Clinical manifestations, laboratory markers, and renal ultrasonographic examinations in 1-month to 12-year-old Iranian children with pyelonephritis: a six-year cross-sectional retrospective study.

BACKGROUND: Upper urinary tract infection (UTI) or pyelonephritis may increase the pathogenesis rate and risk of severe complications in children due to kidney atrophy. OBJECTIVE: A set of clinical symptoms, laboratory markers, and ultrasound findings were assessed to achieve the early diagnosis and prognosis of pyelonephritis in hospitalized pediatrics. METHODS: A cross-sectional study with 104 Iranian children (95 girls and 9 boys) aged 1 month to 12 years with acute pyelonephritis during 2012-2018 was conducted. The ultrasound examination of kidneys and urinary tract during hospitalization, the incidence of clinical symptoms, and laboratory markers in blood and urine were monitored to identify the best predictive factors of early diagnosis of this bacterial infection. RESULTS: Three-fourth of the patients had one of the four clinical symptoms of abdominal pain, constipation, dysuria, and vomiting, while others were asymptomatic. A much frequency of pyuria (88.46%), Escherichia coli in urine (92.31%), leukocytosis (81.73%), and high ESR (> 10 mm/h, 92.30%) and CRP (> 10 mg/L, 82.82%) was observed. The kidney and urinary tract ultrasonography only in 32.7% of children revealed findings in favor of pyelonephritis (cystitis, ureteral stones, and hydronephrosis). CONCLUSION: There was a high frequency of clinical signs and laboratory markers associated with pyelonephritis. Ultrasound alone was not an efficient tool to track febrile UTI as most patients presented normal sonography.

Neutrophil-Macrophage Imbalance Drives the Development of Renal Scarring during Experimental Pyelonephritis.

BACKGROUND: In children, the acute pyelonephritis that can result from urinary tract infections (UTIs), which commonly ascend from the bladder to the kidney, is a growing concern because it poses a risk of renal scarring and irreversible loss of kidney function. To date, the cellular mechanisms underlying acute pyelonephritis-driven renal scarring remain unknown. METHODS: We used a preclinical model of uropathogenic Escherichia coli-induced acute pyelonephritis to determine the contribution of neutrophils and monocytes to resolution of the condition and the subsequent development of kidney fibrosis. We used cell-specific monoclonal antibodies to eliminate neutrophils, monocytes, or both. Bacterial ascent and the cell dynamics of phagocytic cells were assessed by biophotonic imaging and flow cytometry, respectively. We used quantitative RT-PCR and histopathologic analyses to evaluate inflammation and renal scarring. RESULTS: We found that neutrophils are critical to control bacterial ascent, which is in line with previous studies suggesting a protective role for neutrophils during a UTI, whereas monocyte-derived macrophages orchestrate a strong, but ineffective, inflammatory response against uropathogenic, E. coli-induced, acute pyelonephritis. Experimental neutropenia during acute pyelonephritis resulted in a compensatory increase in the number of monocytes and heightened macrophage-dependent inflammation in the kidney. Exacerbated macrophage-mediated inflammatory responses promoted renal scarring and compromised renal function, as indicated by elevated serum creatinine, BUN, and potassium. CONCLUSIONS: These findings reveal a previously unappreciated outcome for neutrophil-macrophage imbalance in promoting host susceptibility to acute pyelonephritis and the development of permanent renal damage. This suggests targeting dysregulated macrophage responses might be a therapeutic tool to prevent renal scarring during acute pyelonephritis.

[Diagnostic evaluation of reflux: significance of voiding cystourethrography]. / Refluxdiagnostik ­ Stellenwert des Miktionszystourethrogramms.

