Frequently Asked Questions
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Have questions about laboratory testing? We’re here to help. If you can’t find an answer to your question here or in the articles on this site, please Contact Us.

Finding Information

What is Lab Tests Online?

LabTestsOnline.org is a health information web resource designed to help patients and caregivers understand the many lab tests that are vital part of medical care.

For more details, see About Lab Tests Online.

How can I find specific test information on this site?

You can use the drop-down menus located at the top of each page to look for a test in the alphabetical listing. You can also search for a term in the Test Index. Alternatively, you can type the term into the search box in the top right corner of the webpage. If you still can’t find what you are looking for, please Contact Us.

Getting Tests Results

Where are my test results?

Lab Tests Online is a patient education web resource. There are no personal test results on this site. It is possible that your patient portal or the lab that performed your test links to Lab Tests Online to provide background information on lab tests. If that is the case, you will need to return to the portal or lab website to ask about your results. If you obtained testing through Health Testing Centers, log in to your account to view your results.

How long does it take to get test results?

The time it takes for test results to be available depends on various factors, such as the type of test, method used, and where the particular test was performed. Rapid tests performed at home or in a clinic can give results within minutes. Tests that are performed at local labs or commercial reference labs may take a few hours or up to several days after the sample is received at the lab.

Getting Tested

Where or how can I get tested?

Lab tests are performed in a variety of settings, depending on the particular test:

  1. You can get tested by visiting a doctor’s office, lab, medical clinic, or hospital. The test is usually ordered by your doctor. After being taken, your sample is sent to a laboratory for analysis.
  2. Sometimes you can get tested in your doctor’s office, at a clinic or health fair. This type of testing is called point-of-care and involves a healthcare worker collecting a sample that is immediately analyzed by a small device or instrument.
  3. You can also order a test from home or over-the-counter. With this type of testing, a kit is sent to your home and the testing is done one of two primary ways:
    1. You collect a sample using materials provided in the kit and send the sample to a lab for analysis.
    2. You collect the sample and use the materials or device included in the kit to perform the test. For example, a drop of blood from a skin prick is placed onto the test strip and a device provides a digital readout.

Visit Find A Lab for resources on locating a lab. You can also view some of the test articles on this site and see Looking to Get Tested? to order a test.

Learn more:

How much does a lab test cost?

There are many factors that determine the cost of a lab test, including the type of test, where the test is performed, and if you have insurance coverage. When prescribed by a doctor, testing is often covered if you have insurance, but you may still have a copay or deductible. There can also be fees charged by the technicians who draw your blood. Check with your doctor and insurance plan about the cost of the test. If you order testing through the Health Testing Centers, you can follow the links to that site and view the costs of tests there. Point-of-care testing at health fairs is usually done at no charge or very low-cost.

How is a blood sample collected?

Typically, a blood sample is taken by inserting a needle into a vein, usually in your arm. Before your blood is drawn, an elastic band is tied around your upper arm to increase blood in the veins, and the puncture location is wiped clean with an antiseptic. A blood draw using a needle may cause a temporary sting. The blood draw normally lasts for less than a minute. Sometimes a blood sample is collected by puncturing the tip of a finger and drop(s) of blood are collected onto a test pad or filter paper, or into a small tube. Find out what happens to your blood sample after it is collected by reading Follow that Blood Sample: A Short Lab Tour

How is a urine sample collected?

Most urine samples are collected by having you urinate into a clean container provided by the lab. One to two ounces of urine is typically needed for testing, and a sufficient sample is required for accurate results. Urine samples usually can be collected at any time, but a first morning sample may be requested because it is more concentrated and more likely to detect abnormalities. For tests requiring a 24-hour urine, all urine produced for 24 hours is collected at home and put into a large container that must be refrigerated during the collection process.

