The abnormal urinalysis

Renal Prognosis in Children With Tubulointerstitial Nephritis and Uveitis Syndrome

Introduction

Tubulointerstitial nephritis (TIN) and uveitis (TINU) syndrome is a rare disease. The renal prognosis is generally thought to be better in children with TINU syndrome than in adults. However, data are scarce. We aimed to investigate the long-term renal prognosis in a French cohort of children with TINU syndrome.

Methods

We performed a national retrospective study including 23 French pediatric nephrology centers enrolling patients with TINU syndrome diagnosed between January 2000 and December 2018.

Results

A total of 46 patients were included (52% female, median age 13.8 years). At diagnosis of TIN, the median estimated glomerular filtration rate (eGFR) was 30.6 ml/min per 1.73 m² (4.9–62.8). The median time between diagnosis of uveitis and TIN was 0.4 months (−4.1; +17.1). All patients had anterior uveitis, but 12 (29%) were asymptomatic. Nearly all patients (44 of 46) received steroid treatment, and 12 patients (26%) received a second-line therapy. At last follow-up (median 2.8 years), the median eGFR was 87.5 ml/min per 1.73 m² (60.3–152.7) and <90 ml/min per 1.73 m² in 20 patients.

Conclusion

In our study, nearly half of the patients had renal sequelae at last follow-up. Given the possible progression to chronic kidney disease, long-term monitoring of children with TINU syndrome is mandatory. Approximately a quarter of the children had asymptomatic uveitis suggesting all children presenting with TIN should undergo systematic ophthalmologic screening even in the absence of ocular signs.

Preoperative bacteriuria positivity on urinalysis increases wound complications in primary total hip arthroplasty regardless of the urine culture result

BACKGROUND

Current evidence does not recommend screening urine culture and curing asymptomatic bacteriuria (ASB) before joint arthroplasty. The bacteriuria count on pre-operative urinalysis is a more common clinical parameter. We aimed to investigate whether the bacteriuria count on preoperative urinalysis can increase postoperative wound complications in primary total hip arthroplasty (THA).

METHODS

We conducted a retrospective study that included patients who underwent primary THA in our institution from 2012 to 2018. We obtained preoperative urinalysis results before THA during the same hospitalization and identified patients with abnormal urinalysis. Receiver operating characteristic (ROC) curves were first generated to evaluate the predicted value of leukocyte esterase (LE), nitrite, bacteriuria, and pyuria in the urinalysis for superficial wound infection. Then, all included patients were divided into two groups according to the preoperative urinalysis: a bacteriuria-positive group and a bacteriuria-negative group. The primary outcome was the superficial wound infection rate within 3 months postoperatively, and the secondary outcomes included wound leakage, prosthetic joint infection (PJI), pulmonary infection, urinary tract infection (UTI), readmission rate within 3 months postoperatively, and length of stay (LOS) during hospitalization. We utilized univariable analyses to compare the outcomes between the two groups. A multivariable logistic regression model was generated to explore the potential association between bacteriuria and the risk of superficial wound infection, wound leakage, and readmission rate controlling for baseline values.

RESULTS

A total of 963 patients were included in the study. One hundred sixty patients had abnormal urinalysis. The AUCs for LE, nitrite, bacteriuria, and pyuria were 0.507 (95% confidence interval (CI), 0.315 to 0.698), 0.551 (0.347 to 0.756), 0.675 (0.467 to 0.882), and 0.529 (0.331 to 0.728), respectively. Bacteriuria was diagnostically superior to LE, nitrite, and pyuria. Among the 963 patients, 95 had a positive bacteriuria on preoperative urinalysis, and only 9 (9.5%) had a positive urine culture. Compared with the bacteriuria-negative group, the bacteriuria-positive group had a higher superficial wound infection rate (4.2% vs. 0.6%, P = 0.008), higher wound leakage rate (11.6% vs. 4.5%, P = 0.007), higher readmission rate (5.3% vs. 1.3%, P = 0.015) within 3 months postoperatively and longer LOS (6.19 ± 2.89 days vs. 5.58 ± 2.14 days, P = 0.011). After adjustment, the bacteriuria-positive group had a significantly increased risk of superficial wound infection (OR = 7.587, 95%CI: 2.002 to 28.755, P = 0.003), wound leakage (OR = 3.044, 95%CI: 1.461 to 6.342, P = 0.003), and readmission (OR = 4.410, 95%CI: 1.485 to 13.097, P = 0.008).