Radiological voiding cystourethrography has long been considered the gold standard for reflux testing in paediatric urology. Additional contrast-based procedures such as voiding urosonography or radionuclide cystography have been established in recent decades. Their main indication is reflux diagnosis after pyelonephritis in early infancy and childhood. The selection of the appropriate method is based on factors such as clinical question, availability, economic aspects, expenditure of human resources and time, and the goal of finding of method that provides as much information as possible while keeping radiation exposure to a minimum. Modern strategies aim for a risk-oriented, individual indication independent of the method of reflux testing.

Renal pyelocalyceal squamous cell carcinoma in a patient with an ectopic kidney presenting with chronic pyelonephritis: a case report.

BACKGROUND: Until now, few cases of pelvis squamous cell carcinoma in various renal anomalies have been reported. To our knowledge, primary squamous cell carcinoma arising from a pelvic ectopic kidney has never been described. In this report, we describe a case of renal pyelocalyceal squamous cell carcinoma in a patient with an ectopic kidney presenting with chronic pyelonephritis. A 73-year-old Caucasian woman presented to our hospital with pyelonephritis symptoms. Abdominopelvic computed tomography revealed heterogeneous and irregular minimal contrast enhancement in the pelvic ectopic kidney parenchyma. Radiologists reported that the images were consistent with chronic pyelonephritis. A Tc-99m dimercaptosuccinic acid renal scan demonstrated a nonfunctioning right pelvic ectopic kidney. The patient underwent open simple nephrectomy via modified Gibson incision. The whole mass was a distended, saclike structure without any grossly visible renal tissue. Pathological examination showed renal pelvis squamous cell carcinoma 8 cm in diameter infiltrating into the renal capsule and perinephritic fatty tissue. The patient was staged as T4N0M1 renal pelvis squamous cell carcinoma. The patient was being treated in the intensive care unit for respiratory distress on the seventh day after the operation. By the first-month follow-up visit, the patient had died of acute respiratory distress syndrome. CONCLUSIONS: Although rare, renal pelvis squamous cell carcinoma should be considered in the differential diagnosis of a renal mass in patients who have renal anomalies and chronic pyelonephritis.

Bilateral acute non-obstructive pyelonephritis presenting as acute kidney injury requiring haemodialysis.

A 54-year-old female patient with hypothyroidism and diabetes mellitus type 2 was brought to emergency room by the family members for acute change in mental status. The laboratory evaluation demonstrated findings consistent with acute renal failure (normal renal function 3 months prior to presentation). She was initiated on hemodialysis due to lack of improvement in renal function. Urine culture done prior to initiation of antibiotics was positive for Escherichia coli, which was later confirmed by renal biopsy. Extensive workup for the cause of renal failure including for connective tissue disease, plasmacytoma, obstruction was negative. She was treated with 6 week course of antibiotics with eventual recovery of her renal function in 4 months.

Vesicoureteral Reflux and Renal Scarring in Infants After the First Febrile Urinary Tract Infection.

INTRODUCTION: The objective of this research was to determine whether vesicoureteral reflux(VUR) was associated with evolution to renal scarring (RS) following a febrile urinary tract infection (UTI) in infants. MATERIALS AND METHODS: Our research included 100 infants, ages up to 1 year with a first febrile UTI. The diagnostic was based on results of: laboratory findings, ultrasonography (USG), voiding cystourethrography (VCUG) and initial and control renal scintigraphy (DMSA renal scan) withtechnetium99mTcsuccimer (dimercaptosuccinic acid), to assess the acute pyelonephritis (APN), VUR and RS. RESULTS: APN was proven with DMSA renal scan in 66 (66%) infants. Twenty-two infants (33.3%) had VUR in-group of patients with APN. On the control DMSA scan, performed 6 months after the first DMSA, the presence of RS was found in 18 (27.27%) infants. In infants with renal scars VUR were discovered in 9 of them (50%). CONCLUSIONS: The pathogenesis of RS after febrile UTI in young children is multifactorial. Children with VUR have an increased risk for APN and RS. However, VUR is not the only precondition for RS. Creating a renal scarring cannot be imagined without the inflammatory process of the upper urinary system. Therefore, early detection and treatment of febrile UTIs in children and identify children at risk for RS are of primary importance.

