Limited evaluation of microscopic hematuria in pediatrics

Variants in genes coding for collagen type IV α-chains are frequent causes of persistent, isolated hematuria during childhood

BACKGROUND

Children with persistent, isolated microscopic hematuria typically undergo a limited diagnostic workup and are monitored for signs of kidney disease in long-term longitudinal follow-up, which can delay diagnosis and allow disease progression in some cases.

METHODS

To determine the clinical utility of genetic screening in this population, we performed targeted genetic testing using a custom, 32-gene next-generation sequencing panel for progressive kidney disease on children referred to the Texas Children's Hospital Pediatric Nephrology clinic for persistent, microscopic hematuria (n = 30; cohort 1). Patients with microscopic hematuria identified by urinalysis on at least two separate occasions were eligible for enrollment, but those with other evidence of kidney disease were excluded. Results were analyzed for sequence variants using the American College of Medical Genetics and Genomics (ACMG) guideline for data interpretation and were validated using a secondary analysis of a dataset of children with hematuria and normal kidney function who had undergone genetic testing as part of an industry-sponsored program (cohort 2; n = 67).

RESULTS

In cohort 1 33% of subjects (10/30) had pathogenic or likely pathogenic (P/LP) variants in the type IV collagen genes (COL4A3/A4/A5), and 10% (3/30) had variants of uncertain significance in these genes. The high diagnostic rate in type IV collagen genes was confirmed in cohort 2, where 27% (18/67) of subjects had P/LP variants in COL4A3/A4/A5 genes.

CONCLUSIONS

Children with persistent, isolated microscopic hematuria have a high likelihood of having pathogenic variants in type IV collagen genes and genetic screening should be considered. A higher resolution version of the Graphical abstract is available as Supplementary information.

Approach to Persistent Microscopic Hematuria in Children

Persistent isolated microscopic hematuria is relatively common in pediatric practice, affecting around 0.25% of children. Isolated microscopic hematuria can be caused by a myriad of potentially benign or serious causes, including urologic issues; kidney stones; glomerular diseases, including disorders of the glomerular basement membrane; hematologic abnormalities; and others. The challenge for the pediatrician or pediatric nephrologist is to distinguish children with potentially progressive forms of kidney disease versus other causes while minimizing cost and inconvenience for the child and family. This manuscript will review the multiple potential causes of microscopic hematuria and provide a framework for the initial evaluation and monitoring of such patients.

Evidence of a link between fever and microscopic hematuria in children

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

CONCLUSION

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

Clinical and histopathological features of asymptomaticpersistent microscopic hematuria in children

BACKGROUND/AIM

We analyzed the clinical and pathological features and prognosis of 106 children with persistent asymptomatic microscopic hematuria (PAMH) with or without mild proteinuria.

MATERIALS AND METHODS

This was a retrospective study of 106 children who were referred to our clinics from 2000 to 2013 for evaluation of PAMH.

RESULTS

Among the 106 patients, 69 (65%) were female and 37 (35%) were male. The patients were divided into two groups: 101 patients with isolated microscopic hematuria (IMH) and 5 patients with asymptomatic microscopic hematuria and mild proteinuria (AMHP). Renal biopsy was performed in all 5 children with AHMP: 2 patients had hereditary nephropathy and 2 patients had focal segmental glomerulosclerosis (FSGS). One biopsy specimen revealed nonspecific findings. Renal biopsy was performed in 9 children with IMH: 4 patients had hereditary nephropathy and 5 patients had nonspecific findings. None of the patients received any specific treatment prior to renal biopsy. During the follow-up period, none of the patients developed impaired renal function. Among all the children, only one patient with AMHP developed hypertension and 2 patients with IMH developed proteinuria.

CONCLUSION

Long-term follow-up must be done carefully for isolated microscopic hematuria and renal biopsy should be performed in selected cases.

Positive trends in paediatric renal biopsy service provision in the UK: a national survey and re-audit of paediatric renal biopsy practice

BACKGROUND

Paediatric renal biopsy standards introduced in the UK in 2010 were intended to reduce variation and improve practice. A concurrent national drive was aimed at building robust paediatric nephrology networks to ensure services cater for the needs of the family and minimise time away from home. We aimed to identify current national practice since these changes on behalf of the British Association for Paediatric Nephrology.

