Cystic kidney disease

Disease Description (Causes and Symptoms)

• Definition summary: A general term for all cases in which cysts develop in the kidneys. These range from simple cysts to complex cysts suspected of being cancerous because of abnormalities in their contents or walls, and may be classified using systems such as the Bosniak classification. Autosomal dominant polycystic kidney disease (ADPKD) is a representative hereditary form.
• Causes and pathophysiology:
  • Hereditary: Autosomal dominant polycystic kidney disease (ADPKD) is associated with abnormalities in the PKD1 and PKD2 genes. Multiple cysts develop, enlarge over time, and eventually impair kidney function.
  • Nonhereditary (such as simple cysts): The cause is often unclear.
  • Complex cysts may contain internal septa, calcification, or solid components, increasing the possibility of malignant transformation (Bosniak categories 1→4).
• Main symptoms:
  • Often discovered incidentally without symptoms, especially in the case of simple cysts.
  • Flank pain, abdominal distension, discomfort, and nausea.
  • In ADPKD, hypertension, palpable kidneys, recurrent hematuria, urinary tract infections, and possible cyst rupture or cystic bleeding.
  • Complications: Chronic kidney disease/end-stage kidney disease, accompanying liver cysts, cerebral aneurysms (which may occur in approximately 10% of cases), cyst infection, and cystic bleeding.

Treatment Methods

• Conservative observation:
  • Simple cysts (without symptoms or complex features) are monitored periodically with ultrasound or CT/MRI.
• Cysts causing symptoms:
  • Symptoms may be relieved by percutaneous aspiration followed by sclerotherapy (such as with ethanol), although there is a risk of recurrence.
  • Surgical excision, such as partial nephrectomy, may be considered depending on the location and characteristics.
• Complex cysts or suspected malignancy:
  • Surgical removal (partial or complete nephrectomy) and treatment according to tumor-treatment guidelines are determined based on imaging findings or biopsy results.
• Specific treatment for ADPKD (hereditary polycystic kidney disease):
  • Blood pressure control: ACE inhibitors (ACEi) or ARBs are recommended as first-line treatments (to preserve kidney function).
  • Drug treatment: In rapidly progressive ADPKD, the vasopressin V2 receptor antagonist tolvaptan may slow the increase in kidney volume and the decline in kidney function — liver function monitoring is necessary during treatment.
  • Infected cysts: For bacterial cyst infections, antibiotics that can penetrate cysts, such as quinolones or TMP-SMX, are used (the choice of antibiotic depends on the source of infection and the patient's condition).
  • In end-stage kidney disease: Dialysis or kidney transplantation.
• Lifestyle and self-management:
  • A low-salt diet (for blood pressure control), weight management, and smoking cessation.
  • Avoid prolonged dehydration, but recommendations for excessive fluid intake should be individualized. In ADPKD, adequate fluid intake may sometimes be recommended because reducing excessive vasopressin activity may be helpful; consult your treating physician.
  • Avoid long-term use of nephrotoxic drugs, such as NSAIDs.
  • If there is a family history, consider genetic counseling and family screening, including genetic testing when necessary.
• Precautions (risk of complications and self-management):
  • Immediate medical attention is needed if high fever, flank pain, or hematuria occurs because these may indicate cyst infection or bleeding.
  • When using tolvaptan, monitor for the risk of elevated liver enzymes (ALT/AST) and side effects such as increased urination and thirst.
  • Depending on the family history, consider screening for cerebral aneurysms, especially if there is a family history of cerebrovascular aneurysms or if high-risk occupations or activities are planned.
  • If planning a pregnancy, counseling is needed regarding genetic risks and plans for stopping and managing medications.

Checklist Before an Outpatient Visit (Including Sample Questions)

• Recommended items to bring:
  • A list of all currently used medications (including prescription drugs, over-the-counter drugs, and health functional foods)
  • Records of past medical conditions and surgeries
  • Family history (especially kidney failure, polycystic kidney disease, and cerebral hemorrhage or aneurysms)
  • Results of previous imaging tests (ultrasound, CT, or MRI films or reports)
  • Recent blood pressure records and a symptom diary, such as changes in urine color and dates of pain episodes
• Useful preparation for the medical consultation:
  • The timing and pattern of symptom onset (location, intensity, and frequency of pain)
  • The presence of fever, urinary symptoms, or hematuria
  • Whether pregnancy is possible or planned
• Sample questions to prepare before the outpatient visit:
  • "Do my cysts currently show any signs of malignancy? Do I need additional imaging?"
  • "Should I undergo genetic testing? How should my family members be screened?"

General Sample Questions to Ask the Doctor

• "How do you determine the rate of progression of my cysts (or disease)? What tests do I need, and how often should I have them?"
• "What are the main side effects of the medication you plan to prescribe (or the treatment you recommend), and how should they be managed?"
• "Are there any particular foods or medications I should avoid in my lifestyle?"
• "If my family members should be advised to undergo screening, who should be tested and when should testing begin?"

Disease-Specific Sample Questions

• "There is a history of ADPKD in my family. Is genetic testing (or family screening) recommended? (Including which tests, the cost, and whether they are covered by insurance)"
• "What criteria must I meet to determine whether I am a candidate for tolvaptan treatment? What are the expected benefits and risks, such as hepatotoxicity, during treatment?"