Urinary System Diseases

Pathophysiology

Review of Urinary Anatomy & Physiology

• Located:

– Under back muscles

– Behind peritoneum

• Thus: retroperitoneal

– Below level of lowest ribs

– Right lower than left

– Adrenal gland on top of

kidney

• Cortex

• Medulla

– Contains Pyramids &

Papilla

• Pelvis

– Calyx = division of pelvis

• Pleural = calyces

• Bladder

– Lined with transitional

epithelium

• Can stretch

– Lined with rugae

– Trigone

• On posterior wall

• Where ureters & urethra

open

• Rigid area with NO rugae

– Micturition (voiding,

urination)

• Internal urinary sphincter

– Involuntary

• External urinary sphincter

– Voluntary

• Stretch receptors in

bladder wall

• Nephron = functional unit

– Consists of:

• Renal Corpuscle

• Renal Tubules

• Renal Corpuscle contains:

– Bowman’s capsule

• Part of collecting

system

– Glomerulus

• Afferent arteriole

• Efferent arteriole

• Renal Tubules

1. Proximal convoluted tubule

2. Loop of Henle

3. Distal convoluted tubule

4. Collecting tubule

• Key point:

– The cortex contains

all the structures of

the nephron

– The medulla contains

only the collecting

ducts & the loop of

Henle

• Functions of the kidney

1. Removes nitrogenous wastes

– Urea

– Uric acid

– Creatinine

– Ammonia

2. Maintains homeostasis– Fluid balance

– Electrolyte balance

– Acid-base balance

3. Excretory Organ– Via blood filtration &

formation of urine

4. Regulation of Blood Pressure

– Juxtaglomerular

apparatus

– RAA system

» Renin

» Angiotensin

» Aldosterone

• Urine formation

1. Filtration

– Occurs in renal corpuscle

2. Reabsorption

– Occurs in proximal convoluted tubule

– Also occurs in distal convoluted tubule

– It takes things back into blood

3. Secretion

– Occurs in distal convoluted tubule

– Blood gives things up to the urine

4. Concentration

– Occurs in collecting tubules

See next slide

Some Key Points of Renal Physiology

• Nitrogenous wastes primarily come from breakdown of proteins

• Aging & renal function

• By age 35, one begins to lose nephrons

• By age 80, one has approx. 30% reduction in nephron capacity

• GFR = glomerular filtration rate

– Normal = 125cc/min (7500cc/hour)

– 99% of filtered product is reabsorbed

» Normal urine output = 60cc/hour (1500cc/day)

• All along the duct system water is reabsorbed

– Includes the prox. conv. tubule, loop of Henle, distal conv. Tubule, & collecting tubule

– Sodium follows water

• Key elements involved in each process

– Reabsorption = H2O(Na), proteins (amino acids), & sugars (glucose)

– Secretion = ions(K+), drugs, ammonia

– Concentration = more reabsorption of H2O

• 2 key factors determine volume of urine produces

1. Glomerular filtration rate (GFR)

– Determined by the unique arrangment of blood

vessels

2. Hormonal secretion

– Determined by fluid & electrolyte balance

Volume of urine also controlled by glomerular filtration rate

• Unique arrangment of blood vessels

– Afferent arteriole -----to----capillary bed-----to----efferent arteriole -----to---

--capillary bed ----to---- veins

• First capillary bed = glomerular capillaries

• Second capillary bed = peritubular capillaries

• Purpose of this = to control the pressure in the glomerular capillaries &

consequently the glomerular filtration pressure

• 3 factors control this:

• (1) autoregulation

• Local feedback from muscle tension in afferent arteriole

• Local feedback from DCT at JGA

• Mediated via endothelial

secretions of glomerular capillaries

• (2) sympathetic nervous system

• (3) renin

• B = increase fluid volume; overhydration; high output heart failure

• C = kidney pathology

• D = hypertension; arteriolar spasm

– Hormones help control the volume of urine via fluid & electrolyte

balance

• The concentration factor essentially deals with urine volume

– Usually more the volume = more the dilution [a direct proportion]

1. Aldosterone

» From adrenal cortex

» Works on distal convoluted tubule

» Causes H2O & Na+ retention

2. Atrial natriuretic hormone(ANH)

» From atrial wall of heart

» Works on distal convoluted tubule

» Works in opposition to aldosterone

» Causes H2O & Na+ loss

3. Antidiuretic hormone

» From posterior pituitary

» Works on collecting tubules

» Causes reabsorption of H2O (Na+ goes with it)

Diagnostic Tests - Urinalysis

1. Physical Characteristics &

Measurements

– appearance

– color

– odor

– volume

– specific gravity

2. Chemical Measurements

– pH

– protein; glucose

– ketones

– bilirubin; urobilinogen

– leukocytes; nitrite

– blood

3. Microscopic

– cells (wbc, rbc, sperm)

