What blood tests should I get for overall health, and which ones require fasting?

What blood tests are part of a routine checkup?

There's no single test that checks "everything." Your clinician picks tests based on your age, sex, symptoms, family history, and risk factors. These are the common building blocks:

Abnormal numbers don't automatically mean you have a disease. MedlinePlus notes that diet, activity, medications, hydration, and other factors can affect results. Your provider interprets them alongside your history.^[2]

Which blood tests require fasting?

According to MedlinePlus (NIH), common tests that usually require fasting are:^[1]

• Blood glucose (blood sugar) tests. Not all glucose tests require fasting, so ask.
• Cholesterol tests (lipid panel)
• Basic metabolic panel (BMP)

Tests that sometimes require fasting include liver function tests and a renal (kidney) function panel. Some liver tests only need fasting when they're ordered as part of a comprehensive metabolic panel.^[1]

Tests that typically don't require fasting include the A1C,^[7] a random blood sugar test,^[6] and a CBC on its own.^[2] If you're having several tests from one blood draw, follow the strictest instructions. Always go by what your provider tells you, and don't fast if you haven't been asked to, because unnecessary fasting can also affect results.^[1]

How do I fast for a blood test?

• How long: usually 8–12 hours. Your provider will give you the exact time.^[1]
• Allowed: plain water only. Staying hydrated can make the blood draw easier.^[1]
• Not allowed: food, coffee, juice, soda, flavored or sparkling water, chewing gum, and smoking.^[1]
• Medications: ask your provider. Don't stop prescription medicines unless they tell you to, and let them know about vitamins and supplements.^[1]
• Timing tip: schedule early in the morning so most of the fast happens while you sleep, and bring a snack for afterward.^[1]
• If you slipped up: tell your provider. You may need to reschedule.^[1]

Should I stop working out before a blood test?

MedlinePlus lists exercise, along with chewing gum and smoking, as things to avoid while you're fasting for a blood test.^[1] Some people ask whether to take a day or more off from hard training before a panel. That depends on the test and your situation, so ask the clinician who ordered it, and mention any hard workouts in the days before your draw.

How often should I get my cholesterol checked?

The CDC says most healthy adults should have their cholesterol checked every 4 to 6 years. People with heart disease, diabetes, or a family history of high cholesterol need it more often.^[4] High cholesterol has no symptoms, so a blood test is the only way to know.^[4] Your care team looks at your numbers together with your age, family history, smoking, blood pressure, and other risk factors.^[4]

Who should be tested for diabetes or prediabetes?

The U.S. Preventive Services Task Force recommends screening for prediabetes and type 2 diabetes in adults aged 35 to 70 who have overweight or obesity (Grade B). It suggests screening every 3 years may be reasonable when results are normal.^[7] Screening can use fasting plasma glucose, A1C, or an oral glucose tolerance test.^[7] The CDC points out that prediabetes and type 2 diabetes often have no symptoms, and that people with risk factors should ask their doctor about testing.^[6]

For reference, the CDC's A1C categories are: below 5.7% normal, 5.7–6.4% prediabetes, 6.5% or higher diabetes.^[6] Only your clinician can tell you what your results mean. Diagnosis usually requires repeat testing,^[7] and some conditions, such as anemia, can make A1C less accurate.^[8]

What about "longevity" or advanced panels?

Many longevity clinics and direct-to-consumer labs sell larger panels with extra markers. Some extra tests can be useful for specific people, but more tests don't automatically mean better care, and none of them replaces the basics above. Before paying for a big panel, ask: What would we do differently depending on this result? If the answer is "nothing," the test probably isn't worth it for you.

How do I get bloodwork done?

The usual route is through your primary care clinic, often during an annual physical. Telehealth services can also order lab work, with the blood drawn at a local lab. [placeholder: Describe the partner process: who orders, where the draw happens, typical cost/insurance, and who reviews results. Only list details that are confirmed.]