Role of the toxic neutrophil count in the early diagnosis of Kawasaki disease.
OBJECTIVE
To determine whether the toxic neutrophil count (TNC), defined as the sum of the number of peripheral blood neutrophils with vacuoles plus the number with toxic granulations per 100 neutrophils examined, can be used as an aid to early diagnosis of Kawasaki disease (KD).


METHODS
Prospective evaluation at a tertiary care pediatric hospital of 56 acutely febrile children with at least one other clinical criterion for KD. Clinical characteristics and TNC were compared for 3 groups of patients: those with (1) definite KD, (2) probable KD, and (3) unlikely KD. The sensitivity and specificity of the TNC at various cutoff points was determined.


RESULTS
We evaluated 56 patients (Group 1, N=27; Group 2, N=4; Group 3, N=25). Mean TNC (TNC/mm3) were higher in the patients with definite KD compared to patients with unlikely KD (38 vs 24; p=0.037). At a TNC cutoff of > or =70, the test had a specificity of 100%, but a sensitivity of only 18%. The likelihood ratio (the number of times more likely this TNC result is to be found in KD versus non-KD subjects) was 8.89. At a cutoff of > or =10, the test had a high sensitivity of 92% and specificity of 38%.


CONCLUSIONS
No laboratory test replaced the need for careful clinical evaluation in cases of suspected KD. The TNC may be a useful adjunct to the clinical assessment of children with KD, particularly at the extremes of measurement.
Birdi
N
N
Department of Pediatrics, Children's Hospital of Eastern Ontario, University of Ottawa, Canada. birdi@cheo.on.ca
Klassen
T P
TP
Quinlan
A
A
Clarke
W
W
Hosking
M
M
Momy
J A
JA
Rowe
P C
PC
D002648:Child; D002675:Child, Preschool; D003594:Cytoplasmic Granules / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D009080:Mucocutaneous Lymph Node Syndrome / Q000097:blood / Q000175:diagnosis*; D009504:Neutrophils / Q000166:cytology / Q000473:pathology*; D011446:Prospective Studies; D015203:Reproducibility of Results; D014617:Vacuoles / Q000473:pathology*