– casts

– crystals

– bacteria

4. Detection of Bacteriuria

– nitrite test

• qualitative or screening test

– C & S

• Colony Count, if done,

make this a quantitative test

• NOTE: Step 4, qualitatively, is

done as part of step 2

• Appearance – Clear = normal

– Cloudy = ? Infection

– If sediment = kidney disease

– Dark = ?blood, ?bilirubin, ?concentrated

• Color– Urochrome pigment = yellow

• comes from breakdown of hemoglobin

– Concentration

• More Concentrated = Deeper Yellow

– Change of Color From:• Meds

– Vitamin = yellow• Diseases

– Blood = red-brown– Liver = Orange

• Foods– Rhubarb = red-brown

• Odor– Normal = ammonia-like smell

• from breakdown of urea– Unpleasant = ? infection

• Quantity

– Average per 24 hours = 1500 cc

• 60 cc per hour

• GFR = 125 cc/min

– Thus, 7500 cc/ hour

• Urine Made Per Hour = 60 cc

• Urine GFR Per Hour = 7500 cc

– KEY: 1 % of filtered urine

remains urine; 99 % becomes

reabsorbed back into blood

– Oliguria = 100 - 400 cc per day

– Anuria = less than 100 cc per day

– Polyuria = diabetes, nerves, diuretics

• Specific Gravity

– Determines Concentration

– Compares Test Liquid to H2O

– Normal = 1010 - 1030

– First AM Specimen = > 1020

– In many kidney diseases, one loses the ability to concentrate urine

– 3 ways to do it:

1. Reagent Strip

2. Refractometer

3. Urinometer

• pH

– Determines Acidity or Alkalinity

– Normal = 6.0

– Range = 4.5 - 8.0

• Acidity example = diabetes

• Alkaline example = UTI

• Protein

– OK to have a Trace in the urine

– Benign Conditions:

• exercise

• exposure to cold

• ⇑⇑⇑⇑ protein consumption

– Generally Means Kidney Disease

• Glucose

– Will only be in urine if exceed Renal

Threshold (160 - 180 mg/dl)

• Ketone (note Acetone is a Ketone)

– Ketones are products of Fat

Metabolism

– If cant breakdown Sugars for

energy, the body will begin using

Fat

– Seen in:

• Uncontrolled Diabetes

• Starvation

• Hi-Fat Diet

• Bilirubin & Urobilinogen Formation

– When used-up RBC’s are broken

down by R-E System, a by-product

is Bilirubin

– Bilirubin removed from blood by

liver & excreted into intestine

– Bacteria in intestine convert

Bilirubin into Urobilinogen

– Some Urobilinogen reabsorbed into

blood

• Of this amount reabsorbed

some my be normally passed in

urine

• Bilirubin

– Normally None in Urine

– Found in urine if it can’t get from

the liver into G-I tract

• From Obstruction of Bile Ducts

– Found in urine if have:

• Liver Disease (hepatitis)

• Blood Disease (hemolysis)

• Urobilinogen

– generally follows whatever happens

to bilirubin

– may get none in urine if on

antibiotics (destruction of gut flora)

– usually get small amount in urine

• Blood

– None is normal

– But may see some if female is

menstruating

• Leukocytes

– from inflammation of kidney or

lower G-U tract

• Nitrites

– screening test for bacteriuria

– bacteria convert nitrate to nitrite

Other Diagnostic Tests

• Blood tests

• BUN / creatinine

• CBC ------ anemia if decreased EPO production

• Renin

• Antistreptolysin titers

• Urine culture & sensitivity (C&S)

• Include colony count

• Imaging

• IVP

• Retrograde pyelography

• CAT/ MRI

• Surgical procedures

• Cystoscopy

• Biopsy

• Incontinence & retention

• UTI’s

• Inflammatory disorders

• Nephrotic syndrome

• Urinary tract obstruction

• Stones

• Hydronephrosis

• Tumors

– Renal cell carcinoma

– Bladder cancer

• Congenital disorders

• Polycystic kidneys

• Wilm’s tumor (nephroblastoma)

• Renal failure

• Acute

• Chronic

• Dialysis

Urinary Tract Disordersoverall outline

• Urinary Incontinence

– Loss of voluntary control of bladder

– Frequently called “neurogenic bladder”

– Many causes

– Enuresis = involuntary control after age 4 or 5

– Types:

– Stress

– Urge

– Overflow

• Urinary retention

– Called “residual urine”

– Causes :

– Anatomical defects

– Neurogenic defects

• Treated with “catheterization”