[Favorable evolution after medical treatment in three cases of emphysematous pyelonephritis: about 3 cases]. / La pyélonéphrite emphysémateuse à évolution favorable après traitement médical: à propos de 3 observations.

Emphysematous pyelonephritis is a necrotic infection of the kidney characterized by the presence of gas within the renal parenchyma, the secretory cavities or the perirenal spaces. It is a severe condition that could be life-threatening. Patient's management remains controversial and is based either on surgery or on medical treatment. Percutaneous drainage can be also used for the treatment of these patients. We report 3 cases with EPN treated with only antibiotics. Patients' evolution was favorable. These results show that medical treatment could be sufficient.

Deriving a management algorithm for emphysematous pyelonephritis: Can we rely on minimally invasive strategies or should we be opting for earlier nephrectomy?

PURPOSE: To analyse the incidence and management of emphysematous pyelonephritis (EPN) in North West London and examine factors that influence immediate and 6-month outcomes with the aim of guiding future management. METHODS: This work analyses EPN cases from the London North West Healthcare NHS Trust from October 2006 to July 2015 (population ≈ 850,000). Diagnosis and stage were confirmed by computed tomography (CT). Demographic, clinical, biochemical and microbiological characteristics were assessed. Treatment modalities were medical management, minimally invasive management (MIM) and surgical. Immediate and 6-month outcomes were analysed. RESULTS: Thirteen cases were identified (f = 8, m = 5) from 5525 CT scans. EPN occurred in patients with diabetes mellitus (n = 11, 84.6%), hypertension (n = 10, 76.9%) or urinary tract calculi (n = 7, 53.85%). Unilateral EPN occurred predominantly (n = 11, 84.6%); 46.1% (n = 6) were class 1 or 2 and 53.8% (n = 7) class 3 or 4. Escherichia coli was most commonly cultured (n = 5, 38.46%). All patients received antibiotics, and ten cases required MIM. Two patients had a delayed nephrectomy, both survived. Mortality was 15.4% (n = 2, grade 1 and 3a), both died acutely post-MIM, neither underwent emergency nephrectomy. At 6 months, eight patients had ongoing renal impairment. No specific poor prognostic factors were identifiable. CONCLUSIONS: Patients with low-grade EPN may also have a high mortality rate. In the two cases who died, earlier consideration for nephrectomy may have been prudent. It may be beneficial to have a low threshold for prompt emergency nephrectomy in severe cases and where MIM treatment has failed. We suggest a management algorithm to guide clinicians and minimise mortality.

Urological evaluation of patients that had undergone in utero myelomeningocele closure: A prospective assessment at first presentation and early follow-up. Do their bladder benefit from it?

AIMS: To report our data on initial urological presentation after in utero myelomeningocele (MMC) closure. METHODS: A prospective urological assessment at first presentation was designed for patients that had undergone in utero MMC closure and referred to our urological facility. The protocol consisted of detailed medical history, renal sonography, voiding cystourethrogram, and urodynamic evaluation. RESULTS: In utero MMC closure was performed in 19 patients at gestational age of 25.6 weeks 25-27. Birth occurred at a mean gestational age of 31.8 weeks 26-36. Hyperactive bladder was observed in 89.5% 17/19. Bladder compliance was normal in two cases (10.5%), was markedly reduced in 10 patients (52.6%) and not possible to be determined due to urinary leakage in 7 patients (36.8%). We observed normal bladder capacity in 8 patients (42.1%), reduced in 11 (57.9%), and detrusor-sphincter dyssynergia in 9 patients (47.4%). Underactive bladder was diagnosed in one case. Clean Intermittent Catheterization was initiated by 11 patients (57.9%) mostly in association with anticholinergics 10/11. Vesicoureteral reflux was found in 5 patients (26.3%) and 9 had pyelonephritis at a mean follow-up of 5.4 months 2-17. CONCLUSIONS: Our data suggested that despite in utero MMC surgery, patients are at risk for bladder abnormal function and renal deterioration and should be aggressively treated, not differently from those operated in the post-natal term. This study has the merit of being a prospectively set evaluation performed by one investigator, including the urodynamic study. We acknowledge the need of long-term follow up.

