Zur Methodik der Ammoniakbestimmung im Urin von Früh- und Neugeborenen: Vergleich zwischen Formoltitration und enzymatischer NH4+-Bestimmung

Abstract

Zahlreiche Verfahren zur NH 4 +-Bestimmung im Blut und im Urin sind bisher angegeben und von anderer Seite auch wieder kritisiert worden. Die seit einigen Jahren für die Bestimmung von Ammoniak im Blut bekannte enzymatische Methode von KIRSTEN et al. ([1963], Biochem. Z. 3*7, 312-319), SCHMIDT & SCHWARZ ([1966] The determination of ammonia in the urine of premature and full-term newborns: Comparison of the formol titrationand the en^ymic NH^~ determination Numerous methods for the determination of NH 4 + in blood and urine have been described and subsequently criticized by other workers. The specificity and reproducibility of the enzymatic procedure for the determination of ammonia in blood according to KIRSTEN et al. ([1963], Biochem. Z. 337, 312-319), SCHMIDT & SCHWÄRS ([1966], Klin. Wochenschr. 44, 591-592) and MÜTING et al. ([1970], Deut. Med. Wochenschr. 95, 1390-1396) was tested on urines by comparing it with the very simple formol titration method. The latter method is unsuitable in spite of its high precision, because of the marked influence exerted by amino acids. On the other hand the enzymatic NH 4 + determination is applicable to the urines of premature and full-term newborns particularly because of the relatively low NH 4 + level and the relatively high amino acid concentration. Its precision is equal to the formol titration method, but in addition it is specific and posesses a high sensitivity.