[Significance of the measurement of serum substrates in children].

Almost daily very many analyses are performed in the clinical laboratory, even if their significance for a given diagnosis is uncertain or unnecessary. In this paper the significance of Na, Cl, Ca, Mg, P, total protein, urea nitrogen, creatinine and uric acid is discussed, as well as methodological aspects, age-dependent reference values, and especially the relevance of these laboratory results for the diagnosis. Each laboratory result represents only a symptom, which may lead to some diagnosis, but the main importance remains with the clinical symptoms.