METHODS

All UK paediatric nephrology centres were invited to complete a survey of their biopsy practice, including advance preparation. From 1 January to 30 June 2012, a national prospective audit of renal biopsies was undertaken at participating centres comparing practice with the British Association for Paediatric Nephrology (BAPN) standards and audit results from 2005.

RESULTS

Survey results from 11 centres demonstrated increased use of pre-procedure information leaflets (63.6 % vs 45.5 %, P = 0.39) and play preparation (90.9 % vs 9.1 %, P = 0.0001). Audit of 331 biopsies showed a move towards day-case procedures (49.5 % vs 32.9 %, P = 0.17) and reduced major complications (4.5 % vs 10.4 %, P = 0.002). Biopsies with 18-gauge needles had significantly higher mean pass rates (3.2 vs 2.3, P = 0.0008) and major complications (15.3 % vs 3.3 %, P = 0.0015) compared with 16-gauge needles.

CONCLUSIONS

Percutaneous renal biopsy remains a safe procedure in children, thus improving family-centered service provision in the UK.

Etiologies of asymptomatic microscopic hematuria in children - systematic review of 1092 subjects

BACKGROUND

Asymptomatic microscopic hematuria is common in children. No systematic review providing an evidence based approach for the differential diagnosis of these children has been performed.

CONTENTS

Multiple data bases were search. The PRISMA criteria were followed. Data regarding the etiology of the hematuria were extracted using a standardized extraction tool. Seven studies encompassing 1092 children (857 with isolated microscopic hematuria and 235 with combined microscopic hematuria and proteinuria), comprise this review. A total 42.4% of isolated microscopic and 81.3% of microscopic hematuria and proteinuria subjects had identified etiologies. Thin basement membrane nephritis (15.2%), IgA nephropathy (10.4%), and hypercalciuria without nephrolithiasis (7.7%), were the most common etiologies among children with isolated microscopic hematuria. IgA nephropathy (44.3%), thin basement membrane disease (12.8%), and mesangial proliferative glomerulosclerosis (8.9%) were the most common etiologies among children with combined microscopic hematuria and proteinuria.

CONCLUSION

The present study provides an evidenced based resource, based on a systematic review, for the differential diagnosis of asymptomatic hematuria in children. Additionally, these observations suggest that children with isolated microscopic hematuria should be followed for persistence of hematuria or the development of proteinuria. Children with combined microscopic hematuria and proteinuria should be comprehensively evaluated.

Pediatric nephrolithiasis and the link to bone metabolism

PURPOSE OF REVIEW

To review the recent publications describing the link between pediatric nephrolithiasis and bone metabolism.

RECENT FINDINGS

Nephrolithiasis incidence is increasing in children and is associated with low bone mineral density (BMD). Affected children are conceptually at risk for fractures and osteoporosis. In addition to abnormal calcium metabolism, inflammation, genetic makeup and dietary habits are being recognized as important factors in the pathophysiology of nephrolithiasis and low bone density. Findings from retrospective reviews suggest that low BMD in children may be improved with citrate or thiazide treatment.

SUMMARY

The healthcare burden from low BMD with subsequent osteoporosis and fracture risk is immense with potential far-reaching effects in patient quality of life and healthcare expense. Bone mass is acquired in the pediatric age range, thus it is important to identify and treat at-risk children. Retrospective reviews in pediatric patients indicate that citrate or thiazide diuretic treatment may improve BMD. We now understand that a relationship exists between nephrolithiasis and low BMD. To improve healthcare for our current patients as well as protect their future health it is important to identify low BMD and initiate strategies to improve BMD in 'at-risk' children.

Random urinary calcium/creatinine ratio for screening hypercalciuria in children with hematuria

Background

Hypercalciuria is one of the most common causes of unexplained isolated hematuria. The diagnostic methods for hypercalciuria have not yet been standardized. The aim of this study was to assess whether random urinary calcium/creatinine ratio could be used as a screening tool for hypercalciuria in children with hematuria.

Methods

This prospective study included 264 children with primary hematuria for whom both random and 24 hr urinary evaluations were performed. Pearson correlation and ROC curve were used to assess the correlations. A multiple linear regression model was used to analyze effects of age, weight, height, body mass index, and body surface area on random urinary calcium/creatinine ratio.

