Reference range (medicine)

Especially in laboratory medicine , reference ranges are used in order to be able to classify measured values at all and thus to be able to give an orientation as to whether this parameter is pathological (diseased) or not.

detection

Reference ranges are determined statistically from test results of healthy people. Results that are found in 95 percent of all healthy subjects are referred to as normal. The reference range is chosen in such a way that 2.5% of the measured values of all test persons lie above and below it.

There is therefore not a single normal value, but a specific range of fluctuations within which all values are considered normal. This area is called the reference or normal area. In addition, there may be dependencies on age, gender, region, ethnicity or the use of different measurement methods.

For the interpretation of laboratory parameters it is important to know that the reference ranges for one and the same parameter - depending on the analytical method used and the measuring device - are highly variable. For this reason, the respective reference ranges should always be specified for each analysis.

special cases

There is also a reference or normal range for the sick. This is usually well above or below the healthy one. For example, the normal value for blood sugar is 60 to 100 mg / dl. A blood sugar patient with 130 mg / dl therefore has laboratory values that are higher than those of the normal population; for his illness, however, they are still in the reference range.

Diagnostic reference value

At the proposal of the Radiation Protection Commission , the Federal Office for Radiation Protection in Germany established diagnostic reference values for radiopharmaceuticals in 2003 and published them in the Federal Gazette. It contains reference values for radiopharmaceuticals for frequent as well as for high-dose nuclear medicine examination procedures. Exceeding these reference values requires justification by a specialist nuclear medicine specialist and must be documented accordingly.

units

Units according to the SI system of units :

Unity - declaration

g / dl - 1 gram per deciliter (100 milliliters)

mg / dl - 1 milligram (1 thousandth of a gram) per deciliter

µg / dl - 1 microgram (1 millionth of a gram) per deciliter

ng / ml - 1 nanogram (1 billionth of a gram) per milliliter

m val / l - milligram equivalent - 1 thousandth of the amount of substance that is equated to a reference atom (hydrogen).

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