All blood tests must be ordered by a licensed practitioner. Thousands of different blood tests can be ordered, and the orders must be specific for the test results to be meaningful. A standard design is used to report blood test results. The design each lab chooses includes several basic information capsules to aid in interpretation of blood test reports.
Laboratory Basics
Information must be included on what laboratory performed the blood tests. The Centers for Medicare and Medicaid Services (CMS) regulates all lab testing performed on humans in the United States through the Clinical Laboratory Improvement Amendments (CLIA). The laboratory's CLIA certification number must be present on all blood test results. The CLIA number ensures that the laboratory has met all government requirements on accuracy, reliability and timeliness of patient test results.
Results Columns
Blood test results are presented in a column format. The test name is at the top. Many tests that can be run off of the same blood specimen are grouped together in a profile with the profile name at the top. An example of a profile would be a basic metabolic profile, with sub columns listing the individual tests on sodium, potassium, chloride, carbon dioxide, glucose, blood urea nitrogen (BUN) and creatinine. In the next column, the actual test result is expressed in a number. Usually, there is a column that is next to the number result listing a flag letter. The next column would state the unit of measurement for the blood test. Another column will list the normal ranges for that particular test. The normal ranges are enclosed in parentheses.
Flag Letters
The flag letters are designed to quickly alert the reader of the test result to unusual or abnormal blood test results. The letter "H" next to a result would indicate that the number is high compared with the normal range. The letter "L" indicates that the number is low compared with the normal range. Sometimes, the results are flagged with colors, with red generally indicating an abnormal result. The letter "C" indicates a critical result. All critical results will be called to a practitioner immediately because action must be taken to remedy the abnormal blood test result.
Normal Ranges
Normal ranges for blood tests are established by each laboratory doing the testing. The normal ranges for one area of the country may not be the same as for another area. Each blood test has an established normal range that must be present on the blood test result report.
Interpreting the Report
A licensed physician must interpret the blood test results. Labs must give results to physicians only. Help for understanding blood test results is available online at Lab Tests Online. Home testing kits are not covered under CLIA and should be interpreted by the user according to package instructions.
