Chronic Kidney Disease

Chronic kidney disease (CKD) is a long-term condition characterised by a gradual loss of kidney function over months or years, or by abnormal kidney structure with normal function. It is often asymptomatic in its early stages but can lead to severe complications if left untreated. CKD is linked to increased cardiovascular risks and has multiple causes and risk factors.

Signs and Symptoms

Initially, CKD is asymptomatic and often detected through routine blood work revealing elevated serum creatinine or protein in the urine. As kidney function declines, symptoms such as leg swelling, fatigue, vomiting, loss of appetite, and confusion may emerge.

Illustration of a kidney from a person with chronic renal failure

Other symptoms include hypertension due to fluid overload, uraemia leading to pericarditis and encephalopathy, hyperkalaemia causing cardiac arrhythmias, fluid overload leading to pulmonary oedema, hyperphosphataemia, hypocalcaemia, and bone disease. Anaemia, cachexia, cognitive decline, and sexual dysfunction are also common.

Uraemic frost on the head in someone with chronic kidney disease

Causes and Risk Factors

The primary causes of CKD are diabetes mellitus, hypertension, and glomerulonephritis. Other causes include vascular diseases, glomerular diseases, tubulointerstitial diseases, obstructive nephropathy, and genetic conditions like polycystic kidney disease. Risk factors include a family history of CKD, low socioeconomic status, and certain racial backgrounds.

Diagnosis

CKD diagnosis involves history taking, physical examination, and laboratory tests such as serum creatinine and urine dipstick tests. Differentiating CKD from acute kidney injury (AKI) is very important as AKI can be reversible. Screening is recommended for individuals with risk factors like hypertension, diabetes, obesity, and a family history of kidney disease.

An ultrasound may be used for diagnostic and prognostic purposes. Additional tests like nuclear medicine MAG3 scans can assess renal blood flow and function.

A 12-lead ECG of a person with CKD and severe electrolyte imbalance: hyperkalaemia (7.4 mmol/L) with hypocalcaemia (1.6 mmol/L). The T-waves are peaked and the QT interval is prolonged.

Chronic renal disease caused by glomerulonephritis with increased echogenicity and reduced cortical thickness

Stages

CKD is staged based on glomerular filtration rate (GFR) and albumin-to-creatinine ratio (ACR):

• Stage 1: Slightly diminished function with normal or high GFR (≥90 mL/min/1.73 m²) and persistent albuminuria.
• Stage 2: Mild reduction in GFR (60-89 mL/min/1.73 m²) with kidney damage.
• Stage 3: Moderate reduction in GFR (30-59 mL/min/1.73 m²), subdivided into 3A (GFR 45-59) and 3B (GFR 30-44).
• Stage 4: Severe reduction in GFR (15-29 mL/min/1.73 m²).
• Stage 5: Established kidney failure (GFR <15 mL/min/1.73 m²), requiring kidney replacement therapy.

Management

Management of CKD involves medications, lifestyle changes, and in severe cases, renal replacement therapy.

Medications

ACE inhibitors or angiotensin II receptor antagonists are first-line agents to slow kidney function decline and reduce cardiovascular risks. Other measures include aggressive treatment of high blood lipids, low-protein and low-salt diet, and treatment for anaemia and metabolic bone disease.

Lifestyle Interventions

Weight management, dietary salt intake reduction, and omega-3 fatty acid supplementation are recommended. Regular exercise and acupressure may help with sleep regulation, though evidence is limited.

Renal Replacement Therapy

At Stage 5 CKD, dialysis or kidney transplant becomes necessary. Dialysis helps remove uraemic toxins, but is not as effective as normal kidney function.

End-stage chronic kidney disease with increased echogenicity, homogenous architecture without visible differentiation between parenchyma and renal sinus and reduced kidney size

Prognosis

CKD significantly increases the risk of cardiovascular disease and mortality. While kidney replacement therapies can extend life, they impact the quality of life. Kidney transplantation offers better survival rates compared to dialysis but comes with its own risks.

Epidemiology

CKD affects about 10% of the global population. It was responsible for 956,000 deaths globally in 2013. Certain populations, like people of African, Hispanic, and South Asian descent, are at higher risk for CKD.