Tubular and Interstitial Pathology

Question 1

What are the types of Tubulo-Interstitial Nephritis (TIN)?

Answer 1

• Primary: infectious (most common kidney diseases), non-infectious (drug and toxin-induced, metabolic, neoplastic)
• Secondary: associated with other diseases (glomerulonephritis, vascular, cystic, etc.)

Question 2

inflammation affecting the tubules, interstitium, and renal pelvis; can be acute and chronic

Answer 2

pyelonephritis

Question 3

What are the pathways of infection in infectious TIN?

Answer 3

• hematogeneous infection (from obstruction, immunosuppression, diabetes, septicemia, endocarditis; common agents are Staph, E. coli, and fungi)
• ascending infection (from reflux, obstruction, other abnormality of urinary tract; common agents are E. coli, Proteus, and Enterobacter)

Question 4

What is the prognosis for pyelonephritis?

Answer 4

good for acute onset; renal failure for chronic

Question 5

What are clinical features associated with acute pyelonephritis?

Answer 5

sudden onset, costovertebral angle pain,, fever, malaise, frequency/urgency

Question 6

Which bacteria are the main etiologic agents (85%) of pyelonephritis?

Answer 6

gram (-) rods, including E. coli, Proteus, Klebsiella, and Enterobacter

Question 7

Pathology associated with acute pyelonephritis?

Answer 7

• patchy interstitial suppurative inflamm. (PMNs in tubules and interstitium)
• tubular necrosis of medulla
• perinephric abscess
• papillary necrosis
• pyonephrosis (sac of pus)

Question 8

What are risk factors for papillary necrosis?

Answer 8

• analgesics
• diabetes
• sickle cell anemia
• obstruction
• tuberculosis

Question 9

Viral pyelonephritis is caused by which virus?

Answer 9

polyoma virus

Question 10

What are the features of chronic pyelonephritis?

Answer 10

• chronic TIN
• many cases bacterial in origin
• insidious onset w/ scarring
• gradual renal insufficiency
• pyuria and proteinuria on UA
• polyuria and nocturia (due to loss of conc. ability)
• contracted kidneys and deformed calyces on X-ray
• reflux nephropathy

Question 11

What is seen on histology with chronic pyelonephritis?

Answer 11

interstitial lymphocytes but no PMNs; glomerular sclerosis, dilated tubules (“thyroidization”)

Question 12

a type of chronic pyelonephritis mimicking malignancy

Answer 12

xanthogranulomatous pyelonephritis

Question 13

What are some causes of xanthogranulomatous pyelonephritis?

Answer 13

Proteus and obstruction

Question 14

What is seen on histology with acute drug-induced interstitial nephritis?

Answer 14

interstitial inflammation, abundant eosinophils, edema

Question 15

What is the classic clinical presentation of acute drug-induced interstitial nephritis?

Answer 15

• rash (25%)

- acute renal failure (50%), esp. older patients

Question 16

What are some of the etiologic agents of acute drug-induced interstitial nephritis?

Answer 16

synthetic antibiotics, diuretics, NSAIDs

Question 17

Which types of tubulointerstitial nephritis are not infectious nor drug-induced?

Answer 17

• Metabolic (urate, oxalate, hypercalcemia)

- Neoplastic (multiple myeloma)

Question 18

What is the immune mechanism behind drug-induced TIN?

Answer 18

• idiosyncratic (NOT dose-related)
• hypersensitivity
• IgE-mediated
• pos. skin test to drug hapten

Question 19

What is the etiology of ATI?

Answer 19

• ischemic tubular injury

- toxic injury

Question 20

What are the ischemic, toxic, and combined causes of ATI?

Answer 20

• ischemic: BP drop, severe trauma, acute pancreatitis
• toxic: drugs (abx), contrast dyes, poisons (heavy metal), organic solvents
• combined (mismatched blood transfusion, hemolytic crises, skeletal muscle injury, intratubular casts)

Question 21

What is the difference b/t acute and chronic urate nephropathy?

Answer 21

• acute: patients with leukemia/lymphoma who are on chemo (tumor lysis syndrome - releases urate deposits)
• chronic: “gouty”; associated w/ tophi (urate crystals + surrounding inflamm. rxn)

Question 22

What is a major cause of oxalate nephropathy?

Answer 22

ethylene glycol (antifreeze) intoxication

Question 23

Chronic oxalate nephropathy can happen after which type of surgery?

Answer 23

bariatric surgery (because it causes malabsorption)

Question 24

What are some other potential causes of oxalate nephropathy aside from antifreeze intoxication?

Answer 24

primary (hereditary), enteric, Vit. B6 deficiency, excessive ingestion of Vit. C, diet rich in oxalic acid

Question 25

What is the typical clinical presentation of a patient with ATI?

Answer 25

• rapid reduction of renal function and urinary output (oliguria)
• “non-oliguric” in 50% of ATI cases
• uremia
• signs of fluid overload
• electrolyte imbalances and acdidosis

Question 26

Which part of the tubule usually undergoes necrosis first with acute tubular injury?

Answer 26

proximal tubules

Question 27

What is the prognosis for ATI?

Answer 27

fairly good, as it is reversible; treatment is mostly supportive

Question 28

Why is there polyuria during the recovery phase of ATI?

Answer 28

because the glomerular filtrate cannot be adequately reabsorbed by the damaged tubular epithelium

Question 29

What are the risk factors/etiology for renal calculi?

Answer 29

infection, urinary stasis, immobility, hypercalcemia, increased uric acid, increased urinary oxalate level