Renal Failure | AKI | CKD

Definition

• Renal failure is a condition where the kidneys lose their ability to filter waste products and excess fluids from the blood effectively. This results in the accumulation of toxins in the body, leading to severe health complications.

Types of Renal Failure

• Acute Renal Failure (ARF):-

  • Definition:- A sudden decline in kidney function, typically occurring over hours to days. It is often reversible if treated promptly.

  • Also known as Acute Kidney Injury (AKI), 

• Chronic Renal Failure (CRF):-

  • Definition:- A gradual loss of kidney function over months to years. This condition is usually irreversible and leads to end-stage renal disease (ESRD) if not managed effectively.

  • Also known as chronic Kidney Disease (CKD)

Stages of Acute Renal Failure (ARF)

1. Initiation Stage:-

   • Timeframe:- Hours to days.

   • Details:- The initial injury to the kidneys occurs, leading to a decrease in urine output and a rise in serum creatinine and BUN levels. Early detection and intervention are critical at this stage.

2. Oliguric/Anuric Stage:-

   • Timeframe:- 1-2 weeks.

   • Details:- Marked by a significant reduction in urine output (oliguria < 400 mL/day or anuria < 100 mL/day). Fluid overload, electrolyte imbalances (e.g., hyperkalemia), and uremic symptoms become prominent.

3. Diuretic Stage:-

   • Timeframe:- 1-3 weeks.

   • Details:- Gradual increase in urine output, sometimes leading to excessive fluid loss (up to 5 L/day). The kidneys start recovering, but they may still struggle to concentrate urine, leading to dehydration and electrolyte imbalances.

4. Recovery Stage:-

   • Timeframe: It may take 1-2 year

   • Details:- Kidney function gradually returns to normal, although some patients may have residual damage. Serum creatinine and BUN levels normalize, and urine output stabilizes.

Stages of Chronic Renal Failure (CRF)

1. Mild to Moderate Kidney Damage (GFR ≥30 mL/min/1.73 m²):-

• Nephron Damage:- Approximately 10-40% of nephrons are damaged.

• Time Frame:- This stage can last for several years.

• Main Findings:-

  • Proteinuria (Protein in Urine):-
    Early damage to the glomeruli allows proteins to leak into the urine, indicating reduced filtering capacity.

  • Hypertension (High Blood Pressure):-
    Impaired kidney function retains fluid and sodium balance, leading to elevated blood pressure.

2. Severe Kidney Damage (GFR 15-29 mL/min/1.73 m²):-

• Nephron Damage:- Approximately 40-85% of nephrons are damaged.

• Time Frame:- Progresses over months to years.

• Main Findings:-

  • Fatigue and Weakness:-
    Accumulation of waste products like urea in the blood causes systemic fatigue.

  • Edema (Swelling):-
    Reduced kidney function leads to fluid retention in tissues, especially in the lower extremities.

  • Anemia:-
    The kidneys produce less erythropoietin, leading to reduced red blood cell production and anemia.

3. End-Stage Renal Disease (GFR <15 mL/min/1.73 m² or on Dialysis):-

• Nephron Damage:- Over 85-90% of nephrons are damaged or non-functional.

• Time Frame:- Rapid progression within weeks to months.

• Main Findings:-

  • Severe Nausea and Vomiting:-
    High levels of uremic toxins irritate the gastrointestinal system.

  • Pulmonary Edema (Fluid in Lungs):-
    Fluid overload due to failing kidneys causes fluid accumulation in the lungs, impairing breathing.

  • Severe Electrolyte Imbalances:-
    The kidneys cannot regulate electrolytes, leading to dangerous levels of potassium and acid-base imbalances.

Causes

• Acute Renal Failure (ARF):-

  • Prerenal Causes:-

    • Hypovolemia:- Severe dehydration, blood loss, or shock.

    • Heart Failure:- Reduced cardiac output leading to decreased renal perfusion.

    • Septic Shock:- Widespread infection causing hypotension and reduced blood flow to the kidneys.

  • Intrarenal Causes:-

    • Acute Tubular Necrosis (ATN):- Prolonged ischemia or exposure to nephrotoxic drugs.( 90% )

    • Glomerulonephritis:- Inflammation of the glomeruli, often due to infections or autoimmune diseases.

    • Acute Interstitial Nephritis:- Allergic reaction to medications or infections, leading to inflammation of the kidney interstitium.

  • Postrenal Causes:-

    • Obstruction:- Kidney stones, tumors, or benign prostatic hyperplasia (BPH) blocking urine flow.

    • Ureteral Stricture:- Narrowing of the ureter due to scarring or surgery.

    • Bladder Dysfunction:- Neurogenic bladder causing urinary retention and backflow of urine.

• Chronic Renal Failure (CRF):-

  • Diabetes Mellitus:- Persistent high blood sugar levels damage the nephrons over time.

  • Hypertension:- Chronic high blood pressure leads to arteriosclerosis of renal arteries, reducing blood flow to the kidneys.

