Blood Ammonia Concentration in Children with Chronic Liver Disease: A Tool for Prediction of Esophageal Varices

Abstract

Background: Esophageal varices (EVs) are a serious complication of portal hypertension in patient with chronic liver disease (CLD). The major portion of ammonia carried by portal blood is shunted into systemic circulation in chronic liver disease. The upper GI endoscopy is currently the best reliable method to diagnose the presence of esophageal varices. But it is invasive, relatively expensive and not easily available. Blood ammonia is a noninvasive and easily accessible laboratory parameter that can predict the presence of esophageal varices. Objectives: To observe the blood ammonia concentration in children with chronic liver disease: a tool for prediction of esophageal varices. Methods: This cross sectional observational study was conducted at the Department of Paediatric Gastroenterology and Nutrition, BSMMU, Dhaka, Bangladesh from January 2018 to December 2019.  A total of 63 cases of CLD were selected. Study sample were selected according to the inclusion and exclusion criteria. Along with proper clinical history, examination & initial investigation, fasting venous blood ammonia level and upper GI endoscopy were done in all patients. Receiver-Operator Characteristic (ROC) curve was analysis to set up a cut-off value of blood ammonia for prediction of esophageal varices. Sensivity, specificity, positive predictive value, negative predictive value and accuracy were determined to see the performance of blood ammonia value as a diagnostic test for esophageal varices. Results: Among the 63 patients, (74.6%) had esophageal varices. Wilson disease was the most common etiology of CLD (43; 68.3%) among the studied patients. The mean blood ammonia level were 40.5± 18.0 (µmol/L), 50.5± 14.3 (µmol/L), 50.7± 9.9 (µmol/L), 53.1± 26.9 (µmol/L) and 71.9± 19.0 (µmol/L) in absent esophageal varices, grade-I, grade-II, grade-III and grade-IV esophageal varices respectively. The difference was statistically significant (<0.05). Moderate correlation (r= 0.452; p value = 0.001) between blood ammonia level and grades of esophageal varices was found.  It was observed that wasting of thenar and hypothenar muscle was the most common stigmata, seen in 15 (23.8%) cases, 2 (3.2%) had clubbing, 7 (11.1%) had leuconychia, 1 (1.6%) had palmer erythema, 3 (4.8%) had gynacomasia and 1 (1.6%) had testicular atrophy. Wilson disease was the most common 43 (68.3%). It was observed that 45 (71.4 %) patients had raised serum ALT and 45 (71.4%) had low serum albumin (<3.5 g/dl). Low haemoglobin (<9 gm/dl) was found in 47 (74.6%) cases, raised serum bilirubin level (>1.2 mg/dl) in 29 (46.03%) cases, thrombocytopenia (platelet count <1.50×109/mm3) in 36 (57.1%) patients and prolonged INR (>1.5) in 29 (46.03%) cases, blood ammonia was raised (>32 µmol/L) in 52 (82.5%) cases. It was observed that the mean ± SD blood ammonia level was 56.2± 17.9 µmol/L in   esophageal varices present group (n = 47) and 40.5± 18.0 µmol/L in absent esophageal varices group (n = 16). Here p value is 0.004, which is statistically significant. Conclusion: Blood ammonia concentration is a biochemical predictor for assessing the grading of esophageal varices. In the present study, a moderate positive correlation was found between blood ammonia concentration and grades of esophageal varices in children with CLD.