How to Read Lab Test Reports

Reading through your laboratory test reports may feel overwhelming to many people at first. But with some helpful information, you can learn the basics and gain knowledge to navigate these reports filled with numbers and various measurements. You can then flag when you see specific laboratory test results that might need more medical attention. Here's a step-by-step guide to help you read and interpret common components in lab test reports to guide you on your path to health and wellness.

Basic Structure of Lab Test Reports

Most lab test reports include the following components of—or some variation of this—information:

• Patient information: name, date of birth, identification number, etc.
• Test name: for example, complete blood count (CBC), basic metabolic panel (BMP), comprehensive metabolic panel (CMP)
• Test result: your specific measurement
• Reference range: the reference range (what one might expect from a healthy individual of your age, sex, etc.) for the test
• Flag: indicates if the result is high (H) or low (L)
• Units: the measurement unit (e.g., mg/dL, mmol/L)

Reading Common Lab Test Panels

Although there's an extensive list of potential lab tests for patients, there are lab test panels that are more common for healthcare providers to order than others. For your reference, here's a list of common test panels, what they measure, and a typical range. As always, the following ranges are examples only. For an accurate interpretation of your clinical laboratory results, always refer to the specific range provided on your report that performed your analysis. If you have questions or concerns about your lab results, make sure to talk to your healthcare provider to discuss your values—and be firm if you feel like your concerns are being dismissed. Dr. Susan Leclair offers the following advice and direct approach: “I want you to sit up as straight as you can, look your provider in the eye and say, ‘Okay, that's nice that you don't think anything's going on. I'm telling you something is going on.’”

Complete Blood Count (CBC)

Measures different components of your blood.

Basic Metabolic Panel (BMP)

Checks your body's metabolism.

Lipid Panel

Assesses cholesterol and heart disease risk.

Blood Test Abbreviations

The following list shows the measurements you'll typically see used in blood lab test reports.

• cmm: cells per cubic millimeter
• fL (femtoliter): fraction of one-millionth of a liter
• g/dL: grams per deciliter
• IU/L: international units per liter
• mEq/L: milliequivalent per liter
• mg/dL: milligrams per deciliter
• mL: milliliter
• mmol/L: millimoles per liter
• ng/mL: nanograms per milliliter
• pg (picograms): one-trillionth of a gram

Interpreting Lab Test Flags

In reading through your lab test reports, you may notice some special symbols or letters that serve to flag results such as higher than normal, lower than normal, or critical values that may need urgent attention. Look for the following symbols:

• H or ↑: Higher than expected – might signal a health issue (or just a temporary condition).
• L or ↓: Lower than normal – could indicate deficiency or dysfunction.
• Critical Values: Marked separately; may need immediate attention.

Using Context in Interpreting Lab Test Results

As with a plethora of medical concerns, context can prove vital in the diagnosis of medical conditions. Much like fingerprints, each patient is unique, and sometimes patient symptoms can prove to have higher significance than lab test results on their own. You know your own body and are the only one who can feel differences in how you're feeling—no matter how slight or how significant the variation.

• Try not to rely on a single lab test result. Statistical trends over time provide more vital information about your health to help diagnose conditions and guide your health and wellness decisions.
• Some test result variations may be normal depending on age, sex, lifestyle, medications, or even hydration levels.

Determining Lab Test Reference Ranges

A reference range is a clinical lab test term that you may encounter in learning about lab test reports. Dr. Brandy Gunsolus provided some expert insight to break down the meaning of the term along with some helpful context. “So a reference range is where you have 100 healthy people…and you were to test that marker, let's say TSH on those 100 people, you take the 95 people are in the middle, and that is the range. It seems fairly arbitrary, it's not, it is embedded in statistics. And so 95 percent of the population will fall within the normal range, which also means that 5 percent of the population being completely healthy will normally fall outside of that range. Just because you have a value that falls outside of the reference range does not mean that there is something wrong.”