CONCLUSION

Preoperative bacteriuria positivity on urinalysis significantly increased the risk of postoperative wound complications, readmission, and LOS in primary THA regardless of the result of the urine culture. Urinalysis is a fast and cost-acceptable test whose advantages have been underestimated.

LEVEL OF EVIDENCE

Level III, observational study.

Discrepancy in results between dipstick urinalysis and urine sediment microscopy

With the advancement of urine test automation and the large-scale application of quality management policies, the source of the most crucial errors has become the pre-analytical phase. This study is an attempt to compare the results obtained from the examination of urine strips with those obtained by microscopic examination of urinary sediment, highlighting discordant results. This observational study was conducted between February and August 2019 in a private medical laboratory in Mureş County, and 2,600 urine samples were analyzed. We calculated the sensitivity, specificity, positive predictive value, negative predictive value for leukocytes, nitrites and red blood cells, taking as reference the microscopic examination of urine summary screening. Urine samples were collected from patients who presented to the laboratory. The 2,600 urine samples were analyzed using strips with 10 parameters: glucose, protein, bilirubin, urobilinogen, pH, specific density, red blood cells, nitrite, and leukocytes, and then using the microscope to examine the urinary sediment. We identified a small percentage (1.92%) of inconsistencies from the 2,600 samples of urine, between urinalysis and the microscopic examination and we identified the causes. The most common discordant results were: false-negatives for nitrite (72%), followed by false-positives results for red blood cells (22%), false-negative results for leukocytes (16%), false-negative results for red blood cells (4%) and false-positives for leukocytes (4%). The study confirmed that discrepancies appear despite the proper instruction of patients.

A Systematic Review of Screening Tests for Chronic Kidney Disease: An Accuracy Analysis

This systematic review was conducted to assess the diagnostic accuracy of chronic kidney disease screening tests in the general population. MEDLINE, EMBASE, Web of Science, Scopus, The Cochrane Library and ProQuest databases were searched for English-language publications up to November 2016. Two reviewers independently screened studies and extracted study data in standardized tables. Methodological quality was assessed using the QUADAS-2 tool. Sensitivity and specificity of all available screening methods were identified through included studies. Ten out of 1349 screened records included for final analysis. Sensitivities of the dipstick test with a cutoff value of trace were ranged from 37.1% to 69.4% and specificities from 93.7% to 97.3% for the detection of ACR>30 mg/g. The diagnostic sensitivities of the UAC>10 mg/dL testing was shown to vary from 40% to 87%, and specificities ranged from 75% to 96%. While the sensitivities of ACR were fluctuating between 74% and 90%, likewise the specificities were between 77% and 88%. Sensitivities for C-G, Grubb and Larsson equations were 98.9%, 86.2%, and 70.1% respectively. In the meantime the study showed specificities of 84.8%, 84.2% and 90.5% respectively for these equations. Individual studies were highly heterogeneous in terms of target populations, type of screening tests, thresholds used to detect CKD and variations in design. Results pointed to the superiority of UAC and dipstick over the other tests in terms of all parameters involved. The diversity of methods and thresholds for detection of CKD, necessitate considering the cost parameter along with the effectiveness of tests to scale-up an efficient strategy.

Urine Specific Gravity and the Accuracy of Urinalysis

BACKGROUND

A recent study in young infants found that different cutoffs maximized the accuracy of the urine white blood cell count in dilute versus concentrated urine samples. We aimed to confirm this finding and to determine its impact on clinical care.

METHODS

We conducted a retrospective analysis of data gathered on consecutive children <24 months of age with visits to the emergency department during a 5-year period. We evaluated the accuracy of screening tests for urinary tract infection (UTI) in dilute and concentrated urine samples. We also calculated the number of children who would have been treated differently in a hypothetical cohort of 1000 children presenting with fever had urine specific gravity (SG) been taken into consideration.

RESULTS

We included 10 078 children. The ability to rule in UTI (as measured by the positive likelihood ratio [LR]) was similar in dilute and concentrated urine for the leukocyte esterase test (11.76 vs 10.71, respectively). The positive LR for urine white blood cell count per high-powered field was higher in dilute urine (9.83 vs 6.12). In contrast, the positive LR for the nitrite test was lower in dilute urine (20.54 vs 47.44). Despite these differences, we found little change in the number of children treated with antibiotics in predictive models that took urine SG into consideration.

