PANCE Blueprint Renal System (5%)

Polycystic kidney disease (Lecture)

Patient will present as → a 34-year-old male with hematuria and flank/abdominal pain. He denies any recent trauma. He reports a history of recurrent urinary tract infections, and his family history is significant for his mother, who died of a "brain bleed" at age 42. Vital signs are significant for a blood pressure of 158/105 mmHg. On physical exam, there is a late systolic crescendo murmur with a midsystolic click and tenderness upon palpation of the abdominal flanks. An ultrasound of the abdomen shows bilateral anechoic renal cysts with posterior enhancement.

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Polycystic kidney disease is characterized by the growth of numerous cysts in the kidneys. The cysts are made of epithelial cells from the renal tubules.  The cysts replace the mass of the kidneys and reduce function, leading to kidney failure

"Polycystic kidney disease frequently presents with abdominal or flank pain with microscopic or gross hematuria. A family history is present in up to 75% of cases. Whenever patients present with resistant hypertension and a palpable abdominal mass, the diagnosis of ADPKD should be entertained."

Adult polycystic kidney disease (ADPKD) is one of the most common human genetic disorders (autosomal dominant)

  • > 30 years old, + family history, and abdominal mass (flank)
  • In a young patient with hypertension and flank/abdominal pain, think PKD
  • Accounts for 5-10% of patients with end-stage renal disease
  • 10% have brain aneurysms (so be worried about the complaint of the worst headache ever), 50% of patients end up on dialysis
  • Cardiovascular abnormalities
    • mitral valve prolapse
    • left ventricular hypertrophy
Polycystic kidneys, gross pathology 20G0027 lores

Gross pathology of polycystic kidneys. Ureters are visible.

The diagnostic test of choice is ULTRASONOGRAPHY, which shows fluid-filled cysts, CT scan will show large renal size and multiple thin-walled cysts

  • Ultrasound is also indicated to test family members of patients
  • Anemia may be noted on complete blood count
  • Urinalysis: proteinuria, hematuria, and commonly, pyuria and bacteriuria
  • Genetic studies for PKD1 and PKD2 can detect the presence of mutation before symptoms develop
Advanced polycystic kidney disease with multiple cysts

Renal ultrasound demonstrating advanced polycystic kidney disease with multiple cysts.

There is no cure for ADPKD - treatment is supportive to ease symptoms and prolong life

  • Control hypertension BP < 130/80 with an ACE-inhibitor or angiotensin receptor blocker (ARB)
  • Infections should be treated vigorously with antibiotics
  • Dialysis or transplantation should be considered when renal insufficiency becomes life-threatening

osmosis Osmosis
Picmonic
Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is an autosomal dominant condition. The majority of cases are thought to result from genetic mutations in the PDK1 and PKD2 genes which are located on chromosomes 16 and 4, respectively. The disease is characterized by cystic enlargement of the renal tubules. Patients are generally asymptomatic early in the disease, with the most common initial presenting symptom being hypertension. Nearly all patients with ADPKD experience progressive deterioration in renal function leading to chronic kidney disease. Patients are also at risk for various extrarenal manifestations including liver cysts, mitral valve prolapse, and intracranial aneurysms. Nephroprotective agents like ACE inhibitors or ARBs are helpful but many patients will require hemodialysis.

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Question 1
A 43-year-old female patient presents with back pain and hematuria. The patient reports having this problem earlier this year and recalls her previous clinician telling her, “they're just cysts.” Denying any history of urinary tract infections, the patient reports her mother was on dialysis before passing away. The patient is afebrile and her physical examination is positive for diffuse back tenderness and bilateral flank masses with palpation. Urine dipstick is positive for 3+ blood and is negative for leukocytes and nitrites. What is this patient's most likely diagnosis?
A
adult polycystic kidney disease
B
renal cyst
Hint:
Renal cysts and renal cell carcinoma generally present unilaterally.
C
horseshoe kidney
Hint:
A horseshoe kidney (fusion of the renal tissue) may be palpated bilaterally; otherwise, the patient is asymptomatic.
D
renal cell carcinoma
Hint:
Renal cysts and renal cell carcinoma generally present unilaterally.
Question 1 Explanation: 
Adult polycystic kidney disease is a hereditary condition that almost always has a bilateral presentation (95% of the cases). It does not appear until after the age of 40, and dialysis or kidney transplantation is necessary for survival. Renal cysts and renal cell carcinoma generally present unilaterally. A horseshoe kidney (fusion of the renal tissue) may be palpated bilaterally; otherwise, the patient is asymptomatic.
Question 2
A 32-year-old woman presents for a routine physical examination. She feels well with no specific complaints. On physical examination, her blood pressure is noted to be 154/92 mm Hg. You note slight fullness to the abdomen on palpation without tenderness or obvious mass. Routine labs are ordered, including a UA, with the following results: UA and sediment analysis: 2+ blood, trace protein, negative leukocyte esterase, negative nitrite; 10 to 20 red blood cells (RBCs) per high power field (HPF), no leukocytes, bacteria, or other cells; rare granular casts. BUN 12, Creatinine 0.8. What is the most likely cause of the hematuria?
A
urinary tract infection
Hint:
Urinary tract infection would not fit this patient scenario, as she has no dysuria, and UA is negative for leukocytes, leukocyte esterase, nitrites, and bacteria
B
glomerulonephritis
Hint:
In the absence of RBC casts and clinical signs and symptoms, this would not be glomerulonephritis.
C
renal calculi
Hint:
Renal calculi would not cause abdominal fullness and hypertension and would be symptomatic on presentation.
D
urinary sample contamination
Hint:
The urine sample is not contaminated as there are no squamous epithelial cells reported.
E
polycystic kidney disease
Question 2 Explanation: 
Polycystic kidney disease (PKD) is an autosomal dominant disorder that affects approximately 500,000 patients in the United States, occurring in about 1 in 800 live births. Fifty percent of patients will reach ESRD by age 60, and PKD accounts for approximately 10% of hemodialysis patients. It is the most common hereditary disorder to result in ESRD. Family history is positive in 75% of cases, but genetic mutations can occur spontaneously, and patients can present without a family history. Signs and symptoms of PKD include abdominal fullness due to enlarged kidneys, abdominal pain due to bleeding into cysts, microscopic or gross hematuria, depending on the extent of the disease, and hypertension. Patients are often asymptomatic, and the first signs of the disease may be hypertension, microscopic hematuria, and mild proteinuria. Abdominal fullness and pain occur later in the disease, as the number and size of cysts increase. Ultrasound is the diagnostic test of choice to detect PKD: three or more cysts in patients younger than 30, three or more cysts in each kidney in patients 30 to 59 years of age, and five or more cysts in each kidney in patients older than 60 are the diagnostic criteria. Complications include pain, gross hematuria from a ruptured cyst, infected cysts, nephrolithiasis, HTN, and cerebral aneurysms (10% to 15% of patients have arterial aneurysms in the Circle of Willis). There is no effective treatment. Good control of blood pressure and a low protein diet may slow disease progression. There are two distinct genotypes of PKD—PKD1 and PKD2. The disease progresses more slowly in the latter. Urinary tract infection would not fit this patient scenario, as she has no dysuria, and UA is negative for leukocytes, leukocyte esterase, nitrites, and bacteria. Renal calculi would not cause abdominal fullness and hypertension and would be symptomatic on presentation. The urine sample is not contaminated as there are no squamous epithelial cells reported. In the absence of RBC casts and clinical signs and symptoms, this would not be glomerulonephritis.
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References: Merck Manual · UpToDate

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