OVERVIEW

What is Chronic Renal Failure?

Chronic renal failure is not an independent disease but a common clinical condition resulting from progressive kidney damage caused by various chronic kidney diseases, eventually leading to complete kidney failure. When chronic renal failure reaches its advanced stage and kidney function is entirely lost, it is commonly known as "uremia."

With current medical capabilities, the non-functional portion of the kidneys cannot be reversed. Treatment focuses on preserving the remaining functional kidney tissue. Through medication and renal replacement therapy, chronic renal failure can be managed as a chronic condition, prolonging the patient's survival.

What Are the Kidneys?

The kidneys are vital organs in the human body, shaped like "cashews" and located on either side of the spine near the junction of the twelfth rib. Most people have two kidneys, while a very small number may have developmental abnormalities such as a solitary kidney (missing one kidney), horseshoe kidney (the lower poles of the two kidneys fuse, resembling a "horseshoe"), or ectopic kidney (e.g., located in the pelvis or other areas).

A normal adult male kidney measures approximately 11 cm × 6 cm × 3 cm, with the left kidney slightly larger than the right. Female kidneys are generally smaller than those of males of the same age. Although the term "kidney" is shared with the organ in traditional medicine, the concepts are entirely different.

What Are the Functions of the Kidneys?

• The primary function of the kidneys is to produce and excrete urine, eliminating metabolic waste from the body, making them a crucial "wastewater treatment plant." At the same time, they reabsorb useful substances filtered from the blood, maintaining internal stability.

• Additionally, the kidneys have endocrine functions, producing various hormones that influence multiple physiological processes and are closely linked to overall health. Examples include erythropoietin, which promotes red blood cell production; the renin system, which regulates blood pressure; and active vitamin D3, which affects calcium-phosphate metabolism and bone health. The kidneys also serve as sites for the degradation and action of certain endocrine hormones.

• These kidney functions ensure the stability of the body's internal environment, allowing normal metabolic processes to occur.

Which Department Should Be Visited for Chronic Renal Failure?

Patients can seek treatment in the Nephrology Department.

SYMPTOMS

What are the manifestations of chronic renal failure?

Chronic kidney disease can be caused by kidney diseases or systemic diseases affecting other organs. In addition to symptoms related to the primary conditions causing chronic kidney disease, impaired kidney function itself can affect various systems throughout the body, leading to broad and nonspecific manifestations.

Common symptoms include reduced urine output, increased nighttime urination, systemic edema, nausea and vomiting, loss of appetite, generalized itching, cough, chest tightness, shortness of breath, inability to lie flat, and even sudden death.

In the early stages of chronic kidney disease, symptoms are often mild and may not significantly impact daily life, which is why many patients remain unaware and neglect the condition.

What diseases can chronic renal failure cause?

As kidney function gradually declines until eventual failure, various systems in the body are affected, leading to complications such as weakened immunity, infections, anemia, mineral metabolism disorders, renal osteodystrophy, osteoporosis, vascular calcification, uremia-related encephalopathy, and neuropathy.

Long-term kidney dysfunction can also induce structural changes in the heart through various mechanisms. Cardiovascular events are the leading cause of death in patients with chronic renal failure; many patients die from cardiovascular complications even before reaching end-stage kidney failure.

CAUSES

Which Groups Are Prone to Chronic Kidney Failure?

• Elderly individuals;

• Patients with long-term diabetes and hypertension;

• Individuals with various autoimmune diseases, such as systemic lupus erythematosus;

• Those with a family history of kidney diseases, such as polycystic kidney disease;

• Individuals who have had acute kidney diseases (e.g., acute nephritis, acute tubular necrosis, acute interstitial nephritis) and need to monitor kidney recovery;

• Patients with long-term gout or hyperuricemia;

• Those with certain infections (e.g., throat, intestinal, urinary tract, or hepatitis B virus infections) or long-term use of nephrotoxic medications (both traditional and Western); cancer patients, such as those with multiple myeloma.

Because the kidneys have strong compensatory abilities, most patients show no symptoms in the early stages of functional impairment. Regular monitoring of kidney-related indicators is essential for early detection.

DIAGNOSIS

What is the relationship between chronic kidney disease and chronic renal failure?

Chronic renal failure represents the entire process from the initial impairment of kidney function to its complete loss. To better evaluate the various stages of chronic renal failure and provide more targeted treatment interventions, the medical field introduced the concept of "chronic kidney disease."