CONCLUSIONS

Although we found that urine SG influences the accuracy of some components of the urinalysis, its inclusion in the decision-making process had negligible effect on the clinical care of children with UTI.

Baseline urinalysis values in common bottlenose dolphins under human care in the Caribbean

Urinalysis is a rapid, simple, inexpensive, and reliable test that documents urine abnormalities reflecting various types of renal, hormonal, or metabolic diseases. Urinalysis could assist proper monitoring of the health of dolphins under human care; however, normal baseline values for dolphin urinalysis have not been reported, to our knowledge. We sampled urine from 193 common bottlenose dolphins ( Tursiops truncatus), living under human care in 24 Caribbean dolphinariums, by voluntary free-catch and analyzed the urine for chemical and microscopic variables using multi-agent dry reagent chemistry dipstick test strips, dedicated pH reagent strips, and unstained sediment slides. Most urine was clear, pale yellow to dark yellow, and had a fishy odor. Dipstick glucose, bilirubin, ketones, and nitrites were negative in all dolphins. The urine pH was acidic ( x¯ ± SD; 5.88 ± 0.58) and specific gravity (SG) was 1.035 ± 0.008. Most animals had 0-2 red blood cells and white blood cells per 40× field, and were negative for proteins. On microscopic sediment, 42.7% of samples had few-to-many squamous epithelial cells; hyaline and epithelial casts were observed only rarely. Crystals were observed in 36.6% of the samples; most were calcium oxalate dihydrate (48.2%) and amorphous urates (42.4%). The values obtained in our study can be used as a reference for health monitoring of dolphins in dolphinariums, and to monitor renal conditions and function in dolphins being rehabilitated or under human care.

Low-power, low-cost urinalysis system with integrated dipstick evaluation and microscopic analysis

We introduce a coupled dipstick and microscopy device for analyzing urine samples. The device is capable of accurately assessing urine dipstick results while simultaneously imaging the microscopic contents within the sample. We introduce a long working distance, cellphone-based microscope in combination with an oblique illumination scheme to accurately visualize and quantify particles within the urine sample. To facilitate accurate quantification, we couple the imaging set-up with a power-free filtration system. The proposed device is reusable, low-cost, and requires very little power. We show that results obtained with the proposed device and custom-built app are consistent with those obtained with the standard clinical protocol, suggesting the potential clinical utility of the device.

The Diagnosis of Urinary Tract infection in Young children (DUTY): a diagnostic prospective observational study to derive and validate a clinical algorithm for the diagnosis of urinary tract infection in children presenting to primary care with an acute illness

BACKGROUND

It is not clear which young children presenting acutely unwell to primary care should be investigated for urinary tract infection (UTI) and whether or not dipstick testing should be used to inform antibiotic treatment.

OBJECTIVES

To develop algorithms to accurately identify pre-school children in whom urine should be obtained; assess whether or not dipstick urinalysis provides additional diagnostic information; and model algorithm cost-effectiveness.

DESIGN

Multicentre, prospective diagnostic cohort study.

SETTING AND PARTICIPANTS

Children < 5 years old presenting to primary care with an acute illness and/or new urinary symptoms.

METHODS

One hundred and seven clinical characteristics (index tests) were recorded from the child's past medical history, symptoms, physical examination signs and urine dipstick test. Prior to dipstick results clinician opinion of UTI likelihood ('clinical diagnosis') and urine sampling and treatment intentions ('clinical judgement') were recorded. All index tests were measured blind to the reference standard, defined as a pure or predominant uropathogen cultured at ≥ 10(5) colony-forming units (CFU)/ml in a single research laboratory. Urine was collected by clean catch (preferred) or nappy pad. Index tests were sequentially evaluated in two groups, stratified by urine collection method: parent-reported symptoms with clinician-reported signs, and urine dipstick results. Diagnostic accuracy was quantified using area under receiver operating characteristic curve (AUROC) with 95% confidence interval (CI) and bootstrap-validated AUROC, and compared with the 'clinician diagnosis' AUROC. Decision-analytic models were used to identify optimal urine sampling strategy compared with 'clinical judgement'.

