Yes, your blood work can absolutely change in 6 months. Depending on your lifestyle, new medications, diet, or underlying health conditions, biomarkers can shift significantly over that time frame.Key Markers That Can FluctuateWhile some foundational elements remain stable, many common markers can change rapidly. Notable examples include:Cholesterol (Lipid Panel): Can show measurable improvement within a few months of dietary changes or the introduction of statins.Blood Sugar (A1C): Measures your average blood sugar over the last 3 months and often requires testing every 3 to 6 months for those managing or monitoring diabetes.Vitamin Levels (e.g., Vitamin D, B12, Iron): Can rise or drop depending on diet changes, supplementation, or absorption issues.White Blood Cells (WBC): Can spike temporarily due to acute factors like stress, sleep deprivation, or an ongoing infection.Why Doctors Monitor 6-Month ChangesTracking patterns rather than isolated numbers helps healthcare providers understand how your body is functioning over time. Typical reasons for retesting include:Monitoring chronic conditions such as thyroid disorders, diabetes, or high cholesterol.Evaluating the effectiveness of a new medication or supplement.Observing trends after a lifestyle intervention like a new workout routine or diet plan

Yes, blood test results can change significantly in 6 months. Biomarkers naturally shift over time. Fasting status, hydration, diet, sleep, recent illness, and medications can all alter your results.

Function Health
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How much and why your numbers change often depends on the specific test:
Glucose (Blood Sugar) & Lipids (Cholesterol): These can change quickly, sometimes within weeks, reflecting recent shifts in diet, weight, or exercise routines.
Thyroid (TSH) & Complete Blood Counts (CBC): These can indicate the onset of new issues, such as an infection or developing anemia.
Vitamin D: Levels often drop during the winter months.

National Institutes of Health (.gov)
 +4
To understand how and why your specific numbers might have shifted, it's best to review the changes with your healthcare provider. You can track your trends over time using your patient portal (like UCLA Health MyChart or Cedars-Sinai My CS Link). If you have questions about specific results, consulting your primary care doctor is the most reliable path forward.

How Often Should You Get a Blood Test? It Depends on These Factors
September 19, 2025
4 minute read
how often to get your blood tested
Blood tests are one of the most important tools in modern healthcare. They provide a window into what’s happening inside your body, sometimes revealing health issues long before you notice any symptoms. But a common question many people have is: How often should I get a blood test?



The answer isn’t the same for everyone. Frequency depends on factors such as age, medical history, lifestyle and existing health conditions.



Why Blood Tests Matter
Blood tests measure a variety of markers that indicate how well your body’s systems are functioning. Some of the most common types of blood tests include:



Complete Blood Count (CBC): Checks red and white blood cells, platelets and overall blood health.

Lipid Panel: Measures cholesterol and triglyceride levels to assess heart health.

Blood Glucose Test: Screens for diabetes and blood sugar imbalances.

Liver and Kidney Function Tests: Assess markers that indicate liver and kidney function to monitor overall organ health.

Thyroid Panel: Evaluates hormone levels for metabolism and energy regulation.


These tests can detect hidden health issues such as anemia, high cholesterol, infections, diabetes or organ damage long before symptoms arise.



General Guidelines for Blood Test Frequency
For healthy adults with no chronic conditions, many doctors recommend having a routine blood test once a year. This annual checkup allows providers to monitor changes, compare results year over year, and catch early signs of disease.



However, annual testing is just a baseline. The ideal frequency depends on your unique health profile and risk factors.



Factors That Influence How Often You Should Be Tested
1. Age
As you get older, your risk of chronic illnesses like heart disease, diabetes and high cholesterol increases. Adults over 40 may need more frequent blood work, especially if they have other risk factors. Seniors often benefit from semi-annual testing to monitor key health indicators.



2. Medical History
If you have a personal or family history of conditions like diabetes, thyroid disease, high cholesterol or cancer, your doctor may recommend testing every 3–6 months. These checkups allow for early intervention if markers begin to shift.



3. Current Health Conditions
For people already living with chronic illnesses, blood tests are a vital part of disease management. For example:



Diabetes: May require blood sugar tests every 3 months.
High Cholesterol: Follow-up tests every 6–12 months.
Thyroid Disorders: Testing every 6–12 months, or more often if medication is being adjusted.


