Mechanisms of severe, immediate reactions to iodinated contrast material.
OBJECTIVE
To measure and elucidate the mechanisms of presumed mediators of unexpected severe, immediate reactions to iodinated contrast materials.


METHODS
In a multicenter study, 20 patients with mild to severe reactions to iodinated contrast material and 20 control subjects without reactions were evaluated. Ionic contrast material was associated with 18 (90%) of 20 reactions. Concentrations of plasma histamine, tryptase, urinary methylhistamine, specific immunoglobulin E (IgE) against ioxitalamate or ioxaglate, and the anaphylatoxins C3a and C4a were measured with radioimmunoassays; complement C3 and C4 levels were measured with nephelometry.


RESULTS
Histamine levels were increased in 14 patients; tryptase levels, in 16; and methylhistamine levels, in six. Histamine and tryptase values correlated with the severity of the reaction (P < .02 and P < .004, respectively). Significantly higher levels of specific IgE against ioxaglate (P < .005) and ioxitalamate (P = .045) were found in patients. No differences were found for complement fractions. Skin test results in two patients with life-threatening reactions were positive for the administered contrast material.


CONCLUSIONS
Histamine release and mast cell triggering are related to severe reactions. An IgE-related mechanism is strongly suspected. Radiologists should be trained to identify and treat anaphylactic shock in patients who react to iodinated contrast material.
Laroche
D
D
Laboratory of Medical Physics, Centre Hospitalier Régional Universitaire, Caen, France.
Aimone-Gastin
I
I
Dubois
F
F
Huet
H
H
Gérard
P
P
Vergnaud
M C
MC
Mouton-Faivre
C
C
Guéant
J L
JL
Laxenaire
M C
MC
Bricard
H
H
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000707:Anaphylaxis / Q000139:chemically induced / Q000276:immunology; D003176:Complement C3 / Q000032:analysis; D003181:Complement C4 / Q000032:analysis; D003287:Contrast Media / Q000008:administration & dosage / Q000009:adverse effects*; D004342:Drug Hypersensitivity / Q000209:etiology* / Q000276:immunology; D005260:Female; D005602:France; D006636:Histamine Release / Q000276:immunology; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000139:chemically induced* / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D008875:Middle Aged; D012882:Skin Tests; D013997:Time Factors
D003176:Complement C3; D003181:Complement C4; D003287:Contrast Media; D007073:Immunoglobulin E