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

Tarantino G, Citro V, Esposito P, Giaquinto S, de Leone A, Milan G, Tripodi FS, Cirillo M, Lobello R - BMC Gastroenterol (2009)

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Clinical and Experimental Medicine, Hepatology in Internal Medicine Section, Federico II University Medical School of Naples, Naples, Italy. tarantin@unina.it

ABSTRACT

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).

Conclusion: 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.

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Comparison of ROC curves using as classification variable the presence of Collaterals. NH4, Ammonia; PLTs, Platelets count; SLD, Spleen Longitudinal Diameter; NH4 cut-off (42 mcM/L) had sensibility of 92% and specificity of 60%, with 8% of false negative results; CI, Confidence Intervals.
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Figure 2: Comparison of ROC curves using as classification variable the presence of Collaterals. NH4, Ammonia; PLTs, Platelets count; SLD, Spleen Longitudinal Diameter; NH4 cut-off (42 mcM/L) had sensibility of 92% and specificity of 60%, with 8% of false negative results; CI, Confidence Intervals.

Mentions: When comparing ROC curves to classify the collaterals presence, NH4 levels gave the best AUROC among PLTS count and SLD at US, significantly superior to the other ones. The AUROC of NH4 in predicting the EV presence alone resulted quite similar to that predicting all the shunts, i.e., 0.75 (95% CI 0.68–0.82; sensitivity 97%, specificity 43% with the same criterion of 42 mcM/L) versus 0.78, Figure 2. As matter of fact, two out of 70 patients, with normal NH4 concentrations (28 and 42 mcM/L, respectively), having certain EV presence, would be excluded by the endoscopic performance and only one out 36 patients would have been missed having large varices if this threshold had been used. The false positive rate at this cut-off was 28.1%, i.e., 43 patients.The AUROCs of NH4 levels and the PLTs/SLD ratio similarly predicted EV existence (0.75 versus 0.73, p = 0.70).


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

Tarantino G, Citro V, Esposito P, Giaquinto S, de Leone A, Milan G, Tripodi FS, Cirillo M, Lobello R - BMC Gastroenterol (2009)

Comparison of ROC curves using as classification variable the presence of Collaterals. NH4, Ammonia; PLTs, Platelets count; SLD, Spleen Longitudinal Diameter; NH4 cut-off (42 mcM/L) had sensibility of 92% and specificity of 60%, with 8% of false negative results; CI, Confidence Intervals.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2662872&req=5

Figure 2: Comparison of ROC curves using as classification variable the presence of Collaterals. NH4, Ammonia; PLTs, Platelets count; SLD, Spleen Longitudinal Diameter; NH4 cut-off (42 mcM/L) had sensibility of 92% and specificity of 60%, with 8% of false negative results; CI, Confidence Intervals.
Mentions: When comparing ROC curves to classify the collaterals presence, NH4 levels gave the best AUROC among PLTS count and SLD at US, significantly superior to the other ones. The AUROC of NH4 in predicting the EV presence alone resulted quite similar to that predicting all the shunts, i.e., 0.75 (95% CI 0.68–0.82; sensitivity 97%, specificity 43% with the same criterion of 42 mcM/L) versus 0.78, Figure 2. As matter of fact, two out of 70 patients, with normal NH4 concentrations (28 and 42 mcM/L, respectively), having certain EV presence, would be excluded by the endoscopic performance and only one out 36 patients would have been missed having large varices if this threshold had been used. The false positive rate at this cut-off was 28.1%, i.e., 43 patients.The AUROCs of NH4 levels and the PLTs/SLD ratio similarly predicted EV existence (0.75 versus 0.73, p = 0.70).

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Clinical and Experimental Medicine, Hepatology in Internal Medicine Section, Federico II University Medical School of Naples, Naples, Italy. tarantin@unina.it

ABSTRACT

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).

Conclusion: 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.

Show MeSH
Related in: MedlinePlus