Congenital And Cystic Renal Disease Flashcards Preview

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Flashcards in Congenital And Cystic Renal Disease Deck (25):
1

Gross Anatomy of the Kidney:

  1. Cortex
  2. Medulla

  1. Cortex
    • usually ~ 1 cm thick, contains glomeruli, proximal tubules and distal tubules
  2. Medulla
    • divided into 8-18 medullary pyramids and contains loops of Henle and collecting ducts

2

1-1.5 million nephrons composed of:

  1. Glomerulus
    • supplied by afferent arteriole ⇒ glomerular capillaries ⇒ efferent arteriole
  2. Proximal tubule
    • first segment of nephron after Bowman’s capsule
    • epithelium with brush border
  3. Loop of Henle
    • begins at transition from thick-walled to thin-walled tubule
  4. Distal tubule
    • thick ascending limb merges with distal tubule
  5. Collecting duct
    • receives ~6 distal tubules and enters medulla
    • join each other to form ducts of Bellini which drain into calyx

3

Describe the Glomerular Endothelial Cells:

  • Fenestrated (70-100 nm)
  • Negatively charged surface
  • Form initial filtration barrier
  • Synthesize and maintain GBM

4

What is the Glomerular Basement Membrane (GBM)?

  • Composed Type IV collagen
  • Size and charge are main determinants of filtration:
    • Heparan sulfate provides negative charge
    • Water and cationic proteins of LMW (are permeable
    • Albumin permeability is limited by its negative charge

5

What is the role of the Visceral Epithelial Cells (Podocytes)?

  • Also synthesize and maintain GBM
  • Cytoplasmic foot processes form filtration slit (slit pore)
  • Podocytes are negatively charged

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6

What is the role of the Mesangial Cells?

  • Cell cytoplasm contains myosin filaments
  • Cells are surrounded by GBM like matrix
  • Provides structural support
  • Modulate glomerular filtration

7

What are the different types of congenital renal  abnormalities?

  1. Aplasia, Hypoplasia, dysplasia
  2. Ectopic kidneys
  3. Fusion abnormalities
  4. Duplication of ureters

8

  • What is the most common congenital kidney disorder?
  • What are characteristics of this disorder?

Horseshoe Kidney

  • 90% are fused at the lower pole
  • Increased incidence with Turner’s syndrome
  • Increased risk of infection and kidney stones

9

Renal Dysplasia:

  • Incidence: 
  • Detection:

  • Incidence:
    • Unilateral – 1 in 4,300 live births
    • Combined incidence – 1 in 3,600
  • Detection:
    • Prenatal ultrasound
    • Palpable mass
    • Asymptomatic (undetected into adulthood)

10

What is the genetic defect in Autosomal Recessive PKD?

PKHD1 gene located on chromosome 6p21

  • Can be diagnosed in utero by ultrasound:
    • large hyperechoic kidneys
    • oligohydramnios
    • decreased urine in fetal bladder

11

How does ARPKD present?

  • Enlarged kidneys at birth
  • Serious cases incompatible with life
    • Perinatal mortality 30-50%
  • Associated with maternal oligohydramnios
    • Potter’s facies
    • Pulmonary hypoplasia

12

What are the main extrarenal manifestations of ARPKD?

  1. Hepatic fibrosis
  2. Cholangitis
  3. Portal hypertension
    • esophageal varices
    • GI bleeding

13

ARPKD: 

Morphology

  • Smooth kidney with numerous small cysts
    • Cortical and medullary cysts
  • Cut sectioncylindrical cysts extending radially through cortex
  • Microscopically – cysts lined by cuboidal epithelium; may see epithelial hyperplasia
  • Glomeruli normal

14

  • How is family hx relevant in Autosomal Dominant PKD?
  • What is the genetic defect in Autosomal Dominant PKD?

  • Affects 1:400 - 1:1000 Americans
  • Family history absent in 25-40%
    • new mutations
    • late-onset renal failure
  • 90% have mutation of PKD1 gene on chr. 16
    • Others have mutation of PKD2 gene on chr. 4
    • Patients with PKD2 mutations progress to renal failure at a later age than PKD1

15

ADPKD

Cyst Formation

  • Abnormal differentiation of epithelial cells
  • High proliferation rate
  • Secretion of fluid into cysts with loss of connection to functioning nephrons
  • Abnormal extracellular matrix

16

What are the renal manifestations in ADPKD?

  • hematuria and mild proteinuria
  • hypertension
  • progressive renal failure
    • 50% reach ESRD by age 57-73
  • infections
  • stones
  • pain

17

What are the extrarenal manifestations in ADPKD?

  • Hepatic cysts (40%)
  • Intracranial aneurysms (10-30%)
  • Cardiac valvular abnormalities
  • Arterial aneurysms (aorta, coronaries)
  • IVC thrombosis
  • Inguinal & umbilical hernias
  • Pancreatic cysts

18

ADPKD:

Diagnosis

Patients present in several different ways:

  • symptomatic presentation: typically flank pain & hematuria
  • multiple bilateral cysts noted incidentally on imaging study
  • screening due to family history with ultrasound:
    • Age <30: at least 2 cysts
    • Age 30-59: at least 2 cysts in each kidney
    • Age >60: at least 4 cysts bilaterally

19

What are the treatment goals for ADPKD?

  • Slow the progression to ESRD (end stage renal disease)
    • Control blood pressure
    • Treat infections
  • Identify and manage extrarenal manifestations
  • Control pain
  • Dialysis/Kidney Transplant

20

What is the main cause of Acquired Cystic Disease?

  • Develop in 50% of patients on dialysis and depends on duration of dialysis
    • more likely with more years on dialysis
  • Usually asymptomatic, but may present with bleeding or pain

21

  • Describe the cysts associated with Acquired Cystic Disease:
  • What can Acquired Cystic Disease lead to?

  • Clear, fluid-filled cysts
    • Uni- or multilocular cysts
    • Cortex (usually), may involve corticomedullary junction and medulla
  • Increased incidence of papillary renal cell carcinoma

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22

What are the indications for renal biopsy?

  • Persistent glomerular hematuria
  • Persistent nephrotic range proteinuria
  • Unexplained renal failure
  • Renal transplant rejection

23

What are contraindications to renal biopsy?

  • Bleeding disorders
  • Anatomic abnormalities (e.g. solitary kidney)

24

What are complications that can result from a renal biopsy?

  • Self limited gross hematuria (10%)
  • Hematoma formation (80% of cases)
  • Hemorrhage (1-2% of cases)
    • Surgery requiring (0.3% of cases)
  • Death (1/8000 cases)

25

What are the routine studies performed on a renal biopsy?

  • Light microscopy:
    • silver, trichrome, PAS, H&E stains
  • Direct immunofluorescence microscopy:
    • IgA, IgG, IgM, C3, C1q, albumin, fibrinogen, kappa, lambda
    • Identifies patterns of immune-complex deposition
  • Electron microscopy:
    • submicroscopic defects and site of damage in glomerulus