[Interpretation of numerical laboratory values]. / Interpretation numerischer Laborwerte.

ABSTRACT

Numerical values for laboratory tests ae usually divided into positive and negative results by a discriminating value. This raises the question of the reliability of the results, i.e. the probability of the presence of the tested disorder, if the result is positive. The present paper shows that this probability depends on the sensitivity and the specificity of the test as well as on the prevalence of the disorder in the population of patients under investigation. The usual reference values for laboratory tests turns out to be highly specific. The predictive value of a test result can be considerably improved by limiting the diagnostic possibilities. Tests with insufficient sensitivity and specificity are not applicable in screening for disorders or diseases.