Kidney: Diseases Affecting Tubules and Interstitium Flashcards
What are the most common forms of tubular injury that also involve the interstitium?
Inflammatory diseases
Acute Tubular (Kidney) Injury
What is the example of inflammatory tubular injury?
Tubulointestinal nephritis (pyelonephritis)
What are the types of acute tubular (kidney) injury?
Toxic
Ischemic
What is tubulointerstitial nephritis?
Inflammatory disease of the kidneys affecting the interstitium and tubules
What happens during the late course of the tubulointerstitial nephritis?
The glomeruli may be affected
What are the causes of tubulointerstitial nephritis?
Mostly by bacterial infection with pelvis involvement: pyelonephritis
What is the term interstitial nephritis used for?
Typically for non-bacterial origin
What are examples of non-bacterial origins of interstitial nephritis?
Drugs
Metabolic Disorders; hypokalemia
Physical Injury; irradiation
Viral Infections
Immune reactions
Can TNI and IN be acute and chronic?
Yes can be both acute or chronic regardless of etiology
What is acute pyelonephritis?
SUPPURATIVE inflammation of kidney and pelvis
What usually causes acute pyelonephritis?
Examples?
Bacteria; E. coli, Klabsiella, Proteus, Enterobacter, Pseudomonas
What are the typical manifestations of acute pyelonephritis?
Same as typical manifestations of UTIs
What is acute pyelonephritis associated with?
Lower UTI
Less commonly associated with upper UTI
What are examples of lower UTIs?
Cystitis, prostatitis, uretheritis
What are examples of upper UTIs?
Pyelonephritis (pelvis and kidneys)
What is the route of infection of acute pyelonephritis?
- Lower urinary tract –> ascending infection
- Through the bloodstream –> hematogenous infection
What is the pathogenesis of acute pyelonephritis? (4)
- Distal urethra: adhesion of bacteria to mucosal surfaces, followed by colonization through fimbriae
- Bladder: expansive growth of the colonies & moving against the flow of urine (obstruction, diabetes)
- Ureters: incompetence of the vesicoureteral orfice, resulting in vesicoureteral reflux (VUR). Allows for bacteria to ascend to ureter into the pelvis
- Pelvis: pyelonephritis
How do the bacteria ascend from the contaminated bladder urine (acute pyelonephritis)?
Along the ureters
What is VUR?
Can either be a congenital defect that results in incompetence of the ureterovesical valve
OR
Acquired in persons with a flaccid bladder
How does acquired VUR result?
From spinal injury or with neurogenic bladder dysfunction secondary to diabetes
What can lead to seeding of the kidneys and thus acute pyelonephritis?
Septicemia
Infective endocarditis
What are the predisposing factors for acute pyelonephritis? (9)
- Urinary Obstruction
- Instrumentation of the UT
- Vesicoureteral reflux
- Pregnancy
- Female gender
- Male gender and age
- Pre-existing renal lesions
- DM
- Immunosuppression and immunodeficiency
How is urinary obstruction a predisposing factor of acute pyelonephritis?
Results to stasis –> facilitates bacterial growth
How is male gender and age a predisposing factor of acute pyelonephritis?
As a result of the development of prostatic hyperplasia, which causes urinary outflow obstruction
Why are pre-existing renal lesions a predisposing factor for acute pyelonephritis?
Causes intrarenal scarring and obstruction
How is DM a predisposing factor for acute pyelonephritis?
This leads to infection and bladder dysfunction
What are the gross features of acute pyelonephritis?
One or both kidneys may be involved
The affected kidney may be normal in size or enlarged
Characteristically, discrete, yellowish, raised abscesses are grossly apparent on renal surface
What are the histological features of acute pyelonephritis (primary)?
Patchy interstitial purulent (consisting of pus)
Tubular destruction in the involved area
Neutrophilic casts in collecting ducts –> pyuria
Where do the neutrophil casts in the urine originate from (primary AP)?
Distal renal tubules and collecting ducts (distal nephron)
What is the second form of AP?
Necrosis of the renal papillae (papillary necrosis)
What are the predisposing conditions to the second form of AP?
Diabetes
UT obstruction
Sickle cell anemia
What are the gross features of second form of AP?
Gray-white to yellow necrosis of the apical 2/3 of the pyramids
One or several papillae may be affected
What are the microscopic features of second form of AP?
The papillary tips show characteristic coagulative necrosis, with surrounding neutrophilic infiltrate
Coagulative necrosis rimmed by acute inflammation
What are the clinical manifestations of AP?
- Sudden pain at the costovertebral angle !!
- Evidence of infection
- Localizing UT signs of dysuria, frequency, and urgency
- Urine appears turbid
- Predisposing factors
What causes the turbid appearance of the urine?
The pus (pyuria)
What are the predisposing factors preset in the clinical course of AP?
The disease may become recurrent or chronic
The development of papillary necrosis
What is the prognosis like if there is papillary necrosis?
Poor prognosis