Transcript RCHRounds-KS

Kidney Stones: An
Overview
Gerald Da Roza
MD, MHSc, FRCPC
March 15, 2010
Overview
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Case
Diagnosis of kidney stones
Acute management
Epidemiology
Risk factors
Work up and treatment
Diet and kidney stones
Case – A Few Years Ago
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30 year old nephrology fellow
Bright, hardworking, driven
Atrocious diet (hospital cafeteria and vending
machines, no fruit and vegetables, ++ salt)
Drinks very little during daytime
Presents with acute onset of R costovertebral
pain, radiating around to anterior abdomen,
10/10 in severity, nauseau and vomiting
Case – A Few Years Ago
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Physical Exam
Tachycardia, normotensive, afebrile
 ++ CVA and RUQ tenderness
 Nil else
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Investigations
U/A shows hematuria,
 CBC, lytes urea, Cr normal
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Diagnosis???
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Kidney Stone - Why?
DDx
Renal Cell Ca w/ blood clot
 Renal Cyst w/ clot
 Pyelonephritis
 AAA/dissection
 Ectopic Pregnancy (if female)
 Intestinal Obstruction
 Appendicitis
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How do we make the diagnosis?
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Investigative Options:
CT Scan
 US
 Abdominal Plain Film
 MRI
 IVP
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Non-contrast Helical CT Scan
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Gold standard
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Dual energy CT (DECT) is new imaging modality may
be able to predict stone composition (future tx)
Helps determine if obstruction present
Provides alternate diagnosis in many cases
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Sensitivity 95 %, Specificity 98%
33 percent had an alternate diagnosis not suspected on
clinical grounds, one-half of whom had significant disease
Only misses stones due to protease inhibitors
CT KUB
Ultrasound
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Procedure of choice for pts who should avoid
radiation
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pregnant women and possibly women of
childbearing age
Sensitive for the diagnosis of obstruction
Can detect radiolucent stones missed on x-ray
May miss small stones and ureteral stones
Ultrasound
Abdominal X-ray
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will identify sufficiently large radiopaque stones
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calcium, struvite, and cystine stones
will miss radiolucent uric acid stones
may miss small stones or stones overlying bony
structures
will not detect obstruction
Other
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Intravenous Pyelogram (IVP)
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higher sensitivity and specificity than plain film for the
provides data about the degree of obstruction
previously the diagnostic procedure of choice, no longer
because of potential contrast rxn, lower sens, higher radiation
Magnetic resonance imaging
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rarely used during the management of stone disease, except
in the evaluation of pregnant patients, because this modality
is not optimal for identifying stones.
Acute Management
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Many pts with acute renal colic can be managed
conservatively with pain medication (NSAIDs &
Opiods) and hydration until the stone passes
If able to take oral medications and fluids can
manage at home
Hospitalization required for those who cannot
tolerate oral intake or who have uncontrollable
pain or fever
Acute Management
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Pts instructed to strain their urine for several
days and bring in any stone that passes for
analysis
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Data suggests faster stone passage tamsulosin
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will enable clinician to better plan preventive
therapy
CCB is other option
Pts are re-imaged if spontaneous passage has
not occurred.
Acute Management
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Urgent urologic consultation warranted in:
Urosepsis
 Acute renal failure
 Anuria
 Unyielding pain, nausea, or vomiting
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Acute Management
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Stone size major determinant of the likelihood
of spontaneous stone passage, although stone
location is also important
Most stones ≤4 mm in diameter pass spontaneously.
For stones larger than 4 mm in diameter, there is a
progressive decrease in the spontaneous passage
rate, which is unlikely with stones ≥10 mm in
diameter
 Proximal ureteral stones are also less likely to pass
spontaneously.
