PE20.1-9 | Genito-Urinary System — Glossary

An intercalating chemotherapy agent used in all stages of Wilms tumor treatment; given with vincristine (EE-4A regimen for Stage I–II) or with vincristine + doxorubicin (DD-4A for Stage III–IV favourable histology).

Sudden deterioration in renal function characterised by rise in serum creatinine (≥0.3 mg/dL in 48 h or ×1.5 baseline in 7 days) and/or fall in urine output (<0.5 mL/kg/h for ≥6 hours), staged 1–3 by KDIGO criteria.

The most common cause of intrinsic AKI; results from ischaemic injury (prolonged prerenal state) or nephrotoxins (aminoglycosides, NSAIDs, contrast); characterised by granular casts on urine microscopy.

Mnemonic for dialysis indications in AKI: Acidosis (pH <7.1), Electrolytes (K⁺ >6.5–7), Intoxication (dialysable poisons), Overload (refractory pulmonary oedema), Uraemia (BUN >200, encephalopathy).

Active forms of vitamin D (1α-hydroxylated) used in CKD; replace the missing renal 1α-hydroxylase step; directly suppress PTH and improve mineralisation; native cholecalciferol cannot be used in renal failure.

A hereditary nephritis caused by mutations in type IV collagen genes (COL4A5 on X chromosome, or COL4A3/A4 on chromosome 2); manifests as haematuria, progressive proteinuria, sensorineural deafness, and anterior lenticonus; males with X-linked form progress to ESRD.

A complement activation route triggered directly by microbial surfaces, bypassing C1 and C4; activated in APSGN producing low C3 with normal C4.

Adverse histological feature defined by nuclear enlargement ≥3× and hyperchromatic multipolar mitoses; diffuse anaplasia = high-risk, requiring intensified chemotherapy; focal anaplasia = intermediate-risk.

A conical forward protrusion of the anterior lens surface, pathognomonic of Alport syndrome; detected on slit-lamp examination; a useful clinical sign for diagnosing hereditary nephritis.

Antibody to streptococcal deoxyribonuclease B; more sensitive than ASO for confirming recent streptococcal skin infection and the preferred serological test in post-impetigo APSGN.

Low-dose continuous antibiotics (typically trimethoprim 1–2 mg/kg/day or nitrofurantoin 1 mg/kg/day at night) given to prevent recurrent UTI in children with VUR grade III–V or recurrent febrile infections.

Acute post-streptococcal glomerulonephritis — an immune-complex-mediated glomerulonephritis following infection with nephritogenic strains of Group A beta-haemolytic Streptococcus; the prototype of post-infectious nephritic syndrome in children.

Anti-streptolysin O antibody titre; elevated in ~75% of post-pharyngitis APSGN but less reliable in post-skin infections where streptolysin O is inhibited by skin lipids.

Overgrowth syndrome from IGF2 upregulation at 11p15 (WT2 locus); features macroglossia, hemihypertrophy, omphalocele, and neonatal hyperinsulinaemic hypoglycaemia; ~5–10% Wilms risk, with higher frequency of bilateral tumors.

Paediatric formula for estimating GFR: eGFR = 0.413 × height (cm) / serum creatinine (mg/dL); gives GFR in mL/min/1.73m²; more accurate than adult Cockcroft-Gault in children.

See thin glomerular basement membrane disease — isolated persistent microscopic haematuria in multiple family members with normal renal function and no progression to CKD.

A long-acting intramuscular penicillin used in APSGN to ensure complete eradication of Group A Streptococcus and reduce transmission; preferred when oral compliance is uncertain.

Synchronous bilateral nephroblastoma (~6% of cases); associated with predisposition syndromes (BWS, WAGR, Denys-Drash); treated with pre-operative chemotherapy + bilateral nephron-sparing surgery to preserve renal function.

Congenital Anomalies of the Kidney and Urinary Tract; the leading cause of paediatric CKD (~50%); includes posterior urethral valves, vesicoureteric reflux, renal dysplasia, and multicystic kidneys; often detected on antenatal ultrasound.

Used intravenously (0.5–1 mL/kg of 10% solution) as the FIRST step in symptomatic hyperkalaemia; stabilises the cardiac myocyte membrane threshold and prevents arrhythmia but does NOT lower serum potassium.

Kidney damage or eGFR <60 mL/min/1.73m² persisting for ≥3 months; staged G1–G5 by eGFR and A1–A3 by albuminuria level; diagnosed by chronicity (not just by level of dysfunction).

The gene encoding the alpha-5 chain of type IV collagen on the X chromosome; mutations cause X-linked Alport syndrome, the most common form of hereditary nephritis.

