Determination of creatinine in the urine as a reference value of substances excreted by the kidney
Bauch, K.; Seitz, W.
Zeitschrift für die Gesamte Innere Medizin und ihre Grenzgebiete 40(7): 201-205
1985
ISSN/ISBN: 0044-2542 PMID: 4002760 Document Number: 243047
The creatinine excretion is often used as reference value of renally excreted substances. It is usual to perform the creatinine determination according to the Jaffe method. However, since this reaction is influenced not only by the creatinine content but also by other substances it was for orientation tested to which extent adequate incorrect determinations may appear. For this purpose the creatinine content was determined in 28 casual urine specimens in the analysis automation (A) and manually (M) according to the Jaffe method as prescribed in the German Pharmacopoeia 7th ed. D. L. As comparison the enzymatic determination (E) was performed. The determinations according to Jaffe showed too high values. The mean relative percental deviation for the determination in the analysis automation was for (Formula: see text) (variation 6.7 to 94.3%). There were firm correlations between the values of the three determination methods. Since the creatinine determination after Jaffe is the cheapest and most practicable method, in clinical routine work in creatinine-related data of concentration of various renally excreted substances one should realize that in the individual case deviations of the concentration are possible on average up to 50%.