When various causes lead to structural or functional abnormalities in the kidneys, particularly a decline in filtration function, affecting their normal operation—primarily manifested as a progressive increase in serum creatinine—and these abnormalities persist for more than 3 months without recovery, we define it as "chronic kidney disease."

These abnormalities may specifically manifest as irregularities in blood or urine components or abnormalities in kidney imaging tests. Based on the degree of kidney function impairment, chronic kidney disease is artificially classified into stages 1 to 5. It must be emphasized that this definition is a human-made classification and must be determined by a doctor based on clinical conditions, not rigidly applied by individuals.

How can kidney function be assessed through tests?

Routine kidney-related tests include:

• Urinalysis, which can detect abnormalities such as proteinuria, red blood cells in urine, and casts;

• 24-hour urine protein test, collecting urine over 24 hours to more accurately measure protein content in urine;

• Kidney function tests, such as serum creatinine, blood urea nitrogen, serum cystatin C, creatinine clearance rate, and renal perfusion ECT;

• Imaging tests, such as kidney ultrasound or CT scans, which can reveal changes in kidney size, polycystic kidneys, etc.;

• Even a biopsy method can be used to obtain a portion of kidney tissue for pathological examination to clarify the cause of kidney damage.

Is kidney function solely represented by serum creatinine?

Due to its simplicity in testing, serum creatinine is a widely used clinical indicator for assessing kidney function. Many people encounter it during routine physical exams, and many doctors also judge kidney function based on whether serum creatinine falls within the normal range.

However, serum creatinine is not equivalent to kidney function. Kidney function refers to the kidneys' ability to filter and cleanse the blood, which cannot be directly measured. Creatinine is a byproduct of muscle metabolism. Over a certain period, its production in the body remains relatively constant, and most creatinine is excreted through the kidneys. Therefore, if kidney filtration function is impaired, creatinine accumulates in the body. Thus, serum creatinine can serve as an indirect indicator of kidney function to some extent, but it is only one indicator.

Serum creatinine has many limitations. Relying solely on it cannot promptly or accurately reflect kidney function, especially in the early stages of chronic kidney disease, where serum creatinine levels may not yet be elevated. Additionally, some medications can lower serum creatinine levels by affecting muscle metabolism, which does not necessarily indicate improved kidney function.

Currently, combining serum creatinine with serum cystatin C (Cystatin C) is considered a more accurate method for assessing kidney function.

TREATMENT

How is chronic kidney disease treated?

Kidney damage caused by various factors, if the affected part has already hardened, cannot be reversed with current medical technology. This means the non-functional part of the kidney cannot recover, and the body must rely on the remaining kidney tissue to perform its functions.

The goal of treating chronic kidney disease is not to fully restore kidney function but to protect the remaining kidney function and delay the progression to kidney failure, thereby extending the patient's lifespan and ensuring their quality of life.

Treatment for chronic kidney disease includes the following aspects:

• Etiological treatment: Identify the root cause of chronic kidney disease and treat the underlying condition to reduce further kidney damage.

• Control of risk factors: If the underlying cause cannot be eliminated, other factors that may worsen kidney function must be minimized. Recognized risk factors include long-term hypertension, diabetes, persistent proteinuria, sustained hyperuricemia, use of nephrotoxic drugs, and contrast agent administration.

• Prevention and treatment of complications: As kidney function gradually declines, various body systems may be affected, leading to complications. Interventions are needed to stabilize these abnormalities.

• Renal replacement therapy for chronic kidney failure: When kidney function is completely lost and insufficient to sustain life, kidney replacement therapy becomes necessary.

How to treat other problems caused by chronic kidney disease?

• Antihypertensive treatment: High blood pressure is a major cause of glomerulosclerosis and loss of residual nephrons. Timely and appropriate antihypertensive therapy can reduce proteinuria, delay the progression of chronic renal failure (CRF), protect target organs like the heart and brain, and improve prognosis. Common antihypertensive drugs include diuretics, beta-blockers, ACE inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), and calcium channel blockers (CCBs).

• Renal osteodystrophy: A common complication in CRF patients, including osteitis fibrosa cystica (caused by secondary hyperparathyroidism), osteomalacia, adynamic bone disease, and osteoporosis. Active vitamin D may be used based on parathyroid hormone (PTH) levels.

