Download Nephrolithiasis

NEPHROLITHIASIS
Priyanka Patel PGY 2
EPIDEMIOLOGY
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Renal stones are relatively
common problem on outpatient
basis and multiple ED visits
Approximately 2 million visits
with PCP yearly
16% men and 8% of women will
have at least one symptomatic
stone by age of 70 years old.
Majority of the stone
compositions of these
individuals are going to be
calcium oxalate.
Prevalence has been increase
from 3.8 percent to 8.4 percent
yearly.
Increased risk in Caucasians
versus Hispanic, Asian, or
African Americans.
ETIOLOGY
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80% of stones are made up of calcium oxalate or less
often calcium phosphate.
Other types include uric acid, struvite (magnesium
ammonium phosphate) or cystine stones
Different theories
1) stones occur when soluble material supersaturates the
urine and begins process of crystal formation. Crystal
aggregates become large enough to be anchored at end of
collecting ducts and slowly increase in size over time.
 2) Calcium phosphate crystals may form in interstitum and
get extruded in papilla forming Randall’s plaque. Calcium
oxalate crystals then formulate on top of these plaques.
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RISK FACTORS
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History of prior kidney stonesre-occurence rate of 10 to 30
percent at 3-5 years.
Family history-these
individuals have twofold
increase in risk.
Enhance enteric oxalate
absorption (gastric bypass,
bariatric surgery, short bowel
syndrome). Due to similar
mechanism as to Crohns.
Frequent upper UTIs (spinal
cord injury) and medications.
Crohns disease (due to fat
malabsorption and fat binds to
calcium, leaving oxalate to be
filtered through the kidneys
and cause build up of oxalate
stones.
RISK FACTORS
Hypertension, diabetes, obesity, gout, and
excessive physical exercise (marathon runners)
which can have increase in crystalluria
 Low fluid intake
 Persistently acidic urine (usually seen in
diarrheal states which bicarbonate loss and
volume depletion leads to concentrated acid urine
 Struvite stones form in patients with upper UTI
due to Proteus or Klebsiella (urine is alkaline pH
>7.0). Therefore, these tend to occur majority of
time in women who have frequent UTIs.
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SYMPTOMS
Symptoms may present when stones pass from
renal pelvis to the ureter.
 Pain waxes and wanes in severity and develops
in waves related to the movement of the stone in
the ureter and ureteral spasms.
 Pain occurs from urinary obstruction or
distention of renal capsule
 Location of pain varies.
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Upper ureteral and renal pelvis obstruction-flank
pain and tenderness
 Lower ureteral obstruction-pain that radiates to
testicle or labium.
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Gross of microscopic hematuria is present
SYMPTOMS
Nausea and vomiting
 Pink, red, or brown urine
 Pain on urination
 Severe pain in side and back, below the ribs
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COMPLICATIONS
Can lead to persistent renal obstruction that can
lead to permanent renal damage of left
untreated.
 Staghorn calculi themselves do not produce
symptoms unless causing obstruction. Can lead
to renal failure over years if present bilaterally.
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Study shown that 28 percent of patients with
staghorn calculi over an 8 year period had renal
failure.
DIFFERENTIAL DIAGNOSIS
Renal cell carcinoma-tumor invasion
 Pyelonephritis(fever-determining factor)
 Ectopic pregnancy (check urine pregnancy or
pelvic ultrasound/renal ultrasound)
 Rupture or torsion of ovarian cyst
 Dysmenorrhea
 Aortic aneurysm
 Intestinal obstruction, diverticulitis, appendicitis
 Biliary colic or cholecystitis
 Acute mesenteric ischemia
 Herpes Zoster
 Individuals seeking attention or narcotic use.
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INITIAL TEST OF CHOICES:
Non-contrast CT renal protocol scan (more
sensitive, radiation exposure)
 Ultrasonography (less sensitive, no radiation
exposure, can be performed at bedside)
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Other tests include
-KUB
 -Urinalysis-RBCs in urine
 -IVP
 -MRI abdomen
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DIAGNOSIS-KUB
Can identify large radiopaque stones such as
calcium, struvite, and cystine stones
 These will miss radiolucent stones such as uric
acid stones and smaller stones or stones that
overlie bony structures.
 This has little role when ultrasound or CT is
available.
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KUB
DIAGNOSIS-ULTRASOUND
Test of choice with patients who should avoid
radiation
 Pregnant women
 Women of childbearing age
 Sensitive for diagnosis of urinary tract
obstruction (hydronephrosis,dilated renal pelvis
calyx).
 This can be done at bedside of patient.
 Can detect radiolucent stones missed on KUB
 However, can miss small stone or ureteral stones
 Distal ureteral stones can be detected more with
TVUS in women.
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KIDNEY STONE ULTRASOUND
HYDRONEPHROSIS
DIAGNOSIS-CT RENAL
Detects both stones and urinary obstruction
 Specificity can be high as 100%, sensitivity 88%
 CT can help detect alternate diagnosis
 Consider contrast in HIV patients on indinavir
since these are radiopaque and signs of
obstruction can be minimal or absent.
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TYPES OF STONES
Calcium oxalate: most common (70-80). Typically,
grown on Randall’s plaque (composed of calcium
phosphate) on renal papilla.
 Calcium phosphate
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15% and in combination of struvite or calcium oxalate
crystals. Usually form in alkaline urine compared to
calcium oxalate crystals.
