Delayed Hemolytic Transfusion Reaction (DHTR), anti-Kp(a)

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Record number: 
Adverse Occurrence type: 
MPHO Type: 
Estimated frequency: 
Mild to moderate DHTR attributable to anti-Kpa have been reported. However, severe overt DHTR has not been reported. This case is an exception. The risk of overt DHTRs to low-incidence antigens is estimated at 1per 650,000 crossmatches
Time to detection: 
10 days
Alerting signals, symptoms, evidence of occurrence: 
A 52-year-old Caucasian woman presented to the emergency room having rectal bleeding due to rectal fissures. Admission Hb was 6.1 g/dL. She was transfused with 5 units of leukoreduced or washed RBCs. 24 hours later the Hb was 12 g/dL. On the 10th postransfusion day, her Hb dropped to 8.7 g/dL. On the 11th day the patient appeared severely jaundiced with signs of acute liver and renal failure, which was supported by her laboratory values. The DHTR investigation showed a negative antibody screen and a DAT also negative. An anti-Kpa antibody was finally identified in a more comprehensively panel of cells. The patient typed negative for Kpa.
Demonstration of imputability or root cause: 
The clinical signs and the laboratory values were compatible with a severe DHTR with intravascular hemolysis. One of the 5 units transfused on day 1 of admission was incompatible with the patient's plasma and typed positive for Kpa.
Imputability grade: 
3 Definite/Certain/Proven
Groups audience: 
Suggest new keywords: 
DHTR, intravascular hemolysis, anti-Kpa
Reference attachment: 
Suggest references: 
Koshy, R, Patel, B and Harrison, JS. (2009). Anti-Kpa-induced severe delayed hemolytic transfusion reaction. Immunohematology 25:44-7
Expert comments for publication: 
In the Kell system, anti-K, -k, Kp(a), Js(b) and -Ku have caused severe immediate hemolytic transfusion reactions. Kp(a) is a low frequency antigen occurring in less than 2 percent of Caucasians. All other Kell antibodies should be considered to have the potential to cause hemolytic transfusion reactions, although these are likely to be delayed.