Intravenous Albumin for Oedema in Children With Nephrotic Syndrome: A Systematic Review and Mapping of the Evidence Landscape.

Nephrotic syndrome is a common glomerular disorder in childhood, often complicated by oedema, which contributes to morbidity, discomfort and prolonged hospitalisation. Intravenous (IV) albumin is frequently used with diuretics in children with resistant oedema, but its effectiveness and safety remain uncertain. Previous reviews are limited by adult populations, small sample sizes or a lack of quantitative synthesis. Our aim was to systematically evaluate the effectiveness and safety of IV albumin, with or without diuretics, versus no albumin in hospitalised children with nephrotic syndrome and oedema, and to map excluded-but-relevant studies to identify evidence gaps. We searched PubMed, Cochrane CENTRAL, Google Scholar and Europe PMC from January 1, 1990, to June 30, 2025, using MeSH terms and free-text keywords for nephrotic syndrome, albumin and paediatric populations. Reference lists of eligible studies and prior reviews were hand-searched. We included randomised controlled trials (RCTs), quasi-RCTs and comparative observational studies in children aged 1-18 years hospitalised with nephrotic syndrome and oedema. Studies without a comparator, non-paediatric populations, non-English publications or single-arm case series were excluded. Two reviewers independently screened records, extracted data and assessed risk of bias using the Cochrane Risk of Bias 2.0 tool (ROB 2) for RCTs. Due to the paucity of eligible studies and heterogeneity, outcomes were narratively synthesised. Excluded-but-relevant studies were mapped to identify evidence gaps. Out of 784 screened records, only one RCT met the inclusion criteria. Albumin plus furosemide significantly increased short-term urine output and weight reduction compared to furosemide alone, but effects were transient, and patient-centred outcomes were largely unassessed. Evidence mapping revealed multiple excluded studies with methodological limitations, inappropriate comparators or adult/mixed populations. Previous reviews corroborated the transient physiological effects but lacked paediatric-specific conclusions. We concluded that evidence supporting IV albumin use in hospitalised children with nephrotic syndrome is extremely limited. Albumin may provide short-term physiological benefit in select cases, but routine use is not justified. High-quality, adequately powered paediatric RCTs with standardised outcomes and systematic safety reporting are urgently needed to guide clinical practice.