Blood ammonia levels in liver cirrhosis: a clue for the presence of portosystemic collateral veins

Abstract

BackgroundPortal hypertension leads to the formation of portosystemic collateral veins in liver cirrhosis. The resulting shunting is responsible for the development of portosystemic encephalopathy. Although ammonia plays a certain role in determining portosystemic encephalopathy, the venous ammonia level has not been found to correlate with the presence or severity of this entity. So, it has become partially obsolete. Realizing the need for non-invasive markers mirroring the presence of esophageal varices in order to reduce the number of endoscopy screening, we came back to determine whether there was a correlation between blood ammonia concentrations and the detection of portosystemic collateral veins, also evaluating splenomegaly, hypersplenism (thrombocytopenia) and the severity of liver cirrhosis.MethodsOne hundred and fifty three consecutive patients with hepatic cirrhosis of various etiologies were recruited to participate in endoscopic and ultrasonography screening for the presence of portosystemic collaterals mostly esophageal varices, but also portal hypertensive gastropathy and large spontaneous shunts.ResultsBased on Child-Pugh classification, the median level of blood ammonia was 45 mcM/L in 64 patients belonging to class A, 66 mcM/L in 66 patients of class B and 108 mcM/L in 23 patients of class C respectively (p < 0.001).The grade of esophageal varices was concordant with venous ammonia levels (rho 0.43, p < 0.001). The best area under the curve was given by ammonia concentrations, i, e., 0.78, when comparing areas of ammonia levels, platelet count and spleen longitudinal diameter at ultrasonography. Ammonia levels predicted hepatic decompensation and ascites presence (Odds Ratio 1.018, p < 0.001).ConclusionIdentifying cirrhotic patients with high blood ammonia concentrations could be clinically useful, as high levels would lead to suspicion of being in presence of collaterals, in clinical practice of esophageal varices, and pinpoint those patients requiring closer follow-up and endoscopic screening.

Non-Invasive Parameters of Oesophageal Varices Diagnosis: Which Sensitive and Applicable; A Pilot Study

“…These results agreed with Tarantino et al, [1] who found that BAL more than 71 µmol/L had 97% sensitivity and 73% specificity for prediction of presence of portosystemic shunts. In addition, Khondaker et al, [18] revealed that blood ammonia at 63µmol/L had 95% sensitivity and 50% specificity in detecting large OV in cirrhotics suggesting its usefulness in identifying patients with large varices who need endoscopy.…”

“…Oesophageal varices (OV), formed as a result of portal hypertension, have a great clinical impact due their severe complications [1]. While they are found in approximately 50% in cirrhosis, they are developed at a rate of 8% per year in patients without varices.…”

“…So, the possibility of non-invasive means for identifying cirrhotic patients with OV or collateral presence is appealing, in that it could decrease the necessity of endoscopic screening with reduced healthcare costs [1].…”

Department of Hepatology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh

“…When Spearman's rho correlation test was done they did not show any correlation with the size of varices (rho: 0.016, p = 0.516; rho: 0.118, p = 0.469 respectively). This finding was in contrast with that found in several cross-sectional studies done by Tarantino, 13 Freeman, 14 Chalasani, 15 Zaman. 16 However, our finding was consistent with the recently published longitudinal study done by the portal hypertension collaborative group of American Association for the Study of Liver Diseases (AASLD) and Qamar.…”

“…A recent study upon 153 consecutive patients with liver cirrhosis of various etiologies have shown that blood ammonia level correlates well with the severity of liver disease as well as with the presence of different portosystemic shunts, particularly esophageal varices of different grades. 13 The sensitivity and specificity of ammonia in predicting esophageal varices presence was 97 and 43% respectively with the cutoff value of ammonia 42 mol/l. The present study was intended to see the correlation of blood ammonia level with esophageal varices in patients with cirrhosis of different etiologies in Bangladeshi population.…”