4. Lifestyle Factors
Unhealthy lifestyle habits can increase the need for regular testing. Smoking, excessive alcohol consumption, poor diet or lack of exercise all elevate risks for heart disease, liver damage and metabolic issues. In these cases, more frequent testing may be necessary.



5. Medications
Certain medications require regular blood monitoring. For example, people on blood thinners, cholesterol-lowering drugs or medications that affect the liver may need routine tests to ensure safety and effectiveness.



6. New or Unexplained Symptoms
If you develop unusual fatigue, unexplained weight loss, persistent infections or other concerning symptoms, your provider may order blood tests regardless of when your last one was.



The Role of Preventive Care
Even if you feel perfectly healthy, regular blood tests can provide reassurance and early detection. Preventive care often means the difference between managing a minor issue and facing a major medical event. For example:



A slightly elevated blood sugar reading can prompt lifestyle changes before diabetes develops.

A borderline cholesterol result can lead to early diet and exercise interventions, reducing heart disease risk.

Abnormal liver enzymes might reveal medication side effects before permanent damage occurs.


Skipping routine blood tests can be risky; your body may be signaling problems that only a lab can detect.



How to Prepare for a Blood Test
To ensure accurate results, some blood tests require fasting for 8–12 hours beforehand, particularly lipid panels and glucose tests. Always follow your provider’s instructions about eating, drinking or taking medications before a test. Staying hydrated is also important since dehydration can affect results.



Making Blood Tests Part of Your Health Routine
Think of blood tests as part of your overall wellness plan, not just something to do when you’re sick. Keeping a consistent schedule makes it easier for your healthcare provider to spot trends and intervene before problems escalate. You can better protect your long-term health by:



Scheduling annual checkups around the same time each year.
Keeping a personal record of your results to track changes.
Asking your provider which specific tests you should prioritize.

Why Do I Need a Repeat Blood Test?

Why do I need a repeat blood test? That’s usually because your doctor, nurse, or pharmacist struggled to accurately interpret your test results. This is quite normal and can happen for a variety of reasons. So, it’s not an immediate cause for concern.

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Medically reviewed by Dr Earim Chaudry

Chief Medical Director

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Last updated 12 April 2024
Table of contents
Understanding Blood Tests
Why Would I Need a Blood Test?...
Why Do I Need a
What to Do If You’ve Been Aske...
Key Takeaways
References
It might be that your results are borderline, i.e. on the threshold of two different readings. Or it could be that your results are completely anomalous, suggesting that there may have been something wrong with the test. There’s also the possibility that more tests are needed to get a full picture of your health.

Regardless, you must take a repeat test if requested. It will help your doctor better understand – and treat – any health problems you may have.

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Understanding Blood Tests
Blood samples are some of the most important tools that doctors have to help you understand your health. Used to gain an insight into everything from your cholesterol and glucose levels to the health of your thyroid, blood pressure, and kidney function, they are incredibly useful. As a result, if you’re having a health check-up, you shouldn’t be surprised if you’re required to take a blood test.

But what about a retest? Why would you need a repeat blood test? When the stakes are high, it can be disconcerting if something unexpected occurs. However, repeat blood tests are normal – and there are many possible reasons why they might be necessary.

To reassure you, here we take a look at some of the reasons why you might need to redo a blood test.

Why Would I Need a Blood Test?
Before any retest, though, you’ll need to take a test in the first place.

Your blood is very helpful for doctors – and for you – to get an insight into your overall health. It carries all of the important nutrients, minerals, and proteins around your body. And it’s particularly helpful as it can be extracted and analysed pretty easily.

So, why might you need a blood test? Here are some of the reasons why a blood test might be useful. Trust us, though, that there are many, many more.

