Kidney and urinary problems in children range from infections and congenital anomalies to immune-mediated kidney disease. Infants concentrate urine poorly and dehydrate quickly; young children cannot describe urinary symptoms, so fever may be the only sign of a urinary tract infection (UTI).
| Disorder | Key mechanism |
|---|
| UTI / pyelonephritis | Ascending infection, most often Escherichia coli. Girls are affected more after infancy (short urethra); uncircumcised male infants have higher risk in the first months |
| Vesicoureteral reflux (VUR) | Urine flows back from the bladder into the ureters (grades I–V). Reflux plus infection → kidney scarring, hypertension, chronic kidney disease |
| Nephrotic syndrome | Glomerular leak of protein. Most children have minimal change disease, which usually responds to steroids. Tetrad: massive proteinuria, hypoalbuminemia, edema, hyperlipidemia |
| Acute glomerulonephritis (AGN) | Most often post-streptococcal: immune complexes deposit in glomeruli about 1–2 weeks after pharyngitis or 3–6 weeks after skin infection (impetigo) → hematuria, sodium and water retention, hypertension |
| Enuresis | Involuntary voiding at night at age 5 or older. Primary (never dry) is usually developmental and familial; secondary (after 6 months dry) suggests a cause (UTI, diabetes, constipation, stress, sleep apnea) |
| Cryptorchidism | Testis not in the scrotum; risk of reduced fertility, torsion, and testicular cancer |
| Hypospadias | Urethral opening on the ventral (under) side of the penis, often with chordee (downward curve) |
| Bladder exstrophy | Bladder open on the lower abdominal wall |
| Testicular torsion | Twisting of the spermatic cord — a surgical emergency |
UTI
- Infants: fever, irritability, poor feeding, vomiting, jaundice, poor weight gain
- Older children: dysuria, frequency, urgency, new daytime or nighttime wetting, foul-smelling urine, suprapubic pain
- Pyelonephritis: high fever, flank or abdominal pain, vomiting, ill appearance
Nephrotic vs. nephritic
| Nephrotic syndrome | Acute glomerulonephritis |
|---|
| Usually age 2–6 years | Usually school age |
| Periorbital edema (worse in the morning) → generalized edema, ascites, scrotal or labial swelling | Mild periorbital and facial edema |
| Frothy urine (proteinuria) | Tea- or cola-colored urine (hematuria) |
| BP usually normal | Hypertension, headache |
| Weight gain, poor appetite, diarrhea | Oliguria, weight gain, recent strep infection |
Genital findings: empty scrotum (cryptorchidism — examine warm and relaxed; retractile testes can be brought down); abnormal meatus or downward curve (hypospadias); sudden severe scrotal pain, swelling, nausea and vomiting, high-riding testis, absent cremasteric reflex (torsion).
Urine specimen in a child not toilet-trained: catheterized specimen (or suprapubic aspiration) for culture. Bag specimens are contaminated too often to be used for culture; they are useful only when negative. Toilet-trained children give a clean-catch midstream sample.
