Correlations between the value of serum cholinesterase and Child-Pugh and Meld-Na scores in cirrhotic patients

Many laboratory tests are utilised in the evaluation of the hepatic functions. Serum cholinesterase has a low serum value in liver disfunction in contrast with other enzymes. The aim of the study was to assess the value of serum cholinesterase in evaluation of the liver reserve function in cirrhotic patients. A total of 70 patients were divided into 3 groups according to the Child-Pugh Score. Using correlation analysis, the correlation between serum cholinesterase and albumin and International Normalized Ratio time was analysed. Cirrhotic patients were divided into A, B and C grades as per Child-Pugh score. The results showed that cholinesterase levels tend to decrease according to the Child-Pugh score, highest in the A group and lowest in the C group. The cholinesterase correlated with the albumin serum levels, value of Child-Pugh score and MELD-Na score and did not corelate to INR. In conclusion, correlated with the damage severity of the liver cells cholinesterase may respond to liver reserve function.


INTRoduCTIoN
Laboratory tests, often known as liver function tests (LFTs), are used in the evaluation and treatment of patients with liver disease, comprising serum aspartate and alanine transaminases, alkaline phosphatase, bilirubin and albumin [1]. These tests often reveal abnormal results in patients with clinical problems other than liver dysfunction [2]. Tests of biosynthetic capacity of the liver include serum albumin, ceruloplasmin, ferritin, alfa1-antitrypsin, lipoproteins and blood clotting factors. These substances are synthetised in the liver and transported into the circulation. Cholinesterase is synthetised almost all in the hepatocytes and it is released into the bloodstream [5]. Serum cholinesterase activity is lower in liver dysfunction due to reduced synthesis. This contrasts with other serum enzymes used in the clinical assessment of liver function whose activities increase because of enhanced release from their cellular sources following cell membrane damage [3] or secondary to treatment. In gastroenterology, the Child-Pugh score (also known as the Child-Turcotte-Pugh score) is used to assess the prognosis of chronic liver disease, mainly cirrhosis. 0riginally was used to predict surgery related mortality, the Child Pugh score is now used to predict prognosis as well as the required intensity of treatment, and the necessity for liver transplantation. Two main clinical measures in Child-Pugh score, serum protein and blood-clotting factors are essential in evaluating the liver reserve function of cirrhotic patients [4]. However, the cirrhotic patients, particularly those with advanced liver disease, Child grades B and C with ascites or haemorrhagic tendency, are usually treated with albumin or blood transfusions, which may affect the real numeric value for calculating the Child-Pugh Score [5]. Additionally, serum cholinesterase is not affected by this treatment. We compared serum cholinesterase with the Child-Pugh score and MELD-NA score to evaluate the liver reserve function of cirrhotic patients. Since serum cholinesterase, albumin and blood-clotting factors are synthesized by the liver with different half-life [6], we also monitored the correlation between cholinesterase, albumin and INR.

Patients
A total of 70 patients presenting to the Fundeni Clinical Institute (Bucharest, Romania), 28 male medium age and 42 females between 2017 and 2018 were included in the present study. Inclusion criteria for the study were: a diagnosis of liver cirrhosis based on histology, clinical or ultrasonographic signs or on transient elastography (FibroScan, Echosens, Paris, France). Exclusion criteria were history of albumin or blood transfusion in the last 4 weeks prior to enrolment, clinical evidence of variceal bleeding at enrolment, history or clinical evidence of hepatocellular carcinoma and history of liver transplantation. Informed consent was obtained from patients included in the study.

Measurement of biochemical serum markers
Blood samples were collected with minimal venostasis. Serum was obtained from clotted blood by centrifugation within 1 h from sampling. LFTs comprising serum albumin and INR were carried out. Serum cholinesterase activity was determined using a chemiluminescent method using a Cobas e601 Roche automatic analyser in 2 hours of sample separation.

Statistical analysis
Database management and statistical analysis were performed using JASP 0.16.3 Software for Win-dows11. Descriptive results were expressed as the mean ± standard deviation (SD) or number (percentage) of patients with a condition. Multiple comparisons for the ANOVA test were used to compare the mean data. The Pearson correction test was applied for comparison of cholinesterase, albumin and serum prothrombin times (INR). The tests were twotailed and P<0.05 was considered to indicate a statistically significant difference.

Patient characteristics
A total of 70 patients mean age 66.47±10.41 years were included. 28 patients were male with a mean age of 63,64±12,74 Years and 42 females with a mean age of 68,35±8,15 years. The main demographic data of the patients are summarized in Table 1 and the clinical and laboratory data in Table 2.

Serum cholinesterase in various Child-Pugh score groups
The cirrhotic patients were strictly grouped into A, B and C groups, based on their Child-Pugh score. The results showed that serum cholinesterase tended to decrease significantly in the three grades: Child A (8055.465±1709.092U/l), Child B (5415.769 ± 1109.270 U/l) and Child C (2543.643±838.512 U/l) (Table 4). Difference between the mean serum cholinesterase activity in the Child A, B and C groups was statistically significant, as was the difference between the mean values for the Child B and C groups (Table 3, Figure 1, Figure 2).

