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

Shear-wave elastography in renal stiffness in children with hematuria and/or proteinuria

BACKGROUND

We sought to evaluate renal stiffness in children with hematuria and/or proteinuria using shear wave elastography (SWE) and to investigate the clinical value of renal stiffness in children with hematuria and/or proteinuria.

METHODS

According to the results of urinary occult blood and urinary protein tests, 349 pediatric patients were categorized into one of four groups: pure hematuria (HU), pure proteinuria (PU), concomitant hematuria and proteinuria (HUPU), or control (non-HUPU). Patient demographic data, laboratory test results, and renal ultrasound data were collected.

RESULTS

There were significant differences in cortical/medullary elasticity among the four groups (the most sensitive cutoff value between HU and PU was 1.72) (P < 0.05). We found that hematuria and proteinuria interacted with renal cortical elasticity (P < 0.05) but that hematuria and proteinuria did not interact with renal medullary elasticity or cortical/medullary elasticity (P > 0.05). Renal elasticity values correlated with sex, age, body surface area, body mass index, qualitative urinary protein, urine N-acetyl-β-D-glucosaminidase, 24-hour urinary protein quantity, renal volume, and renal cortical thickness (P < 0.05).

CONCLUSIONS

SWE can be used to detect changes in renal stiffness in children with hematuria and/or proteinuria. SWE is beneficial for the early detection of glomerular disease in children with abnormal urine test results.

IMPACT

This study evaluated the utility of shear wave elastography for the assessment of renal elasticity in pediatric patients presenting with hematuria and/or proteinuria. Children with pure proteinuria had significantly higher renal cortical/medullary elasticity values than those with pure hematuria. An interaction effect between hematuria and proteinuria on renal cortical stiffness was observed. Shear wave elastography can be used as a tool to assess early renal injury in children with urinalysis abnormalities.

Clinical and diagnostic utility of genomic sequencing for children referred to a Kidney Genomics Clinic with microscopic haematuria

BACKGROUND

Microscopic haematuria in children is associated with the risk of progression to chronic kidney disease. Genetic disease is an important potential aetiology. Genomic sequencing presents the most effective diagnostic route for these conditions, but access remains inequitable internationally.

METHODS

We conducted a retrospective review of the electronic medical records of a Kidney Genomics Clinic (KGC) from January 2016 to December 2021.

RESULTS

Sixty patients were referred to the KGC with haematuria over this period. Forty-three percent of patients had analysis of a limited haematuria panel (COL4A1, COL4A3, COL4A4, COL4A5, MYH9) with 58% receiving a genetic diagnosis. Forty-two percent of referred patients had further analysis of genes implicated in the development of kidney disease, and 36% received a diagnosis. Eight percent of patients underwent cascade testing for a known familial variant, and all received a diagnosis. Children with the highest levels of haematuria (> 500 × 106/L red blood cells) had the highest diagnostic yield (67%). Proteinuria, defined as a urinary protein to creatinine ratio > 20, increased the diagnostic yield from 31 to 65%. Importantly, negative genetic analysis can still have significant clinical utility for patients by altering surveillance and further management; the genetic result had clinical utility in 60% of patients.

CONCLUSIONS

Our KGC review highlights the substantial clinical utility and diagnostic yield of genomic analysis for microscopic haematuria in paediatric patients. Whilst the management of variants of uncertain significance can be challenging, a multidisciplinary team including genetic counselling can help ensure these patients are followed up meaningfully. A higher resolution version of the Graphical abstract is available as Supplementary information.

Evaluation of Proteinuria and Hematuria in Ambulatory Setting

Proteinuria and/or hematuria are common findings in ambulatory settings. Proteinuria can be glomerular and/or tubular in origin and it may be transient, orthostatic, or persistent. Persistent proteinuria may be indicative of a serious kidney pathology. Hematuria, which denotes the presence of an increased number of red blood cells in the urine, can be gross or microscopic. Hematuria can originate from the glomeruli or other sites of the urinary tract. Asymptomatic microscopic hematuria or mild proteinuria in an otherwise healthy child is less likely to be of clinical significance. However, the presence of both requires further workup and careful monitoring.

Persistent asymptomatic isolated microscopic hematuria in adolescents is not associated with an increased risk for early onset urinary tract cancer

OBJECTIVE

To elucidate the association between adolescent microscopic hematuria and early onset urothelial carcinoma and renal cell carcinoma.

METHODS

Nationwide, population-based, retrospective cohort study using medical data of 970,366 adolescents aged 16 through 19 years (58.6% male) examined for fitness for military service between 1980 and 1997. Diagnoses of persistent isolated microscopic hematuria were given after thorough work up process excluding any other renal abnormalities. Incident cases of urothelial carcinoma and renal cell carcinoma diagnosed during the years of 1982 to 2012 were retrieved from the Israeli National Cancer Registry. Cox proportional hazards models were used to estimate the hazard ratio (HR) separately for urothelial carcinoma and renal cell carcinoma.

RESULTS

During a cumulative follow-up of 22,115,629 person-years (median follow-up, 22.8), persistent isolated microscopic hematuria was diagnosed among 5509 (0.6%) adolescents. Urothelial carcinoma and renal cell carcinoma developed in 332 (3 among those with persistent isolated microscopic hematuria) and 292 (2) individuals, respectively. The adjusted HR for incident urothelial carcinoma among adolescents with isolated microscopic hematuria was 1.17 (95% CI, 0.38-3.66) and the adjusted HR for renal cell carcinoma was 1.02 (95% CI, 0.25-4.12).

CONCLUSIONS

Persistent asymptomatic isolated microscopic hematuria at adolescence was not associated with increased risk for urothelial carcinoma nor renal cell carcinoma.

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.

Approach to the Child with Hematuria

The causes of macroscopic and microscopic hematuria overlap; both are often caused by urinary tract infections or urethral/bladder irritation. Coexistent hypertension and proteinuria should prompt investigation for glomerular disease. The most common glomerulonephritis in children is postinfectious glomerulonephritis. In most patients, and especially with isolated microscopic hematuria, the diagnostic workup reveals no clear underlying cause. In those cases whereby a diagnosis is made, the most common causes of persistent microscopic hematuria are thin basement membrane nephropathy, immunoglobulin A nephropathy, or idiopathic hypercalciuria. Treatment and long-term prognosis varies with the underlying disease.