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Renal Pathology
Chapter 15
Dr. Gary Mumaugh and Dr. Bruce Simat
University of Northwestern - St. Paul
Urinary System
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Role of Kidneys: primarily
regulation or homeostasis (rather
than excretion)
• Regulation of blood plasma and
interstitial fluid composition
(homeostasis), especially inorganic ions
– electrolyte balance (e.g. Na+, K+, Cl, Ca2+) and osmolality
• Regulation of body fluid volume -- fluid
balance
• Regulation of blood plasma and
interstitial fluid pH
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• Excretion of (non-volatile) metabolic
end products (e.g. urea, uric acid,
creatinine, NH4+) and “foreign” solutes
(e.g. some drugs)
• Note: The above are functions are vital;
loss of renal function leads to
debilitation beginning in about one day
and terminating in death in one-two
weeks
.
• Endocrine organ
• secreting renin, for regulation of Na+,
ECF (extracellular fluid volume),
vascular resistance,
• erythropoietin, for regulation of
erythrocyte production
• calcitriol, related to calcium regulation
• Metabolic functions: e.g. peptide
degradation, synthesis of NH3 and H+
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Mechanisms of Urine Formation
• Urine formation and
adjustment of blood
composition involves
three major processes
• Glomerular filtration
• Tubular reabsorption
• Tubular secretion
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Figure 25.8
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Urinary Tract Obstruction
• Urinary tract obstruction is an
interference with the flow of urine at
any site along the urinary tract
• The obstruction can be caused by
an anatomic or functional defect
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Urinary Tract Obstruction
• Severity based on:
• Location
• Completeness
• Involvement of one or both upper
urinary tracts
• Duration
• Cause
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Urinary Tract Obstruction
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Upper Urinary Tract Obstruction
• Kidney stones
• Calculi or urinary stones
• Masses of crystals, protein, or other
substances that form within and may
obstruct the urinary tract
• Risk factors
• Gender, race, geographic location,
seasonal factors, fluid intake, diet,
and occupation
• Kidney stones are classified according
to the minerals comprising the stones
.
• Pathophysiology
• 80% of kidney stones are composed
of calcium with oxalate or phosphate
• Kidney stones are the result of
crystallization of stone-forming salts
that separate from the urine
• Affects 5% of the population
• Stones vary in size from microscopic
to one-inch
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• Kidney Stones
• Uteroscopic stone removal
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Kidney Stone Formation
• Supersaturation of one or more salts
• Presence of a salt in a higher
concentration than the volume able
to dissolve the salt
• Precipitation of a salt from liquid to
solid state
• Temperature and pH
• Growth into a stone via crystallization
or aggregation
.
Kidney Stone Formation
• Other factors affecting stone formation
• Crystal growth-inhibiting substances
• Particle retention
• Matrix
• Stones
• Calcium oxalate or calcium
phosphate
• Struvite stones
• Uric acid stones
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Kidney Stones
• Manifestation
• Renal colic
• Evaluation
• Stone and urine analysis
• Intravenous pyelogram (IVP) or kidney,
ureter, bladder x-ray (KUB)
• Spiral abdominal CT
• Treatment
• High fluid intake, decreasing dietary
intake of stone-forming substances,
stone removal
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Lower Urinary Tract Obstruction
• Neurogenic bladder
• Dyssynergia
• Detrusor hyperreflexia
• Detrusor areflexia
• Obstruction
• Low bladder wall compliance
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Urinary Tract Infection (UTI)
• UTI is inflammation of the urinary
epithelium caused by bacteria
• Acute cystitis
• Painful bladder syndrome/interstitial
cystitis
• Interstitial cystitis
• Acute and chronic pyelonephritis
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Urinary Tract Infection (UTI)
• Most common pathogens
• Escherichia coli
• Virulence of uropathogens
• Host defense mechanisms
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Urinary Tract Infection (UTI)
• Acute cystitis
• Cystitis is an inflammation of the
bladder
• Manifestations
• Frequency, dysuria, urgency, and
lower abdominal and/or suprapubic
pain
• Treatment
• Antimicrobial therapy, increased
fluid intake, avoidance of bladder
irritants, and urinary analgesics
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Urinary Tract Infection (UTI)
• Interstitial cystitis
• Nonbacterial infectious cystitis
• Manifestations
• Most common in women 20 to 30
years old
• Bladder fullness, frequency, small
urine volume, chronic pelvic pain
• Treatment
• No single treatment effective,
symptom relief
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Urinary Tract Infection (UTI)
Pyelonephritis
◦ Acute pyelonephritis
 Acute infection of the renal pelvis interstitium
Vesicoureteral reflux, E. coli, Proteus,
Pseudomonas
◦ Chronic pyelonephritis
 Persistent or recurring episodes of acute
pyelonephritis that leads to scarring
 Risk of chronic pyelonephritis increases in
individuals with renal infections and some
type of obstructive pathologic condition
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Chronic Pyelonephritis
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Glomerular Disorders
