Characteristics and predictors of chronic kidney disease in children with myelomeningocele: a nationwide cohort study.

BACKGROUND: Myelomeningocele (MMC) is highly prevalent in developing countries, and MMC-related neurogenic bladder is an important cause of childhood chronic kidney disease (CKD). This nationwide study aimed to evaluate demographic and clinical features of pediatric patients with MMC in Turkey and risk factors associated with CKD stage 5. METHODS: Data from children aged 0-19 years old, living with MMC in 2022, were retrospectively collected from 27 pediatric nephrology centers. Patients > 1 year of age without pre-existing kidney abnormalities were divided into five groups according to eGFR; CKD stages 1-5. Patients on dialysis, kidney transplant recipients, and those with eGFR < 15 ml/min/1.73 m2 but not on kidney replacement therapy at time of study constituted the CKD stage 5 group. RESULTS: A total of 911 (57.8% female) patients were enrolled, most of whom were expectantly managed. Stages 1-4 CKD were found in 34.3%, 4.2%, 4.1%, and 2.4%, respectively. CKD stage 5 was observed in 5.3% of patients at median 13 years old (range 2-18 years). Current age, age at first abnormal DMSA scan, moderate-to-severe trabeculated bladder on US and/or VCUG, and VUR history were independent risk factors for development of CKD stage 5 (OR 0.752; 95%; CI 0.658-0.859; p < 0.001; OR 1.187; 95% CI 1.031-1.367; p = 0.017; OR 10.031; 95% CI 2.210-45.544; p = 0.003; OR 2.722; 95% CI 1.215-6.102; p = 0.015, respectively). Only eight CKD stage 5 patients underwent surgery related to a hostile bladder between 1 and 15 years old. CONCLUSION: MMC-related CKD is common in childhood in Turkey. A proactive approach to neurogenic bladder management and early protective surgery in selected cases where conservative treatment has failed should be implemented to prevent progressive kidney failure in the pediatric MMC population in our country.

Neuropsychiatric involvement in juvenile-onset systemic lupus erythematosus: A multicenter study.

INTRODUCTION: Neuropsychiatric (NP) involvement is a restricted area in juvenile-onset systemic lupus erythematosus (jSLE). AIM: To investigate the prevalence, demographic and clinical features, and outcomes of the neurological involvement in the Turkish jSLE population. METHODS: This study was based upon 24 referral centers' SLE cohorts, multicenter and multidisciplinary network in Turkey. Patient data were collected by a case report form which was standardized for NP definitions according to American Collage of Rheumatology (ACR). Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI) neuropsychiatric part was used to determine NP damage. Variables were evaluated Ward's hierarchical clustering analyses, univariate, and multivariate logistic regression analyses. RESULTS: A hundred forty-nine of 1107 jSLE patients had NP involvement (13.5%). The most common NPSLE findings were headache (50.3%), seizure (38.3%), and acute confusional state (33.6%). Five clusters were identified with all clinical and laboratory findings. The first two clusters involved neuropathies, demyelinating diseases, aseptic meningitis, and movement disorder. Cluster 3 involved headache, activity markers and other SLE involvements. Idiopathic intracranial hypertension, cerebrovascular disease, cognitive dysfunction, psychiatric disorders and SLE antibodies were in the fourth, and acute confusional state was in the fifth cluster. In multivariate analysis, APA positivity; OR: 2.820, (%95CI: 1.002-7.939), P: 0,050, plasmapheresis; OR: 13.804 (%95CI: 2.785-68.432), P: 0,001, SLEDAI scores; OR: 1.115 (%95CI: (1.049-1.186), P: 0,001 were associated with increased risk for neurologic sequelae. CONCLUSION: We detected the prevalence of juvenile NPSLE manifestations in Turkey. We have identified five clusters that may shed light pathogenesis, treatment and prognosis of NP involvements. We also determined risk factors of neurological sequelae. Our study showed that new definitions NP involvements and sequelae for childhood period are needed.

A rare entity in a pediatric patient: coexistence of emphysematous cystitis and emphysematous pyelonephritis.

