Evaluation of plasma ammonia levels in patients with acute liver failure and chronic liver disease and its correlation with the severity of hepatic encephalopathy and clinical features of raised intracranial tension
Introduction
HE is a severe neuropsychiatric syndrome which complicates both acute and chronic liver failure [1]. The mechanisms responsible for the pathogenesis of HE have not been fully elucidated, and many factors have been suggested to induce its development. For over 100 years, hyperammonemia has been believed to be the dominant pathogenetic factor of HE in both acute and chronic liver failure. However, HE is not always accompanied by elevated blood ammonia levels, and the correlation between ammonia levels and the severity of HE remains controversial. With this background in mind, the present study was designed to (a) evaluate and compare plasma ammonia levels (PAL) in patients with ALF and CLD with or without HE; (b) correlate the severity of HE with PAL; and (c) correlate PAL with clinical features of raised intracranial tension in ALF.
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Methods
The study was conducted at Lok Nayak Hospital, a tertiary care hospital in New Delhi, India during the period from January 2002 to July 2002. A total of 40 liver disease patients comprised of 20 consecutive patients with ALF (Group A) and 20 consecutive patients with CLD [Group B, which was comprised of 8 patients with HE (subgroup B1) and 12 patients without HE (subgroup B2)] were evaluated in the present study.
All patients underwent a complete clinical examination and biochemical evaluation
Results
The mean age of all the patients was 34 ± 13.7 years (Group A: 31 ± 15.7 years, Group B: 38 ± 13.4 years, subgroup B1: 40 ± 9.15 years, subgroup B2: 35 ± 16.09 years), and the male:female ratio was 26:14 (Group A — 14:6, Group B — 12:8, subgroup B1 — 5:3, subgroup B2 — 7:5).
The mean PAL (μmol/L) ± SD was as follows: Group A: 172.1 ± 52.55, subgroup B1: 58.75 ± 29.38, subgroup B2: 42.17 ± 18.19 (normal levels: 10–47 μmol/L). All ALF patients showed PAL more than the upper limit of the normal
Discussion
Ammonia has been known to exert a deleterious effect on cerebral function by direct and indirect mechanisms [2]. In the present study, all ALF patients showed PAL more than the upper limit of normal range, and the mean PAL was significantly higher compared to CLD patients. These results indicate that plasma ammonia may have the potential to be an important diagnostic parameter for HE in ALF in the absence of other techniques such as EEG and psychometric tests. There was a significant
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