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Kidney Week

Abstract: FR-PO1091

Delta Bilirubin: A Lesser-Known Bilirubin Fraction and Its Impact on Interpretation of Single-Pass Albumin Dialysis (SPAD) Efficacy

Session Information

Category: Pediatric Nephrology

  • 1700 Pediatric Nephrology


  • Chadha, Vimal, Children's Mercy Hospital, Kansas City, Missouri, United States
  • Wiebold, Amy, Children's Mercy Hospital, Kansas City, Missouri, United States
  • Ferguson, Angela M., Children's Mercy Hospital, Kansas City, Missouri, United States
  • Garg, Uttam, Children's Mercy Hospitals and Clinics, Knasas City, Missouri, United States

Acute liver failure (ALF) is a rapidly progressive disease that leads to multiple organ failure with high mortality. Combination of supportive therapies are utilized to stabilize these patients until recovery, or as a bridge to liver transplant. As MARS is not readily available in all pediatric centers, modification of continuous renal replacement therapy (CRRT) with SPAD is an equally efficacious alternative. During SPAD, bilirubin clearance is used as a surrogate marker for clearance of protein bound-toxins. We have previously shown >10 fold increase in bilirubin clearance with SPAD as compared to CRRT alone. However, we failed to observe increased bilirubin clearance in a group of ALF patients who received SPAD.


We studied 3 patients with ALF who failed to show increased bilirubin clearance. These patients had significant unconjugated hyperbilirubinemia which is not cleared by SPAD as it is tightly albumin-bound. However, we also found significantly decreased clearance of conjugated-bilirubin in these patients. We thus studied the bilirubin fractions in the serum and the effluent by using Vitros 5600 chemistry analyzer, a unique method that uses two slides to measure total, unconjugated and conjugated-bilirubin fractions, and calculates delta bilirubin, a form of conjugated-bilirubin that is covalently bound to albumin.


Review of our raw data showed that these 3 patients had significant proportion of their conjugated bilirubin in the form of delta-bilirubin (Figure), which is not cleared by SPAD due to its tight albumin binding. Delta bilirubin is known to accumulate in patients with prolonged liver failure and biliary atresia.


Decreased bilirubin clearance in this subset of ALF patients was found to be due to increased serum delta-bilirubin. Since most laboratories do not measure or report delta-bilirubin, increased delta-bilirubin may lead to the perception that SPAD is not working efficiently, and may lead to unnecessary and expensive work-up.

Bilirubin fractions