To monitor your overall health. General tests including the full blood count (FBC) and the electrolyte test check the balance of the contents of your blood.
To check your cholesterol levels. Cholesterol is a fatty substance that accumulates in your blood. Tests can tell you just how much of it you have and whether it is a problem for your health.
To see how quickly blood coagulates. Slow blood clotting can be fatal. A test can show you how quickly yours coagulates.
To keep an eye on blood sugar levels. Tests like the HbA1c blood test monitor your blood glucose levels over time. This can be life-saving for people with diabetes.
To identify signs of cancers. Some tests look for the symptoms of cancer in your bloodstream.
Why Do I Need a Repeat Blood Test?
Just as there are plenty of reasons why you might need a blood test in the first place, there are many reasons why you might be asked to have a repeat test.

Here are some of the most common. In all cases, the simple fact is that your doctor will want to be sure that the reading is correct. That’s their job – and they wouldn’t be doing a good job if they weren’t sure.

1. Some tests require more than one sample
To start with the obvious, some tests require more than one sample of blood. The HbA1c test, for example, should ideally be taken every 3 to 6 months. If you are newly diagnosed as diabetic, that may come as a surprise, but it is crucial to do it regularly to monitor your blood sugar levels.

Similarly, some blood tests are used to monitor other chemicals in your blood too. In these cases, one test will rarely be enough.

2. Abnormality, or unexpected results
If a doctor has been monitoring your health over time, they might request a retest if they see something out of the ordinary. This could be an entirely different value to what they usually find, or else a result they were not expecting.

If it is just a random anomaly (which does happen!), then a retest will confirm that. But if it is a potential sign of something more serious, your doctor needs to be sure.

3. ‘Borderline’ results
A common reason for retests is that your results are at one end of the normal range. For doctors to be sure that they are diagnosing you correctly – or that they are providing you with the right advice or medication – then they may request a retest just to be sure.

This doesn’t necessarily mean that your results are anything to worry about, however. Your doctor will tell you in due course if there is evidence of a health condition that needs to be monitored or treated.

4. Mistakes or errors
Even in the best healthcare systems in the world, mistakes and errors are possible. Leaking or broken samples, while uncommon, for example, do happen – and these mean that your sample will be contaminated and unusable. In this case, it’s understandable that you will need to do another test.

5. False positives
During the coronavirus pandemic, a lot of attention has turned to testing for infection. As you may have read during this time, tests – and that includes blood tests – are not always 100% accurate. When tests deliver a wrong result, these are called false positives. They don’t happen often, but it is more likely with some tests than others.

It may be that your test has returned results that your doctors believe to be wrong. In which case, they will order a repeat to double-check.

What to Do If You’ve Been Asked to Take a Retest
If you are told that you will need to retake a blood test, the procedure will be the same as the original test. However, there are some things that you should do your best to bear in mind:

Don’t panic. We know that things can be a little disconcerting when they are unexpected. However, there is no reason for you to worry if you are asked to take a retest or further tests.
Follow your healthcare provider’s instructions. As with any test, you should do exactly what your GP or nurse tells you when taking a test. That means if you need to fast, do it properly (as that may be the reason for your abnormal results). If your doctor tells you not to eat before a blood test, it’s important that you don’t.
Ask any questions you may have. The best way to find out why you need a retest is to ask the healthcare professional with whom you are having your tests. They will be happy to explain the reasons to you – and will be able to put you at ease.
If you have taken a test through Manual, our medical team will give you all the information you need on the reasons behind your retest. Whether it’s through online messaging or a phone consultation, we’ll clear up any doubts you have.

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Key Takeaways
Why do I need a repeat blood test? The answer is simple: your doctor wants to be sure about your results.

What’s important to bear in mind, though, is that this doesn’t necessarily mean bad news. Rather, from damaged samples to surprising results, there are lots of different reasons why you might need a retest. Ultimately, your doctor should explain to you the reason.

