CKD can be diagnosed when there are pathologic abnormalities or markers of kidney damage such as persistent albuminuria (an indicator of ongoing renal injury), or reduced glomerular filtration rate (GFR) <60 mL/min/1.73 m² for ≥3 months (2). Chronic kidney condition is classified into five stages on the basis of the estimated GFR (Table 111.1). End-stage renal disease (ESRD) typically refers to stages IV and V, which require renal replacement therapy (RRT) in the form of either chronic dialysis or renal transplantation. Acute kidney injury (AKI) can become CKD when renal injury and dysfunction persist for >3 months. CKD staging can be used for adults and children at 2 years of age or older.

The prevalence of all stages of CKD has been increasing worldwide (3). In particular, the prevalence of pediatric (0-19 years) ESRD has increased by 32% since 1990. CKD is associated with various comorbidities which could affect ICU outcomes (4). Children with oncologic disease, hematopoietic stem cell transplantation, solid organ transplantation, congenital heart disease, and rheumatologic diseases are at a greater risk for developing CKD. Additional factors contribute to CKD and include repeated insults to the kidney from septic episodes, low cardiac output, and the use of nephrotoxic medications (antibiotics, chemotherapy, and immunosuppressive agents) (5). Patients can also have primary renal disease that progresses to CKD. Common causes of primary renal disease in children include congenital anomalies of the kidney and urinary tract such as aplastic or hypodysplastic kidneys, obstructive uropathy (e.g., posterior urethral valves), and reflux nephropathy. Tubular disease (e.g., nephronophthisis and polycystic kidney disease), glomerular disease due to focal segmental glomerulosclerosis (FSGS), and vasculitis (e.g., lupus nephritis) also contribute to the development of CKD.

Renal dysfunction affects multiple organ systems (Fig. 111.1). The extent and severity of involvement depends on the etiology and stage of CKD (6). CKD stages I and II usually show evidence of renal injury and may have clinical manifestations of proteinuria and hypertension. The primary goal of CKD management for these stages is to prevent the progression by reducing proteinuria and controlling hypertension typically with angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), which offer renal protection. As renal function deteriorates to stages III, IV, and V, patients will have multiple manifestations involving various organ systems (Fig. 111.1). In addition to slowing down renal disease progression, it is imperative to address these complications. Management focuses on the treatment of electrolyte and acid-base disturbances, anemia, hyperparathyroidism, malnutrition, and behavioral and psychological disorders.