Header

UZH-Logo

Maintenance Infos

Blood ammonia and glutamine as predictors of hyperammonemic crises in patients with urea cycle disorder


Abstract

PURPOSE: The aim of this study was to examine predictors of ammonia exposure and hyperammonemic crises in patients with urea cycle disorders.
METHODS: The relationships between fasting ammonia, daily ammonia exposure, and hyperammonemic crises were analyzed in >100 patients with urea cycle disorders.
RESULTS: Fasting ammonia correlated strongly with daily ammonia exposure (r = 0.764; P < 0.001). For patients with fasting ammonia concentrations <0.5 upper limit of normal (ULN), 0.5 to <1.0 ULN, and ≥1.0 ULN, the probability of a normal average daily ammonia value was 87, 60, and 39%, respectively, and 10.3, 14.1, and 37.0% of these patients, respectively, experienced ≥1 hyperammonemic crisis over 12 months. Time to first hyperammonemic crisis was shorter (P = 0.008) and relative risk (4.5×; P = 0.011) and rate (~5×, P = 0.006) of hyperammonemic crises were higher in patients with fasting ammonia ≥1.0 ULN vs. <0.5ULN; relative risk was even greater (20×; P = 0.009) in patients ≥6 years old. A 10- or 25-µmol/l increase in ammonia exposure increased the relative risk of a hyperammonemic crisis by 50 and >200% (P < 0.0001), respectively. The relationship between ammonia and hyperammonemic crisis risk seemed to be independent of treatment, age, urea cycle disorder subtype, dietary protein intake, or blood urea nitrogen. Fasting glutamine correlated weakly with daily ammonia exposure assessed as 24-hour area under the curve and was not a significant predictor of hyperammonemic crisis.
CONCLUSION: Fasting ammonia correlates strongly and positively with daily ammonia exposure and with the risk and rate of hyperammonemic crises, suggesting that patients with urea cycle disorder may benefit from tight ammonia control.

Abstract

PURPOSE: The aim of this study was to examine predictors of ammonia exposure and hyperammonemic crises in patients with urea cycle disorders.
METHODS: The relationships between fasting ammonia, daily ammonia exposure, and hyperammonemic crises were analyzed in >100 patients with urea cycle disorders.
RESULTS: Fasting ammonia correlated strongly with daily ammonia exposure (r = 0.764; P < 0.001). For patients with fasting ammonia concentrations <0.5 upper limit of normal (ULN), 0.5 to <1.0 ULN, and ≥1.0 ULN, the probability of a normal average daily ammonia value was 87, 60, and 39%, respectively, and 10.3, 14.1, and 37.0% of these patients, respectively, experienced ≥1 hyperammonemic crisis over 12 months. Time to first hyperammonemic crisis was shorter (P = 0.008) and relative risk (4.5×; P = 0.011) and rate (~5×, P = 0.006) of hyperammonemic crises were higher in patients with fasting ammonia ≥1.0 ULN vs. <0.5ULN; relative risk was even greater (20×; P = 0.009) in patients ≥6 years old. A 10- or 25-µmol/l increase in ammonia exposure increased the relative risk of a hyperammonemic crisis by 50 and >200% (P < 0.0001), respectively. The relationship between ammonia and hyperammonemic crisis risk seemed to be independent of treatment, age, urea cycle disorder subtype, dietary protein intake, or blood urea nitrogen. Fasting glutamine correlated weakly with daily ammonia exposure assessed as 24-hour area under the curve and was not a significant predictor of hyperammonemic crisis.
CONCLUSION: Fasting ammonia correlates strongly and positively with daily ammonia exposure and with the risk and rate of hyperammonemic crises, suggesting that patients with urea cycle disorder may benefit from tight ammonia control.

Statistics

Citations

Altmetrics

Downloads

21 downloads since deposited on 12 Jan 2016
11 downloads since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Children's Hospital Zurich > Medical Clinic
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:July 2015
Deposited On:12 Jan 2016 10:30
Last Modified:08 Dec 2017 16:53
Publisher:Nature Publishing Group
ISSN:1098-3600
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.1038/gim.2014.148
PubMed ID:25503497

Download

Download PDF  'Blood ammonia and glutamine as predictors of hyperammonemic crises in patients with urea cycle disorder'.
Preview
Content: Published Version
Filetype: PDF
Size: 1MB
View at publisher
Licence: Creative Commons: Attribution-NonCommercial-NoDerivs 3.0 Unported (CC BY-NC-ND 3.0)