RESULTS

A total of 7163 children were recruited, of whom 50% were female and 49% were < 2 years old. Culture results were available for 5017 (70%); 2740 children provided clean-catch samples, 94% of whom were ≥ 2 years old, with 2.2% meeting the UTI definition. Among these, 'clinical diagnosis' correctly identified 46.6% of positive cultures, with 94.7% specificity and an AUROC of 0.77 (95% CI 0.71 to 0.83). Four symptoms, three signs and three dipstick results were independently associated with UTI with an AUROC (95% CI; bootstrap-validated AUROC) of 0.89 (0.85 to 0.95; validated 0.88) for symptoms and signs, increasing to 0.93 (0.90 to 0.97; validated 0.90) with dipstick results. Nappy pad samples were provided from the other 2277 children, of whom 82% were < 2 years old and 1.3% met the UTI definition. 'Clinical diagnosis' correctly identified 13.3% positive cultures, with 98.5% specificity and an AUROC of 0.63 (95% CI 0.53 to 0.72). Four symptoms and two dipstick results were independently associated with UTI, with an AUROC of 0.81 (0.72 to 0.90; validated 0.78) for symptoms, increasing to 0.87 (0.80 to 0.94; validated 0.82) with the dipstick findings. A high specificity threshold for the clean-catch model was more accurate and less costly than, and as effective as, clinical judgement. The additional diagnostic utility of dipstick testing was offset by its costs. The cost-effectiveness of the nappy pad model was not clear-cut.

CONCLUSIONS

Clinicians should prioritise the use of clean-catch sampling as symptoms and signs can cost-effectively improve the identification of UTI in young children where clean catch is possible. Dipstick testing can improve targeting of antibiotic treatment, but at a higher cost than waiting for a laboratory result. Future research is needed to distinguish pathogens from contaminants, assess the impact of the clean-catch algorithm on patient outcomes, and the cost-effectiveness of presumptive versus dipstick versus laboratory-guided antibiotic treatment.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Fluid and Volume Monitoring

Background

Fluid resuscitation is not only used to prevent acute kidney injury (AKI) but fluid management is also a cornerstone of treatment for patients with established AKI and renal failure. Ultrafiltration removes volume initially from the intravascular compartment inducing a relative degree of hypovolemia. Normal reflex mechanisms attempt to sustain blood pressure constant despite marked changes in blood volume and cardiac output. Thus, compensated shock with a normal blood pressure is a major cause of AKI or exacerbations of AKI during ultrafiltration.

Methods

We undertook a systematic review of the literature using MEDLINE, Google Scholar and PubMed searches. We determined a list of key questions and convened a 2-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated clinical practice recommendations and/or directions for future research.

Results

We defined three aspects of fluid monitoring: i) normal and pathophysiological cardiovascular mechanisms; ii) measures of volume responsiveness and impending cardiovascular collapse during volume removal, and; iii) measured indices of each using non-invasive and minimally invasive continuous and intermittent monitoring techniques. The evidence documents that AKI can occur in the setting of normotensive hypovolemia and that under-resuscitation represents a major cause of both AKI and mortality ion critically ill patients. Traditional measures of intravascular volume and ventricular filling do not predict volume responsiveness whereas dynamic functional hemodynamic markers, such as pulse pressure or stroke volume variation during positive pressure breathing or mean flow changes with passive leg raising are highly predictive of volume responsiveness. Numerous commercially-available devices exist that can acquire these signals.

Conclusions

Prospective clinical trials using functional hemodynamic markers in the diagnosis and management of AKI and volume status during ultrafiltration need to be performed. More traditional measure of preload be abandoned as marked of volume responsiveness though still useful to assess overall volume status.

[Assessment of kidney function : Creatinine is not the whole story]

Chronic renal insufficiency has a high prevalence and leads not only to a severe impairment in the quality of life but also to a higher mortality, mainly due to cardiovascular complications; however, in the early stages where there is still a chance for a therapeutic intervention, it is often underestimated because depending on endogenous factors (e.g. age and muscle mass), serum creatinine could falsely remain in the normal range while kidney function is already impaired. An exact measurement of the glomerular filtration rate (GFR) using radionuclide techniques is cumbersome and usually confined to rare cases, such as in clinical studies. Creatinine clearance measurement by 24-h urine collection requires good patient instructions and is error prone, thus it is limited to special circumstances. In routine clinical practice, estimation of the GFR by calculation algorithms provides the best approach. In recent years the chronic kidney disease epidemiology collaboration (CKD-EPI) formula has become established as the most accurate method. This should be used for screening and continuous surveillance. In addition, urinalysis including dipstick tests and urinary microscopy represent non-invasive, technically simple and economic screening tools. Due to its semiquantitative nature, the results of urinalysis should only to be interpreted after comprehensive consideration of the diagnostic and technical limitations, which are reviewed in this article.

