Calculus Disease Flashcards
1
Q
Age of peak incidence of renal stones
A
- 30-60
2
Q
Male:Female ratio of renal stones
A
- 3:1
3
Q
Risk factors for renal stones
A
- 30-60
- Male
- Family history (3x risk)
- Increasing chance w/ weight
- History of stones
*within 1yr - 10-15%
*5yrs - 50-60%
*10yrs - 70-80%
4
Q
Factors influence stone formation
A
- Diet
- Climate
- Genetics
- Gender
- Water supply (hard water inc. chance)
- Occupation/stress
5
Q
Diet factors that contribute to stone formation
A
- Oxalate
- Animal protein and fat
- Vit. D and C
- Phosphorous
- Calcium
- Fish oils
6
Q
Most common renal stone
A
- Calcium oxalate (up to 80%)
- Calcium oxalate monohydrate; hard
- Calcium oxalate dihydrate; less hard
7
Q
Renal stone assoc. w/ hyperparathyroidism and renal tubular acidosis
A
- Calcium phosphate
- Often contain calcium oxalate
8
Q
Effects of animal protein in stone formation
A
- Inc. calcium, sulfate, uric acid
- Dec. pH, citrate
- All increased risk factors for recurrent stone formation
9
Q
Most important factor in the formation of stones?
A
- Urine volume
- Dilute urine really prevents the crystallization of anything
- 2.5L or more urine necessary
10
Q
Urine pH which promotes renal stone formation
A
- pH below 5.5 or above 7.5
11
Q
Uric acid stones
A
- Accounts for 5-10% of renal stones in USA
- 24-40% of gout pts develop uric acid stones
- 25% of pts w/ uric acid stones develop gout
- Prevalence is 2-39% worldwide
- Solubility of stone formation is dependent upon pH of <5.5
- Form secondary to lack of uricase
12
Q
Urica acid stone etiology
A
- Uric acid is the end product of purine metabolism (breakdown of protein)
- Increased dietary purine intake
- Uricosuric drugs impair uric acid reabsorption from proximal tubule
- Obesity and alcohol consumption
- Myelo- and lymphoproliferative diseases
- Inborn metabolic disorders
- Chronic diarrheal syndromes
13
Q
Uric acid stones clinical characterisitcs
A
- Renal colic (not that specific)
- Hematuria (not that specific)
- Low urinary pH (<5.5) (specific)
- Neg. plain x-rays (uric acid is radioluscent)
*calcium oxalate/phosphate are radio-opaque so will show up on x-ray as long as they are large enough
- CT or U/S confirmation
14
Q
Struvite calculi
A
- Named in honor of Baron H.C.G. von Struve
- Composed of magnesium ammonium phosphate and carbonate apatite
- Also referred to as “infection”, “urease” and “triple phosphate stones”
- Compries 10-15% of all human urinary stones
- More prevalent in females than males (3:1)
- Most prevalent form in those w/ supravesical diversions and neurogenic bladders
15
Q
Struvite calculi predisposing factors
A
- Urinary infection w/ urease-synthesizing organism is an essential prerequisite
- Bacteria are contained within the interstices of concretions and are protected from antibiotic therapy
- Urine pH is generally >7.5`
16
Q
Urease producing organisms
A
- Organisms that cause struvite calculi
17
Q
Struvite calculi clincal manifestations
A
- Branched or staghorn calculi are commonly infection induced
- Pts often have few symptoms: females may have recurrent cystitis
- Often assoc. w/ long term use of indwelling catheters
- May have non struvite elements
- Recur often in pts who do not undergo complete removal
18
Q
Cystinuria
A
- Inborn error of metabolism characterized by a disturbance in renal and intestinal handling of cystine
- Result is an excessive excretion of cystine
- More common in 2nd and 3rd decades
- Both sexes w/ equal prevalence
- Urinalysis reveals hexagonal crystals
19
Q
Xanthine stones
A
- Gene mutation results in xanthine oxidase enzyme deficiency
- Inability to convert xanthine into uric acid
- No specific treatment to reliably prevent stones
20
Q
Medical managemnt for 1st time stone former
A
- Should evaluate and treat single stone formers as other individuals w/ recurrent stone disease
- No difference b/w solitary and recurrent stone disease
- 21% of 860 consecutive pts. —> 1st time stone formers
*71% of these pts. had metabolic abnormalities
*relapse rate similiar to multiple stone formers
21
Q
Absolute indicators for a work-up in 1st time stone formers
A
- B/L stones
- Recurrent stones
- Family hx
- Children
- Solitary kidney (1 kidney)
- African american
- Skeletal disease
- Bowel disease
- Bowel surgery
- Medical condition
Any pts. w/ stones composed of cystine, uric acid or struvite
22
Q
Relative indicators for a work-up in 1st time stone formers
A
- Pilots or freq. business travelers
- 1st time stone formers aged <20 or >50
- Pts w/ difficult to treat stones
- Immuno-compromised pts
- 1st time female stone formers
23
Q
Urinary stone conservative medical management measures
A
- High fluid intake (>3L/day)
- Sodium restriction
- Oxalate restriction
- Avoid purine gluttony
- Increase citrus fruit intake
- Moderate calcium restriction in hypercalciuric pts.
