Nphro: Nphrolth Flashcards
Arrange the following from most common to leat
a. Calcium phosphate
b. Calcium Oxalate
c. Cystine
d. Uric acid
e. Calcium carbonate
f. Struvite
B. Calcium Oxalate A. Calcium Phosphate D. Uric Acid F. Struvite C. Cystine
E - not included
3 medications associated with stone formation
ATA
acyclovir, triamterene, atazanavir,
Conditions that predispose to stone formation (4)
Dā POGi
DM type 2 DRTA Primary hyperparathyroidism Obesity Gastrointestinal malabsorption
Medical conditions likely to be present in individuals with a history of nephrolithiasis
HGRC3 Hypertension Gout Reduced bone mineral density Cardiovascular disease Cholelithiasis Chronic kidney disease
True about nephrolithiasis
a. nephrolithiasis does not directly cause UTI
b. UTI in the setting of an obstructing stone is a medical emergency
c. both
d. neither
C
This is the point at which the concentration product exceeds the solubility product.
Supersaturation
Even though the urine in most individuals is supersaturated with respect to one or more types of crystals, why is it that people do not continuously form stones?
the presence of inhibitors of crystallization prevents the majority of the population from continuously forming stones
Most clinically important inhibitor of calcium-containing stones is
urine citrate
T/F calculated supersaturation predict stone formation
F; it does not perfectly predict stone formation
calcium oxalate stones grow on calcium phosphate at the tip of the renal papilla. This is called
Randallās Plaque
3 categories of risk factors for nephrolithiasis
DUN
dietary
urinary
non-deietary
Dietary factors that are associated with increased risk of nephrolithiasis include
FOSSA fructose oxalate sodium sucrose animal protein
Dietary factors associated with lower risk of stone formation
CPP
calcium
potassium
phytate
True about effect of dietary calcium in stone formation
a. Higher dietary calcium intake is related to a lower risk of stone formation
b. Low calcium intake is advised for stone formers
c. Supplemental calcium lower the risk for stone formation
d. NOTA
A
High dietary but not supplemental calcium lower the risk of stone formation.
What is the reason behind risk reduction with higher calcium intake?
reduction in intestinal absorption of dietary oxalate that results in lower urine oxalate
Why is low calcium intake contraindicated in stone formers (2) ?
Increases the risk of stone formation and may contribute to lower bone density
Urinary oxalate is derived from
a. endogenous production
b. absorption of dietary oxalate
c. both
d. neither
C
Strong risk factor for stone formation
a. dietary oxalate
b. urinary oxalate
c. both
d. neither
B; dietary oxalate is only a weak risk factor for stone formation
Higher dietary intake of animal protein may lead to
a. increased excretion of calcium and uric acid
b. Decreased urinary excretion of citrate
c. both
d. neither
C
True about diet and stone formation EXCEPT
a. animal protein increase risk of stone formation
b. higher sodium and sucrose intake increases calcium excretion dependent of calcium intake
c. potassium-rich foods increase urinary citrate excretion due to their alkali content.
d. Magnesium and phytate decrease risk for stone formation
B; independent of calcium intake
The following increase risk for stone formation EXCEPT
a. Vitamin C supplements
b. Vitamin B6
c. sugary-sweetened beverage
d. coffee
D; although supplemental vit B6 may be beneficial in selected patients with type 1 primary hyperoxaluria, the risk is not reduced in other patients, therefore D. Coffee is the best answer.
The risk of stone formation ______ as urine volume decreases
a. increase
b. decrease
A
urine output which more than doubles the risk of stone formation
<1L/d
What is the main determinant of urine volume
Fluid intake
Risk of stoone disease is highest in
a. middle-aged white men
b. middle-aged black men
c. women of reproductive age
d. menopausal women
A
Effect of weight gain on risk of stone formation
increase
True about urinary risk factors for stone formation EXCEPT
a. hypercalciuria increases likelihood of calcium phosphate and calcium oxalate stones
b. there is no widely accepted cutoff that distinguishes between normal and abnormal urine calcium excretion
c. Levels of urine excretion is higher in individuals with a history of nephrolithiasis
d. Primary renal calcium loss is a common cause of hypercalciuria
D; rare
Effect of higher urine oxalate excretion on calcium stone formation
increase
Effect of higher dietary calcium intake on oxalate
decrease GI oxalate absorption
True about urine Citrate
a. natural inhibitor of calcium-containing stones.
