Flashcards in CH12 - Kidney and Urinary Tract Pathology Deck (238)
What is the most common congenital renal anomaly?
Horseshoe kidney - Conjoined kidneys usually connected at the lower pole
In horseshoe kidney where is it located?
Kidney is abnormally located in the lower abdomen
What happens in horseshoe kidney?
The kidney gets caught on the inferior mesenteric artery root during its ascent from the pelvis to the abdomen
What is renal agenesis?
Absent kidney formation; may be unilateral or bilateral
What does unilateral renal agenesis lead to?
hypertrophy of the existing kidney; hyperfiltration increases risk of renal failure later in life.
What does bilateral agenesis lead to?
oligohydramnios with lung hypoplasia, flat face with low set ears, and developmental defects of the extremities (Potter sequence) incompatible with life
What is dysplastic kidney?
Non-inherited, congenital malformation of the renal parenchyma characterized by cysts and abnormal tissue (e.g., cartilage)
Is dysplastic kidney unilateral or bilateral?
Usually unilateral; when bilateral, must be distinguished from inherited polycystic kidney disease
What is polycystic kidney disease?
Inherited defect leading to bilateral enlarged kidneys with cysts in the renal cortex and medulla
How does the autosomal recessive form of polycystic kidney disease present?
in infants as worsening renal failure and hypertension; newborns may present with Potter sequence
What is the autosomal recessive form of polycystic kidney disease associated with?
congenital hepatic fibrosis (leads to portal hypertension) and hepatic cysts
How does the autosomal dominant form of polycystic kidney disease present?
in young adults as hypertension (due to increased renin), hematuria, and worsening renal failure
What is the autosomal dominant form of polycystic kidney disease due to?
A mutation in the APKD1 or APKD2 gene; cysts develop over time.
What is the autosomal dominant form of polycystic kidney disease associated with?
berry aneurysm, hepatic cysts, and mitral valve prolapse
What is medullary cystic kidney disease?
Inherited (autosomal dominant) defect leading to cysts in the medullary collecting ducts
What does parenchymal fibrosis result in?
shrunken kidneys and worsening renal failure
What is acute renal failure?
Acute, severe decrease in renal function (develops within days)
What is the hallmark of acute renal failure?
Azotemia, (increased BUN and creatinine) often with oliguria
What is acute renal failure divided into?
Its divided into prerenal, postrenal, and intrarenal azotemia and is based on etiology
What is prerenal azotemia?
Due to decreased blood flow to kidneys (e.g., cardiac failure)
Prerenal azotemia is a common cause of what?
ARF (acute renal failure)
What does decreased blood flow result in?
decreased GFR, azotemia, and oliguria.
In prerenal azotemia what happens to the ability to absorb fluid?
reabsorption of fluid and BUN ensues (serum BUN:Cr ratio > 15) tubular function remains intact (fractional excretion of sodium [FENa] < 1% and urine osmolality [osm] > 500 mOsm/kg)
What is postrenal azotemia due to?
obstruction of urinary tract downstream from the kidney (e.g., ureters)
In postrenal azotemia what does the decreased outflow result in?
decreased GFR, azotemia, and oliguria
In postrenal azotemia, what happens during the early stage of obstruction?
There is increased tubular pressure which forces BUN into the blood (serum BUN;Cr ratio > 15); tubular function remains intact (FENa < 1% and urine osm > 500 mOsm/kg).
In postrenal azotemia, what happens with long-standing obstruction?
tubular damage ensues, resulting in decreased reabsorption of BUN (serum BUN:Cr ratio < 15), decreased reabsorption of sodium (FENa > 2%), and inability to concentrate urine (urine osm < 500 mOsm/kg)
What is acute tubular necrosis?
It is injury and necrosis of tubular epithelial cells
What is the most common cause of acute renal failure?
Acute tubular necrosis (intrarenal azotemia)