BACKGROUND: Emphysematous cystitis (EC) and emphysematous pyelonephritis (EPN) are rare urinary tract infections. They have a wide spectrum of clinical manifestations; ranging from asymptomatic to septic shock at presentation. In children, EC and EPN are rare complications of urinary tract infections (UTIs). Their diagnosis is based on clinical manifestations, laboratory results and characteristic radiological findings of gas within the collecting system, renal parenchyma and/or perinephric tissue. Computed tomography is the best radiological option in the diagnosis of EC and EPN. Despite the availability of various treatment modalities including medical and/or surgical treatment alternatives, these life-threatening conditions have high mortality rates reaching up to 70 percent. CASE: Urinary tract infection was detected in the examinations of an 11-year-old female patient suffering from lower abdominal pain, vomiting and dysuria for two days. Air was detected in the bladder wall on X-ray. EC was detected in the abdominal ultrasonography. Air formations in the bladder lumen and calyces of both kidneys in abdominal computed tomography confirmed the presence of EPN. CONCLUSIONS: Individualized treatment should be instituted according to the severity of EC and EPN, and the overall health condition of the patient.

Evaluation of non-infectious complications of peritoneal dialysis in children: a multicenter study.

BACKGROUND: Peritoneal dialysis (PD) is the most common kidney replacement therapy in children. Complications associated with PD affect treatment success and sustainability. The aim of this study was to investigate the frequency of PD-related non-infectious complications and the predisposing factors. METHODS: Retrospective data from 11 centers in Turkey between 1998 and 2018 was collected. Non-infectious complications of peritoneal dialysis (NICPD), except metabolic ones, in pediatric patients with regular follow-up of at least 3 months were evaluated. RESULTS: A total of 275 patients were included. The median age at onset of PD and median duration of PD were 9.1 (IQR, 2.5-13.2) and 7.6 (IQR, 2.8-11.9) years, respectively. A total of 159 (57.8%) patients encountered 302 NICPD within the observation period of 862 patient-years. The most common NIPCD was catheter dysfunction (n = 71, 23.5%). At least one catheter revision was performed in 77 patients (28.0%). Longer PD duration and presence of swan neck tunnel were associated with the development of NICPD (OR 1.191; 95% CI 1.079-1.315, p = 0.001 and OR 1.580; 95% CI 0.660-0.883, p = 0.048, respectively). Peritoneal dialysis was discontinued in 145 patients; 46 of whom (16.7%) switched to hemodialysis. The frequency of patients who were transferred to hemodialysis due to NICPD was 15.2%. CONCLUSIONS: Peritoneal dialysis-related non-infectious complications may lead to discontinuation of therapy. Presence of swan neck tunnel and long duration of PD increased the rate of NICPD. Careful monitoring of patients is necessary to ensure that PD treatment can be maintained safely.

Clinical and Demographic Features of Pediatric-Onset Behçet's Disease and Evaluation of Optical Coherence Tomography Findings.

PURPOSE: To evaluate the clinical characteristics, including spectral domain optical coherence tomography (SD-OCT) findings, of pediatric-onset Behçet's disease (PBD) patients. METHODS: Medical records of 23 PBD (15 males and 8 females) and 24 (15 males and 9 females) healthy subjects were evaluated retrospectively. The main outcomes were compared between PBD patients, with and without ocular involvement, and healthy subjects. RESULTS: The mean age at onset was 12.00 ± 2.10 years. Mean follow-up period was 25.17 ± 15.36 months (range 6-48). Retinal vasculitis was the most common ocular finding (7 patients). Most of the complications of systemic treatment were associated with long term corticosteroid therapy. There was no significant difference between the mean retinal thickness of the PBD patients and healthy controls (p > 0.05). The mean choroidal thickness was significantly increased in all measured segments of PBD patients with ocular involvement (p < 0.01). CONCLUSION: Choroidal thickness of PBD patients with ocular involvement was significantly thicker compared to the PBD patients without ocular involvement and to healthy control subjects.

Evaluation of Genetic Polymorphisms for Determining Steroid Response in Nephrotic Children.

