Urinary System Disorders

7/21/2019 Urinary System Disorders

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Urinary System Disorders

Bio 375

Pathophysiology

Incontinence

Incontinence or loss of voluntary controlof the bladder has many causes:

Stress incontinence can occur with:

Coughing

Laughing

Women whose urogenital diaphragm hasweakened from several pregnancies

Age

Spinal cord injuries can interfere withvoluntary neurologic control of the bladder

Retention

Retention is inability to empty bladder

Micturition reflex is located in the sacral

spinal cord and can be blocked by spinalcord injuries

Retention may be caused by anesthesia,either general or spinal



Urinalysis

Constituents may vary with diet anddrugs

Urine is usually clear and straw-coloredwith a mild odor

pH usually 4.5-8.0

Volume 1.0-1.5 liters/day but varieswith intake, sweating, etc

Abnormalities in Urine

Cloudy- may indicate the presence oflarge amounts of protein, blood cells,bacteria or pus

Dark color- may indicate blood,excessive bilirubin content, or highlyconcentrated urine

Unpleasant or unusual odor- may

indicate infection

Abnormal Constituents

Blood (hematuria)

Small amounts associated with infection,

inflammation or tumors of urinary tract Large amounts of red blood cells indicate

increased glomerular permeability or hemorrhagein the tract

Protein (proteinuria, albuminuria)- indicatesthe leakage of albumin or mixed plasmaproteins into the filtrate indicatinginflammation or increased permeability ofglomeruli



Bacteria (bacteriuria) or pus (pyuria)-indicate infection in the urinary tract

Urinary casts- may indicateinflammation of the kidney tubules

Specific gravity- indicates the ability ofthe tubules to concentrate the urine; avery low gravity (dilute urine) usuallyrelated to renal failure

Dialysis

Dialysis provides an “artificial kidney” which can be used to sustain life afterkidneys fail.

Dialysis is used to treat someone whohas acute renal failure (can functionnormally on half of one kidney)

Two forms of dialysis:

Hemodialysis- in hospital or dialysis center Peritoneal dialysis- can be done at home



Hemodialysis required 3-4 timesper week for 3-4 hour sessions

Anticoagulant required to preventclotting

Peritoneal dialysis may be doneat night while patient sleeps

Takes more time than hemodialysis

Continuous ambulatory peritonealdialysis (CAPD)

Urinary Tract Infections Very common

Urine excellent medium for growth ofmicroorganisms Cystitis and urethritis are considered lower urinary

tract infections

Pyelonephritis is an upper urinary tract infection

Most infections are ascending from outside ofbody traveling up the mucous membrane tobladder and then up the ureters to thekidney, often caused by E. coli

Occasionally, pyelonephritis results fromblood-borne infection

Etiology of Urinary Infections

Women are anatomically morevulnerable to urinary tract infections

than men because of: Shortness and width of urethra

Proximity of urethra to anus

Frequent irritation to the tissues fromtampons, bubble bath, deodorants andsexual activity



Older men with prostatic hypertrophyand retention of urine frequentlydevelop infection

Because of the shared structures withthe reproductive system, any infectionof the reproductive organs is likely toextend to the urinary tract

Common Causative Factors inMen and Women

Bladder retention of urine

Any obstruction of urine flow

All these conditions tend to result inincomplete flushing of bacteria from thebladder and urethra by voiding

Congenital abnormalities in children area common cause of UTI

Pregnancy

Scar tissue

Renal calculi

Vesicoureteral reflux all contribute toinfection because the urine and anycontaminants do no flow freely throughand out of the system



Infection may result from decreased hostresistance from immunosuppression

Impaired blood supply to the bladderfrom aging

Diabetes mellitus (vascular impairmentand glycosuria)

Catheters or instruments introduced intothe bladder may introduce bacteria intothe bladder or traumatize bladder wall

SeveralSources ofUTI

Inflammatory Disorders

Glomerulonephritis may have severalcauses

Acute poststreptococcalglomerulonephritis is one example



It typically follows streptococcal infectionwith certain types of group A beta-hemolytic Streptococcus