  • Chronic Glomerulonephritis:– Long-term inflammation and scarring of the glomeruli, often due to autoimmune diseases like lupus.

  • Polycystic Kidney Disease:– Genetic disorder causing the formation of numerous cysts in the kidneys, leading to progressive loss of function.

  • Chronic Obstructive Uropathy:- Prolonged urinary tract obstructions, such as from enlarged prostate or kidney stones, leading to kidney damage.

Symptoms

• Acute Renal Failure (ARF):-

  • Oliguria or Anuria:-

    • Details:- Sudden reduction or complete absence of urine output. Oliguria is defined as urine output < 400 mL/day, and anuria is < 100 mL/day. This symptom indicates severe kidney dysfunction, often accompanied by fluid retention.

  • Fluid Retention:-

    • Details:- Accumulation of excess fluid in tissues, leading to edema, especially in the legs, ankles, and face. Fluid retention can also cause pulmonary edema, leading to shortness of breath.

  • Fatigue and Confusion:-

    • Details:- Accumulation of toxins in the blood, such as urea and creatinine, can lead to uremic encephalopathy. Patients may experience lethargy, difficulty concentrating, and confusion.

  • Nausea and Vomiting:-

    • Details:- Uremic toxins irritate the gastrointestinal tract, leading to persistent nausea, vomiting, and loss of appetite.

  • Hypertension:-

    • Details:- Elevated blood pressure due to fluid overload and increased renin production. Hypertension exacerbates kidney damage and increases the risk of cardiovascular complications.

  • Electrolyte Imbalances:-

    • Details:- Hyperkalemia (high potassium levels) is common in ARF and can cause muscle weakness, paralysis, and life-threatening arrhythmias. Hyponatremia (low sodium levels) can lead to confusion, seizures, and coma.

• Chronic Renal Failure (CRF):-

  • Fatigue and Weakness:-

    • Details:- Anemia due to decreased erythropoietin production by the kidneys leads to chronic fatigue, pallor, and weakness. Patients may also experience shortness of breath on exertion.

  • Loss of Appetite and Weight Loss:-

    • Details:- Uremic toxins suppress appetite, leading to malnutrition and unintentional weight loss. The metallic taste in the mouth and nausea contribute to poor dietary intake.

  • Anemia:-

    • Rationale:- The kidneys produce erythropoietin, a hormone that stimulates red blood cell production. In renal failure, the decreased erythropoietin production leads to a lower red blood cell count, causing anemia and associated symptoms like fatigue, pallor, and shortness of breath.

  • Edema:-

    • Details:- Persistent fluid retention causes swelling in the lower extremities, face, and around the eyes. Severe edema can lead to ascites (fluid accumulation in the abdomen) and pleural effusion (fluid in the lungs).

  • Hypertension:-

    • Details:- Chronic fluid overload and activation of the renin-angiotensin-aldosterone system (RAAS) lead to sustained high blood pressure, further damaging the kidneys and increasing the risk of heart disease.

  • Bone Pain and Fractures:-

    • Details:- Impaired vitamin D metabolism and calcium-phosphate imbalance result in renal osteodystrophy, characterized by bone pain, deformities, and an increased risk of fractures.

  • Hypocalcemia:-

    • Rationale:- The kidneys convert vitamin D into its active form, which is necessary for calcium absorption. In renal failure, reduced vitamin D activation leads to low calcium levels in the blood, resulting in hypocalcemia, which can cause muscle cramps, tetany, and bone pain.

  • Bronze Pigmentation:-

    • Rationale:- Chronic renal failure can cause a buildup of uremic toxins in the body, leading to a bronze or sallow skin tone, particularly in sun-exposed areas.

  • Pruritus:-

    • Details:- Severe itching due to the accumulation of uremic toxins in the skin, often exacerbated by dry skin and secondary hyperparathyroidism.

  • Azotemia:-

    • Rationale:- Azotemia refers to the elevated levels of nitrogenous waste products (such as urea and creatinine) in the blood due to impaired kidney function. This can cause symptoms like confusion, nausea, and vomiting.

  • Proteinuria:-

    • Rationale:- The kidneys normally prevent significant amounts of protein from passing into the urine. In renal failure, damage to the glomeruli allows the protein to leak into the urine, leading to proteinuria, which is an early sign of kidney damage and can contribute to edema.

  • Uremic Frost:-

    • Details:- A rare but distinctive finding in advanced CRF, where urea crystallizes on the skin, especially on the face and arms. This occurs due to the excretion of urea through sweat glands.

Diagnostic Tests

• Blood Tests:-

  • Serum Creatinine:-

    • Test:- Measures creatinine levels, a waste product from muscle metabolism.

    • Normal Value:- 0.6 – 1.2 mg/dL.

    • Significance:- Elevated levels indicate impaired kidney function, with a direct correlation between the severity of renal failure and the rise in serum creatinine levels.