Results

There was a moderately strong correlation between random urinary calcium/creatinine ratio and 24 hr urinary calcium excretion (r=0.584, P<0.001). The most appropriate cutoff value of random urinary calcium/creatinine ratio for the estimation of hypercalciuria was 0.075 mg/mg (sensitivity, 77.8%; specificity, 64.3%; area under the curve, 0.778). Body mass index and 24 hr urinary calcium excretion significantly affected random urinary calcium/creatinine ratio with a low coefficient of determination (r²=0.380, P<0.001).

Conclusions

Random urinary calcium/creatinine ratio is not suitable for screening hypercalciuria in children with hematuria. Twenty-four hour urinary analysis should be performed to diagnose hypercalciuria in children with hematuria.

Highlights for the management of a child with proteinuria and hematuria

The identification of hematuria or proteinuria in an otherwise healthy child can cause anxiety to both the family and the pediatrician. The etiology of hematuria and proteinuria includes a long list of conditions, and detailed workup can be exhaustive, expensive and not essential in most of the patients. As will be described in this paper, most of the children with proteinuria or hematuria have a benign etiology. The primary role of the pediatrician is to identify hematuria/proteinuria, recognize the common causes of hematuria/proteinuria, and more importantly identify children with serious conditions that need referral to the nephrologist in a timely manner.

Pediatric urolithiasis: clinical predictors in the emergency department

OBJECTIVE

The objective of this study was to identify factors that predict the presence of urolithiasis detected with unenhanced computed tomography (UCT) in children.

METHODS

A retrospective study of all subjects <21 years of age who presented to the emergency department at Akron Children's Hospital and underwent UCT of the abdomen between January 2002 and December 2005 was performed. Demographic, clinical, diagnostic, treatment, and disposition data were abstracted by using a standardized form. Univariate and logistic regression analyses of factors associated with urolithiasis were performed.

RESULTS

A total of 339 eligible patients were identified, with 110 cases of urolithiasis detected with UCT for 95 individual patients. The mean age of the study patients was 14.4 years; 72 patients (66%) were female. In 17 cases (15%) of urolithiasis, initial urinalysis results were negative for blood. Fifty-seven stones (51.8%) were ureteral, 26 (23.6%) were renal, and 4 (3.6%) were in the bladder. Among children who did not have a stone identified through UCT, 23 cases (10%) of potentially significant, alternative diagnoses were identified. A history of urolithiasis, a history of nausea and vomiting, the presence of flank pain on examination, and >2 red blood cells per high-power field in urine microscopy were positively associated with urolithiasis. A history of fever or dysuria and costovertebral angle tenderness on physical examination were inversely associated with urolithiasis on UCT scans.

CONCLUSIONS

UCT plays an important role in the diagnostic evaluation of children with flank pain. Approximately 15% of children with urolithiasis do not have hematuria.

Evaluation of pediatric patients with mild-to-moderate hypertension: yield of diagnostic testing

OBJECTIVE

Children and adolescents with newly diagnosed hypertension undergo various tests to define the cause and target organ consequences of the elevated blood pressure. We tested the hypothesis that the diagnostic yield of individual components of the currently recommended assessment does not justify performance for all patients with mild-to-moderate hypertension.

METHODS

A retrospective chart review was conducted of patients who were referred between July 2002 and June 2007 for mild-to-moderate hypertension, defined as maximum blood pressure at >or=95% + 20/10 mmHg. The assessment included history and physical examination, nutritional assessment, urinalysis, biochemical and fasting lipid profile, renal ultrasound, echocardiogram, and 24-hour ambulatory blood pressure monitoring.

RESULTS

A total of 249 patients were identified, and charts for 220 (88%) were available for review. There were 156 boys and 64 girls aged 13.3 +/- 4.4 years. BMI was 26.1 +/- 6.7 kg/m(2), and 143 (65%) had a BMI of >or=90%. Results of urinalysis and serum biochemical testing were clinically normal in all cases. Among those with a lipid profile, 59 (42%) had total cholesterol values of >170 mg/dL, and 26 (19%) had severe hypercholesterolemia (>200 mg/dL). Renal sonography revealed findings plausibly associated with hypertension in 14 (8%) patients; 4 (2%) had renovascular abnormalities. Yield of echocardiography was 17%. On ambulatory blood pressure monitoring, 47 (60%) children had systolic readings of >95% at least 20% of the time, and 28 (36%) had diastolic readings of >95% at least 20% of the time.