GOALS: Although all children with nephrotic syndrome (NS) have similar biochemical abnormalities and clinical manifestations, they seem to have variable grades of steroid responsiveness and patterns of disease relapse. Therefore, this study aimed to examine whether steroid metabolism-related genetic polymorphisms, which are responsible for drug elimination, play a role for steroid response in children with NS. METHODS: The study population consisted of 53 children with idiopathic NS [45 steroid sensitive (SS) and 8 steroid resistant (SR) nephrotic patients] and 22 healthy children as the control group. The genetic polymorphisms of the multi-drug resistance-1 (MDR-1) and human cytochrome P450 3A (CYP3A4 and CYP3A5) genes were analyzed and compared between SS, SR and control groups. In addition, mutations in the podocin and nephrin genes were also investigated. RESULTS: There was no statistically significant difference between NS and control groups in terms of age and gender (P>0.05). Although the NS was more prevalent in boys (39/53, 73.6%), females were more dominant in the SR group (5/8, 62.5%). Serum urea and creatinine values were significantly higher in the SR group than in the SS group. Mutations in the podocin and nephrin genes were not different between the groups (P>0.05). In addition, no difference was found between the groups in regard to the polymorphisms of the MDR-1, CYP3A4 and CYP3A5 genes (P>0.05). CONCLUSION: These results showed that the polymorphisms of the MDR-1, CYP3A4 and CYP3A5 genes were not associated with steroid response.

Clinical features of children with multicystic dysplastic kidney.

BACKGROUND: To evaluate the clinical features of patients with multicystic dysplastic kidney (MCDK). METHODS: The medical files of children diagnosed with MCDK between January 2008 and November 2015 were retrospectively reviewed. The demographic, clinical, laboratory and radiological data were evaluated. RESULTS: Of 128 children with MCDK enrolled in the study, 82 (64.1%) were male, and 46 (35.9%) were female (P < 0.05). MCDK were located on left and right sides in 66 (51.6%) and 62 children (48.4%), respectively (P > 0.05). Antenatal diagnosis was present in 64 patients (50%). The mean age at diagnosis was 2.8 ± 2.7 years (range, 0-8 years), and follow-up duration was 4.5 years. Fifteen patients (20.8%) had vesicoureteral reflux. Of these, four underwent endoscopic surgical correction. Other associated urological anomalies were ureteropelvic junction obstruction (n = 6), hypospadias (n = 1), and kidney stones (n = 1). On technetium-99 m dimercaptosuccinic acid scintigraphy, which was performed in all patients, no significant association between grade of reflux and presence of scarring was seen. Hypertension was diagnosed only in one child (0.8%) who required antihypertensive treatment. The prevalence of unilateral undescended testicle in children aged <1 year in the 82 male patients was 4.9%. Seventy-six patients (59.4%) developed compensatory hypertrophy in the contralateral kidney during a 1 year follow-up period. Of the total, only seven children (5.5%) had undergone nephrectomy. CONCLUSIONS: MCDK follows a benign course with relatively few sequelae, and therefore these patients should be closely followed up and conservatively managed.

Acute peritoneal dialysis in neonatal intensive care unit: An 8-year experience of a referral hospital.

BACKGROUND: The aim of present study was to evaluate the indications, complications and outcomes of acute peritoneal dialysis (APD) in neonates at a referral university hospital during the previous 8 years. METHODS: This retrospective analysis included a total of 52 newborn infants who underwent APD in a neonatal intensive care unit between January 2008 and March 2016. Demographic, clinical, laboratory and microbiological data were extracted from patients' medical files. RESULTS: The primary causes for requiring APD were acute tubular necrosis (n = 36, 69.2%), inborn error of metabolism (n = 10, 19.2%), congenital nephrotic syndrome (n = 2, 3.9%), bilateral polycystic kidney (n = 2, 3.9%), renal agenesis (n = 1, 1.9%), and obstructive uropathy (n = 1, 1.9%). The mean duration of APD was 8.7 ± 15.87 days (range: 1-90 days). Procedural complications were mainly hyperglycemia (n = 16, 47.1%), dialysate leakage (n = 7, 20.6%), peritonitis (n = 3, 8.8%), catheter obstruction (n = 3, 8.8%), bleeding at the time of catheter insertion (n = 2, 5.9%), catheter exit site infection (n = 2, 5.9%), and bowel perforation (n = 1 2.9%). There were 40 deaths (76.9%), mainly due to underlying causes. Ten of the 12 survivors showed full renal recovery, but mild chronic renal failure (n = 1) and proteinuria with hypertension were seen (n = 1) in each of remaining patients. CONCLUSION: Peritoneal dialysis is an effective route of renal replacement therapy in the neonatal period for management of metabolic disturbances as well as renal failure. Although major complications of the procedure are uncommon, these patients still have a high mortality rate due to serious nature of the underlying primary causes.

The Clinical and Mutational Spectrum of Turkish Patients with Cystinosis.

