Diseases of the tubules and interstitium

Question 1

What is the most common cause of acute kidney injury?

Answer 1

AKI most common cause is acute tubular injury/necrosis

Question 2

What can acute tubular injury be caused by?

Answer 2

1. Ischemia

2. Direct toxic injury to tubules

Question 3

Caused by decreased interrupted blood flow

Answer 3

Ischemic acute tubular injury (ATI)

Question 4

Morphology wise, presence of multiple petechial hemorrhages , means there is multi focal severe ischemia, name the disease

Answer 4

Ischemic acute tubular injury (ATI)

Question 5

Name the two types of acute tubular injury

Answer 5

1. ischemic ATI

2. Nephrotic ATI

Question 6

Caused by direct toxic injury to the tubules

Answer 6

Nephrotic acute tubular injury (ATI)

Question 7

What are the endogenous agents that cause nephrotic ATI?

Answer 7

Myoglobin
Hemoglobin
Monoclonal light chains
Bile/bilirubin

Question 8

What are the exogenous agents that cause nephrotic ATI?

Answer 8

Drugs (nephrotoxins)
Radiocontrast dye
Heavy metals
Organic solvents

Question 9

What disease commonly occurs in patients with different clinical setting

Example: severe trauma, vascular and cardiac surgery, severe burns and pancreatitis, sepsis, chronic liver disease

Answer 9

acute tubular necrosis / ischemia

Question 10

Which parts of the nephron are particularly vulnerable to hypoxic injury?

Answer 10

Proximal tubule
&
medullary ascending limb

Question 11

Pathogenesis of _______________.
Include:
• Loss of cell polarity
◦ Due to abnormal ion transport across cells
• Causing increased sodium delivery to distal tubules
• Which causes VASOCONSTRICTION (tubular feedback)
• Cells express cytokines, and adhesion molecules
◦ Recruit leukocytes

Answer 11

Epithelial tubular injury (ischemia)

Question 12

• Vacuolization and loss of brush border in proximal tubular cells
• Sloughing of tubular cells into lumen leads to cast obstruction, manifested by tubular dilation
• Leukocyte infiltration (may be present)
• Necrotic cells are UNCOMMON on renal biopsy

Answer 12

Acute tubular injury

Question 13

Key diagnostic features of _________,
Include:
◦ Widespread sloughing of tubular epi cells
◦ Loss of brush border
◦ Flattened, simplified tubular epithelium

Answer 13

Acute tubular injury

Question 14

What form of AKI is reversible in 2-7 days by discontinuation of drug? This form of AKI rarely occurs in healthy people.

Answer 14

AKI caused by nephrotoxic agents

Question 15

Acute tubular injury happens in a three part sequence:

Which phase is described by:
	‣ Last 36 hours
	‣ Acute decrease in GFR to very low levels
	‣ Slight decline in urine output
	‣ Rise in BUN and creatinine

Answer 15

Initiation phase

Question 16

Acute tubular injury happens in a three part sequence:

Which phase is described by:

	‣ Decreased in urine output (oliguria: 40 & 400 mL/day)
	‣ Sustained reduction in GFR
		• Persists for 1-2 weeks
	‣ Salt and water overload
		• Raises BUN conc.
	‣ Hypercalemia
	‣ Metabolic acidosis
	‣ Uremia

Answer 16

Maintenance phase

Question 17

Acute tubular injury happens in a three part sequence:

Which phase is described by:

‣ Tubular function restored
‣ Increased urine volume upto 3L/day
‣ Decrease BUN and serum creatinine
‣ Subtle tubular function impairment may persists for months, but usually if reach this phase there’s recovery

Answer 17

Recovery phase

Question 18

What type of cast is observed in small volume of concentrated urine, or diuretic therapy

Conditions where this type of cast is seen:
Normal people
Dehydration
Heavy exercise

Answer 18

Hyaline casts

Question 19

What type of cast represent degenerated cellular casts or aggregation of proteins within a cast matrix?

Described as:
Coarse, muddy brown color or hemegranular casts

This type of cast is seen in conditions of:
After strenuous exercise
Chronic renal disease
Acute tubular necrosis

Answer 19

Granular casts

Question 20

What type of casts is the last stage in degeneration of granular casts, nonspecific, observed in AKD, or CKD?

Seen in conditions of:
Severe chronic renal disease

Renal amyloidosis

Answer 20

Waxy casts

Question 21

What type of casts is wider, formed in large dilated tubules w/ little flow. Typically present in CKD

Answer 21

Broad casts

Question 22

What type of casts are described by lipid droplets w/in protein matrix of cast?

