CHRONIC KIDNEY DISEASE

Background: Chronic kidney disease (CKD) is characterized by an irreversible deterioration of renal function that gradually progresses to end-stage renal disease (ESRD). CKD has emerged as a serious public health problem.
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CHRONIC KIDNEY DISEASE CHRONIC KIDNEY DISEASE Background: Chronic kidney disease (CKD) is characterized by an irreversibledeterioration of renal function that gradually progresses to end-stage renal disease(ESRD). CKD has emerged as a serious public health problem. Data from the UnitedStates Renal Data System (USRDS) show that incidence of kidney failure is risingamong adults and is commonly associated with poor outcomes and high cost. In thepast decade, the incidence of the CKD in children has steadily increased, with poorand ethnic minority children disproportionately affected. The major health consequences of CKD include not only progression to kidneyfailure but also an increased risk of cardiovascular disease. Evidence-based clinicalpractice guidelines support early recognition and treatment of CKD-relatedcomplications to improve growth and development and, ultimately, quality of life inchildren with this chronic condition. Appropriate pediatric care may reduce theprevalence of this complex and expensive condition. The definition and classification of chronic renal disease may help identifyaffected patients, possibly resulting in the early institution of effective therapy. Toachieve this goal, the Kidney Disease Outcomes Quality Initiative (K/DOQI) workinggroup of the National Kidney Foundation of the United States defined CKD as“evidence of structural or functional kidney abnormalities (abnormal urinalysis,imaging studies, or histology) that persist for at least three months, with or without adecreased [glomerular filtration rate] GFR (as defined by a GFR of less than 60mL/min per 1.73 m2).” Causes: The chief causes of CKD in children include the following: • Obstructive uropathy • Hypoplastic or dysplastic kidneys • Reflux nephropathy • Focal segmental glomerulosclerosis as a variant of childhood nephriticsyndrome • Polycystic kidney disease, both autosomal-recessive and autosomal-dominantvarieties Lab Studies: • Initial testing must include an examination of the urine and estimation of theGFR. An important aspect of this initial evaluation is the determination of diseaseduration. Although the distinction between acute, subacute, and chronic kidney disease(CKD) or failure is arbitrary, the differential diagnosis can frequently be narrowed ifthe disease duration is known. This assessment is best performed by comparing thecurrent urinalysis or plasma creatinine concentration (PCr) with previous results, ifavailable. • Urine examination is perhaps the most important test and should beconsidered a part of the physical examination in all children being screened orevaluated for CKD. It can be performed at the bedside or in the clinic on a fresh urinesample. o An initial evaluation consists of a multitest detection strip (dipstick) testfollowed by urine microscopy. The dipstick is a quick method of screening anddetecting proteinuria, hematuria, and pyuria and provides an estimate of the specificgravity (urine-concentrating capacity). o Urine microscopy is performed on a centrifuge-spun urine specimen to lookfor RBCs, WBC, and casts. Most children with CKD have broad hyaline casts.Characteristic findings on microscopic examination of the urine sediment may suggesta diagnosis other than CKD. As an example, the presence of muddy-brown granularcasts and epithelial cell casts is highly suggestive of acute tubular necrosis, whereasred cell casts would suggest an acute nephritic process. o The most appropriate, practical, and precise method for estimation ofproteinuria in children is to calculate the protein-to-creatinine ratio in a spot urinespecimen. Patients with a positive dipstick test finding (1+ or greater) should undergoquantitative measurement (protein-to-creatinine ratio or albumin-to-creatinine ratio)within 3 months to confirm proteinuria. When postpubertal children with diabetesmellitus of 5 or more years duration are screened, albumin should be measured in aspot urine sample using either albumin-specific dipstick or albumin-to-creatinine ratiotesting. • Serum chemistry provides a valuable diagnostic tool both in the initialdiagnosis and in the subsequent follow-up in these children. BUN and serumcreatinine assessments are the most important tests. Estimation of the serum sodium,potassium, calcium, phosphorus, bicarbonate, alkaline phosphatase, parathyroidhormone (PTH), and cholesterol and fractionated lipid levels are important in thetreatment and prevention of various CKD-related complications. • Anemia is an important clinical finding in CKD, and a complete blood cell(CBC) count is an important investigation both in the initial evaluation and thesubsequent follow-up in these children. Anemia may indicate the chronic nature of therenal failure in the absence of any other obvious causes and may also be a clue to theunderlying cardiovascular disease. • The GFR is equal to the sum of the filtration rates in all of the functioningnephrons; thus, estimation of the GFR gives a rough measure of the number offunctioning nephrons. A reduction in GFR implies progression of the underlyingdisease. o The current K/DOQI guidelines state that estimates of GFR are the bestoverall indices of the level of kidney function. The reference range of GFR in youngadults is 120-130 mL/min/1.73 m2. However, the reference range of eGFR is muchlower in early infancy, even when corrected for body surface area, and subsequentlyincreases in relationship to body size for up to 2 years. Hence, the eGFR ranges thatare used to define the 5 CKD stages apply only to children aged 2 years and older. TheeGFR can be estimated from the constant k, PCr (in mg/dL), and body length (L, incm) according to the Schwartz formula, as follows: GFR = (k X L) / PC ...