MedlinePlus

MedlinePlus is a service of the National Library of Medicine (NLM), the world's largest medical library, which is part of the National Institutes of Health (NIH). It was built as an online health information resource for patients and their families and friends.

MedlinePlus presents high-quality, easy to understand, relevant health and wellness information that is trusted.

Alphabetical Listings

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MedlinePlus at a Glance

Offers information on health topics, human genetics, medical tests, medications, dietary supplements, and healthy recipes.
Sourced from more than 1,600 selected organizations.
Provides 40,000 links to authoritative health information in English and 18,000 links to information in Spanish.
In 2018, 277 million users viewed MedlinePlus more than 700 million times.

Laboratory Tests

Laboratory tests check a sample of your blood, urine, or body tissues. A technician or your doctor analyzes the test samples to see if your results fall within the normal range. The tests use a range because what is normal differs from person to person. Many factors affect test results. These include:

Your sex, age and race
What you eat and drink
Medicines you take
How well you followed pre-test instructions

Your doctor may also compare your results to results from previous tests. Laboratory tests are often part of a routine checkup to look for changes in your health. They also help doctors diagnose medical conditions, plan or evaluate treatments, and monitor diseases.