Alternative Names SMAC20, sequential multichannel analysis with computer-20, SMA20
Definition CHEM-20 is a set of 20 tests that are performed on a sample of blood. The results give an overview of blood chemistry that is very useful to the healthcare provider.
CHEM-20 indicates the concentrations or levels in the blood of key electrolytes or minerals, enzymes, sugars, proteins and metabolites, or substances produced by chemical processes. Blood delivers nutrients to all of the body's cells and tissues. Blood carries waste products from these cells and tissues, as well. An analysis of blood chemistry can reveal a lot about problems in specific cells and tissues.
Who is a candidate for the test? This test is normally done to evaluate how a number of products, such as proteins, sugars and enzymes, are being used in the body. This test can help a healthcare provider diagnose diseases.
How is the test performed? To perform this set of tests, a blood sample is taken from a vein on the forearm or hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube, or tourniquet, is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow through them. A thin needle is gently inserted into a vein, and the tourniquet is removed. Blood flows from the vein through the needle, and is collected in a syringe or vial for testing in the laboratory. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.
What is involved in preparation for the test? A person should request specific instructions about preparation for the CHEM-20 from his or her healthcare provider.
What do the test results mean? The normal values for substances measured by CHEM-20 are as follows:
Albumin = 3.9 to 5.0 mg/dl
Alkaline phosphatase = 44 to 147 IU/liter
Alanine transaminase (ALT or SGPT) = 6 to 59 IU/liter
Aspartate aminotransferase (AST or SGOT) = 10 to 34 IU/liter
Blood urea nitrogen (BUN) = 7 to 20 mg/dl
Serum calcium = 8.5 to 10.9 mg/dl
Serum chloride = 101 to 222 mmol/liter
Carbon dioxide (CO2) = 20 to 29 mmol/liter
Creatinine = 0.8 to 1.4 mg/dl
Direct bilirubin = 0 to 0.3 mg/dl
Gamma-glutamyl transpeptidase (GGT) = 0 to 51 IU/liter
Glucose = 64 to 128 mg/dl
Lactate dehydrogenase (LDH) = 105 to 333 IU/liter
Serum phosphorus = 2.4 to 4.1 mg/dl
Potassium test = 3.7 to 5.2 mEq/liter
Total bilirubin = 0.2 to 1.9 mg/dl
Total cholesterol = 100 to 240 mg/dl
Total protein = 6.3 to 7.9 g/dl
Uric acid = 4.1 to 8.8 mg/dl
Abbreviations:
dl = deciliter
mg = milligram
mmol = millimole
mEq = milliequivalent
g = gram
IU = International Unit
Author: David T. Moran, MD Reviewer: Eileen McLaughlin, RN, BSN Last Updated: 05/16/00 Contributors Potential conflict of interest information for reviewers available on request
