Pathophysiology of Urinary Tract Disorders

Urinary Tract Homeostasis

Urinary Tract Homeostasis

Maintains continuous downward flow of urine.

Obstruction

Sluggish flow that can cause urinary issues.

Urothelial Cells

Line the collecting system of the urinary tract.

Squamous Cells

Line the terminal urethra.

Urinary Bladder

Reservoir that receives and holds urine.

Micturition Center

Located in lower spinal cord, controls urination.

Renal Function

Five main functions of the kidneys.

Excretion of Metabolic Waste

Removes BUN and creatinine from blood.

Blood pH Adjustment

Regulates acid excretion and HCO3 production.

Blood Volume/BP Adjustment

Involves secretion of renin by kidneys.

Plasma Salt Concentration

Regulates sodium excretion in urine.

Erythropoietin

Stimulates red blood cell production.

Kidney Anatomy

Consists of outer cortex and central medulla.

Glomeruli

Filtering apparatus of the kidney.

Renal Tubules

Processing apparatus crossing cortex to medulla.

Afferent Arteriole

Supplies blood to the glomerulus.

Efferent Arteriole

Drains blood from the glomerulus.

Juxtaglomerular Apparatus (JGA)

Senses BP, blood flow, and electrolyte levels.

Renin

First step in renin-angiotensin-aldosterone system.

Macula Densa

Senses salt and flow in distal tubule.

Juxtaglomerular cells

Cells that store and secrete renin.

Glomerular membrane

Three tissue layers separating blood from Bowman's space.

Hydrostatic pressure

Forces fluid into Bowman's space from glomerulus.

Glomerular filtrate (GF)

Fluid containing water, salts, glucose, and amino acids.

Urine formation

Process of creating urine from glomerular filtrate.

Glomerular Filtration Rate (GFR)

Normal rate is 90-120 ml/min in young adults.

ADH

Hormone that promotes water reabsorption in kidneys.

Aldosterone

Hormone regulating Na+ and K+ balance in kidneys.

Azotemia

Elevated blood urea nitrogen (BUN) and creatinine.

Urinalysis

Test evaluating urine for abnormalities.

Ideal urine specimen

Obtained via catheterization or midstream catch.

Urine color

Pale yellow indicates concentration and infection.

Urine odor

Aromatic scent can indicate metabolic issues.

Urine clarity

Clear urine suggests no particulates or infection.

Nitrite/Leukocyte Esterase

Tests for bacterial infections in urine.

Glucosuria

Presence of glucose in urine, indicates diabetes.

Hematuria

Blood in urine, can indicate stones or trauma.

Ketonuria

Presence of ketones in urine, indicates starvation.

Proteinuria

Presence of protein in urine, indicates kidney issues.

Urobilinogenuria

Urobilinogen in urine, indicates liver disease.

Bilirubinuria

Bilirubin in urine, indicates liver dysfunction.

Specific gravity

Measures urine concentration and hydration status.

Obstructive uropathy

Obstruction affecting ureter or kidney function.

Hydroureter

Dilation of ureter due to obstruction.

Hydronephrosis

Dilation of renal pelvis due to obstruction.

Prostatic hyperplasia

Enlargement of prostate causing urinary obstruction.

Urolithiasis

Formation of stones in the urinary tract.

Neoplasms

Tumors affecting renal pelvis, ureter, or bladder.

Posterior urethral valves

Congenital obstruction in the urethra.

Renal tissue atrophy

Shrinkage of kidney tissue due to obstruction.