The third complement protein, central to both classical and alternative complement pathways; serum C3 is characteristically LOW in APSGN due to alternative-pathway consumption, and should normalise within 6–8 weeks.

Lower UTI confined to the bladder and urethra, presenting with dysuria, frequency, urgency, and suprapubic discomfort without fever or systemic features.

WT1 point mutation causing diffuse mesangial sclerosis (nephrotic syndrome refractory to treatment), male pseudohermaphroditism (46,XY with female external genitalia), and >90% Wilms tumor risk; ESRD occurs in first decade.

Dimercaptosuccinic acid radionuclide renal scan; the gold standard for detecting renal cortical scars; performed 4–6 months after pyelonephritis to distinguish transient photopenic areas from permanent scars.

A triad of constipation, infrequent voiding, and abnormal voiding pattern in children that creates incomplete bladder emptying, predisposing to UTI.

Distorted, irregularly shaped red blood cells (acanthocytes, ghost cells) produced by passage through the damaged glomerular filtration barrier; their presence on urine microscopy confirms glomerular haematuria.

Red blood cells that have been distorted by passage through the damaged glomerular filtration barrier; their presence on urine microscopy confirms glomerular haematuria.

Recombinant erythropoietin preparations (epoetin alfa, darbepoetin alfa) that correct CKD anaemia by replacing deficient endogenous erythropoietin; require adequate iron stores to be effective; target Hb 10–12 g/dL.

Generalised proximal tubular dysfunction causing urinary losses of glucose, amino acids, phosphate, urate, and low-molecular-weight proteins; causes include cystinosis, Wilson's disease, galactosaemia, and nephrotoxic drugs.

The leading glomerular cause of paediatric CKD; presents as steroid-resistant nephrotic syndrome; >50% progress to ESRD over 10 years; may recur in transplanted kidneys.

Calculated as (urine Na × plasma creatinine) / (plasma Na × urine creatinine) × 100%; <1% = prerenal (tubules conserving sodium); >2% = intrinsic renal (tubular injury, sodium conservation lost).

A loop diuretic used in APSGN to relieve fluid overload and oedema; acts by inhibiting the Na-K-2Cl transporter in the thick ascending limb of the loop of Henle.

Proteinuria caused by impaired size-selectivity or charge-selectivity of the glomerular filtration barrier; predominantly albumin; seen in MCNS, FSGS, lupus nephritis, and glomerulonephritis.

Urinary cast containing degenerated cellular debris; non-specific; seen in ATN, CKD, or any significant renal injury; 'muddy brown granular casts' are characteristic of ischaemic or nephrotoxic ATN.

Presence of red blood cells in the urine confirmed by ≥5 RBC/hpf on centrifuged urine microscopy; macroscopic if visible, microscopic if detected only on dipstick or microscopy.

Clinical triad of microangiopathic haemolytic anaemia (MAHA), thrombocytopenia, and AKI; most commonly caused in children by EHEC O157:H7 (Shiga toxin); antibiotics are contraindicated.

Maintenance fluid calculation for children: 100 mL/kg/day for the first 10 kg, plus 50 mL/kg/day for the next 10 kg, plus 20 mL/kg/day for each additional kg; the baseline against which fluid balance is managed in AKI.

Renal involvement in Henoch-Schönlein purpura, an IgA-mediated small-vessel vasculitis presenting with palpable purpura + arthralgia + abdominal pain + haematuria ± proteinuria; mesangial IgA on biopsy, identical to IgA nephropathy.

Excessive urinary calcium excretion (urine calcium-to-creatinine ratio >0.2 in children >2 years); the commonest cause of isolated asymptomatic microscopic haematuria in school-age children; may also cause nephrolithiasis.

Increased GFR per surviving nephron in response to nephron loss; initially adaptive but causes intraglomerular hypertension, endothelial injury, TGF-β release, and progressive glomerulosclerosis — the mechanism of self-perpetuating CKD progression.

Acute cerebral dysfunction due to severe hypertension, presenting as headache, vomiting, visual disturbance, seizures, or altered consciousness; a medical emergency requiring IV antihypertensive therapy.

Low serum albumin concentration, typically <2.5 g/dL in nephrotic syndrome; reduces plasma oncotic pressure, promoting oedema formation in peripheral tissues and body cavities.

A glomerulonephritis in which IgA immune complexes deposit in the glomerular mesangium; distinguished from APSGN by synpharyngitic onset (no latent period), normal C3, and a more chronic, relapsing course.

AKI resulting from direct injury to nephron components — glomeruli (GN), tubules (ATN), interstitium (AIN), or vasculature (HUS); urine indices show tubular dysfunction (high urine Na, FENa >2%).