CONCLUSIONS

For children and adolescents with mild-to-moderate hypertension, on the basis of a cutoff of 5% to 20% abnormal results to define a useful test, the initial evaluation can range from a serum cholesterol level and ambulatory blood pressure monitoring to a panel that consists of a fasting lipid profile, renal ultrasound, echocardiogram, and ambulatory blood pressure monitoring. Additional assessment should be guided by specific clinical features and the nature of the patient population.

Evaluation of hematuria and proteinuria: how should a pediatrician proceed?

PURPOSE OF REVIEW

Finding blood or protein in the urine of a patient can be the source of immense anxiety. The list of diseases that result in these findings is quite long. Thus, many pediatricians believe that an exhaustive investigation is necessary to be certain of the cause. The review will discuss the major causes of hematuria and proteinuria in the pediatric population, and discuss a rational approach to the evaluation of these conditions.

RECENT FINDINGS

A number of recent studies have examined the results of mass screenings of school-age children and the final outcome of examination of children with hematuria and/or proteinuria. Most children with either isolated hematuria or isolated proteinuria had benign disease processes. Children with combined hematuria and proteinuria had a higher prevalence of significant kidney disease.

SUMMARY

The urinalysis combined with the history and physical examination should indicate the cause of hematuria and proteinuria in most cases. Significant renal disease can be ruled out with a minimal amount of work-up in most patients. The presence of hematuria and proteinuria together significantly increases the likelihood of significant renal disease and should prompt a referral to a specialist.

Screening for hypercalciuria in schoolchildren: what should be the criteria for diagnosis?

The methodologies to diagnose hypercalciuria have not yet been standardized. The aims of this study were to assess the correlation between urinary calcium/creatinine ratio (UCa/Cr) > or = 0.21 (mg/mg) and 24 h urinary calcium excretions and to determine the reference values of the UCa/Cr ratio among a large population of schoolchildren in southern Turkey. Non-fasting, second morning urine samples were collected from 2,143 children aged 7-14 years. In children with suspected hypercalciuria [UCa/Cr > or = 0.21 (mg/mg)], 24 h urine samples were collected. The 95th percentile values of the UCa/Cr ratio for each age were calculated and showed a decrease in value with advancing age. In all, 269 (12.5%) of the children had UCa/Cr > or = 0.21 (mg/mg), of whom 66 (24.5%) had daily urinary calcium excretion > or =4 mg/kg per day. A weak correlation was found between spot UCa/Cr ratios and daily urinary calcium excretions in children with UCa/Cr > or = 0.21 (r = 0.27). We conclude that a spot UCa/Cr ratio of 0.21 (mg/mg) as the upper limit of normal cannot be used universally to define hypercalciuria. Age-specific reference values for UCa/Cr should be established for each population, to be used as a screening test for hypercalciuria, and the definite diagnosis should be established with 24 h urinary calcium excretion whenever possible.

Effect of renal Doppler ultrasound on the detection of nutcracker syndrome in children with hematuria

To assess the detection rate of nutcracker syndrome in children with isolated hematuria, renal Doppler ultrasound examinations were routinely performed on 216 consecutive children (176 microscopic hematuria and 40 gross hematuria). Renal Doppler ultrasound was also performed on 32 healthy normal children. The peak velocity (PV) was measured at the hilar portion of the left renal vein (LRV) and at the LRV between the aorta and the superior mesenteric artery. The PV at the aortomesenteric portion (P=0.003) and the PV ratios of the LRV (P=0.003) were significantly higher in children with hematuria than in normal children, while the PV at the hilar portion was not different. If a PV ratio of the LRV of at least 4.1 (the cut-off level set at the mean +/-2 SD of the value for the normal children) was defined as abnormal, 72 cases (33.3%) in children with hematuria and no cases in normal children were diagnosed as having nutcracker syndrome. The prevalence of nutcracker syndrome is relatively high in children with isolated hematuria, and the inclusion of renal Doppler ultrasound as a screening examination has a substantial effect on the detection of nutcracker syndrome.

The long-term outcomes of idiopathic hypercalciuria in children

OBJECTIVE

Idiopathic hypercalciuria (IH) is a metabolic risk factor in patients with urinary calcium stones and implicated in 30%-50% of all urinary stone diseases. Clinical manifestations and distribution of types of IH are reviewed, as well as current treatment methods and long-term outcomes.

PATIENTS

A total of 131 patients (70 boys and 61 girls), aged 1-15 years (mean 7.9+/-3.19 years), were studied. Follow up was between 6 months and 16 years (mean 4.1+/-6.8 years).

