First Time User? Sign Up Now
Home > Health Library > 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:
A chemistry screen may be done:
How you prepare for a chemistry screen depends on what your doctor is looking for in the test.
Many medicines may change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form .
The health professional drawing blood will:
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very little chance of a problem from having blood sample taken from a vein.
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:
Reasons you may not be able to have the test or why the results may not be helpful include:
Current as of:
December 8, 2019
Author: Healthwise StaffMedical Review: E. Gregory Thompson MD - Internal MedicineAdam Husney MD - Family MedicineMartin J. Gabica MD - Family Medicine
Current as of: December 8, 2019
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Adam Husney MD - Family Medicine & Martin J. Gabica MD - Family Medicine
To learn more about Healthwise, visit Healthwise.org.
© 1995-2020 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
Feeling under the weather?
Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.
Get started learning more about your health!
Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.
Nash UNC Health Care
Employee Login - UNC Outlook
Clinical Consortium Orientation
Copyright 2020 UNC Health Care. All rights reserved.