Uniform, non-deformed red blood cells in the urine indicating non-glomerular origin of haematuria; the RBCs have not traversed the glomerular filtration barrier.

Fixed urine specific gravity of approximately 1.010 (the osmolality of plasma filtrate) across multiple specimens regardless of hydration; indicates loss of both tubular concentrating and diluting ability; a marker of advanced renal tubular dysfunction in CKD.

Kidney Disease: Improving Global Outcomes — international guideline body that defines and stages AKI and CKD; KDIGO 2012 AKI guidelines define Stages 1–3 by creatinine and urine output criteria.

International CKD severity classification: G1 (eGFR ≥90), G2 (60–89), G3a (45–59), G3b (30–44), G4 (15–29), G5 (<15); G5 = kidney failure requiring renal replacement therapy.

Plain anteroposterior abdominal radiograph encompassing the Kidneys, Ureters, and Bladder; used to detect radio-opaque urinary calculi, assess renal outlines, and identify calcification patterns in the urinary tract and adjacent structures.

The interval between streptococcal infection and onset of nephritis, reflecting time for immune-complex formation: 1–2 weeks after pharyngitis; 3–6 weeks after impetigo/pyoderma.

An enzyme released by lysed white blood cells; its presence on urine dipstick is a proxy marker for pyuria and rapid screening tool for UTI.

Presence of lipids in the urine in nephrotic syndrome; oval fat bodies (lipid-laden tubular cells) and fatty casts are seen on urine microscopy; a direct consequence of heavy proteinuria and hypoalbuminaemia.

A glomerulonephritis with persistent hypocomplementaemia (low C3); the most important differential when C3 fails to normalise within 8–12 weeks in a child with apparent APSGN.

Haemolytic anaemia caused by mechanical destruction of red blood cells passing through damaged, fibrin-occluded small vessels; produces schistocytes (fragmented red cells) on the blood film; a component of the HUS triad.

Fluoroscopic study in which contrast fills the bladder via catheter and imaging is performed during voiding to detect and grade vesicoureteric reflux and to identify posterior urethral valves in boys.

The commonest cause of nephrotic syndrome in children aged 1–8 years; characterised by podocyte foot process effacement on electron microscopy with normal light microscopy; responds to prednisolone in ~80–90% of cases.

Presence of myoglobin (muscle protein) in urine, causing a positive dipstick blood result with few or no RBCs on microscopy; results from rhabdomyolysis (muscle injury, viral myositis); causes AKI by direct tubular toxicity; managed with aggressive IV hydration.

Surgical removal of the entire kidney along with its surrounding fascia, adrenal gland, and regional lymph nodes; the primary surgical treatment for unilateral Wilms tumor; performed through a transabdominal approach to allow full exploration.

A clinical complex of haematuria (often macroscopic, cola-coloured), hypertension, periorbital oedema, and oliguria with reduced GFR, caused by glomerular inflammation; the presenting syndrome of APSGN.

Specific M-protein serotypes of Group A Streptococcus capable of triggering glomerulonephritis; throat strains (M1, 4, 12) differ from skin strains (M47, 49, 55, 57).

Partial nephrectomy preserving as much normal renal parenchyma as possible; used in bilateral Wilms tumor (Stage V) to prevent the need for bilateral nephrectomy and dialysis; requires pre-operative chemotherapy to shrink tumours first.

A clinical complex defined by nephrotic-range proteinuria (UPCR >2 or >40 mg/m²/hr), hypoalbuminaemia (<2.5 g/dL), oedema, and hyperlipidaemia; the commonest cause in young children is MCNS.

Proteinuria exceeding 40 mg/m²/hr on timed urine, or UPCR >2.0 on spot first morning urine; indicates significant glomerular injury and mandates full nephrotic syndrome evaluation.

Malignant tumour of neural crest cells arising from the adrenal medulla or paravertebral sympathetic chain; the main differential of Wilms tumor; characterised by calcification on X-ray, crossing midline, elevated urinary VMA/HVA, and potentially worse prognosis in advanced disease.

Dipstick analyte converted from dietary nitrates by gram-negative bacteria (E. coli, Klebsiella, Proteus) that possess the enzyme nitrate reductase; false negative occurs with gram-positive UTI (Enterococcus, Staphylococcus saprophyticus) which lack this enzyme.

National Wilms Tumor Study staging system (Stages I–V): I = confined/resected; II = beyond capsule but resected; III = residual abdominal disease; IV = haematogenous metastases; V = bilateral tumours.

Urine output less than 0.5 mL/kg/hour; a cardinal sign of AKI requiring immediate evaluation to differentiate prerenal from intrinsic causes.

