Renal biopsy in children with asymptomatic hematuria or proteinuria: survey of pediatric nephrologists

How to define and assess the clinically significant causes of hematuria in childhood

Given the wide diversity of causes of hematuria, ranging from simple urinary tract infections with rapid recovery to severe glomerulonephritis with fast decline in kidney function, it is essential to recognize the underlying disease. The first objective of the assessment is to determine whether the cause of the hematuria is medically significant. The combination of hematuria with proteinuria, the presence of hypertension, or worsening kidney function can represent signs of progressive kidney disease. Differentiating the various causes of hematuria is often simple and obvious based on the clinical signs and gross appearance of the urine. However, in some instances, additional non-invasive investigations, such as ultrasound imaging, urinary red cell morphology, measurement of calcium and other solutes in the urine, evaluation of kidney function, and protein excretion, are needed to elucidate the nature of the hematuria. Taking a detailed family history can help in establishing the underlying cause in cases of familial hematuria. On the other hand, the decision to perform a kidney biopsy in children with asymptomatic hematuria remains a challenging issue for clinicians. Ultimately, the frequency of diagnosis of glomerular involvement causing hematuria may depend on the threshold for performing a kidney biopsy. The following review will focus on the diagnostics of hematuria, starting with difficulties regarding its definition, followed by various means to differentiate between urinary, glomerular, and other causes, and finally reviewing the most common diseases that, due to their frequency or their effect on kidney function, present a diagnostic challenge in everyday practice.

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.

ESPR uroradiology task force and ESUR Paediatric Work Group--Imaging recommendations in paediatric uroradiology, part VI: childhood renal biopsy and imaging of neonatal and infant genital tract. Minutes from the task force session at the annual ESPR Meeting 2012 in Athens on childhood renal biopsy and imaging neonatal genitalia

The European Society of Paediatric Radiology Uroradiology Task Force and the ESUR Paediatric Work Group jointly publish guidelines for paediatric urogenital imaging. Two yet unaddressed topics involving patient safety and imaging load are addressed in this paper: renal biopsy in childhood and imaging of the neonatal genital tract, particularly in girls. Based on our thorough review of literature and variable practice in multiple centers, procedural recommendations are proposed on how to perform renal biopsy in children and how to approach the genital tract in (female) neonates. These are statements by consensus due to lack of sufficient evidence-based data. The procedural recommendation on renal biopsy in childhood aims at improving patient safety and reducing the number of unsuccessful passes and/or biopsy-related complications. The recommendation for an imaging algorithm in the assessment of the neonatal genital tract focuses on the potential of ultrasonography to reduce the need for more invasive or radiating imaging, however, with additional fluoroscopy or MRI to be used in selected cases. Adherence to these recommendations will allow comparable data and evidence to be generated for future adaptation of imaging strategies in paediatric uroradiology.

Asymptomatic hematuria in childhood: a practical approach to evaluation

The differential diagnosis of hematuria with or without proteinuria is extensive, and isolated hematuria is a common problem in children and adolescents. Extensive evaluation is often necessary for the child presenting with macroscopic plus microscopic hematuria including nonglomerular and glomerular etiologies, while children with only isolated microscopic hematuria can generally be followed after baseline evaluation to rule out infection, hypercalciuria, familial hematuria, sickle cell disease, post-streptococcal glomerulonephritis (GN), and structural abnormalities (cysts, stones, obstruction, Wilms tumor). Children with the combination of hematuria and proteinuria require rapid systematic evaluation, generally including renal biopsy, except in cases where post-streptococcal GN can be clearly documented. Post-streptococcal GN occurs 7-21 days after a streptococcal infection, is associated with an acute fall in C3 levels with return to normal by approximately 8 weeks, rarely causes acute renal failure, and in children has a pattern of gradual resolution of hypertension, hematuria, and proteinuria over a course of 6-12 months.

Limited evaluation of microscopic hematuria in pediatrics

OBJECTIVE

The purpose was to determine the value of the standard laboratory and radiologic evaluation of microscopic hematuria in children, and to determine the prevalence of idiopathic hypercalciuria in those children referred for evaluation of unexplained microscopic hematuria.

METHODS

This was a retrospective study of 325 children referred from 1985 to 1994 for the evaluation of asymptomatic microscopic hematuria. The diagnostic studies reviewed included serum creatinine, blood urea nitrogen, serum electrolyte studies, serum complement concentration, antinuclear antibody, urinalysis, urine calcium to creatinine ratios, urinary protein to creatinine ratio and/or 24-hour urinary protein excretion, renal ultrasounds, intravenous pyelograms, voiding cystourethrograms, and historical information.

RESULTS

All creatinine and electrolyte values were normal for age, and none of the biochemical tests obtained in the children with hypercalciuria was abnormal. Of the 325 patients with idiopathic microscopic hematuria, only 18 had abnormal renal ultrasound examinations and 9 voiding cystourethrograms showed low-grade reflux. Hypercalciuria was found in 29 patients. The family history was positive for urolithiasis in 16% of patients without hypercalciuria compared with 14% of patients with hypercalciuria. A positive family history of hematuria was reported in 25% of patients; 62 patients did not have hypercalciuria and 4 of the patients had hypercalciuria. Microscopic hematuria in children is a benign finding in the vast majority of children.

CONCLUSIONS

Our data demonstrate that a renal ultrasound, voiding cystourethrogram, cystoscopy, and renal biopsy are not indicated in the work-up of microscopic hematuria, and microhematuria in the otherwise healthy child is a minimal health threat, rarely indicative of serious illness.

Asymptomatic microscopic hematuria--is investigation necessary?

Microscopic hematuria is common in asymptomatic adults, but the benefit of screening the general population for blood in the urine has not been established. On the other hand, most studies of referred patients with putatively asymptomatic microscopic hematuria have reported a 2-11% prevalence of urothelial malignancies, leading to the recommendation that all patients with microscopic hematuria be thoroughly investigated. Urinalysis is inexpensive and highly acceptable to the general population, but is neither a sensitive, nor specific test, and has poor predictive value for urothelial malignancies, and nephrological diseases. Furthermore the benefits of early detection of such diseases has not been established. We conclude that screening urinalysis cannot be recommended. Studies are needed to determine which constellation of findings primary physicians use to select patients for referral to centers with urological and nephrological expertise.

Hematuria. An integrated medical and surgical approach

The need to perform a detailed work-up of microscopic hematuria is based on the following set of questions: Does the history or physical examination findings suggest systemic or renal disease? Is the patient able to acidify and concentrate urine? Is proteinuria present? Do other family members have hematuria or other renal problems? Does the microscopic analysis show casts, crystals, or WBCs? Are the RBCs eumorphic or dysmorphic? Using this scheme of questions, most children do not require laboratory tests or radiographic studies. In the case of gross or macroscopic hematuria, the initial evaluation may require only a urine culture, urine calcium-to-creatinine ratio, and renal and bladder sonography or a very detailed evaluation for renal parenchymal disease, stones, tumors, or anatomic abnormalities. In these instances, consultation with a pediatric nephrologist, urologist, or both is necessary.