Working to get more diverse patient populations—not only ethnically and racially diverse but also socioeconomically diverse—is a common goal that many medical laboratory scientists have taken on. Including diverse patient groups will continue to improve reference ranges and work toward diagnostic equity for a higher percentage of all patients.

Common Myths About Lab Tests

“Normal lab test results mean I'm healthy.”

Myth: If lab test results are in the reference range, there's nothing to worry about.

Truth:

• Lab tests are just one piece of each person's health puzzle.
• You can have lab results that fall within the printed reference range but still have symptoms or conditions not detected by routine lab tests.
• Some diseases don't show up in basic lab tests (for example, early autoimmune disease, cancer, or certain infections).

“Abnormal results mean something is wrong.”

Myth: A single out-of-range result means I have a disease or a serious issue.

Truth:

• Slight lab test deviations are common and can result from factors like:
  • Time of day
  • Stress
  • Dehydration
  • Recent exercise
  • Lab error
• One abnormal lab test result usually needs to be rechecked or interpreted in context.

“All clinical laboratories have the same reference ranges.”

Myth: Normal values are universal.

Truth:

• Reference ranges vary slightly between clinical laboratories based on:
  • Testing equipment
  • Local population samples
  • Units used (mg/dL vs mmol/L)
• Always compare results to that specific clinical laboratory's reference range.

“Fasting means not eating. Water is okay, right?”

Myth: I can drink coffee, juice, or smoke while fasting.

Truth:

• True fasting for lab tests often means:
  • No food or drinks except water for 8–12 hours.
  • No coffee, tea, gum, or smoking, which can affect glucose and lipid levels.
• Always follow specific fasting instructions from your doctor or clinical laboratory.

“I can diagnose myself from reading my lab test report.”

Myth: You can Google your results and know exactly what's wrong.

Truth:

• Lab test results should be interpreted in combination with:
  • Your symptoms
  • Medical history
  • Physical exam
• Self-diagnosis can lead to incorrect assumptions and unnecessary worry for patients.

“All lab tests are 100% accurate.”

Myth: Lab test results are always correct.

Truth:

• All tests have a margin of error or variability.
• Factors affecting accuracy:
  • Improper sample handling
  • Biological variation
  • Medications or supplements
  • Lab technician errors

“If one test is normal, I don't need to repeat it.”

Myth: A one-time normal test means you're always okay.

Truth:

• Many medical conditions develop over time.
• Statistical trends matter more than isolated values (especially for things like A1c, cholesterol, and liver enzymes).
• Follow-up testing helps track trends, progression, or early signs of change in lab test results.

Following Up With a Healthcare Provider

Lab test results are just one piece of the puzzle in your healthcare journey. Try not to panic if you notice lab test results out of the reference range. Consultation with a healthcare provider will aid you in delving deeper into your results and in making concrete decisions for moving forward. For example, a doctor or qualified clinician can:

• Interpret results in context of your medical symptoms and health history.
• Order follow-up lab tests if needed.
• Recommend lifestyle changes or treatments for optimal care and wellness over time.

Learning to read lab test reports is another step on your path toward optimal health and wellness. If you have questions or concerns about lab tests that you've received or tests that might be helpful in discovering the cause of bothersome symptoms, make sure to discuss potential tests with your doctor. Diagnostic equity can be a collaborative journey with your healthcare provider. Make sure that you get answers to your lab test questions to shorten your journey to improved health.

Next Step: Ask a Laboratory Professional

Not sure what your lab test report means? You don't have to interpret it alone. Visit the homepage and look for the question box near the top of the page. Type your question directly into the box to connect with medical laboratory professionals who can help you understand your results and support a more informed discussion with your healthcare provider.

Go to Homepage →

You'll receive a human response — no bots, just real professionals ready to help you make sense of your health information.

Diagnostic Equity Resources

Staring at your lab test report with lab test questions? Understanding your lab test results starts here.