b. higher urine citrate excretion increases the risk for calcium oxalate stones
c. Citrate reabsorption is influenced by intracellular pH of distal tubular cells
d. Metabolic alkalosis will lead to a reduction in citrate excretion
A.
lower urine citrate excretion increases risk for claclium oxalate stone
citrate reabsorption is influenced by intracellular pH of proximal tubular cells
metabolic acidosis will lead to a reduction citrate excretion
True about urine uric acid
a. higher urine levels of uric acid is a risk factor for uric acid stone formation
b. excess purine consumption increase uric acid stone formation
c. urine uric acid does not appear to be associated with the risk of calcium oxalate stone formation
d. AOTA
e. NOTA
D
True about urine pH
a. Uric acid stones form when pH is >=5.5
b. Calcium phosphate stones are more likely to form when urine pH is <=6.5
c. Cystine is more soluble at lower urine pH
d. Calcium oxalate stones are not influenced by urine pH
D
Uric acid stones: <=5.5
Calcium phosphate stones: >=6.5
Cystine is more sooluble at higher urine pH
risk of nephrolithiasis is more than ___ greater in individuals with a family history of stone disease.
a. 1.5x
b. 2x
c. 2.5x
d. 3x
B
Two most common and well-characterized rare monogenic disorders that lead to stone formation are
primary hyperoxaluria
Cystinuria
Two common presentations for individuals with an acute stone event
renal colic
painless gross hematuria
True about clinical manifestation of nephrolithiasis
a. renal colic does not subside completely and may vary in intensity
b. when a stone moves into the ureter, discomfort often begins with sudden onset unilateral flank pain.
c. Intensity of pan can increase rapidly and there are no alleviating factors
d. pain is not accompanied by nausea/vomiting
All Except D
pain in the ipsilateral labium, where is the stone?
distal ureter
These symptoms will be felt when stone is at the ureterovesical junction
urinary urgency and frequency
Management for UTI in the setting of ureteral obstruction
Immediate restoration and drainage by placement of either a ureteral stent or a percutaneous nephrostomy tube
True about Diagnosis of Nephrolithiasis
a. Serum Chemistry findings are normal
b. urine sediment will usually reveal RBC and WBC, crsytals
c. absence of hematuria excludes a stone
d. diagnosis is often made on basis of history, PE, and urinalysis
AOTA
T/F Nephrolithiasis: it is not necessary to wait for radiographic confirmation of nephrolithiasis before treating the symptoms
T
Confirmation of diagnosis is made via
appropriate imaging study preferably helical CT
Helical CT detects stones as small as __
1mm
Limitations of abdominal ultrasound in evaluation of nephrolithiasis
not as sensitive as CT
images only the kidney and possibly proximal segment of ureter
most ureteral stones are not detectable by ultrasound
Advantage of using NSAIDS such as ketorolac instead of opioids
As effective, but less side effects
What is the goal in management of nephrolithiasis in terms of volume status
euvolemia
Use of this medication may increase rate of spontaneous stone passage
alpha blocker
Uroligic intervention should be postponed unless (3)
evidence of UTI
low probability of spontaneous stone passage
intractable pain
size of stone thatās less likely to be spontaneously passed
stone measuring >=6mm
Procedure with highest likelihood of rendering patient stone-free in upper-tract stones
percutaneous nephrolithotomy
Percentage of first-time stone formersthat will have a recurrence within 10 years
50%
example of high oxalate foods
spinach
rhubarb
potatoes
fluid intake
Corenerstone of laboratory evaluation in nephrolithiasis, which therapeutic recommendations are based
24-hour urine collection
T/F lifestyle modification should be deferred until urine collection is complete
T
Ideally, how many times should 24-hour urine collection done before commiting a patient to long-term lifestyle changes or medication?
Two
Is calcium loading or restriction recommended in the evaluation of nephrolithiasis?
No. it does not influence clinical recommendations
T/F stone type cannot be determined with certainty from a 24- h urine collection
T; therefore patients are encouraged to retrieve passed stones
What type of stones can be identified by low Hounsfield units on CT?