• Anemia: A frequent issue in CRF patients. Severe anemia in non-dialysis CRF patients should be addressed. Clinical studies show that correcting anemia with recombinant human erythropoietin (rhEPO) and supplementing iron and folic acid can slow kidney function decline.

• Metabolic acidosis: Typically treated with oral or intravenous sodium bicarbonate.

• Hyperkalemia: Treated with intravenous calcium gluconate and/or glucose-insulin infusion. Severe cases require prompt dialysis.

• Hyperphosphatemia: Managed by limiting phosphorus intake and using oral phosphate binders (e.g., calcium carbonate, calcium acetate, lanthanum carbonate, sevelamer).

What are the types of renal replacement therapy?

Currently, there are two established renal replacement methods: kidney transplantation and dialysis (hemodialysis and peritoneal dialysis).

• Hemodialysis: Uses a dialysis machine to filter the patient's blood outside the body before returning it.

• Peritoneal dialysis: Uses the patient's peritoneal membrane to remove toxins and excess fluid.

• Kidney transplantation: Involves transplanting a donor kidney (from a living or deceased donor) to replace the patient's failed kidneys.

With advances in long-term renal replacement therapy, chronic kidney failure is no longer a "terminal disease" but a "chronic condition."

When should renal replacement therapy begin?

Renal replacement therapy helps stabilize the body's internal environment, improve symptoms, and enhance quality of life. However, starting dialysis too early wastes medical resources and increases risks, while starting too late reduces quality of life and longevity.

There is no definitive standard for initiating therapy. Decisions are based on glomerular filtration rate (GFR), nutritional status, and clinical symptoms.

Severe hyperkalemia, acidosis, fluid overload, or acute pulmonary edema are indications for emergency dialysis. Many patients delay until this stage, leading to complications.

What is hemodialysis for chronic kidney disease?

Hemodialysis uses a dialysis machine to purify blood, replacing the kidney's filtration function. Blood is drawn from the patient, filtered through a dialyzer, and returned to the body to remove toxins and correct electrolyte imbalances.

What are the advantages and disadvantages of hemodialysis?

Advantages: More efficient than peritoneal dialysis, quickly removing excess fluid and toxins, especially useful for pulmonary edema, hyperkalemia, and drug poisoning.

Disadvantages:

• Requires frequent visits to dialysis centers, disrupting work and social life.
• Requires stable heart function due to rapid fluid and toxin removal.
• Vascular access risks (bleeding, infection, stenosis, thrombosis).
• Risk of cerebral edema and dialysis disequilibrium syndrome in new patients.
• Hypotension is common, affecting long-term outcomes.

What is peritoneal dialysis for chronic kidney disease?

Peritoneal dialysis uses the peritoneal membrane to filter toxins and fluid. A dialysis solution (dialysate) is infused into the abdomen via a catheter, where waste products diffuse into the fluid, which is later drained and replaced.

What are the advantages and disadvantages of peritoneal dialysis?

Advantages:

• Can be performed at home after training, offering flexibility.
• No vascular access complications.
• Gentler fluid removal, better for cardiovascular stability.

Disadvantages:

• Requires strict hygiene to prevent infections like peritonitis.
• Less effective for acute emergencies (e.g., drug poisoning, hyperkalemia).
• Long-term risks include hernias and catheter-related issues.
• Not suitable for all patients (e.g., small abdominal cavity, infections).
• Metabolic complications (e.g., hyperglycemia from glucose absorption).
• Higher protein loss than hemodialysis, unsuitable for critically ill patients.
• May require switching to hemodialysis as residual kidney function declines.

What are the pros and cons of kidney transplantation for chronic kidney failure?

Pros: Best alternative, restoring full kidney function (including endocrine functions), improving quality of life, and reducing dialysis dependence.

Cons: Surgical risks (infection, bleeding, organ damage), rejection requiring lifelong immunosuppressants (increasing infection and cancer risks), and limited donor availability.

When is kidney transplantation unsuitable for chronic kidney disease patients?

• Inability to tolerate surgery.
• Active or recently treated cancer.
• Limited life expectancy.
• Poorly controlled mental illness.
• Severe obesity (BMI >40).
• Non-adherence to medication.
• Drug/alcohol abuse.
• Poor compliance with prior treatments.