Correlation between the serum cholinesterase, albumin and INR
Cholinesterase was positively correlated with albumin (r=0.633, P<0.001) and negatively correlated with INR (r=-0.404, P<0.001) in the cirrhotic patients, confirming that those substances were synthesized in the liver and reduced in the liver disfunction due to reduced synthesis. Cholinesterase and INR (r=-0.404, p=0.001) have a negative strong correlation. Albumin and INR (r=0.782, p=0.001) have a strong positive correlation (Table 4, Table 5, Table 6).

Correlation between the serum cholinesterase, Child-Pugh Score and MELD-Na
Cholinesterase and Child-Pugh Score have a negative, strong correlation (r=-0.696, p=0.001). Cholinesterase and MELD-Na score (r=-0.548, p=0.001) have the same negative strong correlation. Between the Child-Pugh score and MELD-Na score (r=-0.783, p=0.001) we have a strong significative correlation that validates the data (Table 4, Table 5, Table 6, Table 7).

Serum cholinesterase in Child-Pugh score groups in patients with Virus C
We selected 52 patients with virus C and grouped them into A, B and C groups, based on their Child-Pugh score. The results showed that serum cholinesterase tended to decrease significantly in the three grades: Child A (8237.541±1572.758U/l), Child B (5390.111±1167.291 U/l) and Child C (2702.667 ± 1011.552 U/l) ( Table 8). Difference between the mean serum cholinesterase activity in the Child A, B and C groups was statistically significant, as was the difference between the mean values for the Child B and C groups (Table 8, Figure 3). The values are similar to the values obtained for the entire group.  In biochemistry, cholinesterase is part of a family of enzymes that process the neurotransmitter acetylcholine into choline and acetic acid, a reaction necessary to allow a cholinergic neuron to return to its resting state after activation [7]. There are two types of cholinesterases: acetylcholinesterase (AChE), also known as RBC and erythrocyte cholinesterases or acethylcholine acetylhydrolase, found primarily in the blood and neural synapses. AchE exists in various molecular forms. Pseudocholinesterase, also termed as plasma cholinesterase (BCHE), butyrylcholinesterase or acylcholine acylhydrolase, is found primarily in the liver [8,9].
Estimation of the level of activity of the cholinesterase found in serum was first suggested by McArdle in 1940 [10], as a useful means for differentiating hepatic from post hepatic jaundice. The evidence which has accumulated suggests that cholinesterase activity is an assessment indicator for liver function in patients with liver disease. In China, cholinesterase has been included in scores to distinguish hepatitis severity by society of liver disease [11]. However, few studies are available regarding the value of cholinesterase in evaluating liver reserve function in cirrhotic patients. The Child-Turcotte-Pugh scoring system is the first of its kind in stratifying seriousness of end-stage liver disease, mainly cirrhosis [12]. In our study 70 patients were grouped into A, B and C grades, as per Child-Pugh score. The results show that cholinesterase tended to significantly decrease in the three grades. In the Child A group, the value of serum cholinesterase was 8055.46U/l with a SD of 1709.09U/l, in the Child B group the mean value of serum cholinesterase was 5415.76U/l with SD of 1109.27 and in the Child C the mean value of serum cholinesterase was 2543.64U/l with a SD of 838.51U/l. The result agrees with the findings of Gu and Zhong [13]. Their data demonstrated that the levels of cholinesterase in the three grades were: Child A (5978±535U/l), Child B (3957±454U/l) and Child C (2267±332U/l). The Child-Pugh score is calculated from the values of five clinical measures of liver disease, among which ascites and encephalopathy are subjective measures [14]. Liver cirrhosis is classified into Child-Pugh class A-C, employing the added score from above. Compared with the Child-Pugh score, cholinesterase has the advantage that is easier and more objective in evaluating the liver reserve of cirrhotic patients.
The liver performs an important role in protein biosynthesis. Cholinesterase, albumin and bloodclothing factors are synthetised in the liver than transported into the circulation. Thus, LFT's include cholinesterase, albumin and prothrombin time (INR) and may provide useful information concerning the state of a cirrhotic patient´s liver. In our study, in cirrhotic patients, cholinesterase was positively correlated with albumin and negatively corelated with INR, confirming that those substances were synthesized by the liver and reduced in liver disfunction due to reduced synthesis. In decompen-sated cirrhotic patients, albumin and blood transfusions are usually used, which may affect the real numerical value to calculate the Child-Pugh score [15]. If surgery is needed as a treatment the risk calculated on the Child-Pugh score may be inaccurate if the patient received treatment [16]. In their study, Gu and Zhong [13] demonstrated that three cirrhotic patients (two Child B and one Child A score patient) suffered hepatic encephalopathy following portal azygos disconective operation, with cholinesterase levels of under 2000U/l. Thus, those authors suggested that cirrhotic patients with cholinesterase <2000U/l may have higher risk for liver failure, if undergoing abdominal surgery. Thus, the combination of Child-Pugh score may be more subjective and accurate in evaluating the liver reserve function of cirrhotic patients, which is useful for surgeons to decide on surgery timing.

CoNCluSIoNS
The present study demonstrates that the level of cholinesterase is correlated with the damage severity of the liver cells and may respond to the liver reserve function of cirrhotic patients. Compared with the Child-Pugh score and MELD-Na score, serum cholinesterase is less complex and not easily affected by treatment for decompensated cirrhosis or other disease. The combination of cholinesterase with Child-Pugh score or MELD-Na score may be more subjective and accurate in evaluating the liver reserve function of cirrhotic patients.