| Test | Use |
|---|
| Urinalysis | Leukocyte esterase, nitrite, pyuria, bacteria; protein; blood |
| Urine culture | Diagnosis; febrile infants 2–24 months need pyuria and at least 50,000 CFU/mL of one organism in a catheter sample |
| Renal and bladder ultrasound | After the first febrile UTI in infants and young children |
| Voiding cystourethrogram (VCUG) | Diagnoses and grades VUR; generally after an abnormal ultrasound or a recurrent febrile UTI rather than routinely after the first |
| Urine protein-to-creatinine ratio | Nephrotic-range proteinuria: about 2 mg/mg (200 mg/mmol) or more |
| Serum albumin | Nephrotic: below 3.0 g/dL (30 g/L) |
| Serum C3 complement, ASO or anti-DNase B | Low C3 and evidence of recent strep infection in post-streptococcal AGN |
| Voiding diary and history | Enuresis: toilet-training history, daytime symptoms, fluid intake, bowel habits — the first step in evaluation |
| BUN, creatinine, electrolytes | Kidney function; potassium in kidney failure |
| Doppler ultrasound of the scrotum | Torsion — but do not delay surgery for imaging when torsion is clinically likely |
UTI / pyelonephritis
- Oral antibiotics for most children who can take fluids; IV antibiotics for young infants, ill-appearing or dehydrated children, and those who cannot tolerate oral intake. Obtain the culture before the first dose
- Common agents: cephalosporins (allergy history), amoxicillin-clavulanate (diarrhea), trimethoprim-sulfamethoxazole (rash, avoid in infants under 2 months — kernicterus risk). Adjust to culture results; total course commonly 7–14 days for febrile UTI, with shorter courses (about 5 days) increasingly used for children who improve quickly
VUR
- Many low-grade cases resolve with growth
- Continuous low-dose antibiotic prophylaxis is individualized — it reduces recurrent UTI, particularly in children with higher-grade reflux or bladder-bowel dysfunction, but is not given to every child
- Treat bladder and bowel dysfunction (constipation, holding urine); surgery (ureteral reimplantation or endoscopic injection) for high grades or breakthrough infections
Nephrotic syndrome
- Prednisone (initial episode, typical regimen): 60 mg/m²/day or 2 mg/kg/day (max 60 mg) for 4 weeks, then 40 mg/m² or 1.5 mg/kg on alternate days (max 40 mg) for 4 weeks — or 6 + 6 weeks — then stop as directed. Most children go into remission within 4 weeks; relapses are common
- Steroid safety: weight gain, moon face, hypertension, hyperglycemia, mood changes, infection risk, growth slowing, GI upset (give with food). Never stop abruptly. No live vaccines while on high-dose steroids
- Salt restriction during edema (not strict protein restriction); diuretics or albumin infusion for severe edema with close monitoring
- Steroid-sparing drugs for frequent relapses (e.g., calcineurin inhibitors, rituximab) — kidney function, blood pressure, infection risk
Acute glomerulonephritis
- Supportive: sodium and fluid restriction based on urine output, antihypertensives, loop diuretics
- Antibiotics only if streptococcal infection is still present
- Most children recover fully
Enuresis — enuresis alarm (most effective long-term) and/or desmopressin tablets at bedtime: limit fluids from 1 hour before to 8 hours after the dose because of hyponatremia and water intoxication (headache, vomiting, seizures). Do not give it during illness with vomiting, diarrhea, or fever, or after large fluid intake (hot weather, exercise). Intranasal desmopressin is no longer used for enuresis in the US because of hyponatremic seizures. Treat constipation first.
Kidney stones (uncommon in children; often metabolic or linked to immobility or UTI) — hydration, analgesia, and straining all urine to catch stone fragments for analysis, including after extracorporeal shock wave lithotripsy (ESWL); mild hematuria after ESWL is expected.
Acute kidney injury — treat the cause, fluid balance, hyperkalemia management; continuous kidney replacement therapy (CRRT) or dialysis when needed. Avoid NSAIDs and other nephrotoxins; doses of kidney-cleared drugs are adjusted.
Kidney transplant — lifelong immunosuppressants (e.g., tacrolimus with trough levels — tremor, hypertension, hyperglycemia, nephrotoxicity; mycophenolate — GI upset, leukopenia, teratogenic; corticosteroids). Rejection signs: rising creatinine, reduced urine output, weight gain, hypertension, graft tenderness, fever.
Surgery
- Cryptorchidism: refer by about 6 months (corrected age); orchiopexy ideally by 18 months. Hormone therapy is not recommended
- Hypospadias: repair usually at 6–18 months; no circumcision before repair (foreskin may be used)
- Testicular torsion: detorsion and orchiopexy — testicular survival falls sharply after about 6 hours
- Bladder exstrophy: staged reconstruction
Listed in priority order.