– Foley

– French

Incontinence, retention, & catheters

Urinary Tract Infections

Urethritis; Cystitis; Pyelonephritis

• Etiology

– Ascending infection ----- women > men

– Prostatic hypertrophy with urinary retention

– Incomplete emptying of bladder with urinary stasis

– Pregnancy associated with stasis

– Blood borne pathogens

• Pathophysiology of UTI’s ----- see next slide

• Dx

• Dysuria, urgency, & nocturia

• Systemically get fever & malaise

• CVA tenderness in pyelonephritis

• Note glomerulonephritis is vastly different with regards etiology &

pathophysiology

• Note etiologies

– Inflammation of mucosa

– Trauma of mucosa

– Obstruction

– Vesicoureteral reflux

– Immobility

– Blood-borne pathogens

• TB

• HIV

• Septicemia

• Glomerulonephritis

– Acute

• Sx = proteinuria, edema, oliguria

• Etiol = 1-2 weeks post strept

infect.

– Chronic

• Etiol = autoimmune disease

– e.g. lupus, diabetes, hepatitis C

• Can lead to irreversible kidney

damage

Inflammatory disorders(1) glomerulonephritis

(2) nephrotic syndrome

• Nephrotic Syndrome

– Glomerular disorder where one loses the capacity

to retain protein, especially albumin

– Sx

– severe edema (anasarca)

* can get skin breakdown since

impaired arterial flow

– proteinuria

– hypoalbuminemia

– oliguria

– Etiol:

» Toxic agents (lead, mercury)

» Toxic drugs (aminoglycosides)

» Diseases (diabetes, lupus

» Key = any significant problem with

glomerulus can lead

to nephrotic syndrome

• Tumors

– Note that primary

symptom = hematuria

– Renal Cell Ca = most

common, unilateral, adeno

Ca from tubular epithelium

• See picture

– Bladder Ca = usually from

transitional epithelium

• Neurogenic bladder

• Renal Calculi

– Etiology: Calcium, Uric

acid, Urine crystals

– Symptoms: renal colic, N&V,

chills, fever

– Risk factors: prolong

dehydration, prolong

immobilization, infection

– Treatment:

surgery,lithotripsy

• Anomalies

– Strictures

– Kinks

– Ptosis

– Pelvic kidney

Obstructive Disorders

Major sites of urinary tract obstruction

– These result in:

– Hydronephrosis

– Hydroureter

• If these conditions

exist longer than 2

months get

destruction of

kidney

Congenital Diseases

• Vesicoureteral reflux

• Due to ectopic insertion of ureter into bladder. If far away from trigone, do not get adequate compression of ureter when voiding & get reflux

• Incidence: 1/1000

• If one gets it each sibling(to be) has 50% incidence

• Girls> boys; 10:1 ratio

• Ectopic kidney

• May get kinking of ureter

• Usually in pelvis

• Asymptomatic

• Renal agenesis

• Usually unilateral & left kidney

• 2 types: (1) occurs randomly (2) genetic

• Asymptomatic

• Remaining kidney becomes large since compensatory hypertrophy

Congenital Diseases (cont)

• Polycystic kidney (2 types

– In adults (see picture)

• Genetic etiol ----- autosomal dominant

• Clinically seen in adults

– Between age 30 – 40 one begins to get renal

failure

• Tx = transplant

– In children

• Genetic etiol --- autosomal recessive

• Manifest at birth; usually fatal or infant stillborn

• Rare

• Wilm’s tumor (nephroblastoma)

• Most common tumor of children; usually

unilateral

• Etiol = autosomal recessive (on chromosome 11)

• Manifests between age 2 – 5 years & presents as

abdominal mass

– May produce hypertension

• 5 year survival = 90%

Renal Failure

• Acute renal failure– Abrupt decrease in renal function

• Nitrogenous wastes accumulate

– Usually reversible

– Sx:

• Oliguria

• Drowsiness

• Altered levels of consciousness

– Etiol:

• Glomerular disease

• Severe pyelonephritis

• Nephrotoxins that damages tubular epithelium

• Ischemic causes– shock

• ATN (acute tubular necrosis)

» e.g. burns(hgb accumulates)

» e.g. trauma (myoglobin accumulates)

• Chronic Renal Failure

– Get slow progressive loss

of neurons

– Usually irreversible

– Course = gradual

– Etiol:

• Vascular disease

– e.g.

hypertension

– Disease called

nephrosclerosis

• Glomerular disease

– e.g. diabetes

• Tubular disease

– e.g. toxins

Hypertension & the kidneys

Dialysis in renal failure

• 2 types:

– Hemodialysis

– Peritoneal dialysis

• Mechanism

– Simple diffusion for wastes & electrolytes

– Osmosis for water balance