To collect urine for a urinalysis, you may be asked to collect a “clean-catch” urine sample. To keep the sample from becoming contaminated by bacteria, cells, or fluids from outside the urinary tract, it is important to clean the genital area before collecting the urine. You will be given instructions on how to clean the genital area and void a bit of urine first before collecting the sample into the container. Collecting the urine sample may be awkward but it is not in itself uncomfortable. (An infection, however, can create a burning sensation during urination.)

A urine sample will only be useful for a urinalysis if taken to the healthcare provider’s office or laboratory for processing within a short period of time. If it will be longer than an hour between collection and transport time, then the urine should be refrigerated or a preservative may be added.

To learn more, read Collecting Samples for Testing

Can you test a sample? (e.g., a substance I found at home, or my body sample such as from a wound, etc.)

Lab Tests Online is health information website designed to help you learn about the laboratory testing used in medical care. Lab Tests Online is not a laboratory and does not perform testing, but there are resources you can find here to help you locate a lab and find out how to access testing. Keep in mind that not all labs perform every test. For more details, read Where Lab Tests Are Performed or visit the Find a Lab resources page.

Before the Test - Test Preparation

How should I prepare for my tests?

Most tests do not require any special preparation. Others, however, may require you to fast or avoid specific foods or take other steps in advance of the test. You can read the test articles on this site and find the sections titled “Test Preparation?” or “Before the Test” for test specific information. Always follow carefully any instructions you are provided by your healthcare provider and/or the lab that will perform your test.

For more information, read Test Preparation: Your Role.

Why do I need to fast before some tests?

The results of some tests are intended to be interpreted when you have fasted prior to your sample being collected. Examples include lipid panels and glucose tests. When fasting, drinking only water is permitted. If you do not fast, the results may be affected and/or may not be interpreted correctly. Sometimes your blood sample may be drawn when you have not fasted, and this information is noted on your records. Be sure to follow any instructions you are given and tell the person drawing your blood whether or not you have fasted.

Can I have a cup of coffee before my test?

Follow any instructions provided to you by your healthcare provider or the lab that will perform your test. While fasting, you usually are allowed water but should not drink anything else, including coffee, before your sample is collected. Caffeine and other ingredients in coffee can affect the results of some tests.

Will my tests be affected by diet or medications?

Some tests are affected by diet, medications and supplements. Follow any test preparation instructions from your healthcare provider or the lab that will perform your test. For some tests, you may need to avoid certain medications before your sample is collected, but you should never discontinue your prescribed medications without first consulting with your healthcare provider. For other tests, you may need to avoid certain foods. An example is creatinine, which can be affected by eating cooked meat prior to your test. For information on how to prepare for specific tests, find the test on this site and read the sections titled “Test Preparation Needed?” or “Before the Test“.

I’ve heard that taking biotin (vitamin B7) can affect test results. Is that true?

Yes, taking biotin may affect some test results. Biotin—also known as vitamin B7, vitamin H, and coenzyme R—is a nutrient the body requires in very small amounts. Some people take supplements containing higher doses of biotin (for example, more than 5,000 mcg) because they believe it will help improve the condition of their hair, nails, and skin. Some patients may be treated with biotin mega-doses of 100,000 mcg or more because new research suggests such doses may be helpful in treating certain medical conditions, such as multiple sclerosis.

Individuals who regularly take more than 5,000 mcg of biotin per day may have an excess amount in their blood, which can interfere with some types of laboratory tests. Excess biotin in the blood can cause some, but not all, lab test results to be either falsely increased or falsely decreased, depending on the test. Tell your healthcare provider if you take or plan to take biotin or a supplement containing biotin and alert your healthcare provider if you are concerned about test results and the possibility of biotin interference. Always inform your healthcare provider about medications you take, including supplements.

For more details, read Biotin Affects Some Blood Test Results and New Guideline Addresses Biotin Interference in Some Lab Tests.

Understanding Your Results

What do my lab test results mean?

You will want to discuss your personal results with your healthcare provider, who is the best resource for interpreting them in the context of your medical and family history. To have a more informed discussion and to help formulate your questions, find the tests here on Lab Tests Online and read the articles for background information. You can also ask for help in understanding your results by submitting your question to our partner’s volunteer Consumer Response Service using the Ask a Laboratory Scientist form on this site. Other resources on this site that can help you understand your tests results include:

Where are the reference ranges (normal ranges) for tests?

