URL of this page: https://medlineplus.gov/lab-tests/differential-diagnosis/

Differential Diagnosis

What is a differential diagnosis?

Not every health disorder can be diagnosed with a simple lab test. Many conditions cause similar symptoms. For example, many infections cause fever, headaches, and fatigue. Many mental health disorders cause sadness, anxiety, and sleep problems.

A differential diagnosis looks at the possible disorders that could be causing your symptoms. It often involves several tests. These tests can rule out conditions and/or determine if you need more testing.

How is it used?

A differential diagnosis is used to help diagnose physical or mental health disorders that cause similar symptoms.

How will my provider make a differential diagnosis?

Most differential diagnoses include a physical exam and a health history. During a health history, you'll be asked about your symptoms, lifestyle, and previous health problems. You'll also be asked about your family's health problems. Your provider may also order lab tests for different diseases. Lab tests are often done on blood or urine.

If a mental health disorder is suspected, you may get a mental health screening. In a mental health screening, you will be asked questions about your feelings and mood.

The exact tests and procedures will depend on your symptoms.

For example, you may see your health care provider because you have a skin rash. Rashes can be caused by a wide variety of conditions. Causes can range from mild allergies to life-threatening infections. To make a differential diagnosis of a rash, your provider may:

  • Do a thorough exam of your skin
  • Ask you if you been exposed to any new foods, plants, or other substances that could cause an allergy
  • Ask about recent infections or other diseases
  • Consult medical text books to compare your how your rash looks to rashes in other conditions
  • Perform blood and/or skin tests

These steps can help your provider narrow down the choices of what is causing your rash.

What do my results mean?

Your results may include information about conditions you don't have. It's important to learn this information to narrow down the possibilities of potential disorders. The results may also help your provider figure out which additional tests you need. It can also help determine which treatments might help you.

Is there anything else I need to know about a differential diagnosis?

A differential diagnosis can take a lot of time. But it can help make sure you get the right diagnosis and treatment.

References

  1. Bosner F, Pickert J, Stibane T. Teaching differential diagnosis in primary care using an inverted classroom approach: student satisfaction and gain in skills and knowledge. BMC Med Educ [Internet]. 2015 Apr 1 [cited 2018 Oct 27]; 15: 63. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4404043/?report=classic
  2. Ely JW, Stone MS. The Generalized Rash: Part I. Differential Diagnosis. Am Fam Physician [Internet]. 2010 Mar 15 [cited 2018 Oct 27]; 81 (6):726–734. Available from: https://www.aafp.org/afp/2010/0315/p726.html
  3. Endometriosis.net [Internet]. Philadelphia: Health Union; c2018. Differential Diagnosis: Health Conditions with Similar Symptoms to Endometriosis [cited 2018 Oct 27]; [about 2 screens]. Available from: https://endometriosis.net/diagnosis/exclusion
  4. JEMS: Journal of Emergency Medical Services [Internet]. Tulsa (OK): PennWell Corporation; c2018. Differential Diagnoses are Important for Patient Outcome; 2016 Feb 29 [cited 2018 Oct 27]; [about 2 screens]. Available from: https://www.jems.com/articles/print/volume-41/issue-3/departments-columns/case-of-the-month/differential-diagnoses-are-important-for-patient-outcome.html
  5. National Institute on Aging [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Obtaining an Older Patient's Medical History [cited 2018 Oct 27]; [about 3 screens]. Available from: https://www.nia.nih.gov/health/obtaining-older-patients-medical-history
  6. Richardson SW, Glasziou PG, Polashenski WA, Wilson MC. A new arrival: evidence about differential diagnosis. BMJ [Internet]. 2000 Nov [cited 2018 Oct 27]; 5 (6):164–165. Available from: https://ebm.bmj.com/content/5/6/164
  7. Science Direct [Internet]. Elsevier B.V.; c2018. Differential diagnosis [cited 2018 Oct 27]; [about 2 screens]. Available from: https://www.sciencedirect.com/topics/medicine-and-dentistry/differential-diagnosis

The medical information provided is for informational purposes only, and is not to be used as a substitute for professional medical advice, diagnosis or treatment. Please contact your health care provider with questions you may have regarding medical conditions or the interpretation of test results.

In the event of a medical emergency, call 911 immediately.