What Are Lab Tests and Their Importance?

Lab tests are one tool that doctors use during a wellness exam to evaluate your health. These tests can help make a diagnosis and monitor the effectiveness of current treatments. Blood, urine and saliva are commonly tested in laboratories. 

The test results can tell if certain levels within a patient’s body are in a normal or abnormal range. For example, the tests can show a patient’s cholesterol or glucose level. Such tests are important because the results give doctors insight into a patient’s overall health. 

We recently spoke with Stephanie Whitehead, executive director of pathology services at University Health, to learn more about lab tests. Whitehead explained why a doctor might order lab testing and how patients can learn more about their lab results. 

Why Might I Need a Lab Test?

Doctors may order lab tests for many reasons, but the most common reasons patients may need lab tests include:

  • Preventative care – Lab tests give health care providers information about a person’s health, including identifying risk factors for diseases or other conditions. 
  • Screening – Some lab tests screen the patient for specific condition.
  • Diagnosis – Lab tests can help doctors diagnose medical conditions. 
  • Monitoring – Lab tests help monitor the progression of a disease or medical condition.
  • Treatment – Lab tests provide valuable information that helps doctors decide how to treat a condition.

Common Lab Tests during a Wellness Exam

What should a patient do or not do before having lab tests to help ensure the most accurate results?

  • Follow any specific instructions provided by the doctor in preparation for the test. This may include dietary restrictions, medication adjustments or other special directions. 
  • Stay hydrated. Drinking water can help make it easier to obtain a sample. 
  • Bring a support person to the appointment. Bringing a trusted friend or family member if it will make you feel more comfortable. 
  • Be honest about your lifestyle. It is important to tell your doctor about alcohol consumption, smoking and recreational drug use.
  • Bring necessary documentation to your appointment, including identification cards, insurance information and referral documents.  

How Accurate Are Lab Results? What Can Affect the Accuracy?

Lab results are generally highly accurate. Some potential factors that could affect lab result’s accuracy include:

  • Quality of the sample – The quality of the specimen collected for testing is important. Contaminated or improperly collected samples can lead to inaccurate results.
  • Interference – Certain substances present in the body or in the sample can interfere with the accuracy of lab tests. For example, some medications or supplements can cause interference and lead to false positives or negatives.
  • Timing – The timing of sample collection can be critical for some tests. For example, fasting blood glucose levels may vary depending on the time of day and recent food intake.
  • Laboratory differences – Results could be different depending on the lab preforming the test. Some laboratories utilize different equipment or distinct frames of reference for tests that could result in contrasting results.  

Why Are Some Lab Results Given in Ranges and Others Say Positive or Negative?

Two types of common laboratory tests are quantitative and qualitative.

Quantitative Tests 

These tests measure the quantity or concentration of a particular substance in the sample. Reported as numerical values, these tests use reference ranges that indicate normal and abnormal. Examples of quantitative tests include blood glucose levels or hormone levels.

Qualitative Tests

These tests measure the presence or absence of a specific substance or condition in the sample. Reported as positive or negative, examples include infections agents (bacteria or viruses) and certain biomarkers. 

What Else Should Patients Know about Lab Tests?

  • Communication is key. Be open and honest with your doctor and ask questions.
  • Be patient. In some instances, lab tests may take some extra time to process.
  • Advocate for yourself. Take an active role in your health care by educating yourself and speaking up if you have a concern. 
  • The need for regular monitoring of lab tests is common for chronic conditions. The tests help track the progress of a condition and the need for adjustments.
  • Find information from reputable sources. Instead of searching randomly for terms on Google or the internet, get answers to questions about labs from your doctor or another reputable source.  
  • Keep copies of your test results. This can be helpful when having discussions with your health care provider about your health history. 

For more information about lab tests, contact your primary care provider. University Health patients can also find more details on the MyChart patient portal.

Additional information is available on the American Society for Clinical Pathology or MyPathologyReport websites.

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