Evidence of a link between fever and microscopic hematuria in children

Despite the common conception that febrile illnesses are associated with microscopic hematuria in children, a review of the literature failed to disclose supportive evidence. The aim of this study was to evaluate this relationship. Background data were collected for a convenience sample of children aged 4-18 years who presented to the emergency department (ED) of a tertiary pediatric medical center. Vital signs were measured and a midstream urine specimen was collected. Specimens positive for the presence of blood (>5 erythrocytes/μl; Combur 10 Test Strips) were examined microscopically. Patients found to have microscopic hematuria (>5 erythrocytes/high power field) were asked to undergo repeated urine testing within 3 weeks or at least 1 week after the fever (if present) resolved. A telephone interview was conducted 9-10 years after the ED visit, for all children with microscopic hematuria. Data were coded and transferred to Microsoft Excel 2007 (Raymond Wa), and then analyzed using SPSS 15 (SPSS Inc., Chicago, IL). Six hundred sixty patients were enrolled in the study; 161 were febrile (mean temperature 39.2 ± .08 °C), and 499 were afebrile (mean temperature 36.7 ± 0.4 °C) (p < 0.001). The febrile group was significantly younger than the afebrile group (mean age 8 ± 3.6 years versus 9.4 ± 3.7 years, respectively, p < 0.001). There was no significant between-group difference in sex distribution (55 and 60% boys, respectively, p = 0.199). Microscopic hematuria was found in 12 children, 9 febrile (5.6%), and 3 afebrile (0.6%) (p < 0.001). All repeated urine tests (n = 12) were negative for microscopic hematuria.

The findings suggest that fever is associated with transient microscopic hematuria in children. The study is limited by its single-center setting and relatively small sample. What is known: • It is commonly believed that fever increases the incidence of microscopic hematuria. • However, to the best of our knowledge, this assumption has not been proven. What is new: • This study demonstrates a significant association between fever and transient microscopic hematuria in children. • The transient nature of the hematuria may be reassuring for both parents and healthcare providers.