Chronic Kidney Disease
Paul R. Brakeman
I. DEFINITION
Chronic kidney disease (CKD) is a persistent reduction in renal function lasting for more than 3 months that results in a variety of clinical signs and symptoms and multiple metabolic, hormonal, and organ system abnormalities. CKD is classified by severity (Table 23-1) with the most severe form being kidney failure or end stage renal disease (ESRD).
II. PREVALENCE
The prevalence of chronic kidney disease varies significantly between studies and is in the range of 25 to 50 per million children.
III. CAUSES
The most common causes of CKD in North America are listed in Table 23-2. The most common cause of CKD in children in North America are congenital anomalies of the kidney and urologic tract known as CAKUT and represent nearly half of all cases of CKD in children. In younger patients, congenital anomalies are more common while in adolescent patients the various forms of glomerulonephritis are the most common cause of CKD.
IV. PATHOGENESIS
As CKD progresses, individual nephrons are lost and the total glomerular filtration rate (GFR) decreases. To compensate, the remaining nephrons increase the fraction of filtrate that is excreted as urine. Thus, substances that depend on glomerular filtration for excretion such as urea nitrogen accumulate while substances such as salt, potassium, and water may remain in homeostasis until the final stages of CKD. This is specifically true in the case of CKD resulting from congenital obstructive uropathy or hypoplastic/dysplastic kidneys in which a patient may reach end stage renal disease with a normal urine output and near normal excretion of sodium and potassium.
V. CLINICAL MANIFESTATIONS
Many of the same biochemical abnormalities occur in CKD and ARF; however, in CKD persistence of these abnormalities results in organ system pathology such as renal osteodystrophy.
VI. DIAGNOSIS
A. History: A patient with CKD should be evaluated thoroughly for a family history of renal failure and hearing loss suggestive of hereditary nephritis (Alport syndrome), cystic kidney disease, and family members receiving
dialysis and/or renal transplantation indicating other heritable causes of CKD. A CKD patient should be questioned for a history of abnormal bladder emptying, constipation, recurrent urinary tract infections, vesicoureteral reflux, or meningomyelocele any of which could suggest obstructive uropathy as a cause for CKD. The patient should be evaluated for a history of proteinuria, hematuria, flank pain, or edema consistent with chronic glomerulonephritis (GN) and for previous episodes of skin rashes, fever, adenopathy, or arthralgias consistent with systemic lupus erythematosus (SLE) or a vasculitis. Many times the absence of a previous history of symptoms or renal disease is indicative of CKD due to congenital anomalies of the kidneys such as hypoplasia/dysplasia or medullary cystic disease.
dialysis and/or renal transplantation indicating other heritable causes of CKD. A CKD patient should be questioned for a history of abnormal bladder emptying, constipation, recurrent urinary tract infections, vesicoureteral reflux, or meningomyelocele any of which could suggest obstructive uropathy as a cause for CKD. The patient should be evaluated for a history of proteinuria, hematuria, flank pain, or edema consistent with chronic glomerulonephritis (GN) and for previous episodes of skin rashes, fever, adenopathy, or arthralgias consistent with systemic lupus erythematosus (SLE) or a vasculitis. Many times the absence of a previous history of symptoms or renal disease is indicative of CKD due to congenital anomalies of the kidneys such as hypoplasia/dysplasia or medullary cystic disease.
TABLE 23-1 Classification of Chronic Kidney Disease | |||||||||||||||||||||||||||
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