Pitfalls of diagnosing urinary tract infection in infants and young children.

BACKGROUND: The aim of this study was to examine the sensitivity and specificity of pyuria-based diagnosis of urinary tract infection (UTI) in urine collected by transurethral catheterization, and the reliability of diagnosis of pyuria in urine collected in a perineal bag. The gold standard for UTI diagnosis is significant colony counts of a single organism in urine obtained in a sterile manner. METHODS: We enrolled 301 patients who underwent medical examination at the present hospital for possible UTI between January 2005 and December 2009. We collected 438 urine samples by transurethral catheterization. We investigated the accuracy of pyuria-based diagnosis of UTI using transurethral catheterization urine specimens, and the reliability of diagnosis of pyuria using bag-collected urine specimens. RESULTS: The false-negative rate of UTI diagnosis based on pyuria in transurethral catheterization urine sediments was 9.0%; there was no significant difference in the false-negative rate of UTI diagnosis between boys and girls. Approximately 28% of pyuria-positive bag-collected urine specimens were pyuria negative on transurethral catheterization; this rate was significantly higher in girls than in boys (56.7% vs. 8.9%, P < 0.0001). CONCLUSIONS: The absence of pyuria in transurethral catheterization urine sediments does not rule out UTI. Pyuria in bag-collected urine specimens frequently consists of urine leukocytes from external genitalia as well as from the urinary tract.

Assessment of kidney function in children by enzymatic determination of 2- or 24-h creatinine clearance: comparison with inulin clearance.

BACKGROUND: Although renal inulin clearance (Cin) is the gold standard for evaluation of kidney function, it cannot be measured easily. Therefore, creatinine clearance (Ccr) is often used clinically to evaluate kidney function. Enzymatically measured Ccr was recently found to be much higher than Cin because of the tubular secretion of creatinine (Cr). This study compared three measures of renal clearance, inulin, 2-h Ccr, and 24-h Ccr, in children. METHODS: Kidney function was evaluated in 76 children (51 males and 25 females) aged 1 month to 18 years with chronic kidney disease (CKD) by three renal clearance methods at almost the same time. RESULTS: Correlations between each pair of three renal clearance measurements were determined. Approximate glomerular filtration rate (GFR) was equal to 62 % of 2-h Ccr or 76 % of 24-h Ccr. CONCLUSION: Cr secretion by renal tubules was approximately 50 % of the GFR. In this study, we indicate that the measurements of 2-h Ccr or 24-h Ccr do not show true GFR but we could infer approximate GFR from the values. The use of 2- or 24-h Ccr might contribute to the treatment of pediatric CKD patients.

[Perioperative Blood Pressure Changes in a Patient Undergoing One-stage Bilateral Nephrectomy for Treatment-resistant Hypertension].

We describe our experience with a 15-year-old girl receiving anesthesia during one-stage bilateral nephrectomy for treatment-resistant hypertension due to chronic renal failure. Approximately 10 minutes after removal of both kidneys, a reduction in blood pressure associated with decreased cardiac contractile force was observed and this necessitated catecholamine administration. However, blood pressure was sufficiently improved approximately 60 minutes later, and catecholamine administration was not necessary after she awoke from anesthesia. Although administration of an antihypertensive agent as required after surgery, as had been the case before surgery, the dose was gradually tapered and we were able to stop drug administration on postoperative day 31.

The ratios of urinary ß2-microglobulin and NAG to creatinine vary with age in children.

BACKGROUND: Although urinary biochemical markers can be assessed by their ratio to urinary creatinine (U-Cr) concentration, reference values in adults may not be applicable to children because the amount of Cr excreted varies by body size. We therefore measured the relationship between age and the ratios of urinary ß-2-microglobulin (U-ß2MG), N-acetyl-ß-d-glucosaminidase (U-NAG), calcium (U-Ca) and protein (U-Pr) concentration to those of U-Cr in children. METHODS: Fifty-seven patients aged >1 year with benign familial hematuria (median age, 6.3 years) were divided into three age groups: 1-4, 5-9, and ≥10 years. Urinary biomarkers were assayed using actual values; ratios to actual U-Cr values; and our standardized metric, namely 100-fold the ratio of serum Cr to U-Cr concentration; and the relationship of each of these to age was determined. RESULTS: The ratios of U-ß2MG, U-NAG and U-Ca to Cr varied significantly by age, being higher in younger than in older children, but the actual and standardized values of each did not vary by age, nor did any measurement of U-Pr. CONCLUSIONS: The ratios of urinary markers of tubular function, including U-ß2MG, U-NAG and U-Ca, to Cr vary by age, being higher in younger children. In contrast, the ratios of urinary markers of glomerular filtration (such as U-Pr)to Cr do not vary by age, making them suitable for corrections relative to Cr.

Measurements of serum cystatin C concentrations underestimate renal dysfunction in pediatric patients with chronic kidney disease.

BACKGROUND: In our clinical experience, cystatin C (CysC) concentrations are not as high as expected in patients with chronic kidney disease (CKD) and high-stage renal dysfunction. We therefore investigated whether measurements of serum CysC result in an underestimation of renal dysfunction in pediatric patients with CKD. METHODS: Glomerular filtration rate (GFR) was estimated from serum creatinine (Cr) concentration, using the equation Cr-GFR (%) = [0.30 × body length (m)/serum Cr] × 100; and from serum CysC concentration, using the equation Cys-GFR (%) = (0.70/serum CysC) × 100. We investigated the relationship between GFR estimated by these 2 equations. Patients aged 2-12 years were assorted into 5 groups, based on GFR-Cr categories of <12.5, ≥12.5 to <25, ≥25 to <50, ≥50 to <75, and ≥75%, and GFR-CysC/GFR-Cr ratios were compared in these 5 groups. RESULTS: The median GFR-CysC/GFR-Cr ratio in groups of patients with GFR-Cr of <12.5, ≥12.5 to <25, ≥25 to <50, ≥50 to <75, and ≥75% were 2.28, 1.48, 1.22, 1.18 and 0.98, respectively, with statistically significant differences between any two groups (p < 0.001). CONCLUSION: Measurements of serum CysC concentrations lead to underestimation of renal dysfunction in pediatric patients with CKD.

High prevalence of sinusitis in children with henoch-schönlein purpura.

We evaluated the prevalence and the types of infectious foci in oral as well as ear, nose, and throat diseases, and we examined incidence of renal involvement with active treatment for focal infection in children with Henoch-Schönlein Purpura. A total of 96 children who presented at Aichi Children's Health and Medical Center and were diagnosed as having HSP were evaluated for infectious foci in the ear, nose, throat, and oral cavities. Seventy-one of 96 children (74.0%) had some type of infectious lesion, such as sinusitis or tonsillitis, and the prevalence of sinusitis was the highest (51 cases, 53.7%). In 44 HSP patients without renal involvement at the first examination, the incidence of nephritis was lower (13.6%) than in previous reports (17-54%) due to our aggressive intervention for infectious foci.