Pathophysiology of Renal and Urinary Tract Disorders
Renal/Urinary Tract Function
 Kidneys “filter” @ 150 Liters / day
 Kidneys reabsorb @ 99%
 Process yields @ 1.5 Liters / day of urine
• Urinary Tract Infection
 UTI
 Uncomplicated
 Complicated
 Bladder infection (Cystitis)
 Bacterial
 “Nonbacterial”
 Pyelonephritis
 Acute
 Chronic
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Lower UTIs
Normal urine flow restricts bacteria
Urinary tract normally sterile above urethra
Various antibacterial enzymes / antibodies restrict bacteria
Normal flora in region restrict bacteria
Mucus from glands trap bacteria
• Uncomplicated UTIs
 Causes:
 Escherichia coli (@80%)
 Staphyloccocus saprophyticus et al (@20%)
 Abnormalities of urinary system or compromised immune system will change scenario into a
Complicated UTI
 Cystitis
 Inflammation of bladder
 May be complicated if other disease processes are present
 “Nonbacterial”: Autoimmune reaction?
Signs/Symptoms of UTI
 Pain on urination (dysuria)
 Frequent urination
 Suprapubic or lower back discomfort
 Cloudy, foul smelling urine
In elderly:
 Confusion
 Abdominal discomfort
Acute Pyelonephritis
 Infection of renal pelvis, tubules, & interstitial tissue of one or both kidneys
 Causes:
 Upward spread of bacteria from bladder
 Spread of bacteria via bloodstream
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S/S of Acute Pyelonephritis
Enlarged kidneys w/ abscesses
Fever / chills
Leukocytosis, bacteriuria, pyuria
Low back pain
N/V, headache, malaise
Painful urination
Chronic Pyelonephritis
 Persistent, recurring infection
 Leads to scarring of kidney(s)
 Difficult to determine specific cause
 Kidney stones increase risk
 Vesicoureteral reflux increases risk
Urinary Tract Obstruction
 Lower urinary tract disorders
 Enlarged prostate (men)
 Urethral stricture
 Pelvic organ prolapse (women)
 Kidney stones
 Renal tumors
 Bladder tumors
Enlarged Prostate (Male)
 Often is benign = called Benign Prostate Hypertrophy (BPH)
 Prostate CA
 Either lead to obstruction of urethra
Urethral Stricture (Male or Female)
 Causes:
 Congenital
 Infection
 Injury
 Surgical manipulation
 Any of these may cause scarring & narrowing of lumen
 Pelvic Organ Prolapse (Female)
 Downward protrusion of bladder into vagina
 Causes bladder outlet obstruction
Renal Calculi (Kidney Stones)
 May form anywhere in urinary tract
 Usually form in renal pelvis or calices
 Vary in size, shape, & number
 70-80% made of calcium oxalate or calcium phosphate
Patho of Kidney Stones
 Urine becomes concentrated w/ insoluble materials→Crystals form, then consolidate→ calculi form→Calculi
remain in renal pelvis (damage/destroy kidney tissue), or enter the ureter→Large caluli may cause pressure
necrosis
Causes / Predisposing factors:
 Dehydration
 Infection
 Obstruction
 Changes in urine pH
 Immobilization
 Diet
 Metabolic factors (Ex: gout, hyperparathyroidism)
Calculi—Signs/Symptoms
 Severe pain—may move from lower back to sides to pubic region
 N/V
 Often fever / chills
 May have hematuria
 May have abdominal distention
 May have oliguria
Renal Tumors
 Renal cell carcinoma (RCC) most common
 Tobacco use, obesity, HTN appear to be associated w/ RCC
 Usually occur in one kidney & metastasize to lungs, liver, lymph, & bone
 Renal cell adenoma (benign tumor)
 Encapsulated & located near renal cortex
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Signs/Symptoms of Renal Tumors
Early stages are often silent
Late signs include
 Hematuria
 Flank pain
 Palpable flank mass
 Weight loss
Tobacco use appears to be leading risk factor
Arise from alteration of epithelial tissue at base of bladder
Often involve ureter orifices and bladder neck
Usually metastasize to lymph, liver, bones, & lungs
Signs/Symptoms of Bladder Tumors
 Visible, painless hematuria
 Pelvic or back pain may occur with metastasis
 UTIs are common complications→ frequency, urgency, dysuria
Glomerular Disorders
 Glomerulonephritis
 Acute
 Chronic
 Nephrotic Syndrome
 Nephrosclerosis
Glomerulonephritis
 Inflammation of the glomerulus
 Acute glomerulonephritis is often associated w/ strep throat, or impetigo→develops 2-3 weeks post infection
 Chronic glomerulonephritis is often caused by IDDM or Lupus erythematosus→leads to chronic renal failure
Patho of Glomerulonephritis
 Infection initiates inflammatory process→Antigen-antibody processes deposited in
glomeruli→Nephrosclerosis develops→(In chronic) Cortex layer shrinks→Bands of scar tissue distort
remaining cortex→Branches of renal artery thicken→End-stage renal disease
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Nephrotic Syndrome
Can occur with any renal or systemic disease process that damages the glomerular capillary membrane →
Large amounts of protein excreted in urine (proteinuria)
Decrease of albumin in blood (hypoalbuminemia)
High serum cholesterol and low – density lipoproteins (hyperlipidemia)
Major S/S: Edema (pitting & ascites)
• Nephrosclerosis
 Hypertension & Diabetes main causes→Decreased blood flow to kidneys→Patchy necrosis develops→Fibrosis
develops; glomeruli destroyed→Leads to End-stage renal disease
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Acute Renal Failure
Abrupt reduction in renal function w/elevation of BUN & creatinine levels
Usually associated w/ urine output of <30 ml/hr or <400 ml/day
Most of the time condition is reversible
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Signs/Symptoms of ARF
Oliguria begins within 1 day post hypotensive event & lasts 1 - 3 weeks
Lethargic
Skin / mucus membranes dry
CNS→headache, muscle twitching, seizures
Many body systems affected
 Recovery depends on how long the cause lasted
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Chronic Renal Failure
ESRD is progressive, irreversible deterioration in renal function
End products of protein metabolism (normally excreted in urine) accumulate in the blood
Causes:
 Diabetes mellitus
 HTN
 Chronic glomerulonephritis
 Pyelonephritis
 Obstruction of urinary tract
Signs/Symptoms of ESRD
UREMIA (result of accumulation of toxins in plasma):
HTN
Anorexia
Nausea / vomiting
Diarrhea
Weight loss
Pruritis
Edema
Anemia
Neurological changes