Benign proteinuria present only in the upright posture and absent on first morning urine; common in older children and adolescents; does not progress to renal disease.

Benign condition common in school-age children and adolescents in which proteinuria is present in upright urine specimens but absent in supine (first-morning) specimens; diagnosed by split-urine collection; no treatment required; resolves spontaneously.

A diagnostic test for orthostatic proteinuria: empty bladder before bed, collect first morning specimen (supine), collect second specimen after 2 hours upright; UPCR normal on first specimen and elevated on second = orthostatic proteinuria.

Renal replacement therapy using the peritoneal membrane as a semi-permeable dialyser; preferred modality for young children with AKI in India due to technical simplicity and wide availability.

Medications taken with meals to bind dietary phosphate in the gut and reduce phosphate absorption; examples include calcium carbonate, sevelamer hydrochloride, lanthanum carbonate; used to control hyperphosphataemia and secondary hyperparathyroidism in CKD.

Highly specialised glomerular visceral epithelial cells whose interdigitating foot processes and slit diaphragms form the final filtration barrier; foot process effacement is the hallmark of MCNS.

Congenital obstructive leaflets in the posterior urethra of boys that cause bladder outlet obstruction, hydronephrosis, and predisposition to UTI and renal dysplasia.

AKI due to obstruction of urine outflow, requiring bilateral involvement or a solitary kidney; causes in children include posterior urethral valves, bilateral PUJ obstruction, and bilateral calculi.

Renal transplantation performed before dialysis is ever started; the ideal timing for paediatric CKD; associated with superior growth, quality of life, and graft outcomes compared to post-dialysis transplantation.

Prednisolone 2 mg/kg/day (maximum 60 mg/day) for 4–6 weeks, followed by 1.5 mg/kg alternate-day for 4–6 weeks; the standard Indian protocol for first-episode nephrotic syndrome in children.

AKI caused by reduced renal perfusion with structurally intact nephrons; reversible with fluid resuscitation; most commonly from dehydration or septic shock in children.

Paediatric Risk, Injury, Failure, Loss, End-stage — a five-level staging system for AKI in children using estimated GFR decrease and urine output criteria; more sensitive than KDIGO for early AKI detection in children.

Excretion of protein in the urine above normal levels; significant if UPCR >0.2 on first morning urine in children >2 years.

Upper UTI involving the renal parenchyma and pelvis, characterised by fever, systemic upset, and loin tenderness; carries the risk of permanent renal scarring.

Presence of white blood cells in urine above the threshold: >10 WBC/mm³ in unspun urine, or >5 WBC/hpf in centrifuged sediment; an indicator of urinary tract inflammation.

Urinary calculus that appears white on a plain X-ray because it contains calcium or other dense minerals; types include calcium oxalate (most common), calcium phosphate, struvite (staghorn), and cystine (faintly opaque); uric acid calculi are radiolucent and invisible on plain film.

Urinary cast containing red blood cells enmeshed in Tamm-Horsfall protein; pathognomonic of glomerulonephritis; found ONLY when RBCs enter the tubular lumen through a disrupted glomerular filtration barrier.

Casts formed in renal tubules containing red blood cells; pathognomonic of active glomerulonephritis and indicative of significant glomerular inflammation.

Subcutaneous daily injections of GH used for CKD-associated growth failure in children below the 3rd height percentile; improves height velocity and final adult height; stopped after successful renal transplantation.

Renal scarring caused by recurrent ascending infection in the presence of vesicoureteric reflux; the commonest acquired cause of hypertension and chronic kidney disease in children.

Metabolic bone disease in CKD caused by phosphate retention, low 1,25(OH)2D3 (impaired renal 1α-hydroxylation), hypocalcaemia, and secondary hyperparathyroidism; produces bone pain, growth plate dysfunction, and impaired mineralisation.

Elevated PTH in response to hypocalcaemia from CKD (low active vitamin D + phosphate retention); drives bone resorption and worsens renal osteodystrophy; treated with phosphate binders and active vitamin D.

A bacterial cytotoxin produced by EHEC O157:H7 that damages glomerular endothelium, activates complement, and triggers thrombotic microangiopathy causing HUS; antibiotics that lyse bacteria increase toxin release.

A culture result meeting the method-specific threshold: any growth from SPA; ≥10⁴ CFU/mL from catheter specimen; ≥10⁵ CFU/mL from midstream clean-catch urine.

Failure to achieve remission (urine protein negative/trace for 3 consecutive days) after 4–6 weeks of full-dose prednisolone; indicates need for renal biopsy and nephrology referral; often caused by FSGS.