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results. If you do not have your lab report, contact your healthcare provider or the laboratory that performed the test(s) to obtain it and to view the reference ranges.

Lab Tests Online provides references ranges for only a few tests that have been standardized over many years. The reason there are so few reference ranges for the test articles on this site is because the ranges for most tests vary from lab to lab. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are “within normal limits.” Learn more about Reference Ranges and What They Mean.

What does it mean if my result is outside the reference range?

Your test results are interpreted by your healthcare provider within the context of other tests that you have completed. These results are also measured against other factors like your medical history. The medical significance of a single result that is slightly high or slightly low may be difficult to determine. This is why a healthcare provider may repeat a test, and why they may look at results from your previous tests. However, a result outside the range may indicate a problem and warrant further investigation. Your healthcare provider will evaluate your test results in the context of other relevant factors, and determine whether a result that falls outside of the reference range presents a significant issue.

If my results are normal, does that mean I have nothing to worry about?

If your results are within normal limits, it’s certainly a good sign. But this may be only one set of tests, not a guarantee. There is a lot of overlap among results from healthy people and those with diseases, so there is still a chance that there could be an undetected problem. If you’re trying to follow a healthy lifestyle, take test results that are within range as a good sign, and keep it up. If you’re engaging in unhealthy habits, however, such a poor diet or no exercise, normal results may only mean “so far so good,” and the potential consequences haven’t caught up with you yet. If you had previous results land outside a range, results within the range certainly provide good news. However, your healthcare provider may want to monitor you with a series of tests to make sure you’re still on track and to document any trends. A rise or drop in results, even if they are still within normal limits, could mean something significant.

If my result is abnormal, does that mean I have a problem with my health?

Not necessarily. A test result outside the reference range may or may not indicate a problem, but it signals to your healthcare provider to further investigate your condition. You can have a value outside the range and have nothing wrong—but your provider should try to determine the cause. It is possible that your result is within that 5% of healthy people who fall outside the statistical reference range. In addition, there are many things that could throw off a test without indicating a major problem, such as not preparing for the test properly. Most likely, your provider will want to rerun the test. Some results outside the range may resolve on their own, especially if they are on the border of the reference range. Your provider will also seek explanations for an abnormal result. Key points your provider will consider include how far outside of the reference range the results are, and whether the results are outside the range when the tests are repeated.

After the Test

I have my results. What should I do next? Should I follow up with my doctor?

If you’ve completed testing and now have your results, you can explore this website to find information on your tests and begin to understand what your tests results might mean for you. The information on this site is intended to help you become well-informed about laboratory testing. However, the content is meant to supplement — not replace — the guidance provided by your healthcare providers. We encourage you to discuss your test results with your doctor. A healthcare provider who understands your preferences and knows your personal, family, and medical history is an essential resource when seeking advice and making decisions about your health and medical care.

What can I do to improve my results?

People are often interested in what they can do when their lab results are unfavorable or show unhealthy levels. The actions that you can take and the extent that you can improve your results depends on what the test measures and the purpose of the test. In some cases, results like unhealthy lipid levels or glucose levels can be improved by lifestyle changes, such as eating healthy, getting more exercise, stopping smoking, and losing weight. Taking medication as prescribed by your healthcare provider is another way you may be able to improve your results and manage your condition. In any case, it is important to follow your healthcare provider’s guidance to improve your results.

About Testing

Why are lab tests important?

Laboratory tests are among the most common and important tools of modern medicine. Results from clinical laboratory tests contribute to the majority of healthcare decisions. They provide information about your health status and risk factors, and for making a diagnosis, guiding therapy, and determining outlook (prognosis). Many of the decisions you and your healthcare provider make about your care – obtaining a diagnosis, developing a course of action for treatment, or monitoring your body’s response to therapy – are based on results of laboratory tests. In many cases, there is just no substitute for a laboratory test for providing insight into your health.