BACKGROUND AND OBJECTIVES: Infantile nephropathic cystinosis is a severe disease that occurs due to mutations in the cystinosis gene, and it is characterized by progressive dysfunction of multiple organs; >100 cystinosis gene mutations have been identified in multiple populations. Our study aimed to identify the clinical characteristics and spectrum of cystinosis gene mutations in Turkish pediatric patients with cystinosis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We identified the clinical characteristics and spectrum of cystinosis gene mutations in Turkish patients with cystinosis in a multicenter registry that was established for data collection. The data were extracted from this registry and analyzed. RESULTS: In total, 136 patients (75 men and 61 women) were enrolled in the study. The most common clinical findings were growth retardation, polyuria, and loss of appetite. None of the patients had the 57-kb deletion, but seven novel mutations were identified. The most common mutations identified were c.681G>A (p.Glu227Glu; 31%), c.1015G>A (p.Gly339Arg; 22%), and c.18_21 del (p.Thr7Phefs*7; 14%). These mutations were associated with earlier age of disease onset than the other mutations. To understand the effects of these allelic variants on clinical progression, the mutations were categorized into two major groups (missense versus deletion/duplication/splice site). Although patients with missense mutations had a better eGFR at the last follow-up visit, the difference was not significant. Patients in whom treatment began at age <2 years old had later onset of ESRD (P=0.02). Time to ESRD did not differ between the patients with group 1 and group 2 mutations. CONCLUSIONS: The most common cystinosis gene mutations identified in Turkey were c.681G>A (p.Glu227Glu), c.1015G>A (p.Gly339Arg), and c.18_21 del (p.Thr7Phefs*7). Patients with less severe cystinosis gene mutations tend to have better kidney outcome.

Association of procalcitonin with acute pyelonephritis and renal scars in pediatric UTI.

BACKGROUND AND OBJECTIVE: Urinary tract infections (UTIs) are common childhood bacterial infections that may involve renal parenchymal infection (acute pyelonephritis [APN]) followed by late scarring. Prompt, high-quality diagnosis of APN and later identification of children with scarring are important for preventing future complications. Examination via dimercaptosuccinic acid scanning is the current clinical gold standard but is not routinely performed. A more accessible assay could therefore prove useful. Our goal was to study procalcitonin as a predictor for both APN and scarring in children with UTI. METHODS: A systematic review and meta-analysis of individual patient data were performed; all data were gathered from children with UTIs who had undergone both procalcitonin measurement and dimercaptosuccinic acid scanning. RESULTS: A total of 1011 patients (APN in 60.6%, late scarring in 25.7%) were included from 18 studies. Procalcitonin as a continuous, class, and binary variable was associated with APN and scarring (P < .001) and demonstrated a significantly higher (P < .05) area under the receiver operating characteristic curve than either C-reactive protein or white blood cell count for both pathologies. Procalcitonin ≥0.5 ng/mL yielded an adjusted odds ratio of 7.9 (95% confidence interval [CI]: 5.8-10.9) with 71% sensitivity (95% CI: 67-74) and 72% specificity (95% CI: 67-76) for APN. Procalcitonin ≥0.5 ng/mL was significantly associated with late scarring (adjusted odds ratio: 3.4 [95% CI: 2.1-5.7]) with 79% sensitivity (95% CI: 71-85) and 50% specificity (95% CI: 45-54). CONCLUSIONS: Procalcitonin was a more robust predictor compared with C-reactive protein or white blood cell count for selectively identifying children who had APN during the early stages of UTI, as well as those with late scarring.

Celiac disease in children with urolithiasis.

There are a few studies suggesting a relationship between celiac disease (CD) and kidney disease, but no study has investigated CD in patients with urolithiasis. In this study, we aimed to determine the prevalence of CD in infants and children with urolithiasis. One hundred and eighty-seven infants and children (4 months-17 years) with urolithiasis, and 278 age- and sex-matched healthy children were included. CD was screened using tissue transglutaminase (tTG) immunoglobulin (Ig)A. Seropositive cases, whose parents gave consent, underwent upper gastrointestinal system endoscopy for duodenal biopsy. Seven (3.7%) among those with urolithiasis and one (0.3%) among controls were positive for tTG IgA (p=0.008). Six of the urolithiasis group and one from the control group underwent upper gastrointestinal endoscopy. Intestinal biopsy revealed Marsh-Oberhuber type 1 intestinal lesions in two children. The other five had normal histology. Biopsy-proven CD was detected in two (1%) children with urolithiasis. The prevalence of biopsy-proven CD among all cases was 0.4%. When children were evaluated with respect to age factor, it was found that seropositivity in children younger and older than two years was not different (4% vs. 3.6%; p=0.880). In this first study investigating CD prevalence in children with urolithiasis, we found a higher seropositivity for CD in children with urolithiasis compared to controls, but in terms of biopsy-proven CD, no difference was found.