Glycosuria and Renal Outcomes in Patients with Nondiabetic Advanced Chronic Kidney Disease

Sodium glucose cotransporter 2 inhibitors have shown a potential for renoprotection beyond blood glucose lowering. Glycosuria in nondiabetic patients with chronic kidney disease (CKD) is sometimes noted. Whether glycosuria in CKD implies a channelopathy or proximal tubulopathy is not known. The consequence of glycosuria in CKD is also not studied. We performed a cross-sectional study for the association between glycosuria and urine electrolyte excretion in 208 nondiabetic patients. Fractional excretion (FE) of glucose >4% was 3.4%, 6.3% and 62.5% in CKD stage 3, 4 and 5, respectively. These patients with glycosuria had higher FE sodium, FE potassium, FE uric acid, UPCR, and urine NGAL-creatinine ratio. We conducted a longitudinal study for the consequence of glycosuria, defined by dipstick, in 769 nondiabetic patients with stage 4-5 CKD. Glycosuria was associated with a decreased risk for end-stage renal disease (adjusted hazard ratio: 0.77; CI = 0.62-0.97; p = 0.024) and for rapid renal function decline (adjusted odds ratio: 0.63; CI = 0.43-0.95; p = 0.032); but glycosuria was not associated with all-cause mortality or cardiovascular events. The results were consistent in the propensity-score matched cohort. Glycosuria is associated with increased fractional excretion of electrolytes and is related to favorable renal outcomes in nondiabetic patients with stage 5 CKD.

Characterization of Standard Urine Properties in Noncomplicated Orthotopic Ileal Neobladders: A Prospective Controlled Study

OBJECTIVE

To characterize the standard physical, chemical, and microscopic characteristics of urine in patients with noncomplicated orthotopic ileal neobladders.

MATERIALS AND METHODS

This is a prospective study that included 100 male patients who underwent radical cystectomy and ileal neobladder between 1993 and 2013. All included patients were in a good health and having satisfactory function of the reservoirs with normal upper tract with a minimum 1-year postoperative follow-up. We excluded patients with oncological failure, those with diversion-related complications, those who were maintained on clean intermittent catheterization, or those who have symptoms of urinary tract infection. Patients with medical diseases that may affect urine properties (eg, diabetes mellitus) or receiving special medications (eg, diuretics, alkali therapy, or antibiotics) were also excluded. The patients were subjected to urine analysis, blood chemistry, pH, and blood gases; the results were compared to a control group of 40 normal male volunteers.

RESULTS

Urine analysis in diverted patients showed higher urine pH than in control group but it is still acidic. Pyuria, proteinuria, hematuria, and positive culture were significantly higher in diverted patients. The chemical analysis showed lower urinary calcium, phosphorus, and creatinine contents in diverted patients than in the control group. Serum creatinine was significantly higher in diverted patients, whereas blood pH and bicarbonate were lower, but these values are within normal.

CONCLUSION

Urine from uncomplicated orthotopic ileal reservoirs is acidic. Pyuria, proteinuria, minor degrees of microscopic hematuria, and positive nitrite reaction are normal findings. We also have normal findings for lower urinary calcium, phosphorus, and creatinine contents in patients.

Feasibility and quality development of biomaterials in the pretest studies of the German National Cohort

BACKGROUND

The German National Cohort (GNC) is designed to address research questions concerning a wide range of possible causes of major chronic diseases (e.g. cancer, diabetes, infectious, allergic, neurologic and cardiovascular diseases) as well as to identify risk factors and prognostic biomarkers for early diagnosis and prevention of these diseases. The collection of biomaterials in combination with extensive information from questionnaires and medical examinations represents one of the central study components.

