• epidemiology- male predominance
• pathogenesis- fushion of the inferior poles of the kidney
• complications- increased risk of infection and obstruction of the kidney

• NOT familial
• male predominance

• remaining kidney hypertrophy to compensate for missing one
• some due have unilateral absence of vas deferens/ fallopian tube upon PE

• oligohydramnios (remember, the kidney makes most of the amniotic fluid)- decrease amount of amniotic fluid
• this leads to a increased pressure from the uterus on the fetus, leading to abnormalities such as:
  • depressed, flattened face (Potter's facies)
  • low set ears
  • deformed lower extremities
  • underdevelopment of lungs (pulmonary hypoplasia)

1. obstruction of ureter or bladder
2. leads to increase pressure within CD
3. thus, distoreted kidney development

The metanephros forms, but due to some type of disorganization of renal parenchyma, you make immature nephrons

• a great degree of variation (reflects time in organogenesis when damage occured)
  • some can be normal sized, small, or enlarged
• typically:
  • architecturally distorted
  • multiple cysts

• arrest in development
• simple ducts
• presence of cartilage in ducts (emphasizes lack of normal development

At times, only part of a kidney is affected and the rest is normal

• may be asymptomatic at birth and later be detect due to UTI or an abdominal mass
• similar symptoms to bilateral agenesis

• autosomal dominant
• gene on chromosome 16

• silent in children, young adults
• common presenting symptoms
  • hematuria
  • hypertension
  • vague abdominal pain
  • some have infection in kidney
• kidney enlarged, but usually not readily palpable
• prognosis- live past age 50 and have children before dx

• enlarged kidneys (degree of enlargement varies)
• surface with multiple, variably sized cysts (can affect any part of the nephron)
• cysts can cause compression atrophy of remaining normal tissue (could lead to renal failure)

• cerebral artery aneurysms (at middle cerebral A.) aka berry aneurysms
  • rarely cause symptoms before age of 20
• cysts may also occur in other organs, but are usually clinically silent
• possible increase risk of renal cell carcinoma

• most commonly, children present with renal failure at birth or soon after
• symptoms similar to renal agenesis, but markedly enlarged kidneys palpable at birth
  • may not be as severe and it is detected in childhood as renal masses associated with progressive renal failure
• sometimes, the liver is the dominantly involved organ, leading to:
  • progressive fibrosis of portal areas and gradual liver failure
  • with death usually by age 10 without liver transplant

• usually, renal involvement is bilaterally symmetric
• massively enlarged kidneys by external examination
• cut sections
  • multiple, similarly sized, radial cysts which involve only the collecting ducts
  • functional obstruction of drainage which causes renal failure

• most occur over age of 30
• commmon in males, people with metabolic disorders, those living in hot, arid climates

• composition- magnesium ammonium phosphate
• pathogenesis
  • infection by urea splitting bacteria (Proteus)
  • causes alkaline urine
  • precipitation of magnesium ammonium phosphate

The largest stones, leading to "stag horn" calculi formin within the infected renal pelvis

• formed in acidic urine (can be mixed with calcium phosphate)
• appearance- small, hard

• organic matrix of mucoprotein
• most important factor in stone formation is increased concentration in the urine of stones constituents

This is when you have hypercalciuria without hypercalcemia

• pathogenesis
  • increased absorption of calcium from intestines without hypercalcemia due to prompt renal excretion of excess
  • impairement in renal reabsorption of calcium (aka renal hypercalciuria)

• formed in conditions of hyperuricemia such as gout and conditions of rapid cell turnover
• stones are radiolucent
• formation enhanced in acidic urine

• can be silent or manifest with hematuria
• can grow very large, filling the calyces and pelvis, leading to "stag horn" stones

• decrease GFR
• interfere with medullary blood flow
• if protracted, can lead to dilation of calyces and atrophy of papillae and renal medulla

• flank pain and mass
• when infection develops, symptoms of pyelonephritis
• if bilateral and severe, could lead to renal failure
• stagnating urine may become infected, aggravating the renal parenchymal destruction and in extreme cases you can kill the whole kidney (pyonephrosis)

• can be unilateral or bilateral (depends on site of obstruction)
• may involve urinary bladder
• involved kidney may be enlarged (massive if obstruction for long time)
• first changes appear with dilation of pelvis and calyces
• later, the medulla and renal cortex atrophy

• usually of minimal clinical significance, but if complex on imaging studies, rule out renal cell carcinoma
• dialysis is associated with this
  • leading to increased risk of renal cell carcinoma