Kidney dysplasia

Disease Description (Causes and Symptoms)

• Definition: Renal dysplasia is a congenital malformation in which the renal parenchyma differentiates and develops abnormally during development, resulting in incomplete nephron structures or cystic changes. Obstructive cystic dysplastic kidney may be associated with increased intranephron pressure caused by urinary tract obstruction.
• Causes and pathophysiology: The exact causes vary and have not been clearly established. Abnormalities in apoptosis and cell proliferation patterns, and rarely genetic factors, may be involved. Approximately 90% of cases are reported to be accompanied by urinary tract obstruction or other urinary tract malformations.
• Main symptoms and clinical features: Renal hypoplasia (unilateral or bilateral), oligohydramnios on prenatal ultrasound, nonvisualization of the kidneys, or absence of urine in the bladder. External findings such as a flattened nose and large, low-set ears have been reported.
• Prognosis overview: The incidence is approximately 1 in 2,500–4,000 births and is more common in boys. Approximately one-third of all affected fetuses die in utero; even among survivors, severe bilateral lesions may cause pulmonary hypoplasia and death in the early neonatal period (within tens of hours). In unilateral lesions, the long-term prognosis is determined by whether the opposite kidney is functional.

Treatment Methods

• General principles: Treatment varies depending on the extent of the lesions (unilateral vs. bilateral), accompanying urinary tract malformations, and kidney function. The goals are to preserve remaining kidney function, prevent urinary tract infections and complications, and manage growth and development.
• Conservative management
  • Regular monitoring of kidney function: serum creatinine, glomerular filtration rate (estimated GFR), urine protein testing, and blood pressure measurement.
  • Prevention and early treatment of urinary tract infections (UTIs): use of appropriate antibiotics for UTIs (based on culture results).
  • Lifestyle management: avoidance of dehydration and nephrotoxic medications (e.g., NSAIDs, some antibiotics and contrast agents), and management of fluids and electrolytes.
• Diagnostic/therapeutic procedures and surgery
  • Depending on the results of imaging and functional tests (see the diagnostic items below), surgical correction may be considered if urinary tract obstruction or major anatomical abnormalities are present (e.g., correction of an obstructive lesion, ureteroplasty).
  • Kidney-preserving treatment and surgical approaches should be discussed in cases of recurrent UTIs or declining function.
• Management of end-stage renal disease (ESRD)
  • Dialysis (hemodialysis/peritoneal dialysis) and kidney transplantation may be necessary.
• Genetic counseling: Genetic counseling and, if necessary, genetic testing are recommended when there is a family history or multiple malformations.
• Precautions (during treatment)
  • In unilateral lesions, protecting the opposite kidney is the highest priority (avoidance of nephrotoxic medications, infection management, and blood pressure control).
  • If prenatal diagnosis shows severe bilateral lesions and oligohydramnios, counseling is needed regarding neonatal survival and respiratory prognosis.

Checklist Before an Outpatient Visit (Including Example Questions)

• Items to bring
  • List of current medications (including prescription drugs, OTC medications, and supplements)
  • Copies of previous test results (ultrasound, kidney function tests, voiding cystourethrography (VCUG), nuclear medicine tests, etc.)
  • Recent weight and blood pressure measurements, and records of changes in urination (increased frequency, painful urination, hematuria, etc.)
  • Notes on the presence of fever, weakness, edema, or delayed growth and development
• Items to check before the outpatient visit
  • Current symptoms (urination problems, symptoms of UTI, edema, weight loss, etc.)
  • History and treatment of previous UTIs
  • Birth history (prenatal ultrasound findings and information on amniotic fluid volume), respiratory problems during the neonatal period, etc.
• Example questions (phrases for the patient/caregiver to present to the doctor)
  • "What are the recent blood and urine test results, and what is the trend in kidney function?"
  • "What tests should be performed, and how often, over the next few months?"

General Example Questions to Ask the Doctor

• What are the side effects of this medication (or prescription), and how does it affect the kidneys?
• What is my child's (or my) long-term prognosis? How high is the risk of progressing to chronic kidney failure?
• Are there any medications or activities that should be particularly avoided as part of my lifestyle? (e.g., NSAIDs, certain antibiotics, a high-protein diet)
• How often should regular checkups be performed, and which tests are needed?

Disease-Specific Example Questions

• If only one kidney is dysplastic: "Which tests should be performed to assess the structure and function of the opposite kidney, and until when and how often should they be done?"
• If detected prenatally or if oligohydramnios was present: "What preparations should be made regarding the newborn's respiratory (lung) condition after birth (such as a neonatal intensive care unit and the possibility of mechanical ventilation)?"