OBJECTIVES

In two pretest studies of the German National Cohort conducted between 2011 and 2013, a range of biomaterials from a defined number of participants was collected. Ten study centres were involved in pretest 1 and 18 study centres were involved in pretest 2. Standard operation procedures (SOP) were developed and evaluated to minimize pre-analytical artefacts during biosample collection. Within the pretest studies different aspects concerning feasibility of sample collection/preparation [pretest 1 (a)] and quality control of biomarkers and proteome analyses were investigated [pretest 1 (b), (c)]. Additionally, recruitment of study participants for specific projects and examination procedures of all study centres in a defined time period according to common standards as well as transportation and decentralized storage of biological samples were tested (pretest 2). These analyses will serve as the basis for the biomaterial collection in the main study of the GNC starting in 2014.

MATERIALS AND METHODS

Participants, randomly chosen from the population (n = 1000 subjects recruited at ten study sites in pretest 1) were asked to donate blood, urine, saliva and stool samples. Additionally, nasal and oropharyngeal swabs were collected at the study sites and nasal swabs were collected by the participants at home. SOPs for sample collection, preparation, storage and transportation were developed and adopted for pretest 2. In pretest 2, 18 study sites (n = 599 subjects) collected biomaterials mostly identical to pretest 1. Biomarker analyses to test the quality of the biomaterials were performed.

RESULTS

In pretest 1 and 2, it was feasible to collect all biomaterials from nearly all invited participants without major problems. The mean response rate of the subjects was 95 %. As one important result we found for example that after blood draw the cellular fraction should be separated from the plasma and serum fractions during the first hour with no significant variation for up to 6 h at 4 ℃ for all analysed biomarkers. Moreover, quality control of samples using a proteomics approach showed no significant clustering of proteins according to different storage conditions. All developed SOPs were validated for use in the main study after some adaptation and modification. Additionally, electronic and paper documentation sheets were developed and tested to record time stamps, volumes, freezing times, and aliquot numbers of the collected biomaterials.

DISCUSSION

The collection of the biomaterials was feasible without major problems at all participating study sites. However, the processing times were in some cases too long. To avoid pre-analytical artefacts in sample collection, appropriate standardisation among the study sites is necessary. To achieve this, blood and urine collection will have to be adapted to specific conditions of usage of liquid handling robots, which will be available at all participating study centres in the main study of the GNC. Strict compliance with the SOPs, thorough training of the staff and accurate documentation are mandatory to obtain high sample quality for later analyses. The so obtained biomaterials represent a valuable resource for research on infectious and other common complex diseases in the GNC.

Preanalytical requirements of urinalysis

Urine may be a waste product, but it contains an enormous amount of information. Well-standardized procedures for collection, transport, sample preparation and analysis should become the basis of an effective diagnostic strategy for urinalysis. As reproducibility of urinalysis has been greatly improved due to recent technological progress, preanalytical requirements of urinalysis have gained importance and have become stricter. Since the patients themselves often sample urine specimens, urinalysis is very susceptible to preanalytical issues. Various sampling methods and inappropriate specimen transport can cause important preanalytical errors. The use of preservatives may be helpful for particular analytes. Unfortunately, a universal preservative that allows a complete urinalysis does not (yet) exist. The preanalytical aspects are also of major importance for newer applications (e.g. metabolomics). The present review deals with the current preanalytical problems and requirements for the most common urinary analytes.

Dipstick urinalysis screening of healthy neonates

BACKGROUND

Renal disease may accidentally be discovered during urinalysis. This study was conducted to examine the usefulness of dipstick urinalysis screening in healthy neonates for the diagnosis of underlying renal disease and to study the magnitude of abnormal urinalysis in apparently healthy neonates.

METHODS

In this descriptive study, voided urine samples were obtained from 400 apparently healthy neonates and tested using urine dipstick. The reaction of dipstick strip was read visually by a trained nurse. In cases with an abnormal urine analysis, a second screen test was performed within a week, and for those with persistent abnormalities, complete diagnostic tests were done.

RESULTS

On the first urinalysis, 375 (94%) subjects were normal and 25 (6%) had abnormalities: 23 had proteinuria (5.75%), one was blood positive (0.25%), and one was both protein and blood positive (0.25%). Male neonates had a higher proportion of proteinuria than female neonates (p=0.038). In the second examination, proteinuria was found in five (1.25%) neonates, but the proportion of other abnormalities did not change. In follow-up investigations, ureteropelvic junction obstruction and vesicoureteral reflux were recognized in two infants who had blood-positive or combined blood- and protein-positive results on their first tests.