Seen in conditions of:
Tubular degeneration
Nephrotic syndrome
Hypothyroidism

Answer 22

Fatty casts

Question 23

What type of casts are underlying proliferative glomerulonephritis?

Conditions:
Pyelonephrosis
Glomerulonephritis
Acute interstitial nephritis
Lupus nephritis

Answer 23

RBC casts

Question 24

What type of casts are in interstitial or glomerular inflammation?

Conditions:
Pyelonephritis

Answer 24

WBC casts

Question 25

What type of casts are observed when there’s flakes(scales) of tubular epithelium, included in ATN, acute interstitial nephritis, proliferative glomerulonephritis? Conditions: Renal tubular necrosis Viral diseases Kidney transplant rejection

Answer 25

Renal tubular epithelial cell casts

Question 26

Inflammatory injuries of tubules and interstitium The onset is insidious and manifests azotemia MOST COMMON IN: women in 6th and 7th decades of life, can occur acute or chronic HALLMARKS: • Absence of nephrotic and nephritis syndrome • Presence of defects in tubular function ◦ Impaired concentrate urine (polyuria or nocturia) ◦ Salt wasting ◦ Decreased ability to excrete acids ◦ Isolate defects in tubular reabsorption/secretion

Answer 26

Acute interstitial nephritis (tubular interstitial nephritis)

Question 27

Inflammation affecting the tubules, interstitium, and renal pelvis Can occur acute or chronic Etiology: • 85% UTI caused by gram-negative bacilli ◦ Normal flora • MOST COMMON: escherichia coli, followed by: ‣ Proteus ‣ Klebsiella ‣ Enterobacter

Answer 27

Pyelonephritis

Question 28

What type of pyelonephritis is caused by: Usually caused by bacterial infection, associated w/ lower UTI

Answer 28

Acute pyelonephritis

Question 29

What type of pyelonephritis is caused by: ``` • Bacterial infection • Other factors: ◦ Vesicoureteral reflux ◦ Obstruction ◦ Repeat acute pyelo ```

Answer 29

Chronic pyelonephritis

Question 30

Infection that comes from the blood, it is less common?

Answer 30

Hematogenous infection

Question 31

Infection that comes from the bladder and moves up?

Answer 31

Ascending infection

Question 32

Caused by congenital absence, shortening of intravesical portion of ureter, and inflammation by bacteria

Answer 32

Vesicoureteral reflux

Question 33

How do you see vesicoureteral reflux?

Answer 33

Voiding cystourethrogram

Question 34

Hallmarks of ________: Include: * Patchy interstitial suppurations inflammation * Aggregates of neutrophils * Neutrophil is tubulitis, and tubular necrosis * Suppurations may be discrete focal abscesses

Answer 34

Acute pyelonephritis

Question 35

Morphology of _________: Include: • Early stages: ◦ Neutrophilic infiltration limited to tubules • Tubular lumens conduit extension of infection ◦ Infection extends to interstitium and produce abscesses which destroy tubules

Answer 35

Acute pyelonephritis

Question 36

Clinical features of __________: Include: ``` • Sudden pain at CVA • Systemic symptoms ◦ Fever ◦ Malaise • Bladder and urethral inflammation: ◦ Dysuria ◦ Frequency ◦ Urgency ```

Answer 36

Acute pyelonephritis

Question 37

Disorder where chronic tubulointerstitial inflammation and scarring involve the calyces and pelvis, causes pelvocalyceal damage

Answer 37

Chronic pyelonephritis

Question 38

•MOST COMMON of chronic pyelonephritic scarring • Occurs early in childhood: ◦ As a result superimposition of urinary infection on congenital vesicoureteral reflux and intrarenal reflux.

Answer 38

Reflux nephropathy

Question 39

• Recurrent infections superimposed on diffuse or localized obstructive lesions: ‣ Cause: repeated renal inflammation and scarring Result in chronic pyelonephritis

Answer 39

Chronic obstructive pyelonephritis

Question 40

Morphology can be irregularly SCARRED, or extensive SCARRING due to chronic inflammation from recurrent UTI

Answer 40

Chronic pyelonephritis

Question 41

Clinical features of _________: Include: ``` • Silent onset or manifestations of acute recurrent pyelonephritis such as: ◦ Back pain ◦ Fever ◦ Pyuria ◦ Bacteriuria ``` • Loss of tubular function: ◦ Loss of ability of concentrating causing: ‣ Polyuria ‣ Nocturia • HPI: ◦ HTN ◦ Failure to thrive in children ◦ Flank tenderness

Answer 41

Chronic pyelonephritis