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Acute Management
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Referral to urology for potential intervention
stones larger than 10 mm in diameter
 significant discomfort
 significant obstruction or who have not passed the
stone after four to six weeks
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Urologic Options
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Shock wave lithotripsy (SWL)
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Ureteroscopic lithotripsy with electrohydraulic or laser
probes
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tx choice in 75% pts
works best for stones in renal pelvis and upper ureter
higher stone-free rates, but with an increased incidence of
complications over shock wave lithotripsy
Percutaneous nephrolithotomy
Laparoscopic stone removal
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Rarely needed
Kidney Stones - Epidemiology
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Renal stones (nephrolithiasis) are a relatively
common problem
In US, up to 12% of men and 5% of women
will have at least one symptomatic stone by the
age of 70
Clinical Presentations
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Classic Sx
Renal Colic
 Hematuria (gross or microscopic in majority if
symptoms but not all)
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Atypical Sx
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Vague abdominal pain, nausea, urinary urgency or
frequency, difficulty urinating, penile pain, or
testicular pain.
Asymptomatic
Renal Colic
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Varies from a mild and barely noticeable ache to
discomfort that is so intense that requires parenteral
analgesics
typically waxes and wanes in severity, and develops in
waves or paroxysms that are related to movement of
the stone in the ureter and associated ureteral spasm.
Paroxysms of severe pain usually last 20 to 60 minutes
Pain is thought to occur primarily from urinary
obstruction with distention of the renal capsule.
Stone Composition
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80% are Calcium Stones
Calcium Oxalate (majority)
 Calcium Phosphate (Hydroxapetite stones)
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Stone Composition
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Uric acid
Struvite (magnesium ammonium phosphate)
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Cystine stones
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only form in pts with chronic upper UTI d/t ureaseproducing organism: Proteus or Klebsiella
only develop in pts with cystinuria (an AR disorder) due to
the poor solubility of cystine in the urine
Mixed stone (eg, calcium oxalate and uric acid)
Other: indinavir, sulfadiazine, triamterene, acyclovir
stone
Risk Factors for Stones
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Historical
Anatomic
Dietary
Urinary
Historical Risk Factors
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Prior History of Kidney Stones
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Family History of kidney stones
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Twofold increase by Health professionals study
Individuals with enhanced enteric oxalate absorption
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50% recurrence in 10 yrs
gastric bypass procedures, bariatric surgery, short bowel
syndrome
Frequent upper urinary tract infections
Excessive physical exertion
Historical RF
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Medical conditions assoc w/ stones:
Primary Hyperparathyroidism, Sarcoidosis
 Gout, Obesity, DM (concentrated acidic urine)
 HTN
 RTA
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Use of medications that may crystallize urine
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Indinavir, acyclovir, sulfadiazine, triamterene
Anatomic RF
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Medullary sponge kidney
Horseshoe kidney
Medullary Sponge Kidney
Horseshoe Kidney
Dietary Risk Factors
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? Low or High ?
Calcium
 Fluids
 Oxalate
 Protein
 Salt
 Sucrose
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Dietary Risk Factors
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Low Calcium Intake
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Low fluid intake
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increases absorption & excretion of oxalate d/t less
complexing with calcium in the intestinal lumen
Higher concentration of lithogenic factors in urine
Low potassium
Low phytate
Dietary Risk Factors
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High oxalate intake
High animal protein intake
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High sodium intake
High sucrose intake
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leads to hypercalciuria, hyperuricosuria,
hypocitraturia, and inc urinary acid excretion
may increase calcium and/or oxalate excretion
High Vitamin C Intake
Urinary Risk Factors
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Low volume
Hypercalcuria
Hyperoxaluria
Hypocitraturia
Extremes of pH
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pH greater than 7.5 is compatible with infection pH less than
5.5 favours uric acid lithiasis.
Urine culture +ve urease-producing organism
(struvite)
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Proteus or Klebsiella
Work Up & Treatment
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Controversial whether evaluation and therapy
warranted or cost effective after the first stone
or only in patients with:
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Active stone disease
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formation of new stones, increase in size of old stones, or
the continued passage of gravel
Multiple stones at first presentation
 Pts with a strong family history of stones
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Approaches
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Limited Evaluation
Targeted Evaluation
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base the extent of evaluation upon an estimation of
the risk for new stone formation
Complete Evaluation
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approach should be followed only in individuals
willing to make dietary changes or to take medical
therapy if warranted by the work-up.
Complete Evaluation
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CBC, lytes, bicarbonate, urea, creatinine
Calcium, phosphorus, PTH, uric acid
Urinalysis for pH and crystals
24-hr urine: volume, calcium, uric acid, citrate, oxalate,
sodium, and creatinine
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At least two 24-hour urine collections
while pt maintains usual diet and physical activities
wait at least one to three months after a stone event
should not be performed if renal/ureteral obstruction or
urinary tract infection from existing calculi.