24
Q
Allopurinol
A
- Treats hyperuricosuria
- Reduces uric acid synthesis
- Lowers urinary uric acid
- Retards spontaneous nucleation of calcium oxalate
- May be useful w/ dietary purine overindulgence
25
Potassium citrate for hyperuricosuria
- Effective alternative to allopurinol
- May reduce urinary saturation of calcium oxalate
- Inhibits urate induced crystallization of calcium oxalate
- Useful in mild to moderate hyperuricosuria (\<800mg/day) w/ coexistent hypocitraturia
- Helps to increase urinary pH above 5.5
- Works as an adequate alkalinizing agent
- Can also use sodium bicarbonate
26
Gouty Diathesis treatment
- Potassium citrate
- Helps to increase urinary pH above 5.5
- Works as an adequate alkaliniznig agent
- Can also use sodium bicarbonate
27
Enteric hyperoxaluria treatment
- Multifactorial management
- Oral calcium or magnesium to decrease urinary oxalate
- Restrict dietary oxalate
- Alkalization w/ liquid potassium citrate to correct metabolic acidosis and hypocitraturia
- High fluid intake
- Calcium citrate
28
Hypocitraturia treatment
- Potassium citrate
- Restores normal urinary citrate in all causes
- Lowers urinary saturation and inhibits crystallization of calcium salts
- May correct the metabolic acidosis and hypokalemia found in pts. w/ distal RTA
- Corrects the hypocitraturia due to bicarbonate loss from the intestinal tract
- Thiazide therapy may induce hypocitraturia
29
Uric acid calculi treatment
- Increased urinary volume (2-3L)
- Urinary alkalization (don't overdo it)
\*K-citrate lowers urinary calcium and increases citrate
\*sodium bicarbonate
- Reduce purine rich foods and increase fiber
- Can try Allopurinol for persistently high excretion (\>850 mg/day)
30
Struvite calculi management
- Diagnostic eval
- Biochemical eval of blood and urine
- Bacteriologic eval
- Raciologic documentation
- Surgical removal of all stones and correction of anatomic defect
- Long term antibiotic suppression
- Treatment of underlying metabolic derangement (only 14%)
31
Acetohydroxamic acid
- Used to treat struvite calculi
- Has been shown to reduce the urinary saturation of struvite and retard stone formation
- May prevent recurrence of new stones and inhibit the growth of stones in pts w/ chronic urea splitting organisms
- May cause dissolution of existing struvite calculi in some pts
32
Extracorporeal shockwave lithotripsy (ESWL)
- Least invasive way of surgically removing stones
- Stone is imaged w/ U/S or fluoroscopy
- Focused shockwave is used to break up stone
33
Extracorporeal shockwave lithotripsy (ESWL) disadvantages
- May require multiple procedures
- Not indicated for larger stones
- Not for mid or lower ureteral stones
- Less effective in cystine or calcium oxalate monohydrate stones
- Potential complications
\*"steinstrasse"; bunch of small stones now obstruct ureter
\*bleeding
\*infection
\*kidney dmg
34
Ureteroscopy
- Very common technique for treating stones
- Bladder then ureteral orifice entered
- Stone is visualized
- Laser removal, basket extraction used to remove stone
- Stent often placed
- Flexible and semirigid ureteroscopes available
35
Ureteroscopy disadvantages
- Not indicated for very large stones
- Lower pole stone difficulties
- More invasive than ESWL
- Potential complicatoins
\*ureteral strictures
\*stent discomfort
\*bleeding
\*infection
36
Percutaneous nephrolithotomy (PCNL)
- Surgical technique for removing stones
- Reserved for larger stones \>2cm and staghorns
- Collective system entered thru a flank approach
37
Percutaneous nephrolithotomy (PCNL) disadvantages
- Must be able to tolerate prone position
- Most invasive (open nephrolithotomy rarely performed)
- Potential complications
\*bleeding
\*infection
\*kidney dmg
38
Only type of stone that can be treated medically w/o invasive procedures
- Uric acid stones; can be dissolved
