Medicare covers most lab work and blood tests when your doctor orders them for diagnosis or treatment
Medicare Part B pays for lab work — blood tests, urinalysis, cultures, and other diagnostic tests — when a doctor orders them as part of your medical care. You typically pay nothing out of pocket if your doctor uses a lab that accepts Medicare assignment, which most do. The test has to be medically necessary, meaning your doctor is using it to diagnose, monitor, or treat a condition. Routine screening tests that are part of your annual wellness visit are also covered at no cost.
The coverage applies whether your lab work happens in a hospital, an outpatient clinic, your doctor's office, or an independent lab. What matters is that a doctor orders it and that it serves a medical purpose — not that you requested it on your own.
Key Takeaways
- Medicare Part B covers lab work ordered by your doctor, and you pay nothing if the lab accepts Medicare assignment.
- Routine screening tests during your annual wellness visit — including cholesterol and blood sugar checks — are covered with no copay.
- If you use an out-of-network lab or one that does not accept Medicare assignment, you may owe a percentage of the cost.
- Lab work you order yourself without a doctor's order is not covered, even if you pay a private lab to run it.
- If your doctor orders a test that Medicare considers experimental or not medically necessary, the lab or your doctor should tell you in advance.
What counts as covered lab work
Covered tests include blood work (complete blood count, metabolic panel, lipid panel), urinalysis, thyroid tests, glucose monitoring, cultures for infection, and tests to monitor medications you are taking. If your doctor orders a test to check how a medication is working or to diagnose a symptom you have, Medicare Part B covers it.
Screening tests that are part of your annual wellness visit are also covered. These include a one-time screening for cardiovascular disease (a lipid panel), diabetes screening (fasting glucose test), and colorectal cancer screening if you are between 50 and 75. Some preventive lab work — like hepatitis B screening for people born between 1945 and 1965 — is covered as well.
Tests ordered to monitor a chronic condition you already have, such as diabetes or heart disease, are covered. If your doctor wants to check your kidney function because you take a medication that can affect the kidneys, that test is covered.
Lab work that Medicare does not cover
Medicare does not cover lab work you order yourself without a doctor's order, even if you pay a private company to run it. Direct-to-consumer tests — where you order a blood test online and mail in a sample — are not covered unless a doctor has ordered that specific test for you.
Tests that Medicare considers experimental or not yet proven to be medically necessary may not be covered. This includes some genetic tests, advanced biomarker panels, or tests that are still being studied. If your doctor wants to order a test that might fall into this category, the lab should give you a notice in advance telling you that Medicare may not cover it and what you might owe.
Routine wellness tests that go beyond what Medicare covers — such as comprehensive micronutrient panels, heavy metal screening, or food sensitivity testing — are not covered. If your doctor orders these, you will owe the full cost.
How much you pay
If your lab accepts Medicare assignment, you pay nothing for covered lab work. Medicare pays the lab directly, and that is the end of it. Most labs in the United States accept Medicare assignment because the reimbursement is predictable and the volume is steady.
If a lab does not accept Medicare assignment, you may owe 20 percent of the Medicare-approved amount for that test, even after Medicare pays its share. This is called coinsurance. The lab should tell you before the test whether it accepts Medicare assignment.
If you have a Medigap policy (supplemental insurance), it may cover some or all of the coinsurance you owe. If you have a Medicare Advantage plan, your out-of-pocket cost depends on your plan's rules — some cover lab work with no copay, others charge a small copay, and a few require coinsurance.
How to make sure your lab work is covered
Before your test, ask your doctor's office whether the lab they are sending you to accepts Medicare assignment. If it does, you are covered. If it does not, ask whether your doctor can order the test through a lab that does accept Medicare.
If your doctor orders a test that you are unsure about — especially if it sounds new or experimental — ask whether Medicare covers it. Your doctor's office can check, or you can call Medicare at 1-800-MEDICARE. If Medicare does not cover it, the lab is required to give you a notice before the test so you know what you might owe.
Keep a record of which labs you use and whether they accept Medicare. If you see multiple doctors, they may send tests to different labs. Knowing which ones are in-network saves you from surprise bills.
Lab work through Medicare Advantage plans
If you have a Medicare Advantage plan instead of Original Medicare, your coverage for lab work is similar but the details vary by plan. Most Medicare Advantage plans cover the same preventive lab work as Original Medicare at no cost. For other lab work, you may have a copay (usually $0 to $10 per test) or coinsurance.
Your Medicare Advantage plan has a network of preferred labs, just as it has preferred doctors. Using an in-network lab means you pay less. If you use an out-of-network lab, you may owe more, or the plan may not cover it at all.
Check your plan's summary of benefits or call the plan directly to find out what your cost is for a specific test. The plan can also tell you which labs are in-network in your area.
What to do if you receive a bill for lab work
If a lab bills you for a test that your doctor ordered and Medicare should have covered, do not pay it right away. Call the lab and ask why they are billing you. Ask whether they accept Medicare assignment. If they do, they should not be billing you — Medicare should have paid.
If the lab says the test was not covered because it was not medically necessary, ask them to send you the notice they should have given you before the test. If they did not give you a notice, they may not be able to bill you.
If you believe the bill is wrong, you can file a complaint with Medicare. Call 1-800-MEDICARE and ask to report a billing problem. You can also contact your State Health Insurance information Program (SHIP), which offers free help with Medicare billing questions. Find your state's SHIP at shiptalk.org.
Frequently Asked Questions
Does Medicare cover routine blood work at my annual checkup?
Yes. Lab work that is part of your annual wellness visit — including basic blood tests like cholesterol and glucose screening — is covered with no copay. Your doctor has to order it as part of the visit, not separately.
What if my doctor orders a test and I want to know if Medicare covers it before I get it done?
Ask your doctor's office to check with Medicare, or call Medicare yourself at 1-800-MEDICARE and tell them the name of the test. You can also ask the lab directly — they can tell you whether the test is covered under Medicare.
Do I have to use a specific lab, or can I go anywhere?
You can use any lab that accepts Medicare assignment. If you have a Medicare Advantage plan, using an in-network lab saves you money. Ask your doctor's office which labs they work with, or call your insurance plan to find in-network labs near you.
If I have a Medigap policy, does it cover lab work?
Most Medigap policies cover the coinsurance you would owe for lab work if you use a lab that does not accept Medicare assignment. Check your policy documents or call your Medigap insurer to confirm what is covered.
Can I get a lab test done without my doctor ordering it?
Medicare does not cover lab work you order on your own. Your doctor has to order the test for it to be covered. Direct-to-consumer lab services are not covered by Medicare, even if you pay out of pocket.