[The clinical diagnostic importance of detection of vascular endothelial growth factor in evaluation of progression of pyelonephritis in children].

The article deals with evaluation of clinical diagnostic importance of detection of vascular endothelial growth factor under pyelonephritis in children. The study was implemented on sampling of 60 patients with various degree of compensation process. The level of vascular endothelial growth factor increased significantly in patients proportionally to severity of process and its value correlated with velocity of glomerular filtration and vascularization of kidney.

Impact of host age and parity on susceptibility to severe urinary tract infection in a murine model.

The epidemiology and bacteriology of urinary tract infection (UTI) varies across the human lifespan, but the reasons for these differences are poorly understood. Using established monomicrobial and polymicrobial murine UTI models caused by uropathogenic Escherichia coli (UPEC) and/or Group B Streptococcus (GBS), we demonstrate age and parity as inter-related factors contributing to UTI susceptibility. Young nulliparous animals exhibited 10-100-fold higher bacterial titers compared to older animals. In contrast, multiparity was associated with more severe acute cystitis in older animals compared to age-matched nulliparous controls, particularly in the context of polymicrobial infection where UPEC titers were ∼1000-fold higher in the multiparous compared to the nulliparous host. Multiparity was also associated with significantly increased risk of chronic high titer UPEC cystitis and ascending pyelonephritis. Further evidence is provided that the increased UPEC load in multiparous animals required TLR4-signaling. Together, these data strongly suggest that the experience of childbearing fundamentally and permanently changes the urinary tract and its response to pathogens in a manner that increases susceptibility to severe UTI. Moreover, this murine model provides a system for dissecting these and other lifespan-associated risk factors contributing to severe UTI in at-risk groups.

Preventive effect of phosphodiesterase 5 inhibitor tadalafil on experimental post-pyelonephritic renal injury in rats.

BACKGROUND: To evaluate the effects of Tadalafil, a phosphodiesterase 5 enzyme inhibitor, on Escherichia coli-induced renal damage in an acute pyelonephritis (PN) rat model. METHODS: Experimental PN was induced in 32 Wistar rats, and four groups were formed: group 1 (no treatment), group 2 (antibiotic), group 3 (Tadalafil), and group 4 (antibiotic + Tadalafil). Antibiotic was given on days 3 to 8, and Tadalafil was administered between days 0 and 28 of bacterial inoculation. Half of the rats were killed on the ninth day (early period) and histopathological parameters, immunohistochemical renal fibrosis markers, and oxidant/antioxidant system activities were evaluated. The rest of the rats were killed at the sixth week of the study and evaluated for histopathological parameters and renal fibrosis markers. RESULTS: Inflammatory activity was significantly milder in rats treated with antibiotic + Tadalafil versus no treatment group both in the early and late periods. In the late period, interstitial fibrosis or tubular atrophy was lower in the antibiotic + Tadalafil group versus the no treatment and antibiotic groups, and in Tadalafil versus antibiotic group. Tadalafil administration significantly reduced renal malondialdehyde and nitric oxide levels and enhanced superoxide dismutase and catalase activities. In addition, circulating tumor necrosis factor α, interleukin 1ß was greatly reduced in Tadalafil group versus the no treatment group. CONCLUSIONS: We have provided the first evidence that phosphodiesterase 5 enzyme inhibitor Tadalafil ameliorates circulating inflammatory cytokines, reverses oxidant/antioxidant dysfunction and eventually possesses an overall protective effect on renal tissue from Escherichia coli-induced PN-related kidney injury. Phophodieterase 5 inhibitor might be a novel therapeutic target for PN.

