller- Says 4,500+ labs, including Quest and Labcorp
- Online or by phone. No doctor referral or insurance needed.
- Secure HealthLabs account. Says 1 to 3 business days.
Walk-In Lab
Online lab seller- Lab network not named on its homepage
- Online, no insurance or doctor order needed. Shows a $6 physician fee per order on popular tests.
- Online account. Turnaround not stated on its homepage.
Quest Health
Lab-run- Quest, 2,000+ locations
- Buy online and book a Quest appointment. An independent provider is involved.
- Online as soon as ready, with an email alert. Provider discussion included at no extra cost.
Seller details come from each seller's own site and can change. Confirm price, lab location, and state availability at checkout.
Questions people ask
Should everyone test vitamin D?
No. Major groups do not recommend routine screening for healthy adults. Testing helps when you have risk factors or symptoms.
How much vitamin D should I take?
It depends on your level, diet, and health. Ask a clinician rather than guessing.
Related guides
Comprehensive metabolic panel
14 markers for kidneys, liver, blood sugar, and electrolytes.
ReadAnnual physical blood work
A solid baseline: CBC, CMP, lipids, A1C, and thyroid.
ReadWe may earn a commission if you buy through links on this page, at no extra cost to you. This page is education, not medical advice. How we make money.