Electron-dense immune complex deposits seen on electron microscopy in the subepithelial space of glomeruli in APSGN; their 'hump' shape on the outer surface of the GBM is the pathognomonic EM finding.

Direct needle aspiration of urine from the bladder through the anterior abdominal wall; the gold standard collection method for urine culture in infants, where any growth of a uropathogen is significant.

Gross haematuria occurring simultaneously with, or within 24–48 hours of, an upper respiratory infection; the hallmark of IgA nephropathy, distinguishing it from APSGN (which has a 1–2 week latent period).

The most abundant urine protein; secreted by tubular cells of the thick ascending limb; forms the gel matrix of urinary casts; its polymerisation under low-flow, acid, high-protein conditions is the mechanism of cast formation in the distal tubule and collecting duct.

A benign hereditary condition (heterozygous COL4A3/A4 mutations) causing isolated persistent microscopic haematuria with normal renal function; autosomal dominant; also called benign familial haematuria.

The characteristic histological pattern of Wilms tumor with three components: blastemal (undifferentiated metanephric cells), stromal (mesenchymal spindle cells, smooth muscle, fat), and epithelial (primitive tubules and glomeruli); any component may predominate.

Low-grade proteinuria caused by failure of proximal tubular reabsorption of low-molecular-weight proteins; typically accompanied by glucosuria with normal blood glucose and aminoaciduria; seen in Fanconi syndrome.

Spot urine test quantifying proteinuria; performed on first morning urine; normal <0.2 (children >2 yr); nephrotic-range >2.0; eliminates the need for 24-hour urine collection in routine practice.

Systematic examination of urine including physical properties (colour, clarity, SG), dipstick chemical analysis (protein, blood, glucose, leucocytes, nitrites, pH), and urine microscopy (cells, casts, crystals, organisms); the foundational investigation for all paediatric renal and urological disease.

Microbial invasion of any part of the urinary tract confirmed by urine culture with a pathogen count above the threshold appropriate for the collection method, combined with compatible clinical features.

Spot urine test for hypercalciuria; normal <0.2 (mg:mg) in children >2 years; >0.2 suggests idiopathic hypercalciuria, a common cause of microscopic haematuria and nephrolithiasis in children.

Examination of centrifuged urine sediment under the microscope; detects RBCs, WBCs, epithelial cells, urinary casts, crystals, and organisms; performed at high-power field (HPF); significant pyuria = >5 WBCs/HPF, significant haematuria = >5 RBCs/HPF.

First-morning urine sample ratio used in children to quantify proteinuria; A1 <15 mg/mmol (normal), A2 15–50 (moderately increased), A3 >50 mg/mmol (severely increased); correlates with 24-hour urine protein without a timed collection.

Systemic inflammatory response (sepsis) arising from a urinary source; particularly dangerous in neonates and immunocompromised children with UTI.

Ultrasound of the kidneys, ureters, and bladder; the first-line imaging investigation after febrile UTI in children, detecting structural anomalies such as hydronephrosis and bladder wall thickening.

Retrograde flow of urine from the bladder into the ureter and renal pelvis due to an incompetent vesicoureteric junction; graded I–V and the commonest structural risk factor for renal scarring in UTI.

Properties of uropathogenic E. coli that enable UTI: P-fimbriae (bind uroepithelium), type-1 fimbriae, haemolysin production, aerobactin for iron uptake, and serum-resistance.

Vanillylmandelic acid and homovanillic acid — catecholamine metabolites excreted in urine; elevated in ~90% of neuroblastoma cases; normal in Wilms tumor; used as biochemical confirmation of neuroblastoma diagnosis.

Contiguous gene deletion syndrome at chromosome 11p13 causing Wilms tumor + Aniridia + Genitourinary anomalies + intellectual Retardation; ~50% lifetime Wilms tumor risk; requires surveillance ultrasound until age 7.

Urinary cast containing white blood cells; indicates pyelonephritis (infection ascending to the renal parenchyma) or acute interstitial nephritis (drug hypersensitivity or immune-mediated tubular inflammation).

The most common primary renal malignancy of childhood, arising from persistent metanephric blastema; triphasic histology (blastemal + stromal + epithelial); peaks at 3–4 years; highly curable with multimodal treatment.

The commonest renal malignancy in children under 5 years; presents with a painless abdominal mass, haematuria, and hypertension; requires urgent surgical oncology referral.

Wilms tumor suppressor gene on chromosome 11p13; encodes a transcription factor required for normal metanephric kidney development; mutated or deleted in WAGR syndrome, Denys-Drash syndrome, and ~10–15% of sporadic Wilms tumors.