What Should I Do If My Blood Test Results Are Abnormal?

Seeing a blood test result marked high, low, abnormal, or outside the reference range can be concerning. However, an abnormal blood test does not automatically mean that you have a disease or that something is seriously wrong.

The appropriate next step depends on which test is abnormal, how abnormal it is, whether you have symptoms, how the result compares with previous testing, and the rest of your medical history.

In many cases, a mildly abnormal value simply needs to be reviewed in context or repeated. In other situations, an abnormal result may identify a medical condition that requires additional evaluation or treatment.

The most important step is to avoid interpreting a single highlighted number in isolation.

If you would like a broader explanation of how physicians interpret blood work, start with our Understanding Laboratory Testing: A Complete Guide for Patients.

First, Find Out Exactly What Is Abnormal

Most laboratory reports compare your result with a reference range established by the laboratory.

If a result falls above or below that range, it may automatically be flagged.

That flag is useful, but it is not a diagnosis.

Reference ranges are generally developed by examining results from groups of people considered healthy. Because of normal biological variation, some healthy individuals will occasionally have values slightly outside a reference range. Likewise, a result that falls inside the reference range does not guarantee that there is no health problem.

When reviewing an abnormal result, your physician may consider:

• How far the result is outside the reference range

• Whether the abnormality is new

• Whether the same result has been abnormal before

• Whether related laboratory markers are also abnormal

• Your age and sex

• Your symptoms

• Your medical history

• Your medications and supplements

• Your hydration and fasting status

• Recent illness or exercise

• Previous laboratory trends

This is why the clinical interpretation of blood work is often more important than simply identifying which numbers are highlighted.

For a patient-friendly overview of reference ranges and laboratory reports, see our Patient’s Guide to Understanding Blood Work.

How Abnormal Is the Result?

The degree of abnormality can be important.

A laboratory result that is barely outside its reference range may have a very different clinical significance from a result that is substantially abnormal.

For example, physicians often distinguish between:

• A mild isolated abnormality

• A significant abnormality

• Several related abnormal results

• A result that has progressively changed over time

• A potentially critical result requiring immediate attention

The laboratory flag itself does not tell you which category you fall into.

Your physician must interpret the number within the larger clinical picture.

Could Something Temporary Have Affected the Test?

Yes. Some laboratory abnormalities are temporary.

Blood test results can sometimes be influenced by factors such as:

• Dehydration

• Fasting or not fasting when required

• Recent illness

• Recent strenuous exercise

• Medications

• Supplements

• Alcohol use

• Changes in diet

• Timing of the blood draw

• Normal biological variation

Your physician may therefore ask what was happening around the time your blood was collected.

If a result seems inconsistent with your health history or previous testing, repeating the laboratory test under appropriate conditions may sometimes be the simplest next step.

Should an Abnormal Blood Test Be Repeated?

Sometimes.

Repeating a test can help determine whether an abnormal result represents a persistent change or a temporary variation.

For example, your physician may recommend repeat testing when:

• The result is only mildly abnormal

• The result is unexpected

• Temporary factors may have affected the test

• The result does not match previous laboratory trends

• Confirmation is needed before beginning treatment

• A treatment or lifestyle change has been started

• A medical condition needs continued monitoring

However, not every abnormal laboratory result should simply be repeated.

Some findings warrant additional evaluation immediately, while others may require an entirely different test.

The timing of repeat laboratory testing should therefore be individualized. You can learn more about appropriate testing intervals in How Often Should I Have Routine Blood Tests?.

What Happens If the Result Is Still Abnormal?

A persistent abnormality may lead your physician to investigate further.

The next step depends entirely on what was found.

Additional evaluation could include:

• A repeat blood test

• Additional laboratory markers

• Urine testing

• Imaging

• A physical examination

• Medication review

• Nutritional assessment

• Additional screening

• Referral to a specialist

The goal should be to answer a specific clinical question rather than simply ordering more and more tests.