Usually begins as upper respiratoryinfection, middle ear infection, skin infectionor “strep throat”

The glomerulonephritis develops about 7-10days after the original infection

Primarily affects children between 3-7especially boys

Pathophysiology of APSGN

Antistreptococcal antibodies formedfrom the earlier infection, create anantigen-antibody complex that

lodges in the glomerular capillaries

Activates complement

Causes an inflammatory response in bothkidneys



In most cases, recovery takes placewith minimal residual damage

Some cases, particularly in adults, arenot easily resolved:

Acute renal failure occurs in about 2% ofcases

Chronic glomerulonephritis persists inabout 10% of cases which graduallydestroys the kidneys

Urinary Tract Obstructions

In older men, benign prostatichypertrophy or prostatic cancerfrequently obstructs the urinary tract

Renal calculi (kidney stones) are acommon cause of obstruction in bothmen and women

Kidney Stones



Urolithiasis (Calculi or KidneyStones)

Calculi may develop anywhere in theurinary tract

Stones may be small or very large (e.g.staghorn calculus)

Any solid material may act as a nidusaround which other material mayaccumulate

Immobility may result in calculi becauseof the stasis of urine

Calculi may form when:

There are excessive amounts of relativelyinsoluable salts in the filtrate

Insufficient fluid intake creates a highlyconcentrated filtrate

About 75% of calculi are composed ofcalcium salts, especially calcium oxalatethe remainder consisting primarily of uric

acid, struvite (magnesium ammoniumphosphate), or other oxalates

Foods high in oxalate include:

Dark green vegetables, such as spinach.

Rhubarb. Chocolate. Tea and cola. Wheat bran. Nuts. Cranberries. Beans. Coffee.



Stones usually only cause problemswhen they obstruct the flow of urine,e.g. in the ureter

Calculi may cause infection becausethey cause stasis of urine in the areaand may also irritate tissues

When located in the kidney or ureter,calculi may cause the development ofhydronephrosis, with dilation of calycesand atrophy of renal tissue

Adult Polycystic Kidney

The most common form of this geneticdisease is transmitted as an autosomal

dominant gene on chromosome 16 No indications in the child or young

adult; first manifestations appeararound age 40

At this time renal failure occurs anddialysis is required



Wilm’s Tumor

This is the most common tumor of the urinarytract occurring in children

Both a sporadic (most common) and inheritedform

The inherited form is associated with genes(WT1 & WT2) on chromosome 11 and mayoccur in conjunction with other congenitaldisorders including aniridia, hemihyperplasia,horseshoe kidneys, hypospadias, polycystic

kidneys, ureteral duplication and uterineabnormalities

It is usually unilateral

Usually diagnosed at about ages 2-5

when a large abdominal mass presents

With treatment of surgery, radiationand chemotherapy, survival rate about90%



Renal Failure

Acute renal failure Sudden kidney failure

May be reversible if primary problem istreated successfully

Dialysis may be needed during treatmentperiod

In some cases, some permanent damageto the kidneys may occur

Acute Kidney Failure Etiology

Numerous causes:

Acute bilateral kidney disease such asglomerulonephritis

Severe and prolonged circulatory shock orheart failure

Shock associated with burns or crushinjuries (hemoglobin from hemolysis ofRBC’s causes obstruction of kidney tubules

Nephrotoxins such as drugs, chemicals ortoxins



Chronic Renal Failure

Chronic renal failure is the gradualirreversible destruction of the kidneysover a long period of time. It mayoccur as a result of:

Chronic kidney disease

Bilateral pyelonephritis

Congenital polycystic kidney disease

Systemic disorders

Hypertension

Diabetes mellitus

Stages of Renal Failure

Decreased renal reserve (around 60%nephron loss) GFR reduced but no clinical signs)

Renal insufficiency (around 75%nephron loss: 25-30 ml/min GFR) Changes in blood chemistry

End-stage renal failure or uremia(around 90% nephron loss) Regular dialysis or kidney transplant

required to maintain patient’s life



Documents

Urinary System Disorders