Urolithiasis Prevalence

Afflicts 5-10% of population; Peak incidence Age 20-30

Urolithiasis Stone Characteristics

Stones may be numerous & small or they may grow large

Urinary Stasis

Predisposing condition for urolithiasis caused by medications (antihistamines)

Infection

Predisposing condition for urolithiasis, includes cystitis and urethritis (bacteria may cause crystal clumping)

Concentration of Stone Constituents

Predisposing condition for urolithiasis, such as hypercalciuria

Urine Volume

Predisposing condition for urolithiasis, dehydration leads to supersaturation of minerals

Calcium Stones

75% of stones; most patients have elevated levels of urinary calcium, including Ca oxalate and Ca phosphate

Magnesium Stones

20% of stones; bacterial infection changes urine pH from acidic to alkaline, most amenable to Mg++ calculus formation

Uric Acid Stones

About 25% of patients with gout

Cystine Stones

Least common stones associated with cystinuria - faulty reabsorption

Asymptomatic Urolithiasis

30-45% of cases are asymptomatic and found on radiography, US, CT

Flank Pain Radiating to Groin

Known as renal colic; caused by spasmodic contraction of ureter smooth muscle

Obstruction in Urolithiasis

Can lead to hydronephrosis

Nausea and Vomiting

Common symptoms associated with urolithiasis

Renal Cell Carcinoma

Most significant renal neoplasm; adenocarcinoma from renal proximal tubular epithelium, 90% of renal malignancies

Risk Factors for Renal Cell Carcinoma

Increased risk in smokers and obese individuals

Symptoms of Renal Cell Carcinoma

Flank pain/mass and/or hematuria

Transitional Cell Carcinoma

From uroepithelium; can occur at multiple points in urinary tract, 95% occur in the urinary bladder

Risk Factors for Transitional Cell Carcinoma

Increased risk in smokers and exposure to aniline dyes

Symptoms of Transitional Cell Carcinoma

Grossly visible, painless hematuria; ⅓ also have dysuria & urgency

Polycystic Kidney Disease - Adult Type

Autosomal dominant; fairly common (1 in 500-1,000 people); does not usually become symptomatic until after age 30

Complications of Polycystic Kidney Disease

Kidneys riddled with numerous expanding cysts leading to ischemia, necrosis, fibrosis, and chronic renal failure

Symptoms of Polycystic Kidney Disease

Hematuria, chronic infection, hypertension

Treatment for Polycystic Kidney Disease

Transplantation due to end-stage renal failure

Cystitis

Inflammation of the bladder; most common form of UTI caused by E. coli (90-95%)

Predisposing Factors for Cystitis

Short female urethra, instrumentation, prostatic hypertrophy

Symptoms of Cystitis

Frequency, urgency, dysuria/pain, hematuria

Diagnosis and Treatment of Cystitis

Urine culture and appropriate antimicrobial

Pyelonephritis

Acute pyogenic infection of the kidney, most cases due to ascending infection from lower urinary tract

Flank Pain

Sudden onset pain in the side.

Fever

Elevated body temperature indicating infection.

WBC Count

Elevated white blood cells indicate inflammation.

Urosepsis

Sepsis originating from a urinary tract infection.

Acute Pyelonephritis

Kidney infection characterized by flank pain.

Nephritic Syndrome

Glomerular inflammation causing hematuria and hypertension.

Poststreptococcal Glomerulonephritis

Follows streptococcal infection; causes glomerular inflammation.

Antistreptococcal Antibodies

Antibodies that rise after streptococcal infections.

Oliguria

Low urine output, often ≤400ml/day.

Uremia

Clinical syndrome due to renal failure.

Acute Renal Failure

Rapid onset renal dysfunction over days.

Acute Tubular Necrosis

Most common cause of acute renal failure.

Chronic Renal Failure

Progressive loss of kidney function over time.

Renal Reserve

Kidney function capacity before significant impairment.

End-Stage Renal Disease

Final stage of chronic renal failure.

Incontinence

Inability to control urination.

Stress Incontinence

Urine leakage due to increased abdominal pressure.

Urge Incontinence

Sudden urge to urinate, often in elderly.

Overflow Incontinence

Urine dribbling due to overfilled bladder.

Horseshoe Kidney

Renal fusion anomaly; kidneys joined at midline.

Ectopic Kidney

Kidney located outside its normal position.