Procalcitonin is a predictor for high-grade vesicoureteral reflux in children: meta-analysis of individual patient data.

OBJECTIVE: To assess the predictive value of procalcitonin, a serum inflammatory marker, in the identification of children with first urinary tract infection (UTI) who might have high-grade (≥3) vesicoureteral reflux (VUR). STUDY DESIGN: We conducted a meta-analysis of individual data, including all series of children aged 1 month to 4 years with a first UTI, a procalcitonin (PCT) level measurement, cystograms, and an early dimercaptosuccinic acid scan. RESULTS: Of the 152 relevant identified articles, 12 studies representing 526 patients (10% with VUR ≥3) were included. PCT level was associated with VUR ≥3 as a continuous (P = .001), and as a binary variable, with a 0.5 ng/mL preferred threshold (adjusted OR, 2.5; 95% CI, 1.1 to 5.4). The sensitivity of PCT ≥0.5 ng/mL was 83% (95% CI, 71 to 91) with 43% specificity rate (95% CI, 38 to 47). In the subgroup of children with a positive results on dimercaptosuccinic acid scan, PCT ≥0.5 ng/mL was also associated with high-grade VUR (adjusted OR, 4.8; 95% CI, 1.3 to 17.6). CONCLUSIONS: We confirmed that PCT is a sensitive and validated predictor strongly associated with VUR ≥3, regardless of the presence of early renal parenchymal involvement in children with a first UTI.

Results of medical treatment and metabolic risk factors in children with urolithiasis.

Data on conservative treatment in children with urolithiasis are limited. The aim of the study was to determine the metabolic etiology and results of conservative treatment in children with urolithiasis. We evaluated the clinical presentation and metabolic features of 112 children with urolithiasis. The mean age at diagnosis of urolithiasis was 3.9 (range 0.1-18) years, and follow-up duration was 16.7 (range 1-36) months. The most common presenting symptoms were flank or abdominal pain and restlessness (25%). Urine analysis revealed metabolic abnormalities in 92% of cases, including hypocitraturia (42%), hyperoxaluria (32.1%), hypercalcuria (25%), hyperuricosuria (9.8%), and cystinuria (2.7%). Patients who had metabolic risk factors were treated according to underlying metabolic abnormalities. About half of these patients were stone free or stones were diminished in size. These results showed that early recognition and treatment of urinary metabolic abnormalities will reduce the number of invasive procedures and renal damage in children with urolithiasis.

Role of sodium during formation of edema in children with nephrotic syndrome.

BACKGROUND: The pathogenesis of edema in nephrotic syndrome is not entirely understood. The aim of this study was to contribute to the discussion on edema pathogenesis in nephrotic syndrome by following changes in volume and sodium retention for the course of the disease in children with steroid-sensitive nephrotic syndrome (SSNS). METHODS: Forty-one children with SSNS were included in the study. The patients were divided into three groups (group I: relapse-edematous; group II: relapse-edema free; group III: remission). We investigated the value of the significance and area of sodium retention and vasoactive hormones. In addition, we measured parameters such as inferior vena cava collapsibility index, left atrium diameter, and total body water (TBW) to determine the volume load and cause of edema in children with SSNS. RESULTS: TBW increased in the relapse-nephrotic syndrome group and the difference was statistically significant among groups (P < 0.001). However, inferior vena cava collapsibility index and left atrium diameter were not different among groups. Fractional sodium excretion was lower in children with relapse nephrotic syndrome (P < 0.05). CONCLUSION: Although TBW increases in children with SSNS, intravascular volume is normal. In addition, hypoalbuminemia and sodium retention of the proximal tubule cause edema in children with SSNS.

Circulating endothelial microparticles in children with Henoch-Schönlein purpura; preliminary results.

