Pyuria may not be an adequate marker for diagnosing Kawasaki disease

Although patients with acute Kawasaki disease experienced pyuria more frequently and severely than patients in a febrile control group, the presence of this symptom is neither specific nor sensitive enough to qualify it as a diagnostic marker for the disease, findings of a recently published study suggest.

Researchers from several sites in California compared urinalysis data from 135 patients with KD and 87 participants in a febrile control group to determine characteristics of Kawasaki disease-associated pyuria.

Pyuria was identified in 79% of patients with Kawasaki disease; a rate higher than the previously recognized 33% to 62% identified using manual cell-count methods in studies published elsewhere. Although more patients with Kawasaki disease experienced pyuria, it was also observed in 54% of the patients in the febrile control group. The presence of pyuria was not a sensitive or specific marker for Kawasaki disease, but the magnitude of pyuria was significantly higher in patients with Kawasaki disease compared with the control group.

However, patients with Kawasaki disease had a significantly higher median white blood cell count compared with the control group. The identified white blood cells originated in the urinary tract somewhere above the urethra, according to the researchers. No associations were reported between the symptom and patient age or duration of illness. -- by Nicole Blazek

Shike H. et al. Pediatr Infect Dis J. 2009;28:440-443.

This study seems to confirm that patients with Kawasaki disease more frequently manifest pyuria than febrile control children do and that these patients have significantly higher median numbers of WBC/mcL of urine, although perhaps not to the degree previously thought.

It is particularly true when the data from patients with Kawasaki disease are compared with those of febrile controls who did not have a bacterial infection documented. Both voided and particularly catheter-collected urine specimens showed more pyuria in Kawasaki disease patients, suggesting a supra-urethral origin of WBCs in contrast to the previous notion of likely urethral origin.

-Stanford T. Shulman, MD

Infectious Diseases in Children Editorial Board