For example, an abnormal blood count may lead to a different evaluation than abnormal liver enzymes, blood sugar, thyroid testing, kidney function, cholesterol, or electrolytes.

This is one reason routine laboratory testing works best when results are interpreted together rather than as unrelated numbers.

What Do Common Abnormal Blood Tests Mean?

The meaning of an abnormal laboratory value depends on the specific test.

Complete Blood Count

A complete blood count, or CBC, evaluates red blood cells, white blood cells, hemoglobin, hematocrit, platelets, and other blood-cell measurements.

Abnormal findings can have many possible explanations. Depending on the pattern, your physician may consider conditions such as anemia, infection, inflammation, medication effects, nutritional deficiencies, or other medical concerns.

An abnormal CBC by itself rarely identifies the exact cause of the problem.

Comprehensive Metabolic Panel

A comprehensive metabolic panel, or CMP, provides information about several areas including:

• Kidney function

• Liver-related markers

• Blood glucose

• Electrolytes

• Calcium

• Protein levels

Because many different medical conditions and temporary factors can affect these measurements, your physician generally interprets the individual numbers together.

Cholesterol and Lipid Testing

Abnormal cholesterol results are usually interpreted as part of your overall cardiovascular risk rather than from one number alone.

Your physician may consider LDL cholesterol, HDL cholesterol, triglycerides, blood pressure, diabetes status, tobacco exposure, family history, age, and other cardiovascular risk factors together.

Blood Sugar and Hemoglobin A1C

Elevated glucose or hemoglobin A1C may raise concern for abnormal blood-sugar regulation, prediabetes, or diabetes.

The next step depends on the test, the degree of elevation, your symptoms, and whether additional confirmation is needed.

Thyroid Testing

Abnormal thyroid results are commonly interpreted by examining several factors together, particularly TSH and thyroid hormone levels when clinically appropriate.

Medications, pregnancy, illness, and other factors may also influence thyroid testing.

These examples illustrate why a single abnormal number should not be interpreted without context.

Should I Change My Diet, Supplements, or Medication After an Abnormal Result?

Usually, you should speak with your healthcare provider before making major treatment changes based on one laboratory result.

It can be tempting to search online for a supplement, diet, or medication change that appears to correct the abnormal number.

But the important question is not simply:

“How do I make this number normal?”

The more useful question is:

“Why is this result abnormal, and does it actually require treatment?”

The appropriate response may be lifestyle modification, medication, nutritional treatment, additional evaluation, monitoring, or sometimes no treatment at all.

Do not stop a prescribed medication because of a laboratory result unless the prescribing healthcare professional instructs you to do so, except when emergency medical care is otherwise indicated.

Compare the Result With Your Previous Blood Work

One of the most useful ways to interpret blood tests is to look at trends over time.

A single measurement provides a snapshot.

Several measurements may show a pattern.

Your physician may ask:

• Is the result stable?

• Is it gradually increasing?

• Is it gradually decreasing?

• Is this the first abnormal measurement?

• Did the change occur after starting a medication?

• Did it change after modifying your diet, weight, exercise, or treatment plan?

• Are several related biomarkers changing together?

Whenever possible, keep copies of your previous laboratory reports and make them available to the physician reviewing your current results.

Different laboratories can use different testing methods and reference ranges, so comparisons are often easiest when testing is performed consistently. MedlinePlus also recommends considering laboratory-specific reference ranges when comparing results.

When Is an Abnormal Blood Test an Emergency?

Most abnormal routine blood tests are not emergencies, but certain results can indicate potentially serious problems.

If a laboratory or healthcare professional tells you that a result is critical, follow the instructions they provide promptly.

You should also seek emergency medical attention based on your symptoms rather than waiting to interpret a laboratory report.