RESULTS

Fifty-three patients (40%) were diagnosed following calcium challenge as renal type, and 51 (39%) as absorptive type of hypercalciuria. Whereas 72 patients (54.9%) had a family history of nephrolithiasis, 59 patients did not. Nephrolithiasis was found in 27 patients (20%) on admission (absorptive=9.9%, renal=4.5%, undetermined=6.1%), but developed in eight other patients (6.1%) (absorptive=2.2%, renal=0.7%, undetermined=3.8%). Urinary calcium excretion reversed in 65 patients with the suggested diet therapy; it recurred in 30 patients (22.9%) (absorptive=9.1%, renal=11.4%, undetermined=2.2%) but 35 returned to normal definitively (26.7%) (absorptive=11.4%, renal=12.9%, undetermined=2.2%). No change was seen in the status of 50 patients (38.1%) (absorptive=18.3%, renal=16%, undetermined=3.8%).

CONCLUSION

IH may be accompanied by nephrolithiasis; type must be determined and those patients with absorptive type should be followed for nephrolithiasis. Our results suggest that formation of new stones could be prevented with diet and thiazide therapies in IH.

Evaluation of gross hematuria

Gross hematuria in children is a common complaint that often leads patients to seek urgent care. The diagnostic evaluation can be chosen based on specific patient history and physical examination. When a patient is asymptomatic, hypercalciuria and mild forms of glomerulonephritis are common causes of gross hematuria. Although they are less common in children, special care should be taken to investigate for renal and bladder tumors.

The abnormal urinalysis

The urinalysis is one of the most commonly performed tests in pediatrics, and whether expected or incidental, abnormal findings are common. Understanding the strengths and limitations of the urinalysis allows one to maximize its use as a screening tool while avoiding expensive and unnecessary evaluations. This article reviews the significance of abnormal results on urine dipstick testing and urine microscopy. Causes of false positive and false negative results are summarized. Initial diagnostic considerations of abnormal urinalysis findings are provided where appropriate.

Pediatricians' screening urinalysis practices

OBJECTIVE

To determine pediatricians' routine screening urinalysis practices.

STUDY DESIGN

This was a survey of a nationally representative sample of pediatricians practicing in the U.S. regarding their screening urinalysis practices in childhood.

RESULTS

Of the 1502 pediatricians sampled, 653 eligible subjects participated, for an estimated response rate of 49.5%. The vast majority of participants (78%) routinely screen asymptomatic children with urinalysis in at least 1 age group. Pediatricians' screening urinalysis practice varies based on age group: 9% screen during infancy (<1 year), 60% screen during early childhood (1 up to 5 years), 55% screen during late childhood (5 to 12 years), and 58% screen during adolescence (13 to 20 years). The majority of pediatricians (58%) routinely screen more than 1 age group. Some 38% of the pediatricians surveyed believe that the overall health of children is improved by screening all asymptomatic children with urinalysis.

CONCLUSIONS

Many pediatricians routinely conduct screening urinalysis during childhood, frequently at ages not recommended by the American Academy of Pediatrics.

Evaluation of hematuria in children

The detection of blood in a child's urine is alarming and often prompts many laboratory studies. Hematuria is one of the most important signs of renal or bladder disease, but proteinuria often is a more important diagnostic and prognostic finding. The physician should ensure that serious conditions are not overlooked, avoid unnecessary laboratory studies, reassure the family, and provide guidelines for additional studies if there is a change in the child's course. This article provides an approach to the evaluation and management of hematuria in a child. Many tests have been recommended for the child with hematuria, but no consensus exists on a systematic evaluation.

Hematuria in children

Children with hematuria require a thorough history and physical examination. Not all children with hematuria require the same investigations. The only laboratory test uniformly required for children with the various presentations of hematuria is a complete urinalysis with a microscopic examination. The rest of the evaluation is tailored according to the pertinent history, physical examination, and other abnormalities on the urinalysis. This article has provided a brief summary of the more common causes of pediatric hematuria and suggestions for tailoring the patient's evaluation according to the presentation. Most causes of hematuria in pediatrics represent medical conditions that often require referral to a pediatric nephrologist. Indications for referral to a urologist are more limited and include stones that do not pass spontaneously or are more than 5 mm in diameter, renal injury from trauma, anatomic abnormalities, or gross hematuria that seems to originate from the urinary tract and is without an identified cause.