Plasma Ammonia Levels Over the Course of a Hospitalisation for Overt Hepatic Encephalopathy

Background & Aims

The role of ammonia in the assessment of Overt Hepatic Encephalopathy (OHE) remains debated. The aim of the present study was to assess the time course of ammonia levels in relation to the severity and duration of an episode of OHE requiring hospitalisation.

Methods

104 patients discharged between January 2021 and July 2024 with a diagnosis of OHE were included [80 males, 72 ± 11 years]. Clinical and laboratory indices, including ammonia levels prior to/during/after the hospitalisation, were recorded, along with the duration of the hospitalisation, precipitants, ammonia-lowering and psychoactive treatment, where applicable.

Results

Over the studied time frame, 58 (56%) patients had single OHE hospitalisations, while 20 (19%) had 2–7 OHE hospitalisations. Of the 104 hospitalisations, 30/63/7% were for OHE grades II/III/IV, respectively. Of the 58 single hospitalisations, 40/57/3% were for OHE grades II/III/IV, respectively. Ammonia levels increased significantly with increasing OHE grade; those prior to admission/after discharge were significantly lower than those on admission. Hospitalisations for grade IV OHE were longer. Ammonia levels on admission were lower in patients who were not fully recovered from OHE on discharge and those on chronic treatment with psychoactive drugs. All the above held true when analyses were restricted to the 58 single hospitalisations.

Conclusions

Ammonia levels correlated with OHE presence and severity, and with the duration of hospitalization. Incomplete recovery and chronic treatment with psychoactive drugs were associated with lower ammonia levels.