Note: Many factors are relative contraindications, requiring individualized assessment.

DIET & LIFESTYLE

What dietary precautions should patients with chronic renal failure take?

As chronic kidney disease progresses, dietary requirements are not static.

• Before developing chronic kidney disease, as primary prevention, dietary focus should be on managing risk factors like hypertension and diabetes, such as adopting a low-salt diet and diabetic diet.

• During the progression of chronic kidney disease, as secondary prevention, the goal of dietary adjustments is to slow disease progression, delay the onset of chronic renal failure, and prevent complications. Depending on clinical conditions, a low-salt, diabetic, low-purine, or low-phosphorus diet may be necessary, along with controlling the type and amount of protein intake. The principle is: adequate but not excessive—too much becomes a burden.

• In the chronic renal failure stage, especially for patients undergoing dialysis, malnutrition becomes a critical factor threatening survival, making adequate nutrition a higher priority.

Why should chronic kidney disease patients follow a low-phosphorus diet?

Phosphorus is an essential mineral in the body. Organic phosphorus is a key component of proteins, cell membranes, and energy substances, while inorganic phosphorus, along with calcium, builds strong bones.

Impaired kidney function means waste products, including phosphorus, accumulate in the body. Excess phosphorus adversely affects the heart, blood vessels, and bones. Thus, managing blood phosphorus levels is crucial for chronic kidney disease patients.

What is a low-phosphorus diet?

Phosphorus is a component of protein, so protein-rich foods like pork, poultry, and fish are high in phosphorus. However, insufficient protein intake can lead to malnutrition, which also harms health and increases mortality. The goal is to limit phosphorus intake (800–1000 mg/day).

• Limit total protein intake while ensuring adequacy. Opt for foods with a low phosphorus-to-protein ratio, such as egg whites.
• Avoid processed foods: These contain higher and more absorbable phosphate levels than fresh foods. Check ingredient labels for phosphorus content.
• Avoid beverages like cola.
• Reduce intake of bran, milk, dairy products, dried beans, soy products, shrimp, egg yolks, peanuts, almonds, walnuts, sunflower seeds, chestnuts, chocolate, peanut butter, organ meats, and mushrooms.

Why should chronic renal failure patients follow a low-protein diet?

Modern research shows that reducing protein intake (while meeting physiological needs) can slow kidney function decline in chronic kidney disease patients. Prioritize high-quality proteins rich in essential amino acids, such as eggs, fish, lean meat, and milk.

Minimize plant-based proteins like peanuts and their products. Daily protein intake recommendations vary, but around 0.6 g/kg body weight meets basic needs. Emphasize balanced nutrition—low-protein diets aim to avoid excess, not eliminate protein.

Why should chronic renal failure patients follow a low-salt diet?

Salt (sodium chloride) is a major source of dietary sodium. Excess sodium worsens disease control in chronic kidney disease patients, especially those with edema, low urine output, or hypertension.

Recommended intake: The WHO advises adults to consume no more than 5 g of salt (~2000 mg sodium) daily.

Why should chronic renal failure patients follow a low-purine diet?

Impaired kidney function reduces uric acid excretion, often leading to hyperuricemia, which further damages the kidneys. Since uric acid is a purine metabolite, most chronic kidney disease patients need a low-purine diet.

Purines are essential for cells, so foods with more cells (e.g., organ meats, seafood, legumes) are high in purines. Avoid alcohol and limit intake of seafood, organ meats, and soy products.

What preparations should pre-dialysis chronic renal failure patients and families make?

Patients expected to progress to uremia should prepare in advance.

• Physically: Manage complications like heart function, anemia, and renal osteodystrophy.

• Mentally: Understand the disease correctly to avoid unnecessary fear. Chronic kidney disease is manageable—communicate with doctors and peers to learn about future adjustments.

• Explore kidney replacement options (e.g., dialysis, transplant) based on medical, financial, insurance, and social factors. Each method has pros and cons and may complement each other.

PREVENTION

How to Prevent Chronic Renal Failure?

• Actively treat diseases that may affect kidney function, such as hypertension and diabetes, to help preserve renal function;

• After kidney disease occurs, follow the doctor's instructions for standardized treatment to delay disease progression as much as possible;

• Additionally, avoid blindly trusting unverified folk remedies or tonics of unknown composition and origin to prevent unnecessary kidney damage.