TYPES OF STONES
Uric acid crystals usually about 8% of patients
and usually form in acidic urine pH 5.5 or lower
 Struvite crystals form only in presence of urease
producing bacteria (proteus/klebsiella)
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They are present in 1% of stones and more common
in women (due to high increase of UTIs)
 Urease splits into CO2 and 2 molecules ammonia so
reaction gives a urine pH that is 8.5 or 9 even.
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URIC ACID CRYSTALS
Urine sediment loaded with uric acid
crystals. These crystals are pleomorphic,
most often appearing as rhombic plates
or rosettes. They are yellow or reddishbrown and form only in an acid urine.
CALCIUM OXALATE CRYSTALS
Urine sediment showing both dumbbell-shaped calcium
oxalate monohydrate (long arrow) and envelope-shaped
calcium oxalate dihydrate (short arrows) crystals. Although
not shown, the monohydrate crystals may also have a
needle-shaped appearance. The formation of calcium oxalate
crystals is independent of the urine pH.
CALCIUM OXALATE CRYSTALS
Urine sediment viewed under polarized
light showing coarse, needle-shaped
calcium oxalate monohydrate crystals.
These crystals have a similar appearance
to hippurate crystals.
CALCIUM OXALATE
CYSTINE CRYSTALS
Urine sediment showing hexagonal
cystine crystals that are essentially
pathognomonic of cystinuria.
STRUVITE
Urine sediment showing multiple "coffin
lid" magnesium ammonium phosphate
crystals that form only in an alkaline
urine (pH usually above 7.0) caused by
an upper urinary tract infection with a
urease-producing bacteria.
STRUVITE
MEDICAL THERAPY
Acute treatment involves aggressive IVF
hydration and pain control with NSAIDs or
opiods.
 Toradol is commonly used analgesic.
 NSAIDs cause they decrease ureteral smooth
muscle tone and treat pain
 Hospitalize those with uncontrollable pain or
fever and if they are unable to take oral intake
 Flomax, nifedipine, and tadalafil have been
studied to help passage of stone.
 Flomax is used for 4 weeks to help facilitate
stones <10mm.
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UROLOGICAL CONSULTATION
Urgent: urosepsis, ARF, anuria, etc
 Outpatient referral when stone is >10mm in
diameter and patients who fail to pass stone with
conservative management.
 Current options in urology include shock wave
lithotripsy, ureteroscopic lithotripsy and
percuteanous nephrolithotomy and laparoscopic
stone removal
 If stones are are >1.5cm then SWL is only
successful in 50 percent.
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SHOCK WAVE LITHOTRIPSY
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Employs high energy
shock waves produces by
electrical discharge.
Waves are transmitted
through water and directly
focus onto renal/ureteral
stone with aid of biplanar
fluoroscopy.
Change in density between
soft renal tissue and hard
stone causes a release of
energy at the stone
surface. Energy then
fragments the tissue.
Stones are broken down
that can easily pass.
PERCUTANEOUS NEPHROLITHOTOMY
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Indications: >2cm in diameter
or complex calculi, cystine
stones, horseshoe kidney, or
stones with diverticula
Retrograde ureteral catheter is
placed using a flexible
cystoscope
Patient gets turned in prone
position and collecting system
is accessed via 18 gauge needle
under fluro.
Then, dilate tract with balloon
and sheath is placed in
collecting system.
Calculi are extracted using
forceps with rigid/flex scope
and fragmented using
ultrasonic or pneumatic
lithotripsy.
URETEROSCOPY
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Ureteral access and
dilation
If stone is small enough,
stone baskets or
grasping forceps can be
used for stone removal.
Reasons for placement
of stent:
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Urinary tract
abnormalities or solitary
kidneys, when bilateral
simultaneous
ureteroscopy is
performed, or if residual
edema or inflammation
is present after stone
removal.
URETERAL STONES
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Stones >10mm are
unlikely to pass
Proximal ureteral stones
are also likely to pass
Distal ureteral stones
are treated with
ureteroscopy which is
best initial option but
SWL can be used as
well.
Mid-ureteral stones –
flex ureteroscopy is
preferred over SWL
PREVENTION
Dietary modification: increase intake of fluid,
dietary calcium, potassium
 Decreasing intake of oxalate, animal protein,
sucrose, fructose, sodium, vitamin C and
supplemental calcium
 Drug therapy: Allopurinol, thiazide, potassium
 24 urine collection workup to test for response
with medication or diet. Test for urine volume,
calcium, citrate, and oxalate.
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DRUGS CAUSING CRYSTAL FORMATION
●Acyclovir
 ●Sulfonamide antibiotics
 ●Ethylene glycol
 ●Megadose vitamin C
 ●Methotrexate (MTX)
 ●Protease inhibitors
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ALGORITHIM
INHERITED SYNDROMES
Primary hyperoxaluria-condition where body
makes too much oxalate from liver and
accumulates in kidneys.
 Cystinuria-kidney handles cystine in abnormal
way causing too much to enter in urine which can
turn into stones cause it does not dissolve well.
 APRT deficiency-stones made up of 2,8
dihydroxyadenine. Can appear to look like uric
acid stones.
 Dent disease-affects kidneys in male. They
usually have high calcium in urine, low levels of
phosphorus in blood, deposits of calcium in
kidneys.
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REFERENCES:
Manjunath A, Skinner R, Probert J. Assessment
and management of renal colic. BMJ 2013;
346:f985
 Taylor EN, Curhan GC. Body size and 24 hour
urine composition. Am J Kidney Dis 2006; 48:905
 Colistro R, Torreggiani WC, Lyburn ID, et al.
Unenhanced helical CT in the investigation of
acute flank pain. Clin Radiol 2002; 5:435
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