Clinical Practice Guideline: Microhematuria in Children and Young Adults

Abstract

Background: Occult blood in the urine, or microhematuria, is a common finding (about 10%) in children and young adults. It is often of brief duration and therefore harmless. In persistent microhematuria, acanthocytes in the urine are a frequently unrecognized early marker of glomerular kidney disease. The purpose of this guideline is to promote the early detection of kidney disease in children and young adults with practical, evidence-based recommendations.

Methods: A systematic search for pertinent publications up to January 2023 was conducted in Pubmed, the Cochrane Database, and Livivo. 474 publications were retrieved, summarized in terms of method and content, and classified by Oxford (2011) evidence level.

Results: Approximately 1% of children and young adults have undiagnosed chronic kidney disease. Microhematuria is an early warning sign. A timely nephrological evaluation is indicated if microhematuria persists for 3 to 6 months, if ≥ 5% acanthocytes are detectable in the urine, and if there is also proteinuria, hypertension, or impaired renal function. Ultrasonography of the kidneys and urinary tract is the imaging method of choice; cystoscopy should be avoided. For patients with glomerular microhematuria, molecular genetic testing is recommended. Renal biopsy is recommended in case of florid glomerular diseases, after the determination of various laboratory param eters and clinical findings, including molecular genet ic testing especially in children.

Conclusion: In the absence of a guideline until now, findings have often been incorrectly assessed, leading either to an inadequate work-up or to excessive diagnostics. As a result, in approximately 30% of young patients, valuable opportunities for early treatment to protect the kidneys have been missed.

Figure

Workflow for evaluation of microhematuria: proposed on the basis of the recommendations as the primary structure and principal component of the guideline Red flag = fast track, should be clarified immediately by a (pediatric) nephrologist. ACE, angiotensin converting enzyme; eGFR, estimated glomerular filtration rate; FSGS, focal segmental glomerulosclerosis; IgA, immunoglobulin A; NGS, next generation sequencing; pat., patient; BP, blood pressure

Figure:

Microscopic difference between non-glomerular (a) and glomerular hematuria (b) Photos: Margit Schmude, University Medical Center Mainz

eFigure

PRISMA flow diagram of the bibliographic database search – search strategy structure PubMed, Public Medicine (medical database of the US-American National Institutes of Health); Livivo, internet-based search portal for live sciences; CDSR, Cochrane Database of Systematic Reviews