Anaphylaxis during hemodialysis associated with a polysulfone membrane: evidence from basophil activation testing.

Dialyzer-associated anaphylaxis is an uncommon but serious complication of hemodialysis. Although severe anaphylaxis is rare, milder hypersensitivity reactions are likely underrecognized and frequently misattributed to cardiopulmonary or volume-related causes. In clinical practice, the diagnosis is often inferred indirectly from symptom resolution after dialyzer substitution rather than confirmed by immunologic testing. Serum tryptase is widely used as a marker of mast cell activation in anaphylaxis; however, its diagnostic utility is limited in patients with chronic kidney disease (CKD), in whom baseline tryptase levels may be chronically elevated due to reduced renal clearance. A patient with advanced CKD developed acute anaphylaxis with respiratory failure and hypotension during the initial hemodialysis session using a polysulfone-based dialyzer, requiring endotracheal intubation. Reexposure during a subsequent session reproducibly elicited the same reaction, strongly implicating dialyzer-associated anaphylaxis. Given the limitations of serum tryptase and the indirect nature of membrane substitution alone, a membrane-specific immunologic evaluation was pursued. Basophil activation testing (BAT) demonstrated polysulfone-specific basophil activation with upregulation of CD63 and CD203c, confirming immediate hypersensitivity. To our knowledge, this represents the first reported case in Korea of dialyzer-associated anaphylaxis immunologically confirmed by BAT. Using this case as a framework, we review the clinical spectrum and immunologic mechanisms of dialyzer-associated hypersensitivity and highlight the complementary diagnostic role of BAT in enabling definitive diagnosis and safe continuation of hemodialysis.