Renal - Pathology (Pyeloephritis, Interstitial nephritis, and Necrosis)

Question 1

What is acute infectious cystitis?

Answer 1

Inflammation of urinary bladder.

Question 2

How does acute infectious cystitis present? What is usually absent from presentation?

Answer 2

Presents as suprapubic pain, dysuria, urinary frequency, and urgency. Systemic signs (e.g., fever chills) are usually absent.

Question 3

What are 3 risk factors for acute infectious cystitis?

Answer 3

Risk factors include female gender (short urethra), sexual intercourse (“honeymoon cystitis”), and indwelling catheters.

Question 4

What are 5 causes of acute infectious cystitis? Which is most common?

Answer 4

(1) E. coli (most common) (2) Staphylococcus saprophyticus - seen in sexually active young women (E. coli is still more common in this group) (3) Klebsiella (4) Proteus mirabilis - urine has ammonia scent (5) Adenovirus - hemorrhagic cystitis

Question 5

Name a cause of acute infectious cystitis associated with each of the following: (1) Urine has ammonia scent (2) Most common (3) Hemorrhagic cystitis (4) Seen in sexually active young women?

Answer 5

(1) Proteus mirabilis (2) E. coli (3) Adenovirus (4) Staphylococcus saprophyticus

Question 6

What are the lab findings in acute infectious cystitis? What do nitrities suggest? What does sterile pyuria and (-) urine cultures suggest?

Answer 6

Positive for leukocyte esterase. Nitrites appear for gram-negative organisms (especially E. coli). Sterile pyria and (-) urine cultures suggest urethritis by Neisseria gonorrhoeae or Chlamydia trachomatis.

Question 7

What structure(s) does acute pyelonephritis affect versus spare?

Answer 7

Affects cortex with relative sparing of glomeruli/vessels.

Question 8

How does acute pyelonephritis present?

Answer 8

Presents with dysuria, fever, costovertebral angle tenderness, nausea, and vomiting.

Question 9

What are causes of acute pyelonephritis?

Answer 9

Causes include ascending UTI (E. coli is most common), vesicoureteral reflux, and hematogenous spread to kidney.

Question 10

What is often seen in the urine of patients with acute pyelonephritis? What will their CT show?

Answer 10

Often presents with white cell casts in urine; CT shows striated parenchymal enhancement

Question 11

What are risk factors for acute pyelonephritis?

Answer 11

Risk factors include indwelling urinary catheter, urinary tract obstruction, diabetes mellitus, and pregnancy.

Question 12

What are complications to consider with acute pyelonephritis?

Answer 12

Complications include chronic pyelonephritis, renal papillary necrosis, and perinephric abscess.

Question 13

What is the treatment for acute pyelonephritis?

Answer 13

Treatment: Antibiotics

Question 14

Chronic pyelonephritis is the result of what? What else is typically required?

Answer 14

The result of recurrent episodes of acute pyelonephritis; Typically requires predisposition to infection such as vesicoureteral reflux or chronically obstructing kidney stones.

Question 15

Describe the gross kidney features seen in chronic pyelonephritis.

Answer 15

Coarse, asymmetric corticomedullary scarring, blunted calyx.

Question 16

What can the tubules contain in chronic pyelonephritis, and what does this resemble?

Answer 16

Tubules can contain eosinophilic casts resembling thyroid tissue (thyroidization of kidney).

Question 17

What mechanism defines drug-induced interstitial nephritis (tubulointerstitial nephritis)?

Answer 17

Acute interstitial renal inflammation. Pyuria (classically eosinophils) and azotemia occurring after administration of drugs that act as haptens, inducing hypersensitivity.

Question 18

What are drugs associated with drug-induced interstitial nephritis, and what is the the timeline for nephritis in each case?

Answer 18

Nephritis typically occurs 1-2 weeks after certain drugs (e.g., diuretics, penicillin derivatives, sulfonamides, rifampin), but can occur months after staring NSAIDs.

Question 19

With what symptoms is drug-induced interstitial nephritis associated?

Answer 19

Associated with fever, rash, hematuria, and costovertebral angle tenderness, but can be asymptomatic

Question 20

What is diffuse cortical necrosis?

Answer 20

Acute generalized cortical infarction of both kidneys

Question 21

What are 2 likely causes of diffuse cortical necrosis?

Answer 21

Likely due to a combination of vasospasm and DIC.

Question 22

With what 2 conditions is diffuse cortical necrosis associated?

Answer 22

Associated with obstetric catastrophe (e.g., abruptio placentae) and septic shock.

Question 23

What is the most common cause of intrinsic renal failure?

Answer 23

Acute tubular necrosis

Question 24

Briefly describe the prognosis of acute tubular necrosis.

Answer 24

Self-reversible in some cases, but can be fatal if left untreated

Question 25

When does death most often occur with acute tubular necrosis?

Answer 25

Death most often occurs during initial oliguria phase.

Question 26

What is the key finding in acute tubular necrosis?

Answer 26

Key finding: granular (“muddy brown”) casts

Question 27

What are the 3 stages of acute tubular necrosis?

Answer 27

3 stages: (1) Inciting event (2) Maintenance phase (3) Recovery phase

Question 28

What word describes the maintenance phase of acute tubular necrosis? How long does it last?

Answer 28

Maintenance phase - oliguric; lasts 1-3 weeks

Question 29

What are the risks in the maintenance phase of acute tubular necrosis?

Answer 29

Risk of hyperkalemia, metabolic acidosis

Question 30

What word describes the recovery phase of acute tubular necrosis? What major event(s) happen(s) during it?

Answer 30

Recovery phase - polyuric; BUN and serum creatinine fall

Question 31

What are the risks in the recovery phase of acute tubular necrosis?

Answer 31

Risk of hypokalemia

Question 32

What are 2 major causes of acute tubular necrosis?

Answer 32

Can be caused by ischemic or nephrotoxic injury

Question 33

To what is acute tubular necrosis due to ischemic injury secondary?

Answer 33

Secondary to decreased renal blood flow (e.g., hypotension, shock, sepsis, hemorrhage, CHF).

Question 34

What is the result of acute tubular necrosis due to ischemic injury?

Answer 34

Results in death of tubular cells that may slough into tubular lumen (proximal tubule and thick ascending limb are highly susceptible to injury)

Question 35

To what is acute tubular necrosis due to nephrotoxic injury secondary?

Answer 35

Secondary to injury resulting from toxic substances (e.g., aminoglycosides, radiocontrast agents, lead, cisplatin), crush injury (myoglobinuria), hemoglobinuria.

Question 36

Which part of the kidney is particularly susceptible to nephrotoxic injury leading to acute tubular necrosis?

Answer 36

Proximal tubule is particularly susceptible to injury.

Question 37

What are the signs/symptoms associated with renal papillary necrosis, and what causes them?

Answer 37

Sloughing of renal papillae –> gross hematuria and proteinuria

Question 38

What are potential triggers of renal papillary necrosis?

Answer 38

May be triggered by a recent infection or immune stimulus

Question 39

What are 4 conditions with which renal papillary necrosis is associated?

Answer 39

Associated with: (1) Diabetes mellitus (2) Acute pyelonephritis (3) Chronic phenacetin use (acetaminophen is phenacetin derivative) (4) Sickle cell anemia and trait