Making sense of your blood test results, and understanding their impact on your health, can help you make good decisions about your lifestyle and your future.
Unfortunately, there are a few things your doctor may not tell you about those results…unless you know what to ask.
A typical routine blood test is the Complete Blood Count, also called a CBC. This test counts your red and white blood cells and measures your hemoglobin levels and other blood components.
This test can uncover anemia, infection, and even cancer of the blood.
Another common blood test is the Basic Metabolic Panel (a BMP) which checks your heart, kidney and liver function by looking at your blood glucose (blood sugar), calcium, and electrolyte levels.
To check for heart disease risk, you may have a Lipid Panel which measures the levels of fats in your blood, like good cholesterol (HDL), bad cholesterol (LDL), and triglycerides.
Triglycerides are a type of fat (lipid) found in your blood and an important measure of heart health.
When you eat, your body converts any calories it doesn’t need to use right away into triglycerides.
The triglycerides are then stored in your fat cells. Later, hormones release the triglycerides to give you energy between meals.
If you regularly eat more calories than you burn, particularly from high-carbohydrate foods, your triglyceride levels will be high.
Just to clear things up:
- Triglycerides store unused calories and provide your body with energy.
- Cholesterol is used to build cells and certain hormones.
Important questions to ask your doctor:
1. What are the full results of my blood test?
Routine blood tests are generally done to look for problems, so if your CBC, blood chemistry and cholesterol results are within normal ranges, the doctor’s office may not reach out to you with the results. Or they may send you a copy with little or no explanation.
But even if things appear normal, the National Heart, Lung, and Blood Institute (NHLBI) recommends you follow up and discuss your blood test with your doctor or nurse practitioner.
Ask if there have been changes since the last test of the same type, and what those changes mean.
2. Keep in mind that “Normal” may not be the same between men and women.
If you compare the results of your blood tests with someone of the opposite sex, you may be surprised to find differences.
3. ‘Normal’ may or may not vary by age
For some tests, such as the hemoglobin test, normal results vary by age. But for other tests, such as for LDL cholesterol (the bad kind) a level of fewer than 100 milligrams/deciliter (mg/dl) is considered optimal regardless of age.
That being said, your age and other risk factors for heart disease may influence how your doctor reacts if your blood test shows a higher-than-optimal LDL cholesterol level.
If you’re a man over 45 or a woman over 55 and you have heart disease or diabetes, your doctor will likely advise you to take steps to lower your LDL cholesterol if it is higher than 100 mg/dl.
If you’re a woman, the recommended levels are less than 200 mg/dL.
4. A “Positive” test result does not mean it’s positive news.
Some blood tests look for diseases by searching for certain “markers” in your blood sample. The most common are the tests for sickle cell anemia, the HIV test, the test for hepatitis C, and the screening tests for breast and ovarian cancer risks (the BRCA1 or BRCA2 gene tests).
In the case of the above, the test results are considered “positive” when the test finds the disease marker — DNA, antibody, or protein — that it’s looking for.
If they’re found, a positive test result means you may have the disease or disorder.
In the case of infectious diseases, it means that you may have been exposed to it in the past.
On the other hand, a “Negative” test result Is usually good news because “negative” is not the same as “bad” when talking about blood tests.
A negative result means that the test did not detect what it was seeking, whether it was a disease marker or a risk factor for a health condition.
When you’ve had a blood test to check for an infectious disease, such as tuberculosis, getting back a negative result is good news — it means the test found no evidence of an infection.
5. And, because medical-type folk like to confuse patients, even more, you have “False-Positive” test results…which means they’re “possible.”
Confused yet? Bear with me!
The first screening test for a condition often has to be confirmed by a second, more specific test to find out whether the results are accurate and meaningful for your health. The HIV test is one of those.
- A False-Positive means that even though the test result is accurate, the person does not actually have the disease…
This can happen with certain tests that measure antibodies. Someone may have an immune condition (such as rheumatoid arthritis or multiple myeloma) that also produces antibodies and interferes with the test.
And, of course, False-Negative test results happen, too. Sometimes a test doesn’t pick up evidence of a disease or condition, even though you actually do have it.
For example, if you had a blood test for hepatitis C and the results came back negative, but you were exposed to the virus in the past few months, you could still have an infection and not realize it.
Similarly, if you’re tested for Lyme disease within the first few weeks of an infection, your blood test is likely to come back negative because your body has not yet developed antibodies.
In the above two tests, count on them to be done again at a later time.
8. Test Values Can Be Different From Lab to Lab
Lab technicians’ reports compare your blood test results with a range that is considered normal for that laboratory. The lab’s reference range is based on test results from many people previously tested in that lab.
According to the Food And Drug Administration (the FDA), this “normal” range may not be the same as another lab’s. so don’t be surprised if you find that a prior blood test report is different than newer reports — the difference could be in the lab.
It’s up to your physician to figure this out and give you a complete explanation if you’re asked to take the test again. Hold them accountable.
9. Abnormal Results May Not Be Due to a Disease
A test result outside the normal range of expected lab values does not necessarily mean you have a disease or disorder. Test results can be abnormal for other reasons.
If you had a fasting plasma glucose test, for instance, and you ate something before the test, or were drinking alcohol the night before or taking certain medications, your results could be temporarily outside the normal ranges, but are not evidence of a disease.
To avoid such problems, talk with your doctor before any lab tests about whether you need to make any special preparations before your blood is drawn, such as fasting the night before.
10. Mistakes Happen
Although mix-ups of blood test samples are rare, they do happen.
How your blood sample is handled before it’s analyzed can affect results, too.
For example, if the sample is collected in the wrong container, shaken inappropriately, or stored for too long or at the wrong temperature, you may get an incorrect result.
OK…so now what? How do you deal with all of this?
First, make sure you have a well-recommended and reliable physician.
Then, discuss the tests he/she has ordered, at length, before you head to the lab or have them drawn in his office.
Make sure the person(s) drawing your blood is experienced, washes their hands even before they put on their gloves to draw your blood, cleans the area of your body being tested prior to inserting the needle, and can actually explain what the test is for specifically.
If the lab does not meet the above criteria, leave. Call your doctor and ask to be sent somewhere else. It’s your health and the course of treatment your doctor will choose depends on the accuracy of those tests. Speak Up!
Never be timid when it comes to questions about your condition or the methods used to detect abnormalities. Remember this:
A well-informed patient is a patient with the best chance of successful treatment and recovery.
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