Alterations of Renal and Urinary Tract Function in Children

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Alterations of Renal and Urinary Tract Function
in Children

• Chapter 37

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Development of the Urinary Renal System

• Pronephros
• Mesonephros
• Metanephros
• 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
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Fluid and Electrolyte Balance

• 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

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Fluid and Electrolyte Balance

• 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

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Structural Abnormalities

• Ectopic kidneys
• Horseshoe kidneys
• Hypospadias
• Chordee
• Epispadias
• Exstrophy of the bladder

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Structural Abnormalities

• Ureteropelvic junction obstruction
• Bladder outlet obstruction
• Hypoplastic or dysplastic kidneys
• Renal agenesis
• Polycystic kidney disease

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Glomerulonephritis

• Acute poststreptococcal glomerulonephritis (PSGN)
• PSGN occurs after a throat or skin infection with
  certain strains of group A a-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

• Immunoglobulin A nephropathy
• 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
• Also referred to as anaphylactoid purpura
• IgA nephropathy that causes inflammation and
  damage to the glomerular blood vessels

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Hemolytic-Uremic Syndrome (HUS)

• HUS is the most common cause of acute renal
  failure in children
• There is an association of HUS with bacterial and
  viral agents
• Escherichia coli O157H7
• 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)

• 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

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Nephrotic Syndrome

• Nephrotic syndrome describes a group of symptoms
  characterized by proteinuria, hypoproteinemia,
  hyperlipidemia, and edema
• 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)

• 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

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Vesicoureteral Reflux (VUR)

• 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)

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Vesicoureteral Reflux (VUR)
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Vesicoureteral Reflux (VUR)
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Wilms Tumor

• 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
• 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
• 4 to 5 years old
• Primary enuresis
• The child has never been continent
• Secondary enuresis
• Diurnal, nocturnal, or both

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Enuresis

• Theories
• Organic causes
• Maturational lag
• Genetic factors
• Sleep patterns
• Psychosocial theories