Call 911 or seek emergency care for symptoms such as:

• Significant difficulty breathing

• Chest pain or pressure

• Fainting or loss of consciousness

• Sudden confusion

• Sudden weakness or numbness, particularly on one side of the body

• Sudden difficulty speaking

• Other severe or rapidly worsening symptoms

MedlinePlus identifies breathing problems, chest discomfort, fainting, changes in mental status, and other severe symptoms as potential medical emergencies. The CDC similarly advises calling 911 immediately for sudden symptoms suggestive of stroke.

Do not wait for an online message or routine appointment when you are experiencing symptoms of a possible medical emergency.

Questions to Ask Your Physician About Abnormal Blood Work

If you receive abnormal laboratory results, consider asking:

• Which result is abnormal?

• How far outside the expected range is it?

• Is this result clinically significant?

• How does it compare with my previous blood work?

• Could medication, supplements, fasting, hydration, illness, or exercise have affected it?

• Should the test be repeated?

• Do I need additional testing?

• Does this result suggest a specific medical condition?

• Do I need treatment now?

• Are there lifestyle changes that may help?

• When should I repeat my blood work?

• Are there symptoms that should prompt urgent medical attention?

Understanding the reason behind the abnormality can often be much more useful than focusing only on whether the result is marked red on the laboratory report.

Frequently Asked Questions

Can one abnormal blood test result be normal for me?

Possibly. A mildly abnormal value can sometimes reflect normal biological variation, temporary circumstances, or differences in laboratory reference ranges. Your physician should interpret the result alongside your symptoms, medical history, previous results, and related laboratory measurements.

Does an abnormal blood test mean I have a disease?

No. An abnormal laboratory result may suggest that additional evaluation is appropriate, but a single abnormal result does not automatically establish a diagnosis.

Should I be worried if several results are abnormal?

Several related abnormalities may provide more useful clinical information than one isolated result, but their significance depends on which tests are involved and how abnormal they are. Discuss the complete panel with your healthcare provider.

Should I repeat an abnormal blood test?

Sometimes. Repeat testing may be appropriate when an abnormal result is mild, unexpected, potentially temporary, or needs confirmation. Significant abnormalities may require more immediate evaluation instead.

Can dehydration affect blood test results?

Yes. Hydration status can influence certain laboratory measurements. Your physician may consider hydration, fasting status, illness, medication use, exercise, and other circumstances when interpreting unexpected findings.

The Bottom Line

If your blood test results are abnormal, do not panic—but do not ignore them either.

An abnormal laboratory value is information that needs to be interpreted.

The next step may be as simple as repeating the test, or it may involve additional laboratory testing, lifestyle changes, treatment, imaging, or evaluation for an underlying condition.

What matters most is the pattern, severity, clinical context, and trend over time.

If you want to better understand why blood testing is performed in the first place, read Why Do I Need Blood Work?, or explore the complete Routine Laboratory Testing Resource Center.

Physician-Written, Evidence-Informed Patient Education

This article was written for patient education and is designed to help patients better understand how abnormal laboratory results are evaluated.

Laboratory results should be interpreted using the reference range provided by the performing laboratory and considered alongside symptoms, medical history, medications, physical examination findings, previous results, and other diagnostic information.

For additional evidence-based patient information, see the National Library of Medicine's MedlinePlus guide to understanding laboratory results. Guidance regarding potentially serious symptoms is also available through MedlinePlus and the Centers for Disease Control and Prevention.

The educational information on this page is not intended to diagnose or treat an individual medical condition and does not replace personalized medical care.

About the Author

Dr. YiQiu Hu, NMD is an Arizona naturopathic physician and founder of Ask Dr. Hu. His clinical interests include preventive healthcare, health optimization, laboratory testing, and individualized medical care. He created Ask Dr. Hu to provide patients with more time, clearer explanations, thoughtful medical evaluation, and practical treatment options.

Ask Dr. Hu provides personalized medical care for patients throughout Arizona, including physician-guided laboratory evaluation and ongoing preventive healthcare.