Renal Replacement Therapy – Types, Indications & Treatment

What Is Renal Replacement Therapy?

Renal replacement therapy (RRT) refers to a group of medical treatments that substitute or support the vital functions of the kidneys when they are no longer able to perform adequately. Healthy kidneys filter approximately 180 liters of blood per day, removing waste products, excess fluids, and regulating electrolyte and acid-base balance. When the kidneys fail, these functions must be replaced by technical or biological means.

Causes and Indications

Renal replacement therapy is indicated when kidney function has declined to a point that threatens the patient life. Common causes of kidney failure requiring RRT include:

• End-stage renal disease (ESRD) – the final stage (Stage 5) of chronic kidney disease
• Acute kidney injury (AKI) – caused by shock, poisoning, or severe infection
• Diabetic nephropathy – kidney damage due to diabetes mellitus
• Hypertensive nephropathy – kidney damage from long-standing high blood pressure
• Glomerulonephritis – inflammation of the kidney filtration units
• Polycystic kidney disease – an inherited condition causing cyst formation in the kidneys

Types of Renal Replacement Therapy

Hemodialysis

Hemodialysis is the most widely used form of renal replacement therapy worldwide. The patient blood is drawn through a vascular access site – most commonly a surgically created arteriovenous fistula in the arm – and passed through a dialysis machine. Inside the machine, the blood flows past a semipermeable membrane that removes uremic waste products and excess fluid into a dialysis solution. The cleaned blood is then returned to the body. Sessions typically last 3 to 5 hours and are performed three times per week, either at a dialysis center or at home (home hemodialysis).

Peritoneal Dialysis

In peritoneal dialysis, the patient own peritoneum (the membrane lining the abdominal cavity) serves as a natural filter. A dialysis solution is introduced into the abdominal cavity through a surgically placed catheter. Waste products and excess water pass from the blood vessels in the peritoneum into the solution, which is then drained and replaced. In continuous ambulatory peritoneal dialysis (CAPD), exchanges are done manually several times a day; in automated peritoneal dialysis (APD), a machine performs exchanges overnight. Peritoneal dialysis can be performed at home and offers greater flexibility.

Kidney Transplantation

Kidney transplantation is considered the optimal treatment for end-stage renal disease. A healthy donor kidney – from either a living or deceased donor – is surgically implanted into the recipient pelvis. After a successful transplant, the new kidney assumes all essential filtration functions. Patients must take immunosuppressive medications for life to prevent rejection of the transplanted organ. Due to a shortage of donor organs, waiting times can be lengthy.

Continuous Renal Replacement Therapy (CRRT)

In intensive care settings, continuous renal replacement therapy (CRRT) is used for hemodynamically unstable patients with acute kidney injury who cannot tolerate conventional intermittent hemodialysis. Methods such as continuous venovenous hemofiltration (CVVH) or continuous venovenous hemodiafiltration (CVVHDF) operate continuously over 24 hours, providing gentle and steady blood purification.

Diagnosis and Decision-Making

The decision to initiate renal replacement therapy is based on clinical assessment, laboratory values, and imaging findings. Key indicators include:

• Serum creatinine and blood urea nitrogen (BUN) as markers of kidney filtration capacity
• Glomerular filtration rate (GFR): A value below 10–15 ml/min is a typical threshold for initiating RRT
• Electrolyte disturbances, especially hyperkalemia (elevated potassium levels)
• Fluid overload with treatment-resistant edema or pulmonary congestion
• Uremic symptoms such as nausea, confusion, or pericarditis

Treatment and Long-Term Management

The choice of renal replacement modality depends on several factors, including the severity and cause of kidney failure, the patient general health status, comorbidities, and personal lifestyle preferences. In most cases, treatment is ongoing. Regular nephrology follow-up visits and consistent management of conditions such as hypertension and diabetes are essential to minimize complications and maintain quality of life.

Risks and Complications

• Hemodialysis: Vascular access infections, blood pressure fluctuations, muscle cramps, anemia
• Peritoneal dialysis: Peritonitis (abdominal cavity infection), catheter infections, hernias
• Kidney transplantation: Organ rejection, infections due to immunosuppression, increased cancer risk
• CRRT: Bleeding risk from anticoagulation, electrolyte imbalances, hypothermia

References

1. Kidney Disease: Improving Global Outcomes (KDIGO) – Clinical Practice Guideline for Acute Kidney Injury. Kidney International Supplements, 2012.
2. National Kidney Foundation – KDOQI Clinical Practice Guidelines for Chronic Kidney Disease, 2002 (updated 2012). Available at: www.kidney.org
3. Palevsky P.M. et al. – Intensity of Renal Support in Critically Ill Patients with Acute Kidney Injury. New England Journal of Medicine, 2008; 359(1): 7–20.