[Imperative and obstructive urination disorders in patients with chronic inflammatory diseases of the urinary tract].

The estimation of functional parameters of the lower urinary tract in 116 patients with chronic cystitis and 51 patients with chronic nonobstructive pyelonephritis was performed. Urethral instability was revealed in 53 (45.68%) patients with chronic cystitis (mean age, 40.72 +/- 14.45 years), detrusor overactivity--in 10 (8.62%, mean age, 45.55 +/- 13.45 years) patients. Variations in detrusor pressure were 22.16 +/- 15.8 cm H20. Combination of urethral instability and detrusor overactivity was diagnosed in 26 (22.4%) patients of the study group (mean age, 65.16 +/- 10.49 years). The maximum urethral pressure was 75.5 +/- 21.44 cm H2O, variations in urethral pressure--37.45 +/- 17.44 cm H2O. Reduction in the maximum urinary flow rate less than 15 ml/s was detected in 47 (40.5%) patients. Signs ofdetrusor-sphincter dyssynergia were observed in 29 (25%) patients. After processing the urodynamic studies of patients with non-obstructive pyelonephritis, 20 (39.21%) patients with severe detrusor hypotension, 18 (35.29%)--with detrusor overactivity, 26 (50.98%)--with urethral instability were identified. Based on the results of the study, it was concluded that women's chronic inflammation in the bladder and kidneys may not be the cause but the consequence of functional disorders of the lower urinary tract infections associated with the disorders of the nervous regulation of these organs. Inflammation in the bladder wall against the background of dysfunction of the lower urinary tract, in turn, can support a dysfunction of the bladder and/or urethra. Drugs affecting the function of the sympathetic and parasympathetic elements of the autonomic nervous system can be used for the elimination of functional disorders of the lower urinary tract and improvement the functioning of these organs. Thus, the pathogenetic treatment of chronic cystitis should be based on the disruption of "vicious circle" dysfunction--inflammation. In view of these data, and due to the frequent detection of imperative and functional obstructive urination disorders, in addition, based on the neurophysiological concept of their occurrence, the use of alpha-adrenoblockers and M-anticholinergics agents is important in the treatment strategy with regard to patients with chronic recurrent cystitis and non-obstructive pyelonephritis.

Systematic kidney biopsies after acute allograft pyelonephritis.

OBJECTIVES: Scarce data exist regarding the effect of acute graft pyelonephritis on kidney histology after a kidney transplant. This study sought to assess the kidney histology at 1 month, and kidney function at 1 year, after acute graft pyelonephritis in kidney transplant patients. MATERIALS AND METHODS: All kidney transplant patients with acute graft pyelonephritis between October 2006, and December 2008, underwent a kidney biopsy 1 month later (n=28). Histologic findings were compared with those observed in a control group (n=28) who underwent a protocol kidney biopsy at 1 year posttransplant and did not present with acute graft pyelonephritis. Patients were matched according to age, sex, and immunosuppressive regimen. RESULTS: Kidney function was impaired by the acute graft pyelonephritis episodes at the time of biopsy. In 40% of patients, the estimated glomerular filtration rate did not return to baseline by 1 month after acute graft pyelonephritis and remained impaired thereafter. Three patients had features of acute rejection. Tubulitis was seen more frequently in the acute graft pyelonephritis group, especially in patients in whom estimated glomerular filtration rate did not completely recover by 1 month after acute graft pyelonephritis. Patients with acute graft pyelonephritis who had inflammatory infiltrate of > 20% 1 month after acute graft pyelonephritis had worse kidney function 1 year later. CONCLUSIONS: After transplant, when kidney function remains impaired 1 month after acute graft pyelonephritis, kidney biopsies allowed graft rejection diagnosis and predicted kidney function recovery.

[Proinflammatory cytokines in patients with pyelonephritis].