Treatment of Kidney Stones
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General treatment strategies for all stone
formers
Specific treatment strategy is based on:
stone composition if available (assume calcium if
not most of the time)
 findings from metabolic evaluation
 Patient dietary patterns
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General Treatment
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Increase fluid intake to target u/o > 2L per day
At 5 yrs, incidence of new stone formation 12% v
27%
 increases urine flow rate and lower urine solute
concentration
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Avoid high animal protein diet
Avoid high salt diet
Specific Tx – Calcium Stones
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If hyperoxaluria present, low oxalate diet should
be tried first
primary foods to avoid are spinach and nuts
 increasing dietary calcium or adding calcium
supplement with meals should be considered in
addition to a low oxalate diet if insufficient.
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Thiazide diuretic for refractory hypercalciuria
Potassium citrate for refractory hypocitraturia
Specific Tx – Uric Acid Stones
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If hyperuricosuria present, lifestyle modification
with the aim of reducing uric acid production
decreased purine intake
 weight loss should be implemented
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Allopurinol for refractory hyperuricosuria
Potassium citrate to alkalinize urine
Specific Treatment – Cystine Stones
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urinary alkalinization
drugs such as tiopronin
Specific Tx – Struvite Stones
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typically require complete stone removal with
percutaneous nephrolithotomy & aggressive
prevention and tx of future UTI’s
Monitoring
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Monitoring w/ US or plain film for new stone
formation
initially at one year
 if –ve then every 2-4 yrs based on risk recurrence
 not nearly as sensitive for identifying stones as CT,
but CT exposes pt to significant amt of radiation
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Asymptomatic Stone
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Balance risk of stone becoming asymptomatic vs.
morbidity assoc with therapy
Specific factors will dictate how to manage
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stone size and location
Active surveillance reasonable approach in
asymptomatic pts with
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small, non-infected calculi
no evidence of obstruction
not "at risk" for stone episodes (solitary kidney, urinary tract
reconstruction, immunosupression, etc)
What about overall diet?
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While one can modify diet after one discovers a
kidney stone is there any type of diet that
prevents kidney stones?
Any data available?
Dash Diet & Kidney Stones
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Dash-style Diet Associates with Reduced
Risk for Kidney Stones
Eric Taylor, Teresa Fung and Gary Curhan
 J am Soc Nephrology 20: 2253-2259, 2009
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Dietary Approaches to Stop Hyperstension
(DASH)
Dash Diet & Kidney Stones
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Examined relationship between DASH-style Diet and
incident kidney stones in
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Health Professionals Follow-up study (n-45,821 men; 18 yr
follow up)
Nurses’ Health Study (n= 101,837 women; 14 year follow up)
Goal to look at dietary pattern as opposed to individual
dietary factors
In many cases consuming less of one dietary factor to
decrease stone risk may lead to consumption of other
factors that increase risk
Dash Diet & Kidney Stones
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DASH score based on eight components
High intake of
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Fruits
Vegetables
Nuts and legumes
Low-fat dairy products
Whole grains
Low intake of
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Sodium
Sweetened beverages
Red and processed meats
Dash Diet & Kidney Stones
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Pts with higher DASH scores had
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higher intakes of calcium, potassium, magnesium, oxalate and
vitamin C
lower intakes of sodium
Participants in highest compared to lowest quintile of
DASH score had an adjusted relative risk of 0.55 in
men and 0.58-0.60 in women for kidney stones
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Robust despite adjustments & substantial differences in
individual dietary factors and risk between men and women
Dash Diet & Kidney Stones
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Study Conclusion
“consumption of DASH style diet is associated
with marked decrease in kidney stone risk”
(though limited as cohort study)
My conclusion:
I AM IN BIG TROUBLE !
Take Home Points
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Kidney Stones are fairly common
CT KUB is best test for diagnosis in acute
setting
Most acute renal colic tx conservatively
Focus on risk factors in work up to guide
investigations
Drink lots of fluids and eat healthy DASH style
diet