Urinary Tract Obstruction and kidney stones Flashcards
What are complications of urinary tract obstructions
Hydroureters, hydronephrosis and pyelonephritis
Examples of intrinsic and extrinsic UTO
Intrinsic
- calculi
- strictures
- tumors inside the bladder
- blood clots
- neurogenic (neurons damaged)
Extrinsic
- pregnancy
- periureteral inflammation
- endometriosis
- prostate hypertrophy
- tumors outside of the bladder (usually prostate)
What is the relationship between location of UTO and unilateral vs bilateral UTO?
Unilateral = tends to be more proximal
Bilateral = tends to be more distal
Sclerosis retroperitoneal fibrosis
Ormond disease
Rare cause of urethral narrowing due to fibrosis of the retroperitoneal structures.
Causes hydronephrosis and is more common in middle- late aged males
- infection, prior surgery, drug exposures and excess radiation are common risk factors
- **most cases however are idiopathic
Etiology = IgG4 released disease in which IgG4 secreting plasma cells cause the fibrosis due to autoimmune functions
Treatment = corticosteroids and urethral stents (once resistance starts to develop)
Urolithiasis
Affects 5-10% of Americans and can present anywhere in the renal system (however usually inside the kidney)
Men are more affected and the peak onset age is 20-30s
- there is a genetic component released to this
- direct correlate with obesity and diabetes
- recurrence rates = 20% within 5 years
80% are unilateral and tend to have an average diameter of 2-3 mm in the renal pelvis
Can sometimes look “stag horn apperence” when they surround collecting tubules
Symptoms
- abdominal and renal colic pain
- hematuria
- increased risks of super infections
What are the four main types of urolithiasis?
1) calcium stones (70%)
- consist of calcium oxalate or calcium phosphate
- are radioopaque (white) appearing
2) triple stones/struvite stones (15%)
- consists of ammonium phosphate
- are radioopaquish(white) appearing (not as bright as calcium but brighter than uric acid)
3) uric acid stones (5-10%)
- are radiolucent (clear/gray) appearing
4) cystine stones (1-2%)
Calcium stones (urolithiasis)
Are associated with 5% of all patients who have hypercalcemia and hypercalciuria
Can occur with hyperparathyrodism, diffuse bone diseases and sarcoidosis
- about 55% of patients though have hypercalciuria without hypercalcemia
- this is caused either by intestinal hyper absorption or impaired renal tubular reabsoption of calcium
these are radioopaque stones
Struvite (magnesium ammonium and phosphate stones)
Largely formed after infections by urea-splitting bacteria which convert urea -> ammonia
- includes proteus and staph species as well as e. Coli and klebsiella
- *more common in women since they are more likely to get UTIs
High levels of ammonia produces alkaline urine which causes precipitation of magnesium ammonium salts which can accumulate
often appear “stag horn” appearance since they occur in the renal pelvis and take its shape
Uric acid stones
Common in individuals with gout or rapid cell turnover diseases (such as cancer and tumor lysis syndrome)
- more common in men
- *however more then half of the patients with these stones have neither hyperuricemia nor increased urinary excretion of uric acid**
- this is believed to be due to lower pH (acidic urine) since uric acid is insoluble in acidic urine
**patients will always have acidic urine (<5.5)
these are radiolucent stones
Cystine stones
Caused by cystineuria
**Form only at acidic pH urine (<5.5)
What are some common inhibitors of stone formations in the renal system?
Pyrophosphate
Diphosphonate
Citrate
Glycosaminoglycans
Osteopontin
Nephrocalcin
it is proposed that a deficiency in any of these can lead to an increase in urolithiasis formation
Hydronephrosis
Dilation of the renal pelvis and calyces with accompanying atrophy of the parenchyma
Obstruction may be sudden of insidious and can occur at any level of the urinary tract
- can only be bilateral if the lesion/obstruction is below the ureters*
- if unilateral = can be anywhere but most likely a over the ureters
- bilateral = renal failure
Causes diminished GFR overtime
- irreversible damage:
Takes 3 weeks in complete obstruction
Takes 3 months in incomplete obstruction
**uremia tends to stop natural course of lesion
Causes of hydronephrosis
Congenital causes:
- atresia of the urethra
- poor valvular formations
- aberrant renal arteries
Acquired:
- foreign bodies
- proliferative lesions
- inflammatory lesions/ infection
- neurogenic causes
- pregnancy
How does bilateral complete obstruction and incomplete bilateral obstruction differ in hydronephrosis symptoms?
Complete = anuria
- *Incomplete = polyuria
- this is kinda strange but this is due to defective tubular concentration which just wants to push everything out without filtration
Medications that have known risks for developing urinary stones
Carbonic anhydrase inhibtors
HIV medications
Laxative abuse
Loop diuretics
Triamterene
Etc.