Yes, getting a blood test is highly worth it. It is one of the most effective, accessible tools for preventative healthcare, allowing you to catch hidden conditions before they become serious, monitor how well your organs are functioning, and establish a baseline for your long-term health.A blood test can be a good idea depending on your specific situation and goals:For Preventative Health & ScreeningCatching silent conditions: Many serious issues like type 2 diabetes, high cholesterol, or early-stage kidney disease often develop without any obvious symptoms.Nutritional insights: A test can identify deficiencies in key nutrients like iron, Vitamin D, or B12, which are often the root causes of unexplained fatigue or low mood.Peace of mind: Routine blood panels confirm whether your lifestyle choices and diet are keeping you in optimal health.When You're Experiencing SymptomsDiagnosing the cause: If you are feeling unwell, blood work is usually the first diagnostic step. It can rule out or confirm infections, anemia, hormone imbalances, and immune system issues.Treatment tracking: If you are already managing a chronic illness or taking daily medications, regular blood tests allow your doctor to evaluate if the treatment is working and check for any harmful side effects.When It May Not Be NecessaryNo specific symptoms or risk factors: If you feel perfectly healthy and have already had comprehensive blood work done within the last year, a repeat might not be strictly necessary unless your doctor recommends it.As a solo diagnostic: Blood work is just one piece of the puzzle. It does not provide a definitive diagnosis on its own; doctors use it in combination with your symptoms, physical exams, and other tests.

Blood Tests
Medically Reviewed.
Last updated on 12/06/2022.
A blood test is one of the most common tests healthcare providers use to monitor your overall health or help diagnose medical conditions. You may have a blood test as part of a routine physical examination or because you have certain symptoms.

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Contents
Overview
Test Details
Results and Follow-Up
Overview
What are blood tests?
Blood tests are common medical tests. You may have a blood test as part of a routine physical examination or because you have certain symptoms.

There are many different blood tests. Some tests focus on your blood cells and platelets. Some evaluate substances in your blood such as electrolytes, proteins and hormones. Others measure certain minerals in your blood.

Regardless of why you’re having a blood test, it’s important to remember that blood tests help healthcare providers diagnose health issues. But blood test results aren’t diagnoses. An abnormal blood test result may not mean you have a serious medical condition.

When would I need to have a blood test?
Your blood plays a big role in your overall health and contains a lot of information about what may be going on in your body. That’s one reason why blood tests are a common medical test. A healthcare provider may do a blood test because:

It’s time for your regular physical. During a checkup, your provider may order blood tests to check on your overall health. They may order a blood test that evaluates many parts of your blood, such as a complete blood count (CBC), basic metabolic panel (BMP) or a comprehensive metabolic panel.
Your provider recommends screening tests. Screening tests are done before you have any symptoms. They may recommend screening tests if you’re at risk of developing certain conditions, such as cancer. For example, if you’re at risk for developing coronary artery disease, your healthcare provider may order several blood tests to evaluate that risk.
You don’t feel well. If you have specific symptoms, your provider may order blood tests to determine what’s causing them. For example, if you have symptoms that may be signs you’re pregnant, your provider will do a pregnancy test. The blood test looks for a specific hormone your body only ever makes when you’re pregnant.
You have a medical condition that happens when certain genes change (mutate). Depending on your situation, your blood cells and platelets may show information about the specific changes. Understanding which genes changed may help your provider plan your treatment.
You’re receiving treatment for a medical condition. Your provider may use regular blood tests to see if treatment is working.
You may have inherited certain genetic mutations that cause medical conditions. Your provider may take blood samples for genetic analysis so you know if you’re at risk of developing a specific condition.
What do blood tests show?
In a broad sense, a blood test shows changes in your body. Blood test results don’t show a complete picture. Instead, they’re a kind of snapshot. After seeing that snapshot, your provider may do other blood tests to get a closer view. Here’s a glimpse of what your healthcare provider may see with blood tests:

The tests show if your blood is working as it should. For example, your red blood cells carry oxygen throughout your body. A blood test may show you have low red blood cell levels (anemia). If healthcare providers look at your cells under a microscope, they may see your red blood cells are larger than normal or shaped differently than normal red blood cells. These differences may be signs of blood disorders or blood cancers.
They show if you have normal levels of enzymes and electrolytes. Enzymes are proteins that help speed up the chemical reactions that build up and break down substances in your body. Electrolytes do several things, such as helping your body regulate chemical reactions and maintaining the balance between fluids inside and outside your cells.
What are the most common blood tests?
There are many different blood tests. Some tests — such as complete blood count tests, basic metabolic panels, complete metabolic panels and electrolyte panels — check on several different elements in your blood at the same time. Other blood tests look for very specific elements in your blood.

