Chronic Kidney Disease

Basics

Description

  • The Kidney Disease: Improving Global Outcomes (KDIGO) 2012 clinical practice guideline defines pediatric chronic kidney disease (CKD) based on a child meeting one of the following criteria for >3 months:
    • Glomerular filtration rate (GFR) <60 mL/min/1.73 m2 with implications for health, regardless of whether other CKD markers are present.
    • GFR >60 accompanied by markers of kidney damage including structural abnormalities, proteinuria, renal tubular disorders, or histologic abnormalities
  • The criteria for >3 months duration does not apply to infants <3 months of age.
  • The criteria for GFR does not apply to children <2 years of age.
  • CKD is classified based on cause, GFR category, and albuminuria category.
  • GFR categories
    • G1: GFR ≥90
    • G2: GFR 60 to 89
    • G3a: GFR 45 to 59
    • G3b: GFR 30 to 44
    • G4: GFR 15 to 29
    • G5: GFR <15
  • Albuminuria categories—albumin to creatinine ratio in mg/g
    • A1 <30
    • A2 30 to 300
    • A3 >300

Epidemiology

Incidence

~5 to 12 cases per year per million of age-related population

Prevalence

  • Prevalence of CKD has been reported to be between 21 and 74 cases per million of age-related population from various studies in Europe and Latin America.
  • Incidence and prevalence of CKD are higher among males, due to higher incidence of congenital anomalies of the kidney and urinary tract (CAKUT).

Risk Factors

  • Risk factors for CAKUT include genetic and environmental factors (maternal diabetes, exposure to medications such as ACE inhibitor/NSAIDs).
  • Low birth weight, prematurity, and rapid weight gain in early childhood increase risk of CKD.
  • Hypertension and proteinuria increase risk of CKD progression.

Pathophysiology

  • Cardiovascular: Hypertension secondary to activation of renin-angiotensin system, fluid overload, and anemia from erythropoietin deficiency contribute to cardiovascular morbidity.
  • Bone and mineral bone disorder of CKD: Decreased excretion of phosphorous and decreased synthesis of 1,25-dihydroxy vitamin D leads to hyperparathyroidism and bone disease.
  • Growth: Metabolic acidosis, anemia, and perturbations in the growth hormone insulin-like growth factor-1 (GH-IGF-1) axis lead to poor growth.

Etiology

  • CAKUT constitute ~60% of cases of childhood CKD and include the following:
    • Renal dysplasia/hypoplasia
    • Obstructive uropathy (posterior urethral valves [PUV], prune belly syndrome)
  • Cystic disorders
    • Autosomal recessive and dominant polycystic kidney disease
    • Juvenile nephronophthisis
  • Hereditary metabolic disorders
    • Cystinosis
    • Oxalosis
  • Glomerular diseases
    • Focal segmental glomerulosclerosis (FSGS)
    • Hemolytic uremic syndrome (HUS)
    • Systemic lupus erythematosus (SLE)
    • IgA nephropathy
    • Alport syndrome
    • Others—membranoproliferative glomerulonephritis (MPGN), membranous nephropathy, pauci-immune glomerulonephritis, congenital nephrotic syndrome

Commonly Associated Conditions

  • Many genetic syndromes are associated with CAKUT including Alagille, Bardet-Biedl, Beckwith-Wiedemann, branchio-oto-renal, and Townes-Brocks syndromes.
  • CAKUT also occurs with congenital malformation syndromes such as VACTERL association (vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, renal anomalies, and limb abnormalities), CHARGE syndrome (coloboma, heart defects, atresia choanae, retardation of growth, genital abnormalities, and ear abnormalities), and in patients with conditions causing neurogenic bladder such as spina bifida.

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