What is dialysis and when is it needed? 

Dialysis is a medical procedure that performs the essential functions of the kidneys when they are no longer able to work effectively. It involves removing waste products, toxins, and excess fluid from the blood to prevent them from reaching dangerous levels in the body. Dialysis is typically required when a person develops end-stage renal failure, often defined as having lost about 85 to 90 per cent of kidney function. 

What We’ll Discuss in This Article 

• The primary role of dialysis in treating kidney failure 

• The clinical indications for when dialysis should begin 

• Key differences between haemodialysis and peritoneal dialysis 

• The procedures involved in preparing for treatment 

• Comparison of lifestyle impacts for different dialysis types 

• Guidance on managing symptoms and when to seek help 

Understanding the Process 

Dialysis is a life-saving treatment that filters the blood to remove waste and extra water when the kidneys can no longer do so. It helps maintain the body’s chemical balance by controlling levels of salts like potassium and sodium. While it is not a cure for kidney disease, it allows individuals with kidney failure to live longer and feel better by managing the buildup of toxins. 

There are two main methods used in the UK: 

• Haemodialysis: An external machine (dialyser) acts as an artificial kidney to clean the blood. 

• Peritoneal dialysis: The lining of your own abdomen (peritoneum) is used as a filter, with a special fluid pumped in and out through a catheter. 

Clinical Requirements for Treatment 

Dialysis is needed when the kidneys reach end-stage renal failure, meaning they can no longer keep you healthy. This is often determined by measuring the estimated glomerular filtration rate (eGFR). NICE guidance suggests starting dialysis when symptoms of uraemia (toxin buildup) impact daily living, when fluid overload becomes uncontrollable, or when the eGFR falls to around 5 to 7 ml/min/1.73 m^2, even if symptoms are not yet severe. 

Common reasons for starting treatment include: 

• Symptom Management: Feeling very tired, short of breath, or experiencing persistent itching. 

• Biochemical Levels: High levels of potassium or acid in the blood that cannot be managed with medication. 

• Fluid Overload: Significant swelling or fluid on the lungs that does not respond to diuretics. 

• Acute Kidney Injury: Sometimes dialysis is needed temporarily to help the kidneys recover after a sudden illness or injury. 

Common Causes of Renal Failure 

Kidney failure is rarely sudden; it is often the result of long-term damage to the internal filtering units of the kidneys. 

• Diabetes: High blood sugar can damage the small blood vessels in the kidneys over many years. 

• High Blood Pressure: Chronic hypertension puts strain on the kidney’s vessels, leading to scarring. 

• Glomerulonephritis: Inflammation of the kidney’s filtering units. 

• Polycystic Kidney Disease: An inherited condition where cysts grow in the kidneys. 

• Long-term Medication Use: Certain medications, such as non-steroidal anti-inflammatory drugs (NSAIDs), can contribute to damage if used excessively. 

Indicators for Starting Dialysis 

The transition to dialysis is usually a planned process involving a multidisciplinary renal team. Triggers that move a patient from monitoring to active treatment include: 

• Uraemic Symptoms: Nausea, loss of appetite, and a metallic taste in the mouth. 

• Neurological Changes: Confusion or brain fog caused by waste buildup. 

• Reduced Urine Output: The body stops being able to clear enough fluid, leading to high blood pressure and heart strain. 

• Planned Preparation: If a patient is preparing for a transplant, dialysis may be started to keep them stable while waiting for a donor. 

Comparing Treatment Modalities 

Choosing between the two types of dialysis depends on clinical suitability and personal lifestyle preferences. 

Feature	Haemodialysis (HD)	Peritoneal Dialysis (PD)
How it works	Blood is cleaned outside the body by a machine.	The abdomen lining filters blood inside the body.
Location	Usually in a hospital or clinic (3 times a week).	Usually at home (daily or every night).
Access needed	A fistula in the arm or a neck catheter.	A permanent catheter in the abdomen.
Time commitment	~4 hours per session, plus travel time.	Done daily (CAPD) or overnight (APD).
Dietary limits	Stricter limits on fluid, salt, and potassium.	Generally more flexible diet and fluid intake.
Main risks	Muscle cramps, low blood pressure, fatigue.	Risk of peritonitis (abdominal infection).

My final conclusion 

Dialysis is a vital treatment for those with advanced kidney disease, acting as a bridge to a kidney transplant or as a long-term management strategy. While it requires significant lifestyle adjustments, modern techniques allow many people to maintain a good quality of life. The choice of treatment is a shared decision between the patient and their clinical team, based on medical needs and personal circumstances. 

If you experience severe, sudden, or worsening symptoms, such as extreme breathlessness or confusion, call 999 immediately. 

Authority Snapshot 

This article has been reviewed by Dr. Rebecca Fernandez to ensure it aligns with current UK clinical guidelines regarding renal replacement therapy. Dr. Fernandez is a UK-trained physician with extensive experience in internal medicine and emergency care. The article provides an evidence-based overview of dialysis procedures and indications for treatment to reassure patients and provide accurate medical information.