CONCLUSION

The findings of this study show that dipstick test during neonatal period could be used for early diagnosis of renal diseases.

Recent and potential developments in the analysis of urine: a review

Analysis of urine is a widely used diagnostic tool that traditionally measured one or, at most, a few metabolites. However, the recognition of the need for a holistic approach to metabolism led to the application of metabolomics to urine for disease diagnostics. This review looks at various aspects of urinalysis including sampling and traditional approaches before reviewing recent developments using metabolomics. Spectrometric approaches are covered briefly since there are already a number of very good reviews on NMR spectroscopy and mass spectrometry and other spectrometries are not as highly developed in their applications to metabolomics. On the other hand, there has been a recent surge in chromatographic applications dedicated to characterising the human urinary metabolome. While developments in the analysis of urine encompassing both classical approaches of urinalysis and metabolomics are covered, it must be emphasized that these approaches are not orthogonal - they both have their uses and are complementary. Regardless, the need to normalise analytical data remains an important impediment.

Urinalysis interpretation

DURING INTRAUTERINE LIFE, the placenta is primarily responsible for electrolyte management in the fetus. The most important function of the kidney before birth is its role in formation and excretion of urine to maintain and promote an adequate amount of amniotic fluid.1 However, postnatally, the kidneys are responsible for fluid and electrolyte homeostasis. The kidneys mature at a rate proportional to gestational age. Thus, the kidneys of preterm infants are at a significant disadvantage.

Urinalysis is not reliable to detect a urinary tract infection in febrile infants presenting to the ED

OBJECTIVE

Urinary tract infections are a common source of serious bacterial infections in febrile infants younger than 2 years. Our objective was to compare urinalysis with urine culture in the emergency department evaluation of febrile infants.

METHODS

A febrile infant registry was instituted at a tertiary care hospital treating an average of 55000 patients annually (27% children), from December 2002 to December 2003. Patients were eligible if they were younger than 3 months and had a temperature of at least 38 degrees C or if they were between 3 and 24 months of age and had a temperature of at least 39 degrees C. Data abstracted included age, sex, and temperature. Urinalysis (UA) and urine culture (UCx) results were obtained from electronic hospital archives.

RESULTS

Nine hundred eighty-five patients were entered into the febrile infant registry. Male patients comprised 55%. The mean age of patients was 12.6 months; median was 12 months. Four hundred thirty-five (78% of eligible patients) had both a UA and UCx from the same specimen, and there were 45 (10.3%) positive UCx result. Females accounted for 33 (73%) of 45 positive results. The sensitivity of UA for predicting a positive UCx result was 64% (95% confidence interval [CI], 49%-78%), whereas the specificity was 91% (95% CI, 88%-94%). The positive predictive value was 46% (95% CI, 31%-53%), with a negative predictive value of 96% (95% CI, 93%-97%).

CONCLUSION

Urinalysis is not reliable for the detection of urinary tract infections in febrile infants when compared with urine cultures.

School urinalysis screening in Korea

Since 1998, by law, all school children in Korea must have an annual urinalysis. The first early morning urine specimen is examined by a simple dipstick method for the detection of proteinuria, haematuria and glucose. If a urine test is positive, a second test is performed by paediatric nephrologists. We analysed urinalysis data of school urinalysis screening. We also analysed the results of clinical data and the renal biopsy findings of patients referred to our medical centre due to abnormal urinalysis result. To date, about five million students have been screened since annual school urinalysis started in January 1998. Among them, isolated proteinuria was about 0.2%, occult blood was about 0.8%, and glucosuria was about 0.07% from January 1998 to December 2004. Among referred patients, renal biopsy was taken in 63.1% of isolated haematuria, 10.5% of isolated proteinuria and 69.9% of haematuria combined with proteinuria. Histopathological findings are IgA nephropathy in 43.8%, mesangial proliferative glomerulonephritis in 38.4%, Henoch-Schönlein nephritis in 2.7%, membranoproliferative glomerulonephritis in 1.6% and lupus nephritis in 0.5%. Alport disease showed 0.6% as a hereditary disease. In conclusion, the school urinalysis screening could detect chronic renal disease in its early stage. Early detection using school urinalysis screening and confirmatory diagnosis by renal biopsy seems to be helpful for assessment of prognosis and intervention of chronic renal disease progression.