What does a complete blood count (CBC) test show?
This is the most common blood test that includes several specialized tests. CBC tests:

Count and measure your red blood cells, white blood cells and your platelets. A CBC test includes a hematocrit test that measures the percentage of red blood cells in your blood.
Measure your hemoglobin levels.
Measure variations in your red blood cells’ size and volume with an RDW blood test (RDW stands for “red blood cell distribution width”).
Measure the average size of your red blood cells with a mean corpuscular volume (MCV) test.
What does a basic metabolic panel show?
A basic metabolic panel (BMP) measures several substances in your blood. Healthcare providers use BMPs to evaluate your overall health and screen for or monitor health issues. A BMP may include a:

Blood glucose test: Screens for diabetes.
Calcium blood test: Checks to make sure you have appropriate levels of calcium, a mineral that helps with many of your body’s functions.
Blood urea nitrogen (BUN) test: Measures the amount of urea, a waste product that passes through your kidneys. BUN tests show the amount of urea nitrogen in your kidneys.
Creatine kinase (CK) test: Screens for a waste product your muscles produce. High CK levels may be a sign of injured or damaged muscles.
Sodium levels.
CO2 blood test: Measures the amount of bicarbonate in your blood. This test detects carbon dioxide.
Serum potassium test: Measures potassium levels. Potassium supports your heart, nerve and muscle function and your metabolism.
Chloride blood test: Checks on chloride, an electrolyte that helps keep your body fluids and acids balanced.
Globulin blood test: Measures how much of this protein your liver produces.
What does a comprehensive metabolic panel show?
Comprehensive metabolic panels (CMP) include all the blood tests done as part of a basic metabolic panel. Additional blood tests include:

Albumin blood test: Albumin is a protein in your blood plasma. This test checks on kidney and liver function.
Alanine transaminase (ALT): Healthcare providers use this test to assess liver health.
Alkaline phosphatase (ALP): High levels of this enzyme may indicate liver disease or certain bone disorders.
Ammonia levels: Blood tests will show the amount of ammonia in your blood. High ammonia levels may be a sign of liver and kidney damage.
Bilirubin blood test: Bilirubin is a substance in your liver’s bile. Too much bile in your blood may be a sign of liver issues.
Aspartate transferase: Sometimes called AST, this test measures the amount of the enzyme aspartate transferase in your blood. Providers use this test to assess liver health.
What does an electrolyte panel show?
Electrolytes are minerals in your blood. Imbalance with electrolytes may be a sign of issues with your heart, kidneys or your lungs. An electrolyte panel includes all electrolyte tests in BMPs and CMPs. Additional electrolyte levels tested include magnesium and anion gap. Magnesium supports your brain, heart and muscles. Anion gap tests check the acid-base balance in your blood.

What blood tests do healthcare providers use to help diagnose specific conditions?
While the various blood and electrolyte panel tests provide a lot of information, there are disease-specific blood tests that help providers diagnose and treat specific conditions.

Allergies
An allergy blood test checks your blood for increased levels of immunoglobulin E (IgE) antibodies. The test can help detect allergies to foods, pets, pollen or other irritating substances.

Autoimmune diseases
Autoimmune diseases happen when your immune system accidentally attacks your body instead of protecting it from intruders like viruses, parasites and cancer. Your provider may order the following blood tests:

Antinuclear antibody test: Antinuclear antibodies (ANA) are antibodies that mistakenly attack your immune system. Large amounts of ANA in your blood may be a sign of certain autoimmune disorders.
CE complement blood test: Providers may use this test to diagnose and monitor autoimmune disorders like rheumatoid arthritis or lupus.
C-reactive protein (CRP) test: Your liver makes and releases this protein. High C-reactive protein levels may be a sign of inflammatory conditions, including some autoimmune diseases.
Erythrocyte sedimentation rate (ESR): ESR tests help detect inflammation.
Peripheral blood smear (PBS): This is a technique healthcare providers use to examine your red and white blood cells and your platelets under a microscope.
Cancer/Noncancerous blood disorders
Healthcare providers may use several different tests to diagnose and treat cancer, blood cancer and noncancerous blood disorders.

