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.
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).
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.