Naslov
Ammonia level changes in icteric samples

Autori
Fressl Juroš, Gordana ; Čeri, Andrea ; Rako, Ivana ; Rogić, Dunja

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Clinical Chemistry and Laboratory Medicine / - , 2015, S1272-S1272

Skup
21st IFCC-EFLM European Congress of Clinical Chemistry and Laboratory Medicine

Mjesto i datum
Pariz, Francuska, 21.06.2015. - 25.06.2015

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
ammonia icteria

Sažetak
BACKGROUND-AIM Emergency laboratory often receives icteric samples for ammonia measurement. Reagent manufacturer declares that there is no interference of unconjugated bilirubin up to the concentration of 513 µmol/L but not whether the interference is negative or positive. So we investigated the influence of bilirubin on ammonia measurement. METHODS Three EDTA plasma pool samples with low (43 µmol/L), medium (76 µmol/L) and high (132 µmol/L) ammonia concentrations were spiked with unconjugated bilirubin stock solution to get five different bilirubin concentrations, approx. 70, 130, 190, 250 and 300 µmol/L. Ammonia and bilirubin were measured on Roche Cobas c501. The percentage of difference between ammonia concentration in samples with normal bilirubin level (non-icteric) and samples with high bilirubin concentration (icteric) was calculated using the following formula: (ammonia icteric – ammonia nonicteric)/ammonia nonicteric*100. Statistical analysis was performed using paired t-test. RESULTS In the pool with low ammonia concentration, the difference between icteric and non-icteric samples at bilirubin level of 75, 140, 194, 255 and 308 µmol/L were -4%, -15%, -22%, -39% and -32%, respectively. In the pool with medium ammonia level, the difference between icteric and non-icteric samples at bilirubin concentration of 73, 128, 190, 246 and 303 µmol/L were -8%, -8%, -15%, -22% and -36%, respectively. In the pool with high ammonia concentration, the difference between icteric and non-icteric samples at bilirubin level of 69, 118, 166, 211 and 258 µmol/L were -4%, -7%, -7%, -10% and -18%, recpectively. Paired t-test showed statistically significant difference (p<0.05) in ammonia level between non-icteric and icteric samples. CONCLUSION Our investigation has shown that icteria causes negative interference on ammonia measurement. We observed that the higher bilirubin concentration the stronger negative interference, particulary at the low ammonia level.

Izvorni jezik
Engleski

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