The aim of this study was to investigate the levels of circulating endothelial microparticles (EMPs) in children with HSP and to determine whether there was a difference between patients with nephritis and those without nephritis. Twenty patients with HSP aged between 2.5 and 15 and 10 age-and sex-matched healthy controls were enrolled in the study. The HSP group was divided into two groups, including patients with nephritis (n = 9) and those without nephritis (n = 11). In all groups, circulating EMPs were enumerated by flow cytometry, after staining platelet-free plasma with PE-conjugated anti-CD144. At the same time, human umbilical vein endothelial cells (HUVEC) were incubated with the platelet-free plasma of patients with HSP and that of the control group. Then, circulating EMPs were counted in HUVEC supernatant incubated with the platelet-free plasma of patients and control groups, after staining the supernatant with PE-conjugated anti-CD146. Circulating EMPs were significantly higher in both the active and the remission period of the patient groups compared with the control subjects. In the patient group, there were no statistically significant differences in the level of circulating EMPs between patients with nephritis and those without nephritis. Both CD144 and 146+EMP in patients with HSP nephritis in the active period were substantially higher than in those remissions. CD144+EMP in the active period were substantially higher than in the remission period in patients without nephritis. We detected that circulating EMPs increased in patients with HSP in both active and remission periods. Although clinical and laboratory findings return to normal in the remission period, the increased circulating EMPs may show that the subclinical inflammatory process is continuous. We think that circulating EMPs could be used as a surrogate marker for subclinical inflammation in HSP.

Prediction of high-grade vesicoureteral reflux after pediatric urinary tract infection: external validation study of procalcitonin-based decision rule.

BACKGROUND: Predicting vesico-ureteral reflux (VUR) ≥3 at the time of the first urinary tract infection (UTI) would make it possible to restrict cystography to high-risk children. We previously derived the following clinical decision rule for that purpose: cystography should be performed in cases with ureteral dilation and a serum procalcitonin level ≥0.17 ng/mL, or without ureteral dilatation when the serum procalcitonin level ≥0.63 ng/mL. The rule yielded a 86% sensitivity with a 46% specificity. We aimed to test its reproducibility. STUDY DESIGN: A secondary analysis of prospective series of children with a first UTI. The rule was applied, and predictive ability was calculated. RESULTS: The study included 413 patients (157 boys, VUR ≥3 in 11%) from eight centers in five countries. The rule offered a 46% specificity (95% CI, 41-52), not different from the one in the derivation study. However, the sensitivity significantly decreased to 64% (95%CI, 50-76), leading to a difference of 20% (95%CI, 17-36). In all, 16 (34%) patients among the 47 with VUR ≥3 were misdiagnosed by the rule. This lack of reproducibility might result primarily from a difference between derivation and validation populations regarding inflammatory parameters (CRP, PCT); the validation set samples may have been collected earlier than for the derivation one. CONCLUSIONS: The rule built to predict VUR ≥3 had a stable specificity (ie. 46%), but a decreased sensitivity (ie. 64%) because of the time variability of PCT measurement. Some refinement may be warranted.

Urinary uric acid : creatinine ratios in healthy Turkish children.

BACKGROUND: Determining uric acid : creatinine ratios in random urine samples may be useful to assess the excretion of uric acid in children. Because it was shown that urinary uric acid excretion varies with age and geographic area, it is important to have accurate reference values of uric acid excretion. The aim of the present study was therefore to obtain regional reference values for urinary uric acid : creatinine ratios in healthy Turkish children. METHODS: A total of 1306 children aged 1 month-15 years were analyzed for uric acid and creatinine, and urinary uric acid : creatinine ratios were determined from each sample. The second non-fasting morning urine samples were taken from all the children. Urine samples were analyzed for uric acid using the uricase method, and for creatinine with the Jaffe reaction. RESULTS: The mean +/- SD and 5th-95th percentiles of urinary uric acid : creatinine ratios (mg/mg) were 1.09 +/- 0.48 and 0.27-1.87 at 1-6 months, 0.86 +/- 0.41 and 0.19-1.64 at 7-12 months, 0.76 +/- 0.32 and 0.32-1.43 at 1-3 years, 0.63 +/- 0.29 and 0.20-1.23 at 4-6 years, 0.44 +/- 0.24 and 0.14-0.93 at 7-11 years, and 0.30 +/- 0.14 and 0.12-0.62 at 12-15 years. Uric acid : creatinine ratios were not significantly different between boys and the girls except at 12-15 years. Girls aged 12-15 years had higher urinary uric acid : creatinine ratio when compared with boys (P < 0.05). There was no correlation between urinary uric acid : creatinine ratio and protein intake. CONCLUSIONS: Urinary uric acid : creatinine ratio changes with age. When assessing urinary uric acid : creatinine ratio, the clinician should consider the age of the child.