Can dialysis (hemodialysis or peritoneal dialysis) lower elevated liver enzymes in a patient with chronic kidney disease?

Dialysis Does Not Directly Lower Liver Enzymes—It Actually Reduces Them Through Hemodilution, Not Therapeutic Effect

Dialysis does not therapeutically decrease elevated liver enzymes; rather, hemodialysis artificially lowers measured aminotransferase levels through hemodilution and ultrafiltration effects, which can mask underlying liver disease and complicate diagnosis. 1, 2

Mechanism of Enzyme Reduction During Dialysis

Hemodialysis Effects on Liver Enzymes

• Hemodialysis causes artifactual reduction in aminotransferase levels through hemodilution during the dialysis procedure, with significantly lower AST and ALT values measured before dialysis sessions compared to after sessions 2

• Post-dialysis hemoconcentration temporarily increases enzyme levels: aminotransferase and gamma-glutamyl transferase levels collected after hemodialysis sessions are significantly higher than samples collected before the session, reflecting fluid removal rather than true enzyme changes 2

• Chronic kidney disease patients on hemodialysis have persistently lower baseline aminotransferase levels compared to the general population, even when correcting for viral hepatitis status (AST 16.6 ± 11.6 vs 20.4 ± 6.8 IU/L; ALT 16.3 ± 9.4 vs 21.7 ± 11.3 IU/L) 3

Peritoneal Dialysis Comparison

• Peritoneal dialysis patients show slightly higher aminotransferase levels than hemodialysis patients measured pre-session, but slightly lower than post-hemodialysis values, suggesting less dramatic hemodilution effects 2

• Hematocrit levels are significantly lower in peritoneal dialysis patients compared to hemodialysis patients, further supporting the hemodilution mechanism for enzyme reduction 2

Clinical Implications for Liver Disease Detection

Diagnostic Challenges

• The reduction in aminotransferase activity hampers recognition of liver damage in dialysis and pre-dialysis CKD populations, where serum aminotransferases are commonly used to screen for liver disease 3

• Even massive hepatic siderosis (iron overload) was not associated with elevated liver enzymes in historical dialysis cohorts, with liver enzymes seldom increased despite significant hepatic iron deposits 4

• HCV-infected dialysis patients have lower aminotransferase levels than HCV-infected patients without CKD, despite active viral hepatitis—this reduction is multifactorial, involving decreased viremia from dialysis, hepatocyte growth factor production, and endogenous interferon-α 1

Monitoring Recommendations

• ALT monitoring remains useful for HCV surveillance in hemodialysis units: a newly elevated ALT level has 83% sensitivity and 90% specificity for acute HCV infection, making monthly testing valuable for patients initiating or transferring between dialysis facilities 4

• Pathological elevations of liver enzymes occur in only 50% of HCV-positive kidney transplant patients, whereas HCV-positive hemodialysis patients generally exhibit raised aminotransferases compared to HCV-negative dialysis patients—but still lower than non-CKD populations 4

• Normal ALT values cannot exclude significant liver disease in dialysis patients; individuals on hemodialysis with significant fibrosis on liver biopsy are less likely to have abnormal ALT values than HCV-infected persons with similar histologic findings who have normal renal function 4

Multifactorial Causes of Reduced Enzymes

Biochemical Mechanisms

• Reduced pyridoxine (vitamin B6) levels in CKD patients decrease aminotransferase activity, as these enzymes require pyridoxine as a cofactor 1

• Elevated homocysteine levels in CKD may contribute to lower measured aminotransferase activity 1

• Decreased viremia caused by the dialysis method itself reduces hepatocyte injury in HCV-infected patients, along with lymphocyte activation that decreases viral action on hepatocytes 1

Progressive Reduction with Renal Dysfunction

• Pre-dialysis CKD patients already show lower aminotransferase levels than healthy individuals (AST 17.9 ± 8 vs 20.4 ± 6.8 IU/L; ALT 17.5 ± 10 vs 21.7 ± 11.3 IU/L in seronegative patients) 3

• Dialysis patients demonstrate even lower levels than pre-dialysis CKD patients (AST 16.6 ± 11.6 vs 17.9 ± 8 IU/L; ALT 16.3 ± 9.4 vs 17.5 ± 10 IU/L), showing progressive reduction with worsening renal function 3

• Multivariate analysis shows serum creatinine level is negatively related to AST levels (P = 0.0001), confirming the inverse relationship between renal function and measured aminotransferase activity 3

Critical Clinical Pitfalls

Common Errors to Avoid

• Do not rely solely on aminotransferase levels to exclude liver disease in dialysis patients—use non-invasive fibrosis assessment (transient elastography, FIB-4 index, APRI) as initial screening tools 4

• Recognize that "normal" liver enzymes in dialysis patients may represent significant hepatic pathology: transient elastography was superior to APRI in detecting advanced hepatic fibrosis in hemodialysis patients with chronic HCV 4

• Draw NAT samples before dialysis sessions when monitoring HCV, as hemodialysis reduces viremia levels (though this reduction is not dependent on dialysis schedule or membrane type) 4

When Dialysis May Be Indicated for Liver Disease

• Dialysis for acute liver failure with renal dysfunction requires realistic expectations: in a series of 84 patients with liver disease and renal failure, none of the 25 cirrhosis patients survived, but 6 of 50 with fulminant hepatic failure recovered completely 5

• Prolonged dialysis support (up to 7 weeks) may be necessary before diuresis occurs in patients with reversible hepatorenal pathology 5

• Dialysis is only worthwhile when recovery of the underlying liver lesion is possible, not as a means to lower liver enzymes themselves 5