- Recognize emergencies — sepsis signs in an infant with UTI; hypertensive encephalopathy in AGN (severe headache, vomiting, visual change, seizures); hyperkalemia in kidney failure; torsion (keep NPO and notify surgery immediately)
- Obtain urine culture correctly (catheterized specimen in infants) before the first antibiotic dose, then give antibiotics promptly
- Fluid balance
- Daily weight (same scale, same time) — the most sensitive measure of fluid retention; strict intake and output; abdominal girth in nephrotic syndrome
- Nephrotic syndrome and AGN: sodium restriction; fluid limits as ordered; BP monitoring
- UTI: encourage fluids unless restricted
- Nephrotic syndrome — skin care for edematous areas (turn frequently, support the scrotum, keep skin folds dry); infection prevention (peritonitis, cellulitis); watch for thrombosis (hypercoagulable state); daily urine dipstick for protein at home as taught
- CRRT / dialysis — hourly fluid balance, frequent electrolytes (potassium, calcium, phosphate), filter and circuit checks, catheter site care, temperature (circuits cool the child), bleeding with anticoagulation
- Postoperative GU care
- Hypospadias: protect the dressing and urethral stent; double diapering (stent drains into the outer diaper); acetaminophen for pain; bladder spasm medication as ordered; encourage fluids
- Exstrophy and reimplantation: secure catheters and stents, monitor urine output and hematuria
- Transplant — medication timing, drug levels, infection precautions, early rejection signs
- UTI prevention: wipe front to back; treat and prevent constipation; void regularly and do not hold urine (timed voiding); avoid bubble baths and irritating soaps; cotton underwear; frequent diaper changes
- Finish the prescribed antibiotic course; follow-up culture or imaging as ordered; return for fever
- Nephrotic syndrome at home: test first-morning urine for protein daily and record; weigh daily; low-salt diet; take steroids exactly as directed and do not stop suddenly; avoid people with infections; report chickenpox exposure promptly; call for fever, abdominal pain, decreased urine, or rapid weight gain
- AGN: expect urine color to clear over weeks; limit salt; keep follow-up BP and urine checks
- Enuresis: reassure that it is common and not intentional; no punishment; void before bed; record wet and dry nights; with desmopressin, no drinking from 1 hour before bedtime dose until morning, and skip the dose on days with vomiting, diarrhea, or fever
- Kidney after nephrectomy or transplant: avoid contact sports that risk abdominal blows per the team
- Transplant: take immunosuppressants at the same times daily; never skip or stop; no live vaccines for the child; household members should be up to date on vaccines, including yearly inactivated influenza; report fever, reduced urine, weight gain
- Testicular torsion: sudden scrotal pain is an emergency — go to the hospital immediately
| Red flag | Concern |
|---|
| Febrile infant with UTI, lethargy, poor perfusion | Urosepsis |
| Severe headache, vision change, seizure with hematuria and edema | Hypertensive encephalopathy (AGN) |
| Abdominal pain and fever with ascites | Spontaneous bacterial peritonitis (nephrotic) |
| Leg swelling, flank pain, neurologic change | Thrombosis (nephrotic) |
| Oliguria, peaked T waves, muscle weakness | Hyperkalemia / acute kidney injury |
| Sudden scrotal pain with vomiting | Testicular torsion |
| Headache, vomiting, seizure on desmopressin | Hyponatremia |
| Rising creatinine after transplant | Rejection |
- UTI in infants: fever may be the only sign; culture by catheter, never a bag
- Obtain urine culture before antibiotics; finish the course
- VUR + UTI → kidney scarring; prevent constipation and urine holding
- Nephrotic: proteinuria, hypoalbuminemia, edema, hyperlipidemia; frothy urine; steroids — never stop abruptly, no live vaccines on high doses
- AGN: cola-colored urine, hypertension, low C3, after strep; restrict sodium and fluid
- Daily weight is the best indicator of fluid retention
- Enuresis: rule out UTI and diabetes (secondary); alarm or desmopressin — restrict fluids around the dose (hyponatremia)
- Kidney failure: watch potassium; avoid NSAIDs
- Hypospadias: no circumcision before repair; double diaper around the stent
- Cryptorchidism: orchiopexy by about 18 months
- Torsion: surgical emergency — do not delay
Country Notes
United States
- Many children with nephrotic syndrome or kidney transplants attend school with individualized health plans for medications and infection alerts.
- ACIP recommends inactivated influenza vaccine yearly for household contacts of immunocompromised children.
Philippines
- Post-streptococcal glomerulonephritis following skin infection (impetigo, infected insect bites or scabies) remains common in children; teach prompt treatment of skin sores.
- Creatinine and albumin are often reported in SI units (µmol/L and g/L) — check the unit before interpreting.