Chronic kidney disease (CKD) is defined as the presence of kidney damage or decreased kidney function (glomerular filtration rate [GFR] < 60 mL/min per 1.73 m²) for 3 months or more and is caused by a multitude of etiologies.  

The extent of kidney dysfunction is categorized into several stages based on GFR: stage 1 with GFR > 90 mL/min per 1.73 m², stage 2 with GFR 60-89 mL/min per 1.73 m², stage 3 with GFR 30-59 mL/min per 1.73 m², stage 4 with GFR 15-29 mL/min per 1.73 m², and stage 5 with GFR < 15 mL/min per 1.73 m².  

Progressive renal dysfunction results in the accumulation of unfiltered wastes and fluids in the body and is characterized by edema, hematuria, pruritus, fatigue, nausea, and sleep disturbance. Early stages may be asymptomatic or present with few symptoms. With progression of renal dysfunction, several nonspecific symptoms may develop including ecchymosis, vomiting, anorexia, hyposmia, foot and leg edema, pallor, altered taste, and seizures. Urea crystals (uremic frost) may appear on the skin. An infant or child may present with poor growth, polyuria, anemia, hypertension, and uremia (weakness, fatigue, vomiting, and anorexia). 

Causes are myriad and include diabetes, hypertension, hyperlipidemia, cardiovascular disease, glomerulonephritis, prior kidney disease, and a history of childhood kidney disease. Diabetes is the most common cause of CKD and is responsible for 40% of new cases. About 30% of cases diagnosed in childhood involve a genetic cause (typically monogenic diseases, caused by mutations in any one of more than 200 genes, eg, congenital anomalies of the kidneys and urinary tract, nephronophthisis, and glomerular disease). Variants in the apolipoprotein L1 gene (APOL1), found exclusively in persons of African descent, have been associated with a greater risk of CKD and focal segmental glomerulosclerosis in Black individuals. CKD can occur in up to 45% of HIV cases, both from infection and complications of treatment, or from comorbid diseases. Agricultural communities, where people are exposed to heat and dehydration and may be exposed to increased nitrate levels in well water, are at increased risk.

Incidence and prevalence vary from nation to nation due to differences in underlying disease rates. In the United States, the risk of CKD is 4 times as high for Black individuals as it is for White individuals and the incidence is close to 400 per million. Dialysis is the primary means of management once patients progress to renal failure; dialysis patients have an average survival of 3-5 years and prevalence of 1800 cases per million.

Related topics: acute kidney injury, pruritus without rash