Kidney Failure

Kidney failure, also known as end-stage renal disease (ESRD), is a condition where the kidneys can no longer filter waste products from the blood effectively. This condition can be classified as either acute kidney failure, which develops rapidly, or chronic kidney failure, which progresses slowly and is often irreversible.

Classification

Kidney failure can be categorised into acute and chronic types. Acute kidney failure is characterised by a sudden loss of kidney function, generally identified by oliguria (reduced urine production) and fluid and electrolyte imbalances. It can result from prerenal, intrinsic, or postrenal causes. Chronic kidney disease (CKD), on the other hand, develops slowly and is often a long-term consequence of irreversible acute kidney injury or other diseases. CKD is divided into five stages, based on the estimated glomerular filtration rate (eGFR), ranging from CKD1 (normal eGFR) to CKD5 (eGFR less than 15 ml/min).

Signs and Symptoms

Symptoms of kidney failure vary and may not be noticeable in early stages. As the condition progresses, waste accumulates in the blood, leading to azotaemia. Common symptoms include:

• High levels of urea causing vomiting, diarrhoea, nausea, weight loss, nocturnal urination, and blood in the urine.
• Accumulation of phosphates resulting in itching, bone damage, and muscle cramps.
• Elevated potassium levels leading to abnormal heart rhythms and muscle paralysis.
• Fluid retention causing swelling of extremities and shortness of breath.
• Polycystic kidney disease causing back or side pain.
• Decreased erythropoietin production resulting in anaemia, fatigue, memory problems, and dizziness.
• Protein leakage manifesting as foamy urine and swelling in various body parts.
• Other symptoms include appetite loss, difficulty sleeping, skin darkening, and seizures with high doses of penicillin.

Illustration of a kidney from a person with chronic renal failure

Causes

Acute Kidney Injury

Acute kidney injury (AKI) typically occurs due to sudden interruptions in blood supply to the kidneys or toxin overload. Causes include accidents, injuries, surgeries, drug overdoses, and infections. AKI can often be reversible with supportive treatment.

Chronic Kidney Failure

Chronic kidney failure is often due to long-term conditions such as diabetes and uncontrolled hypertension. Other causes include polycystic kidney disease, systemic lupus erythematosus, overuse of certain medications, and infections like hantavirus. Genetic factors, such as variants in the APOL1 gene, also contribute to chronic kidney disease, particularly in individuals of African origin.

Diagnostic Approach

Measurement for CKD

Chronic kidney failure is measured using the glomerular filtration rate (GFR). The disease is staged from 1 (mildly diminished function) to 5 (severe illness requiring renal replacement therapy). GFR is considered the best indicator of kidney function.

Renal Failure Indices

Other diagnostic measures include the fractional sodium excretion (FENa) index and the renal failure index (RFI). These indices help confirm acute renal failure.

Treatment

Acute Kidney Injury

Treatment of AKI depends on the underlying cause and may include supportive measures until kidney function recovers.

Chronic Kidney Failure

Chronic kidney failure treatment options include haemodialysis, peritoneal dialysis, and kidney transplants. Haemodialysis involves using a machine to filter the blood outside the body, while peritoneal dialysis uses fluid in the abdominal cavity. Kidney transplantation involves surgically placing a donor kidney and requires immunosuppressant medication to prevent rejection.

Diet and Slowing Progression

A low protein diet is beneficial for non-diabetics and type 1 diabetics in slowing CKD progression, but not for type 2 diabetics. A whole food, plant-based diet may also help. Early referral to a nephrologist, minimising exposure to nephrotoxins, and avoiding NSAIDs and intravenous contrast can reduce disease progression.

Complications

Complications include spontaneous intra-abdominal bleeding, non-occlusive mesenteric ischaemia for haemodialysis patients, and peritonitis and gastrointestinal perforation for peritoneal dialysis patients. However, the rate of acute pancreatitis is similar to the general population.

Self-assessment MCQs (single best answer)

What is another name for kidney failure?

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Which of the following is a symptom of elevated potassium levels in kidney failure?

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Which stage of chronic kidney disease (CKD) has an estimated glomerular filtration rate (eGFR) of less than 15 ml/min?

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What is the primary diagnostic measure for chronic kidney disease?

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Which treatment option involves using a machine to filter the blood outside the body?

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What is a common cause of chronic kidney failure?

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Which of the following is a symptom of decreased erythropoietin production in kidney failure?

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What is the benefit of a low protein diet for non-diabetics with chronic kidney disease?

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Which complication is associated with peritoneal dialysis?

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What is often a reversible cause of acute kidney injury?

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