• The glomerulopathies are disorders
that directly affect the glomerulus
• Urinary sediment changes
• Nephrotic sediment
• Nephritic sediment
• Sediment of chronic glomerular
disease
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Glomerular Disorders
• Glomerular disease demonstrates a
sudden or insidious onset of
hypertension, edema, and an
elevated blood urea nitrogen (BUN)
• Decreased glomerular filtration rate
• Elevated plasma creatinine, urea,
and reduced creatinine clearance
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Glomerular Disorders
• Glomerular damage causes a
decreased glomerular membrane
surface area, glomerular capillary blood
flow, and blood hydrostatic pressure
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Glomerular Disorders
• Increased glomerular capillary
permeability and loss of negative
ionic charge barrier result in passage
of plasma proteins into the urine
• Resulting hypoalbuminemia
encourages plasma fluid to move into
the interstitial spaces
• Edema
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Glomerular Disorders
• Glomerulonephritis
• Inflammation of the glomerulus
• Immunologic abnormalities (most
common)
• Drugs or toxins
• Vascular disorders
• Systemic diseases
• Viral causes
• Most common cause of end-stage
renal failure
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Glomerulonephritis
• Mechanisms of injury
• Deposition of circulating soluble
antigen-antibody complexes, often
with complement fragments
• Formation of antibodies against the
glomerular basement membrane
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Glomerulonephritis
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Nephrotic Syndrome
• Excretion of 3.5 g or more of protein
in the urine per day
• The protein excretion is caused by
glomerular injury
• Findings
• Hypoalbuminemia, edema,
hyperlipidemia, and lipiduria, and
vitamin D deficiency
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Nephrotic Syndrome
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Acute Renal Failure (ARF)
• Prerenal acute renal failure
• Most common cause of ARF
• Caused by impaired renal blood
flow
• GFR declines because of the
decrease in filtration pressure
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Acute Renal Failure (ARF)
• Intrarenal acute renal failure
• Acute tubular necrosis (ATN) is the
most common cause of intrarenal
renal failure
• Postischemic or nephrotoxic
• Oliguria
• Postrenal acute renal failure
• Occurs with urinary tract
obstructions that affect the kidneys
bilaterally
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Acute Renal Failure (ARF)
• Oliguria phase
• Diuretic phase
• Recovery phase
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Chronic Renal Failure
• Chronic renal failure is the
irreversible loss of renal function
that affects nearly all organ
systems
• Stages
• Chronic renal insufficiency
• Chronic renal failure
• End-stage renal failure
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Chronic Renal Failure
• Proteinuria and uremia
• Creatinine and urea clearance
• Fluid and electrolyte balance
• Sodium and water balance
• Phosphate and calcium balance
• Potassium balance
• Acid-base balance
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Chronic Renal Failure
• Alterations seen in following systems:
• Musculoskeletal
• Cardiovascular and pulmonary
• Hematologic
• Immune
• Neurologic
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Chronic Renal Failure
• Gastrointestinal
• Alteration in protein, carbohydrate,
and lipid metabolism
• Endocrine and reproduction
• Integumentary
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Renal Dialysis
• Renal Dialysis- wastes, uremia toxins,
excess water are cleared from blood;
electrolyte balance is restored
• Dialysate– dialysis fluid
• 2 Methods:
1. Hemodialysis–moving the patient’s
blood to a hemodialyzer
• Extracorporeal Dialysis– dialysis
outside the body
2. Peritoneal Dialysis– dialysis through the
peritoneum dialysate introduced into
and removed from cavity
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Kidney Transplantation
• Obstacles
• Obtaining replacement kidney
• Working quickly to avoid ischemia
damage
• Implantation
• Positioned in different area- closer
to bladder
• Nephrectomy– kidney removal
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Kidney Transplantation
C. Immune
Rejection (3 forms)
• Hyperacute Rejection- due to presence of host
antibodies against donor’s red cells or renal
antigens
• Minutes  hours after implantation
• Acute Rejection- recipient’s immune system
attacks both nephron tubules and arteries in
donated organ
• 2nd or 3rd week post-op
• Chronic Rejection– antibody against graft
binds to the implant’s vascular endothelium
• Develops over several months
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Transplant Rejection
Donor Kidney rejected after 16 months
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Tumors
• Renal tumors
• Renal adenomas
• Renal cell carcinoma (RCC)
• Bladder tumors
• Transitional cell carcinoma
• Gross, painless hematuria
• Most common in males older than 60
years
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Urinary Tract Tumors
• Renal Cell Carcinoma
• Dominant, malignant renal tumor in adults
• Almost 90% of adult kidney cancers
• Prognosis is usually poor- extensive
metastasis
• Wilms’ Tumor or Nephroblastoma
• Common tumor among children
• Prognosis usually good
• Surgery, radiation, or chemotherapy are
usually effective
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