Elsevier

Clinical Biochemistry

Volume 38, Issue 8, August 2005, Pages 696-699
Clinical Biochemistry

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

https://doi.org/10.1016/j.clinbiochem.2005.04.013Get rights and content

Abstract

Objectives:

The present study was designed to (a) evaluate and compare plasma ammonia levels (PAL) in patients with acute liver failure (ALF) and chronic liver disease (CLD) with or without hepatic encephalopathy (HE); (b) correlate the severity of HE with PAL; and (c) correlate PAL with clinical features of raised intracranial tension in ALF.

Design and methods:

A total of 40 patients, comprised of 20 patients with ALF (Group A) and 20 patients with CLD [Group B, which was comprised of 8 patients with HE (subgroup B1) and 12 patients without HE (subgroup B2)], were studied. PAL was estimated using an enzymatic UV-method (RANDOX). The clinical and biochemical profile of all the patients was recorded. Correlation between the grade of HE and PAL was derived using Pearson's correlation coefficient. The mean PAL of ALF patients with and without raised intracranial tension was compared using the standard error of difference between the two means.

Results:

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 patients with ALF showed PAL more than the upper limit of the normal range, and there was good correlation between the severity of HE and PAL [r = 0.91 at P < 0.05]. In subgroup B1 (CLD with HE), 3/8 patients (37.5%), and in subgroup B2 (CLD with HE), 4/12 patients (33.3%) patients had PAL more than the upper limit of normal range. Within Group A, 14 patients had clinical features of raised intracranial tension/cerebral edema, and the mean PAL of these patients (188.21 ± 49.15 μmol/L) was significantly higher than those who did not have features of raised intracranial tension (134.5 ± 42.36 μmol/L) [SE of difference between two means].

Conclusions:

Raised PAL appears to be an important laboratory abnormality seen in patients with ALF, and there seems to be a significant correlation between the severity of encephalopathy and PAL in these patients. However, among patients with CLD, the proportion of patients with PAL more than the upper limit of normal range is not significantly different between those with or without HE. Our study also suggests that high PAL in ALF patients appears to correlate with clinical features of cerebral edema and 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.

Section snippets

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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