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Fasting Blood Ammonia Predicts Risk and Frequency of Hepatic Encephalopathy Episodes in Patients with Cirrhosis.
Clin Gastroenterol Hepatol. 2015 Dec 17;
Authors: Vierling JM, Mokhtarani M, Brown RS, Mantry P, Rockey DC, Ghabril M, Rowell R, Jurek M, Coakley DF, Scharschmidt BF
Abstract
BACKGROUND & AIMS: There is controversy over the utility of measuring blood levels of ammonia (NH3) in the management of patients with overt hepatic encephalopathy (HE).
METHODS: We performed a retrospective analysis of data from a randomized, double-blind study of 178 patients with cirrhosis given glycerol phenylbutyrate (an NH3-lowering agent) or placebo for 16 weeks. Blood samples were collected at baseline and on study days 7 and 14 and NH3 levels were measured. The probabilities of having an HE episode, based on ammonia values, were modeled using binary logistic regression. A Cox proportional model was used to determine the risk of HE episodes in patients with a baseline fasting NH3 levels ≤ 1.5-fold the upper limit of normal (ULN) vs patients with fasting NH3 levels > 1.5-fold the ULN.
RESULTS: The risk and frequency of HE episodes and HE-related hospitalizations correlated with baseline (mean, 51±6 μmol/L; ULN =35 μmol/L) as well as on-study fasting levels of NH3, and increased sharply at levels >1.5-fold the ULN. Regardless of baseline level, NH3 exposure and the relative risk of HE episodes were decreased by glycerol phenylbutyrate.
CONCLUSIONS: In analysis of data from a phase 2 study of the effects of glycerol phenylbutyrate in patients with cirrhosis, we found that fasting levels of NH3 in blood can identify patients at risk for HE-related morbidity. Patients with HE might benefit from NH3-lowering therapy. ClinicalTrials.gov no: NCT 00999167.
PMID: 26707685 [PubMed - as supplied by publisher]