Acute kidney failure

Disease Description (Causes and Symptoms)

• Definition summary: Acute renal failure (acute renal failure, acute kidney injury) is a condition in which the glomerular filtration rate (GFR) rapidly decreases over a short period (days to weeks), causing creatinine and uremic toxins to rise and disrupting fluid, electrolyte, and acid-base balance.
• Main pathophysiology: Insufficient blood flow (hypoperfusion), kidney parenchymal injury (glomeruli, tubules, and interstitium), and urinary tract obstruction lead to a decrease in GFR, resulting in the accumulation of water, K, H+, and uremic toxins in the body.
• Main causes (classified by priority):
  • Prerenal: Reduced renal perfusion due to severe dehydration (vomiting or diarrhea), bleeding, heart failure, sepsis, hypotension, excessive diuretic use, etc.
  • Renal (intrinsic): Acute tubular necrosis (ATN), acute glomerulonephritis, acute interstitial nephritis, and drug-induced injury (nephrotoxins; NSAIDs, aminoglycosides, cancer treatment drugs, etc.)
  • Postrenal: Urinary tract obstruction (urinary stones, prostate enlargement or cancer, bladder or urinary tract tumors, ureteropelvic junction obstruction, neurogenic bladder)
• Main symptoms: Decreased urine output (oliguria) or anuria, although nonoliguric forms are also common. Nausea and vomiting, generalized edema, shortness of breath (pulmonary edema), muscle weakness and arrhythmia due to hyperkalemia, metabolic acidosis, hypertension, altered consciousness and seizures (in cases of severe uremia), etc.

Treatment Methods

• General principles: Correct the underlying cause (restore perfusion, remove obstruction, discontinue harmful medications), actively manage complications (hyperkalemia, fluid overload, acidosis, and uremia), and use renal replacement therapy (dialysis) when necessary. The goal is recovery of kidney function; depending on the cause, complete recovery or progression to chronic disease may occur.
• Initial and emergency treatment:
  • Normalize renal perfusion with fluid replacement (crystalloid solutions)—use caution in cases of fluid overload.
  • In cases of hypotension, use appropriate vasopressors (e.g., norepinephrine) and provide critical care.
  • Discontinue or adjust harmful drugs (NSAIDs, some antibiotics, contrast agents, etc.).
• Electrolyte and acid-base management:
  • Hyperkalemia: If there are ECG abnormalities, use calcium gluconate, insulin + glucose, β2 agonists, and intestinal K removal (selecting an appropriate preparation); use emergency dialysis when necessary.
  • Acidosis: In severe cases (e.g., pH < 7.1), consider bicarbonate administration or dialysis.
  • Fluid overload: Use diuretics when there is a response; if there is no response or the condition is severe, use dialysis (consider CRRT initially).
• Indications for renal replacement therapy (dialysis) (general criteria):
  • Excessive fluid retention unresponsive to treatment, causing shortness of breath/pulmonary edema
  • Life-threatening hyperkalemia (ECG abnormalities or levels above 6.5 mmol/L, etc.)
  • Severe metabolic acidosis (e.g., pH < 7.1)
  • Concerning uremic symptoms (uremic encephalopathy, pericarditis, etc.)
  • When removal of specific toxic substances is necessary
  • The dialysis method is selected according to the patient's hemodynamic status: intermittent hemodialysis (HD) or continuous renal replacement therapy (CRRT).
• Diagnostic and therapeutic procedures:
  • If urinary tract obstruction is suspected, perform imaging (abdominal ultrasound/CT) and insert a urological urinary catheter for drainage; surgery or stent placement may be necessary.
  • If the cause is unknown, consider a kidney tissue examination (biopsy), particularly when glomerular or interstitial disease is suspected.
• Medication and nutritional management:
  • Adjust medication dosages according to kidney function (including antibiotics and anticoagulants).
  • Control protein, potassium, and phosphorus intake and provide sufficient calories.
• Lifestyle management and precautions:
  • Avoid factors that cause dehydration or hypotension (indiscriminate diuretic use, fasting, and excessive alcohol consumption).
  • Avoid NSAIDs and nephrotoxic drugs; take preventive measures when contrast agents are used (fluid replacement, low-dose use, and consideration of alternative imaging).
  • Manage risk factors for neurogenic bladder and urinary tract obstruction (prostate enlargement and tumors).
• Prevention of complications: Manage infections and frequently monitor electrolytes, body weight, blood pressure, and blood tests (creatinine, potassium, and acid-base status).

Checklist Before an Outpatient Visit (Including Example Questions)

• Items to prepare/bring:
  • A list of currently used medications (including prescription drugs, OTC medications, herbal medicines, and supplements)
  • Recent test results (blood tests: creatinine, BUN, electrolytes, and acid-base status; urinalysis; ECG if possible)
  • Records of changes in urine output and body weight (over the past 24–72 hours), including whether edema or shortness of breath is present
  • When symptoms began and how they have progressed (when they started and whether they have gradually worsened or improved)
  • A history of recent surgery, contrast-enhanced examinations, infection, vomiting, diarrhea, or bleeding
  • Urinary symptoms (difficulty urinating, hematuria, a feeling of incomplete bladder emptying) and past urinary history (prostate or bladder problems)
• Examples of useful questions during the consultation:
  • "Have you recently started or taken any medications, especially diuretics, antibiotics, NSAIDs, or contrast agents?"
  • "Have you recently had symptoms such as vomiting, diarrhea, fever, or bleeding?"
  • "What is your average daily urine output, and has it changed recently?"
  • "Are you short of breath or experiencing swelling in your legs? Has your weight increased rapidly?"

Examples of General Questions to Ask the Doctor

• "What do my creatinine and electrolyte levels mean? Are they at a level requiring dialysis?"
• "Are there any of my current medications that I should stop or have the dosage adjusted?"
• "How likely is it that my kidney function will recover with treatment? What is the prognosis?"
• "If an emergency occurs, such as ECG changes or severe shortness of breath, when should I go to the emergency room?"
• "What special precautions should I take regarding food and fluid intake?"

Examples of Disease-Specific Questions

• "I recently had an examination using contrast agents. Could this be a possible cause of acute renal failure? What should I do for prevention?"
• "My urine output has decreased but has not stopped completely (nonoliguric). How does this affect the prognosis or treatment approach?"
• "I am currently taking a blood pressure medication (ACEi/ARB). Do I need to stop it temporarily, and when can I restart it if it is stopped?"