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The definition of chronic kidney disease (CKD) and
its different stages are outlined in Table 477-1.
The term chronic kidney disease has been introduced
to ensure consistency of terminology in relation to patients with
sustained renal disorders, and to replace the terms chronic renal
insufficiency and chronic renal failure.1 The definition
of CKD excludes patients younger than 2 years whose renal function
improves markedly in the first 2 years of life; therefore, a glomerular
filtration rate (GFR) < 90 mL/min/1.73 m2 in
a 6-month-old child may not represent any abnormality of renal function.
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Causes of Chronic Kidney
Disease in Children
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Causes of chronic kidney disease (CKD) in children do not vary
substantially between disease registries from a variety of countries.2,3 In
younger children, the most common causes are congenital abnormalities
of the genitourinary system that are accompanied by vesicoureteric
reflux or obstruction to urinary outflow leading to renal hypoplasia
or dysplasia. The most common obstructive lesions are posterior
urethral valves and prune belly syndrome, both of which only occur
in boys (see Chapter 476). Renal cystic diseases,
including multicystic kidneys, cystic renal dysplasia, juvenile
nephronophthisis, and autosomal-recessive polycystic kidney disease,
may cause significant loss of renal function during childhood (see Chapter 470). Glomerular diseases causing significant
renal disease in early childhood rarely include congenital nephrotic
syndrome, or more commonly, focal segmental glomerulosclerosis or
hemolytic uremic syndrome (see Chapter 472).
In teenage years, membranous nephropathy and membranoproliferative
glomerulonephritis may be seen, and CKD may be seen in association
with systemic lupus erythematosus.
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Incidence and Prevalence
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According to the US Renal Data Systems report, there were 1325
incident patients ages 0 to 19 years with end-stage renal disease
or renal transplants treated in 2005, with a prevalent population,
including renal transplant patients, of 7362.4 The prevalence
is too low to provide accurate estimates of prevalence of each chronic
kidney disease (CKD) stage. However, more detailed information is
available in the Italian registry from 1990 to 2000, including 1197
children with a creatinine clearance < 75 mL/min/1.73
m2 body surface area (BSA) (predialysis) and age younger
than 20 years at the time of registration. This registry reported
a mean incidence ...