Cancer blood tests
Blood tests for cancer fall into four basic categories — complete blood count, tumor markers, blood protein testing and circulating tumor tests. CBC, tumor markers and circulating tumor tests may help detect some solid tumors. Blood in your poop (stool) or pee (urine) may also be a sign of cancer.

Complete blood count (CBC)
A CBC measures red and white blood cell and platelet levels. Abnormally high or low blood cell or platelet levels may be a sign of some types of cancer.

Tumor markers
Tumor markers are substances made by cancerous cells or your body’s normal cells in response to cancer. Tumor marker blood tests include:

Alpha-fetoprotein (AFP) for liver cancer.
CA-125 blood test for ovarian cancer.
Calcitonin for thyroid cancer.
Cancer antigens 15-3 and 27-29 for breast cancer.
Carcinoembryonic antigen (CEA) for a range of cancers.
Human chorionic gonadotropin (HCG) for testicular cancer and ovarian cancer.
Prostate-specific antigen (PSA) for prostate cancer.
Circulating tumor test
The circulating tumor test is a relatively new blood test for cancer. This test looks for cancerous cells that have broken away from a tumor and into your bloodstream. Currently, it can help monitor certain types of cancer, such as breast, prostate and colorectal cancers. Scientists are still developing the technology.

Other blood tests
Healthcare providers may use the same tests to diagnose blood cancer or noncancerous blood disorders:

D-dimer test: Healthcare providers use this test to diagnose blood clotting disorders.
Fibrinogen test: Fibrinogen is a protein that helps with blood clotting.
Kappa or Lambda free light chain: This test detects high protein levels in your blood plasma. Healthcare providers may use this test to diagnose amyloidosis, which is a noncancerous blood disorder, or to diagnose blood cancers such as multiple myeloma.
Prothrombin time test (PTT): Healthcare providers may use this test to diagnose blood clotting disorders.
Reticulocyte count: This test checks to see if your bone marrow is producing enough healthy red blood cells.
Some blood tests don’t involve providing blood samples, such as:

Fecal occult blood test (FOBT): FOBTs screen for colorectal cancer by looking for blood in your poop (stool).
Urinalysis: Healthcare providers may use this test to detect blood cells in your pee (urine).
Endocrine system disorders
Your endocrine system is made of organs called glands. Glands produce hormones. Healthcare providers may use blood tests to diagnosis conditions affecting parts of your endocrine system. Common blood tests include:

Blood glucose test: This test measures your blood glucose level. It’s used to diagnose diabetes. Another diabetes blood test is A1C, which measures blood glucose over time.
Thyroid stimulating hormone test (TSH): There are several blood tests to diagnose thyroid disorders.
Pancreas blood tests: Your pancreas produces enzymes. These tests check lipase and amylase levels.
Heart disease
Some blood tests evaluate your risk of developing heart disease:

Cardiac blood tests: Your healthcare provider may order these tests if you’re at risk of having a heart attack or developing heart disease.
Arterial blood gas (ABG) test: This test measures oxygen levels and carbon dioxide levels, among other things. Healthcare providers may do this test to diagnose acute heart failure and cardiac arrest.
Specialized blood tests
Your healthcare provider may recommend specialized blood tests, including:

Ammonia levels: Blood tests will show the amount of ammonia in your blood. High ammonia levels may be a sign of liver and kidney damage.
Blood alcohol content (BAC): This test measures the amount of alcohol in your system.
Ferritin: You may have a ferritin test if your CBC tests show you don’t have enough iron.
When should I have a blood test?
That depends on your situation and your overall health. Most healthcare providers recommend annual physical examinations that may include a complete blood count test. In general, providers recommend tests based on what they know about you. For example, they may recommend regular blood glucose tests if you have overweight (a Body Mass Index or BMI over 25) or obesity (a BMI greater than 30).