Are lab tests accurate?

No lab test is 100% accurate. However, medical testing that takes place in certified laboratories in the U.S. is performed by trained professionals and conducted with rigorous standards, quality assurance, and extensive oversight. You can trust the data generated by today’s exacting medical tests. One caveat to remember is that a diagnosis and treatment plan for a serious disease should never be based on a single medical test. Test findings are just one of the pieces of the diagnostic puzzle. Test results are most reliable when used in conjunction with other meaningful information, such as your medical and family histories and a physical exam. Additionally, there should be open communication between you and your doctor or other members of your healthcare team. To learn more, read How Reliable is Laboratory Testing?

What does a routine blood test check for? What does routine lab work include?

Typically, “routine blood testing” or “routine lab work” refers to panels of tests that measure several analytes to check your general health status. Two of the most common are a comprehensive metabolic panel (CMP) that measures 14 analytes to check the health of organs, such as your liver and kidneys, and a complete blood count (CBC) that evaluates your blood cells to check for conditions like anemia or infections. Other, more specific types of panels can be used as a routine check of the health of your liver, thyroid or kidneys.

Can cancer be detected with a blood test?

Blood tests cannot definitively tell whether or not a person has cancer. However, some blood cancers may be detected if there are abnormal findings on a complete blood count (CBC). Additional tests, such as a bone marrow biopsy, are performed to confirm the diagnosis. For other types of cancers, your healthcare provider may order testing if it is suspected that you have cancer. Typically, other procedures — such as a physical exam and imaging tests — are necessary to help make a diagnosis. For more details, read the article on Tumor Markers.

Can a blood test detect other specific conditions like heart, liver, or kidney problems?

A blood test may provide clues to health problems, like heart or kidney conditions. However, initial test results that are abnormal are usually followed by additional testing that can help make a definitive diagnosis. Additionally, other tests may be performed to determine the cause of the condition so that it may be treated appropriately.

What is the difference between a screening test and a diagnostic test?

Screening tests are laboratory tests that can help detect a disease even before a person develops symptoms, usually in the earliest and most treatable stages. Screening tests are also used to help to identify people who have an increased risk for a condition so that preventive measures can be taken. Examples of these tests include cholesterol testing for heart disease risk, HIV testing, and Pap smears for cervical cancer.

Screening tests are intended to be sensitive – that is, able to correctly identify people who have a given disease or risk. If a screening test is sensitive, then very few people who have a disease or risk are missed (false negatives). However, a screening result may sometimes indicate that a person has a condition or risk when, in fact, they don’t (false positive). That’s why a positive screening test often requires further testing with a more specific test to confirm a diagnosis. For example, if an HIV screening test is positive, a second test is performed to confirm the diagnosis.

A diagnostic test may be used for screening purposes, but a diagnostic test is generally used to confirm a diagnosis in a person who has signs, symptoms, or other evidence of a particular disease, condition, or risk.

Why do lab tests sometimes need repeating?

There are a few reasons why a test may be repeated. For example:

  1. A test may be repeated when a result indicates that you may have a disease or condition. Repeat test results that match the initial results confirms a diagnosis. For example, if the results from a fasting glucose test are high, the test is repeated. If it is high again, then a diagnosis of diabetes is confirmed.
  2. If a result does not seem to fit with the rest of your clinical picture, such as signs and symptoms and physical exam, your healthcare provider may reorder the test. Here are a few examples of why the results can be unexpected:
    1. It is possible that the analyte measured in the test happened to be high or low because of something you ate, recent physical exercise, or other circumstantial situation.
    2. Though uncommon, errors due to improper processing or transportation of the sample (such as refrigeration issues, exposure to heat, etc.) can occur.
  3. A test may be repeated if there was not enough sample collected to perform the full panel of tests, or if the sample was not collected properly. For instance, if you do not collect all of your urine for a 24-hour urine test, it may need to be repeated.