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Chemistry Screen

A chemistry screen is a blood test that measures the levels of several substances in the blood (such as electrolytes). A chemistry screen tells your doctor about your general health, helps look for certain problems, and finds out whether treatment for a specific problem is working.

Some chemistry screens look at more substances in the blood than others do. The most complete form of a chemistry screen (called a chem-20, SMA-20, or SMAC-20) looks at 20 different things in the blood. Other types of chemistry screens (such as an SMA-6, SMA-7, or SMA-12) look at fewer. The type of chemistry screen you have done depends on what information your doctor is looking for.

For more information about specific parts of a chemistry screen, see:

Why It Is Done

A chemistry screen may be done:

  • As part of a routine physical examination.
  • To help you and your doctor plan changes in your meal plan or lifestyle.
  • To look for problems, such as a low or high blood glucose level that may be causing a specific symptom.
  • To follow a specific health condition and check how well a treatment is working.
  • Before you have surgery.
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WebMD Medical Reference from Healthwise

Last Updated: September 09, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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