Alterations of Renal and
Urinary Tract Function in
Children
Chapter 37
1
Development of the Urinary Renal
System
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Pronephros
Mesonephros
Metanephros
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Ureteric bud
Metanephrogenic blastema
Urine formation and excretion begin by the
third month of gestation
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Development of the Urinary Renal
System
3
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Fluid and Electrolyte Balance
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Blood flow to the kidney in a newborn is
primarily to the medullary nephrons
Due to the short loops of Henle in the
medullary nephrons, an infant produces more
dilute urine
Infants are in a high anabolic state, so their
urea excretion is low

Urea is required to establish the concentration
gradient in the medulla
4
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Fluid and Electrolyte Balance
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Infants have a narrow chemical safety margin
due to high hydrogen ion concentration, low
osmotic pressure, and limited ability to
regulate their internal environment
Diarrhea, infection, fasting, and poor feeding
can rapidly lead to severe acidosis and fluid
imbalance
5
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Structural Abnormalities
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Ectopic kidneys
Horseshoe kidneys
Hypospadias
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Chordee
Epispadias
Exstrophy of the bladder
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Structural Abnormalities
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Ureteropelvic junction obstruction
Bladder outlet obstruction
Hypoplastic or dysplastic kidneys
Renal agenesis
Polycystic kidney disease
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Glomerulonephritis
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Acute poststreptococcal glomerulonephritis (PSGN)
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PSGN occurs after a throat or skin infection with certain
strains of group A α-hemolytic streptococci
The patient experiences a sudden onset of hematuria,
edema, hypertension, and renal insufficiency
Antigen-antibody complexes and complement are
deposited in the glomerulus
The immune complexes initiate inflammation and
glomerular injury
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Glomerulonephritis
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Immunoglobulin A nephropathy
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IgA nephropathy is characterized by the
deposition of mostly IgA but some IgM
antibodies and complement in the mesangium of
the glomerular capillaries.
Henoch-Schönlein purpura nephritis
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Also referred to as anaphylactoid purpura
IgA nephropathy that causes inflammation and
damage to the glomerular blood vessels
9
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Hemolytic-Uremic Syndrome
(HUS)
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HUS is the most common cause of acute renal
failure in children
There is an association of HUS with bacterial and
viral agents
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Escherichia coli O157:H7
The bacterial toxin from E. coli damages red cells
and endothelial cells
The endothelial lining of the glomerulus becomes
swollen and occluded with fibrin clots
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Hemolytic-Uremic Syndrome
(HUS)
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HUS causes a decreased glomerular filtration rate
with hematuria and proteinuria
The swollen vessels damage red cells as they pass
The damaged red cells are removed from the
circulation by the spleen, causing acute hemolytic
anemia
The microcirculation develops numerous thrombi
11
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Nephrotic Syndrome

Nephrotic syndrome describes a group of
symptoms characterized by proteinuria,
hypoproteinemia, hyperlipidemia, and edema
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Minimal change nephropathy (MCN)
Focal segmental glomerulosclerosis (FSGS)
Mesangial proliferation
Nephrotic syndrome can develop as part of
numerous renal diseases
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Urinary Tract Infections (UTI)
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UTIs are common 7- to 13-year-old girls
E. coli, the most common pathogen, ascends
the urethra in cystitis or the ureter in
pyelonephritis
Cystitis
Acute pyelonephritis
13
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Vesicoureteral Reflux (VUR)
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Retrograde flow of urine from the bladder into the
ureters
Reflux encourages infected urine from the bladder to
be swept up into the kidneys
Leads to frequent pyelonephritis
Caused by a congenital abnormality or ectopic
insertion of the ureter into the bladder
Diagnosed by a voiding cystourethrogram (VCUG)
and an intravenous pyelogram (IVP)
14
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Vesicoureteral Reflux (VUR)
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Vesicoureteral Reflux (VUR)
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Wilms Tumor
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Wilms tumor is an embryonal tumor of the
kidney
Wilms tumor arises from the proliferation of
abnormal renal stem cells (metanephric
blastema)
Three cellular components:
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
Stromal, epithelial, and blastemic
Inherited and sporadic forms
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Enuresis

Involuntary passage of urine by a child who is
beyond the age when voluntary bladder
control should have been acquired
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Primary enuresis
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4 to 5 years old
The child has never been continent
Secondary enuresis
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Diurnal, nocturnal, or both
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Enuresis
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Theories
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Organic causes
Maturational lag
Genetic factors
Sleep patterns
Psychosocial theories
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