A chemistry screen is a blood test that measures the levels of several substances in the blood (such as electrolytes).
Normal values vary from lab to lab and depend on which tests were included in your chemistry screen. Results are usually available in 1 to 2 days.
Many conditions can change chemistry screen test levels. Your doctor will talk with you about any abnormal results that may be related to your symptoms and medical history.
For more information about normal and abnormal values, see:
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
- Taking medicine. Some medicines can cause changes in the normal values of a chemistry screen.
- Eating high-fat foods or drinking alcohol.
- Recent intravenous (IV) fluids, such as fluids given during surgery.
What To Think About
There are several different chemistry screens. For example, an SMA-7 looks at 7 substances in the blood, including uric acid, potassium, and sodium. A complete chemistry screen (or SMA-20) looks at the same things as an SMA-7 plus 13 others (such as phosphorus, carbon dioxide, and bilirubin). Which chemistry screen your doctor orders depends on why you are having the test, your symptoms, and whether you have any specific conditions or diseases.
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerThomas M. Bailey, MD - Family Medicine
Current as ofSeptember 9, 2014