What is CAKUT (Congenital Anomalies of the Kidney and Urinary Tract)?

CAKUT: Congenital Anomalies of the Kidney and Urinary Tract

CAKUT represents a spectrum of developmental disorders affecting the kidneys and urinary tract that collectively form the most common cause of kidney failure in children worldwide. 1, 2

Definition and Epidemiology

• CAKUT encompasses a range of structural malformations that occur during fetal development of the kidneys and urinary tract 1
• Affects over 1% of live births and accounts for 40-50% of chronic kidney failure cases in children 2
• These anomalies represent approximately 30% of all prenatally diagnosed malformations 3

Spectrum of Anomalies

• Kidney anomalies:

  • Renal agenesis (unilateral or bilateral)
  • Renal hypoplasia or dysplasia
  • Multicystic dysplastic kidney
  • Simple renal cysts
  • Horseshoe kidney 2, 4

• Urinary tract anomalies:

  • Vesicoureteral reflux (VUR)
  • Ureteropelvic junction obstruction
  • Megaureter
  • Ureterocele
  • Posterior urethral valves
  • Hydronephrosis 1, 3

Etiology

• Genetic factors:

  • Over 50 genes have been identified in CAKUT pathogenesis
  • Monogenetic variants cause up to 20% of cases
  • Key genes include PAX2, TBX18, NRIP1, REX, SIX2, and BMP4 2
  • Can be syndromic (affecting multiple organ systems) or non-syndromic 3

• Environmental factors:

  • Maternal diabetes
  • Obesity
  • Malnutrition
  • Alcohol consumption
  • Medications affecting kidney development 2, 4

Clinical Presentation and Diagnosis

• Many cases are detected through prenatal ultrasound screening 2

• Presentation varies widely based on severity:

  • Severe cases may present with oligohydramnios or anhydramnios prenatally
  • Milder forms may remain undetected until adulthood 4
  • May present with urinary tract infections, especially in children 5

• Diagnostic approaches:

  • Prenatal ultrasonography is the primary screening tool
  • Postnatal renal ultrasound to confirm and further characterize anomalies
  • Voiding cystourethrography (VCUG) to detect vesicoureteral reflux
  • Renal cortical scintigraphy (RCS) to evaluate renal scarring 5
  • Genetic testing may be indicated, especially in syndromic cases 2

Associated Conditions

• CAKUT may be associated with other congenital anomalies:
  • Ear anomalies (such as ear skin tags) often warrant renal imaging 6
  • Other dysmorphic features like facial asymmetry or eye abnormalities should prompt evaluation for CAKUT 6

Management Approach

• Management should be individualized based on the specific type and severity of CAKUT

• Goals include:

  • Preserving kidney function
  • Preventing urinary tract infections
  • Managing complications 4

• Treatment options:

  • Antibiotic prophylaxis for vesicoureteral reflux to prevent recurrent UTIs 5
  • Surgical correction for obstructive lesions
  • Monitoring for hypertension and proteinuria 3
  • Preparation for renal replacement therapy in severe cases 4

Long-term Outcomes and Monitoring

• Outcomes vary widely depending on the specific anomaly and its severity 1

• Regular monitoring is essential for:

  • Kidney function
  • Blood pressure
  • Proteinuria
  • Growth and development 4, 3

• Children with CAKUT should be followed by pediatric nephrologists and urologists as appropriate 7

• Even milder forms may lead to significant renal problems in adulthood 3

Prevention and Screening

• Screening of family members may be considered in familial cases 3
• Monitoring for signs of urinary tract infection is recommended for babies with associated anomalies like ear tags 6
• Prenatal care to minimize environmental risk factors during pregnancy 2