ASN's Mission

To create a world without kidney diseases, the ASN Alliance for Kidney Health elevates care by educating and informing, driving breakthroughs and innovation, and advocating for policies that create transformative changes in kidney medicine throughout the world.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005


The Latest on X

Kidney Week

Please note that you are viewing an archived section from 2023 and some content may be unavailable. To unlock all content for 2023, please visit the archives.

Abstract: SA-PO604

Dialyzing or Hemolyzing? A Case of Continuous Renal Replacement Therapy (CRRT) Filter Hemolysis

Session Information

Category: Dialysis

  • 801 Dialysis: Hemodialysis and Frequent Dialysis


  • Maggio, Tyler, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States
  • Honkanen, Iiro, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States

Evidence of hemolysis in the inpatient setting evokes a broad differential. Devices are frequently employed to support vital organ functions that can introduce an additional mechanism for hemolysis that expands the differential. Here we describe a case of hemolysis secondary to filter induced lysis as part of a continuous renal replacement therapy (CRRT) circuit.

Case Description

A 43-year-old man presented with altered mental status, shortness of breath, and hypotension. He had a history of systolic heart failure, CKD stage 4, Type 2 diabetes, and chronic normocytic anemia. Workup was pertinent for worsening ejection fraction with elevated NT-proBNP consistent with cardiogenic shock with AKI on CKD for which he remained oliguric despite diuretic challenge. CRRT was initiated on day 2. On hospital day 16 the hemoglobin dropped to a nadir of 5.9 g/dL that did not respond appropriately to blood transfusions. Plasma free hemoglobin was elevated with undetectable haptoglobin. Direct antibody testing was negative. Liver enzymes, fibrinogen, and platelets were stable. There was concern for intradialytic hemolysis based on amber tinge in the effluent dialysate bag and otherwise unrevealing workup. CRRT pressures were reviewed and within normal ranges and no kinks were identified in the circuit. Plasma free hemoglobin was measured pre and post filter which identified a 20% increase from 1017 to 1282 mg/dL. The CRRT circuit was discontinued with subsequent improvement in serum hemoglobin and normalization in plasma free hemoglobin. No additional evidence of hemolysis was identified. The CRRT circuit was resumed with a new filter from a different lot on hospital day 18 with no further hemolysis observed.


Hemolysis is a serious condition that may be associated with worse morbidity and mortality in the setting of severe illness. CRRT access sites as well as the individual components of the circuit serve as potential sources of mechanical hemolysis. Plasma free hemoglobin can be sampled at various points of the circuit to suggest the source of hemolysis. Once an implicated component has been identified, the circuit should be reset with monitoring for improvement of hemolysis. CRRT use is increasing in ICUs, so clinicians should be aware that filter induced mechanical hemolysis is a rare but plausible cause of hemolysis that can be easily corrected.