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


METHODS
One 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.


RESULTS
Based 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).


CONCLUSIONS
Identifying 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.
Tarantino
Giovanni
G
Department of Clinical and Experimental Medicine, Hepatology in Internal Medicine Section, Federico II University Medical School of Naples, Naples, Italy. tarantin@unina.it
Citro
Vincenzo
V
Esposito
Pasquale
P
Giaquinto
Sabrina
S
de Leone
Annalisa
A
Milan
Graziella
G
Tripodi
Francesca Saveria
FS
Cirillo
Michele
M
Lobello
Roberto
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000641:Ammonia / Q000097:blood*; D015331:Cohort Studies; D003097:Collateral Circulation / Q000502:physiology*; D004724:Endoscopy; D004932:Esophageal and Gastric Varices / Q000097:blood / Q000453:epidemiology* / Q000473:pathology; D005260:Female; D006801:Humans; D008103:Liver Cirrhosis / Q000097:blood* / Q000150:complications / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D011168:Portal System / Q000503:physiopathology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013154:Spleen / Q000000981:diagnostic imaging / Q000473:pathology; D014463:Ultrasonography
D000641:Ammonia