Uric acid stones
Gold standard for imaging of stones
helical CT without contrast
Minimum amount of urine for prevention of new stone formation
2L/d
Risk factors for calcium oxalate stones (3)
higher urine calcium
higher urine oxalate
lower urine citrate
Which stone type is insensitive to urine pH?
Calcium oxalate stones
Diuretic give in doses higher than those used to treat hypertension leading to lower urine calcium excretion
thiazide diuretic
When giving thiazide diuretics to lower urine calcium excretion, what dietary change should be done?
Dietary sodium restriction; it is essential to obtain reduced urine calcium excretion while minimizing urinary potassium loss
True about bisphosphonates
a. reduce urine calcium excretion
b. reduce stone formation
c. both
d. neither
A
2 ways to reduce absorption of exogenous oxalate
- avoid foods that contain high amounts of oxalate
2. reduce absorption by high calcium intake
Effect of increased consumption of foods rich in alkali e.g. fruits and vegeatbles
increase urine citrate thus inhibit calcium oxalate and calcium phosphate stone formation
effect of urine pH on calcium oxalate stone formation
none
The following dietary changes are recommended in preventing calcium oxalate stones
a. restriction of nondiary animal protein
b. reduce sodium intake to <2.5g/d
c. minimize sucrose and fructose intake
d. AOTA
D
Type of stone more common in patients with distal renal tubular acidosis and primary hyperparathyroidism
Calcium phosphate
Two main risk factors for uric acid stones
- persistently low urine pH
2. higher uric acid excretion
Thiazide diuretics with sodium restriction may be used to reduce urine calcium for prevention of
a. calcium oxalate stones
b. calcium phosphate stones
c. both
d. neither
C
Increased risk of calcium phosphate stones with what pH of urine?
> =6.5
Alkali supplements helpful in
a. calcium oxalate stones
b. calcium phosphate stones
c. both
d. neither
C; but careful monitor pH in calcium phosphate stones
predominant influence on uric acid solubility
urine pH
mainstay of prevention of uric acid stone formation
increase urine pH
3 ways to alkalinize urine
- increase intake of foods rich in alkali
- reduce intake of foods that produce acid
- supplementation with bicarbonate or citrate salts
recommended urine pH goal throught day and night to prevent uric acid stones
6.5
How to prevent uric acid stones if alkalinization of urine is not successful and if dietary modificationns do not reduce urine uric acid sufficiently
Xanthine oxidase inhibitor
febuxostat
allopurinol
what class of drugs are they?
Xanthine oxidase inhibitor
Xanthine oxidase inhibitor reduce urine uric acid secretion by
40-50%
The following dietary changes are recommended in preventing calcium oxalate stones
a. restriction of nondiary animal protein
b. reduce sodium intake to <2.5g/d
c. minimize sucrose and fructose intake
d. AOTA
D
Type of stone more common in patients with distal renal tubular acidosis and primary hyperparathyroidism
Calcium phosphate
Two main risk factors for uric acid stones
- persistently low urine pH
2. higher uric acid excretion
Thiazide diuretics with sodium restriction may be used to reduce urine calcium for prevention of
a. calcium oxalate stones
b. calcium phosphate stones
c. both
d. neither
C
Increased risk of calcium phosphate stones with what pH of urine?
> =6.5
Alkali supplements helpful in
a. calcium oxalate stones
b. calcium phosphate stones
c. both
d. neither
C; but careful monitor pH in calcium phosphate stones
predominant influence on uric acid solubility
urine pH
mainstay of prevention of uric acid stone formation
increase urine pH
3 ways to alkalinize urine
- increase intake of foods rich in alkali
- reduce intake of foods that produce acid
- supplementation with bicarbonate or citrate salts
recommended urine pH goal throught day and night to prevent uric acid stones
6.5
How to prevent uric acid stones if alkalinization of urine is not successful and if dietary modificationns do not reduce urine uric acid sufficiently
Xanthine oxidase inhibitor
febuxostat
allopurinol
what class of drugs are they?
Xanthine oxidase inhibitor
Xanthine oxidase inhibitor reduce urine uric acid secretion by
40-50%