The antiinflammatory cytokines participate in antiinfective immunity, that is why it is advisable to study their peculiarities in determination of the role in immunologic pathogenesis of pyelonephritis. Of the work is to study the levels of pro-inflammatory blood cytokines in the patients with pyelonephritis (PN), to determine the peculiarities in acute and chronic its course in children and adults. The immuno-enzymic method ELISA and the corresponding test-systems were used to study the levels of cytokines in blood. There were studied the levels of pro-inflammatory cytokines (TNF, MCP and IL-23) in blood serum of patients with acute (APN) and chronic (CPN) pyelonephritis. The analysis showed the reliable increase in levels of all studied findings in both forms of PN--both in all 173 patients and in every group--children (87) and adults (86). The MCP-1 levels in APN are reliably higher than in CPN, while in TNF-b and IL-23--do not differ. The levels of all three cytokines in blood of adults were higher than in children in APN, but TNF--in CPN as well. The high level of TNF, MCP-1 and IL-23 in blood of adults and children confirm their important role both in APN and CPN, but MCP-1 can be considered as a predictor of acute/exacerbation of chronic pyelonephritis. By the findings of the studied cytokines, more expressed immune response was noted in the adults.

Ovarian cyst torsion coexisting with acute pyelonephritis in an eight-year-old premenarchal girl.

We report the case of a premenarchal eight-year-old girl with an adnexal torsion accompanied by acute pyelonephritis with vague, non-specific symptoms. In young girls, symptoms may be vague, with patients complaining of non-specific gastro-intestinal problems. Combination with other complications such as pyelonephritis makes the diagnosis of adnexal torsion even more difficult as in the present case. To preserve future reproductive function, early surgical intervention is required. Although the impact on menarchal development of oophorectomy or partial removal of ovarian tissue before menarche remains to be evaluated, timely recognition and treatment of adnexal torsion clearly increases the possibility of retaining the ovary. Therefore, to decrease the time between the onset of symptoms and the identification of patients at risk, sonography should be considered as a first imaging modality for evaluating children with any degree of abdominal pain accompanied by non-specific symptoms.

[The role of examination of lower urinary tract function in choice of treatment policy in patients with chronic cystitis and chronic nonobstructive pyelonephritis].

The latest investigations evidence for growing number of women with urination disorders in the absence of pathological changes in the urine. This fact suggests the conclusion that dysuria may be caused by neuroendocrine disorders in such women. Besides hemodynamic disorders, urodynamic ones are also involved in pyelonephritis pathogenesis. Our investigations show that chronic non-obstructive pyelonephritis and chronic cystitis can be both a cause and a result of functional disorders of the lower urinary tract related to defects in nervous regulation. Long-term dysfunction of the lower urinary tract may provoke progressive inflammation. In this case antibacterial and anti-inflammatory treatment of chronic cystitis and chronic non-obstructive pyelonephritis may be low effective without normalization of functional condition of the urinary bladder and urethra.

[Intravesical electrostimulation and magnetotherapy in chronic pyelonephritis and cystitis in children with urodynamic disorders].

The results of the treatment of 38 children (6 boys and 32 girls, age 6-14 years) with chronic pyelonephritis and/or cystitis complicated with neurogenic dysfunction of the urinary bladder (NDUB) and/or vesicoureteral reflux (VUR) of the first-third degree demonstrate efficacy of intravesical electrostimulation (IVES) and adrenal magnetotherapy. IVES was conducted with high-frequency current impulses (2.2 kHz) by means of INTRASTIM attachment to the device AMUS-01-INTRAMAG in the region of the urethrovesical anastomosis via solution of the drugs for instillation. As the result of exposure to both physical factors in the presence of standard medication, NDUB symptoms alleviated (by E.L. Vishnevsky's criteria) by 59.5% against 38.1% in the control group. Dopplerographic examination of renal vessels stated a 24.3% increase in blood flow in the major renal artery in the study group against 10.5% in the control. The proposed complex pharmacological plus physiotherapeutic treatment of chronic pyelonephritis and cystitis in abnormal urodynamics resulted in a 2.2-fold decrease in the number of recurrences compared to the standard treatment.

