Paeds · nephrology-urology-fluids-and-electrolytes
Urinalysis, renal function and paediatric kidney assessment
Also known as Bedside Schwartz eGFR children · Urine dipstick interpretation paediatrics · Estimated GFR children · Protein-to-creatinine ratio children · Urinalysis interpretation paediatrics · Renal function testing children
A fellowship approach to paediatric kidney assessment at the bedside: how to collect and interpret urine, read the dipstick and microscopy, estimate glomerular filtration rate with the bedside Schwartz equation, stage chronic kidney disease, and combine urine and blood data into a safe plan from neonate to transition.
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Target exams
Red flags
- A normal serum creatinine treated as proof of normal kidney function in a sick or fluid-overloaded child
- Acting on a bag-urine culture without recognising the high contamination rate
- Quoting an estimated GFR without knowing which equation and which units produced it
- Applying adult reference intervals to a neonate or infant
- Discharging persistent unexplained haematuria or proteinuria without quantification or follow-up
- Missing acute kidney injury because creatinine has not yet risen from baseline
Life stages
Care settings
Clinical exam formats
Board mappings
- Nephrology, urology, fluids and electrolytes
- General and Community Paediatrics
- Learning objective: investigate and interpret abnormal urinalysis and renal function in infants, children and young people
- Learning goal 5: Clinical assessment — essential general paediatrics
- Learning goal 6: Clinical management — essential general paediatrics
- Learning goal 15: Essential general paediatrics
- Clinical Applications
- Medical Sciences
- Long Cases
- Short Cases
- 4. Professional skills and knowledge: Patient management
- 7. Patient safety, including safe prescribing
- 11. Complex long-term paediatric conditions
- Foundation of Practice (FOP)
- Theory and Science (TAS)
- Applied Knowledge in Practice (AKP)
- Clinical
- History
- Communication
- General Pediatrics Content Outline — Universal Task 3: Diagnosis
- General Pediatrics Content Outline — Universal Task 4: Management and Treatment
- General Pediatrics Content Outline — Domain 11: Nephrology and Urology
- Patient Care 4: Clinical Reasoning
- Patient Care 5: Patient Management
- Systems-Based Practice 1: Patient Safety
- Medical Expert
- Pediatrics: Foundations EPA #1 — Recognizing deteriorating and/or critically ill patients and initiating stabilization and management
- Pediatrics: Foundations EPA #8 — Communicating assessment findings and management plans to patients and/or families
Overview & Definition
A child passes urine, and you send blood to the laboratory. The two streams tell you different things, and the skill is making them speak to each other. Urinalysis tells you what is happening at the kidney surface and along the tubule right now. Renal function testing tells you how much filtration the kidney is performing. Together they separate pre-renal, intrinsic and post-renal problems, and they show whether a kidney is acutely injured, chronically scarred or working well. [2] [4]
Urinalysis means the macroscopic appearance of urine, the chemical dipstick, and the spun-urine microscopy. Each layer adds resolution. The dipstick is a screening tool; microscopy and culture confirm what it suggests. A dipstick is never the end of a diagnostic sentence in a sick child. [2] [3]
Renal function is the clearance work the kidney performs, summarised as the glomerular filtration rate. Direct measurement with iohexol or inulin clearance is the standard, but it is invasive and slow. At the bedside you estimate GFR from serum creatinine and height, because creatinine is freely filtered at the glomerulus and barely secreted or reabsorbed. [1] [11]
The bedside kidney-assessment pathway
- 1
Collect urine you can trust
Clean-catch or catheter for diagnosis; avoid bag urine where the result will change treatment.
- 2
Read dipstick plus microscopy
Pair the chemistry strip with cells and casts; never read the strip alone in a sick child.
- 3
Estimate GFR with Schwartz
eGFR equals 0.413 times height in cm divided by creatinine in mg per dL, indexed to 1.73 m2.
- 4
Quantify any abnormality
Protein-to-creatinine ratio and culture confirm a dipstick signal before you act.
- 5
Combine and trend
Marriage of urine and blood data, then trend the creatinine over hours to days.
References12ShowHide
- [1]Schwartz GJ, et al New equations to estimate GFR in children with CKD J Am Soc Nephrol, 2009.PMID 19158356
- [2]Simerville JA, et al Urinalysis: a comprehensive review Am Fam Physician, 2005.PMID 15791892
- [3]Whiting P, et al Rapid tests and urine sampling techniques for the diagnosis of urinary tract infection (UTI) in children under five years: a systematic review BMC Pediatr, 2005.PMID 15811182
- [4]Stevens PE, et al Evaluation and management of chronic kidney disease: synopsis of the kidney disease: improving global outcomes 2012 clinical practice guideline Ann Intern Med, 2013.PMID 23732715
- [5]Pottel H, et al Estimating glomerular filtration rate at the transition from pediatric to adult care Kidney Int, 2019.PMID 30922665
- [6]Hessey E, et al Evaluation of height-dependent and height-independent methods of estimating baseline serum creatinine in critically ill children Pediatr Nephrol, 2017.PMID 28523356
- [7]Clark M, et al Etiologies of asymptomatic microscopic hematuria in children - systematic review of 1092 subjects Diagnosis (Berl), 2015.PMID 29540037
- [8]Shaikh N, et al Prevalence of Asymptomatic Bacteriuria in Children: A Meta-Analysis J Pediatr, 2020.PMID 31787323
- [9]Bogie AL, et al Is There a Difference in the Contamination Rates of Urine Samples Obtained by Bladder Catheterization and Clean-Catch Collection in Preschool Children? Pediatr Emerg Care, 2021.PMID 34772880
- [10]Forster CS, et al Accuracy of NGAL as a Biomarker for Urinary Tract Infection in Young Febrile Children: An Individual Patient Data Meta-Analysis J Pediatr, 2023.PMID 37001635
- [11]Salvador CL, et al Estimating glomerular filtration rate in children: evaluation of creatinine- and cystatin C-based equations Pediatr Nephrol, 2019.PMID 30171354
- [12]Ng DK, et al Self-reported Race, Serum Creatinine, Cystatin C, and GFR in Children and Young Adults With Pediatric Kidney Diseases: A Report From the Chronic Kidney Disease in Children (CKiD) Study Am J Kidney Dis, 2022.PMID 34974031