Decision limits are values that represent either the upper or lower quantity of an analyte that are consistent with a disease state or indicate a need for treatment.
Blood glucose is an example of an analyte for which decision limits have been established and are widely used by health care providers. If you need further explanation of your results, you should talk to your health care provider. For adults in a routine setting in which fasting blood glucose testing is done to detect type 2 diabetes, a fasting glucose level of 126 mg/dL (7.0 mmol/L) or above, obtained on more than one testing occasion, indicates diabetes. We want you to be informed, but we don't pretend to take the place of communication between you and your health care provider. Treatment is required to reduce the risk for cardiovascular disease, kidney disease, and other long-term complications of diabetes.
In this situation, it is a value above a particular limit that provides information rather than a value that falls within or outside a set range of numbers.Remember, a reference range is merely a guide for your health care provider. We want you to understand what each test on this site is for, but because we can't be aware of all the factors that could affect your test results, we can't interpret the results without more information. He or she will interpret the result in the context of your medical history and current presentation - something that no website is yet able to do.
For a small number of tests, long-term studies of certain disease processes have led to the establishment of decision limits that are more useful than reference ranges in determining clinical outcomes and guiding treatment decisions. This remains true even for those tests, such as the components of the basic metabolic panel (BMP), for which we have included reference ranges.
Depending on the test and factors that may influence its results, reference populations may be chosen based on age, sex, race, general health, and/or medical history.
Next, a large number (minimum of 120) of people who fit the profile of the reference population are tested under nearly identical conditions, and the results are analyzed.
For many tests, reference ranges include the values that are statistically analyzed and reported for the middle 95% of the reference population.To determine ranges, labs may conduct their own studies for the tests they perform, they may adopt reference ranges from test manufacturers or other labs, or they may derive reference ranges from existing patient data.
The most important step in determining a reference range for any test is to define the reference population - the group of people who will be represented in the reference range.