Vesicoureteral reflux associated renal damage: congenital reflux nephropathy and acquired renal scarring.

PURPOSE: The pathophysiology, evaluation, description and clinical implications of renal damage associated with vesicoureteral reflux remain controversial. We summarized the current understanding of this important aspect of clinical vesicoureteral reflux. MATERIALS AND METHODS: We performed a detailed review of the literature on clinical, pathological and experimental data related to congenital vesicoureteral reflux and bladder dynamics. We also reviewed the clinical context and imaging evaluation with underlying experimental data related to post-infectious reflux nephropathy. RESULTS: Congenital reflux nephropathy is a pattern of impaired renal function and development with renal dysplasia as the most severe but not the only form. Mechanisms of developmental disruption are potentially related to vesicoureteral reflux dynamics during gestation and associated bladder dynamics, which may continue into postnatal life. Acquired renal injury associated with infection is related to particular bacterial and host factors that determine infection virulence, host inflammatory response and tissue recovery. As best seen on dimercapto-succinic acid scan, acute changes may resolve but may also persist as permanent renal scarring. Specific risk factors for acute pyelonephritis and renal scarring in patients with vesicoureteral reflux include higher reflux grade, dysfunctional voiding/elimination, recurrent pyelonephritic episodes and delayed initiation of antibiotic therapy. Low pressure sterile reflux is not a cause of reflux nephropathy. CONCLUSIONS: Renal damage associated with vesicoureteral reflux may be congenital or acquired and the respective pathophysiological mechanisms are likely different. Congenital damage is often dysplasia, which may be a result of disordered renal development secondary to significant alterations in bladder dynamics. These processes may continue into the newborn period while kidney maturation continues. Recognizing the clinical potential for ongoing effects on renal function and the role of bladder development are important for clinical care. Post-pyelonephritic acquired damage is the result of a complex interaction of host and bacterial factors that leads to acute alterations in renal function, and may lead to permanent renal scarring. Strategies for timely intervention as well as prevention are essential to limit the risk of permanent renal injury, which may predispose to hypertension and renal insufficiency in some patients.

Gender differences in inflammatory markers in children.

No clear explanation exists to understand how sex hormones and/or chromosomes affect the immune system. In vitro studies of human lymphoid cells also show sex differences in immune function. To evaluate these differences in frequent pediatric emergencies, we analyze the expression of inflammatory markers (C-reactive protein, erythrocyte sedimentation rate, and neutrophil count) underlying inflammatory processes in children: 482 children (241 girls and 241 boys) hospitalized for pneumonia (n = 384), pyelonephritis (n = 39), or bronchiolitis (n = 59) matched for age and sex. All patients were younger than 10 years. A control population of 97 children (50 girls and 47 boys) admitted for day surgery (tonsillectomy, circumcision, or strabismus) was included. We observed highly significant differences between girls and boys: median C-reactive protein concentration of 5.45 mg/dL (range, 0.2-36.0 mg/dL) for girls and 2.6 mg/dL (range, 0.3-37.3 mg/dL) for boys (P < 0.0001), and median erythrocyte sedimentation rate of 39.5 mm/h (range, 2-104 mm/h) for girls and 24 mm/h (range, 4-140 mm/h) for boys (P < 0.005). Neutrophil counts were also significantly different: a median of 8,796 cells/microL (range, 328-27,645 cells/microL) for girls and 6,774 cells/microL (range, 600-38,668 cells/microL) for boys (P < 0.02). The duration of fever after initiating antibiotic therapy was longer in girls than in boys, but there was no difference (Fisher exact test, P < 0.06). The present study documents a relationship between sex and both the production of inflammatory markers and neutrophil recruitment. Sex difference also showed more direct clinical relevance with associations seen between sex and both duration of fever and duration of disease (bronchiolitis P < 0.0007).