Test Details
What should I do to prepare for my blood test?
That depends on the kind of test you’re having. For example, some blood tests require you to fast for several hours before the test. You may be asked not to drink any liquids apart from a few sips of water. Most blood tests don’t require fasting, but it’s a good idea to ask your healthcare provider what to avoid before your blood test. Other steps may include:

If you don’t need to fast before your blood test and you’re able to drink water, try to drink as much as you can before your test. Being well-hydrated may make it easier for healthcare providers to obtain blood.
Use moisturizer on your arms. It may make it easier for your provider to insert the needle and obtain blood.
Boost your blood pressure right before your blood test by doing some gentle exercise while waiting to be called in for your test.
What happens during blood tests?
Phlebotomists — healthcare providers with special training in drawing blood — do blood tests. During the blood test process:

You’ll sit in a chair with an armrest where you can stretch your arm out in front of you.
If you’re wearing a long-sleeve shirt, you’ll roll up your sleeve past your elbow.
The phlebotomist will wipe an antiseptic liquid in the bend of your arm (on the other side of your elbow) and put an elastic band around your arm (above your elbow).
They may ask you to make a fist to encourage blood flow.
They’ll insert a needle into your arm. This typically happens very quickly. You may feel the needle go into your skin. This is called venipuncture.
The blood flows into a tube that’s sealed and sent to a lab for analysis. The phlebotomist may need to take several samples of your blood, depending on the blood tests your healthcare provider ordered.
Once the phlebotomist has obtained enough blood, they’ll remove the stretchy band that’s strapped around your arm and removes the needle.
Then, they’ll put a bandage on the area where the needle went into your skin.
Are there different ways to do blood tests?
All blood tests involve obtaining blood samples. Venipuncture (from a vein) is the most common procedure. Other procedures are:

Finger stick: Your provider pricks one of your fingers with a needle to collect a tiny amount of blood. The blood sample is saved on a special strip of paper that’s sent to a lab for analysis.
Heel stick: All babies born in the U.S. have blood tests by pricking their heel with a needle to obtain a blood sample.
Arterial blood gas test: In this test, providers take blood from one of your arteries instead of a vein.
How much blood is taken during blood tests?
That depends on the kind of blood test. On average, a complete blood count (CBC) test may take as much as 30 milliliters (mL) of blood. It may sound like a lot of blood, particularly if you’re watching your blood flow into several sample tubes. But it’s not — the average adult has 4,500 to 5,700 milliliters of blood in their body.

Do blood tests hurt?
They can, depending on the kind of blood test you have. It’s important to remember that phlebotomists receive training on how to obtain blood samples quickly and without causing pain.

That said, tests that take blood from an artery tend to hurt more than tests that take blood from a vein. And with venipuncture, taking blood from a vein may hurt a bit if the phlebotomist has trouble inserting the needle into your vein. Let your phlebotomist know if you have any discomfort. They’ll try different ways to obtain samples of your blood.

I’m always anxious about having blood tests. What can I do to relax?
Many people feel anxious about blood tests. Some ways to cope include:

Understanding why you’re having specific blood tests.
Taking deep breaths as the needle goes into your arm.
Looking away so you don’t see the needle enter your arm.
Finding a way to distract your attention, such as silently counting to 10.
What happens after my blood test?
Your provider will put a bandage on the spot where the needle went in. Depending on the blood test, they may recommend you rest for a minute or so before standing up and leaving.

Results and Follow-Up
When will I know my test results?
That depends on the blood test and your provider’s preferences. Your provider likely will explain how you’ll receive results. Some blood test results are available within a few hours. Others, like genetic test results, typically take longer.

Some healthcare organizations offer online access to test results. But your provider may prefer to discuss your results in a telephone conversation or in person.

My healthcare provider wants to talk to me about my test results. Does that mean something’s wrong?
Not necessarily. If your tests were part of your routine medical checkup, your healthcare provider may want to review results with you. They may have recommendations about ways you can improve your health. If you’ve received treatment for a medical condition, your provider may want to discuss your test results in detail and put the results in context.

A note from Cleveland Clinic
It’s probably fair to say blood tests are last on most people’s list of fun things to do. But blood tests are an essential tool healthcare providers use to monitor your overall health or diagnose medical conditions. You may have a blood test as part of a routine physical examination or because you have certain symptoms.

Regardless of why you’re having a blood test, it’s important to remember that while blood tests help providers diagnose health issues, they aren’t diagnoses. An abnormal blood test result may not mean you have a serious medical condition. If your healthcare provider recommends blood tests, they’ll be glad to explain why they recommend the test and what the test may show.