Stones Flashcards
1
Q
2 basic ways ESWL breaks stones
A
- cavitation and 2. direct stress (comprssive and shear)
2
Q
at what point does cavitation have its effect
A
negative portion of pressure wave
3
Q
at what point does direct stress have its effect
A
positive portion of pressure wave
4
Q
cavitation in eswl and tissue injury
A
formation of microbubbles in renal tissue parenchyma/blood vessels proposed as mediator of ESWL induced tissue injury
5
Q
absolute contraindications to ESWL - 5
A
pregnancy, coagulopathy, distal obstruction, calcified renal artery aneurism, untreated UTI
6
Q
if cant correct coagulopathy/ stop antiplatelet - stone tx of choice
A
URS
7
Q
what is max skin to stone distance and where is this applicable
A
< 10 cm on axial CT as MEAN distance at 0,45,90 deg in obese people
8
Q
BMI and ESWL
A
BMI is independent predictor of ESWL failure
9
Q
SFR for 2 cm stone with ESWL
A
20%
10
Q
stone hounsefield and ESWL success
A
> 1000 = inferior SFR rate
11
Q
stone types that dont work in ESWL
A
CaOx monohydrate, cystine, brushite
12
Q
infundibulopelvic angle and ESWL
A
> 70 is good
13
Q
infundibular width and ESWL
A
< 5 mm is good
14
Q
infundibular length and ESWL
A
> 3 cm is good
15
Q
ESWL machine with higher perinephric hematoma rate
A
SLX-F2 (3%)
16
Q
RF’s for bleeding - 4
A
DM, HTN, obesity, coagulopathy
17
Q
mechanical percussion and inversion
A
helps in SFR after ESWL
18
Q
alpha blockers after ESWL
A
helps in SFR after ESWL, and pain
19
Q
when to place stent prior to ESWL - 2
A
large stone burden with steinstrasse risk, high grade obstruction
20
Q
ideal shock wave rate
A
60/min= higher stone clearance/reduce retreatment
21
Q
stricture rate for URS
A
2%
22
Q
ureteral perforation rate for urs
A
5%
23
Q
why get renal access to calyx end-on vs side-on
A
end on have lower risk of hitting interlobular arteries which cross infundibula
24
Q
4 indications for PCNL other than stone > 2 cm
A
lower pole stone > 1 cm, cystine stone, pts who must be stone free (pilots), anatomic abnormalities
25
location of ideal calyx for PCNL access
upper pole calyx eventhough there is risk of pulm complications
26
absolute indications for tube after pcnl besides stones - 5
significant collecting system inj, excessive hemorrhage, multiple tracts, pyonephrosis
27
hydrothorax rate for PCNL
2%
28
prone considerations in anesthesia for obese pts - 2
reduced total lung capacity and FRC w abd compression, IVC compression with reduced preload and impaired oxygenation
29
ways to overcome anesthesia considerations for obese patients - 3
1. lateral decubitus and supine positioning, 2. awake endotracheal intubation and self positioning, 3. PCNL under local anesthesia and sedation.
30
indications for PCNL - 7
> 2 cm stone, staghorn, lower pole > 1 cm, cystine stone, pts who must be stone free (pilots), failure of other treatments, assd anatomical abnormalites
31
3 differences in pcnl outcome in obese patients
1. longer operative time, 2. decreased SFR, 3. significantly higher retreatment rate
32
problem with stent/nephrostomy during pregnancy
increased # procedures due to encrustation and pain
33
ureteroscopy in obese patients
equal outcome to non-obese
34
imaging for stones in pregant females
can do ultra low does ct - not associated with fetal or maternal harm
35
stone passage and location at dx
20% @ prox ureter, 70% @ diatal ureter
36
who gets expectant mgmt of stone
< 10 mm and well controlled sx + periodic evaluation + medical therapy
37
2 medical adjuncts
CCB (65% passage) and alpha blockers (55% passage)
38
why alpha blocker
less side effects vs ccb
39
how meds work in stones
stops ureteral spasm
40
"indication" to ESWL
uncomplicated < 2 cm
41
contraindications - 6
1. bleeding problm, 2. preg, 3. aneurism (aortic > 5 cm, renal > 2 cm), 4. untx UTI, 5. obstruction distal to stone, 6. inability to visualize stone
42
4 effects of ESWL on stone
1. spall, 2. cavitation, 3. squeezing aka sheer stress, 4. superfocusing
43
what is squeezing/ sheer stress?
shock wave passes through stone faster than water resulting in acoustic mismatch and squeezing effect on surface
44
what is superfocusing
as shock wave moves through stone (moves faster) wake of pressure forms behind shock wave and focus in mid stone.
45
what is spall
Some energy is internally reflected into stone
46
what is cavitation
negative pressure of shock wave creates cavitation bubble
47
4 factors affecting ESWL outcome
1. body habitus, 2. stone size, 3. stone location, 4. stone composition
48
ideal skin to stone distance
< 10 cm ideal, >12 cm is bad
49
how to determine skin to stone distance
PICTURE p.406
50
stone free rate for 1, 1.5, 2 cm stone
80%, 72%, 60%
51
J urol 2001, albala and woods - ESWL vs PCNL for lower pole stones
SWL 35%, PCNL 95% stone free
52
stone density and ESWL success
hounsfield units suggest stone fragility - HU < 500 = 100% success, > 1000 = 50% success
53
SWL attributes affecting stone fragmentation
acoustic output and focal volume
54
focal zone vs focal point
focal point - acoustic energy focused to a point in space. Focal zone - zone of high pressure (50% focal point) around focal point. The latter varies by lithotriptors
55
2 biggest effects on stone breakage
acoustic mismatch causing sheer stress and cavitation - both happen on SURFACE of stone
56
effect of focal zone size on stone breakage
focal zone should include stone surface to expose stone to cavitation/sheer stress
57
stone motion and focal zone
larger focal zone keeps stone exposed to shock wave during motion (breathing)
58
4 physician controlled variables in SWL
1. coupling, 2. rate, 3. anesthesia, 4. power
59
what is coupling
joining pt to lithotriptor via medium (water bath, or jel)
60
potential effect of coupling
air pockets can form at junction btw pt and coupler - more bubbles = poorer effect. 8% coverage by air pockets = 60% decrease breakage
61
anesthesia effect on stone free rate
GETA 90% stone free, sedation 55%
62
power effect on stone
shocks cause hematoma on kidney. pre-treatment with low energy shock waves can have protective effect on kidney - vasoconstrictive effect on kidney
63
complications of SWL
hematoma, ureteral obstruction, delayed issues (DM/HTN)
64
effect of SWL on HTN
dose dependent, and older ppl more suceptible
65
indications for URS
unfavorable for SWL (HU >1000, lower pole), bleeding diathesis
66
holmium stone breakage MOA
photothermal
67
1 year recurrence rate after 1st stone
10-15%
68
5 year recurrence rate after 1st stone
50-60%
69
10 year recurrence rate after 1st stone
70-80%
70
Initial work-up for new stone former
```
Dietary History (fluids, meat, calcium)
Medical History (DM, gout, obesity, bowel surgery, RTA, parathyroid)
BMP
UA
Urine Culture
```
71
What medications increase stone risk?
```
Topiramate
Zonisamide
Acetazolamide
Triamterene
Probenecid
Protease Inhibitors (-navir)
Vitamin C
```
72
If serum calcium is high, next lab?
PTH
73
#1 risk factor for uric acid stones
low urine pH
74
#1 risk factor for struvite stones
recurrent UTIs
75
Radiolucent stones
uric acid & cystine
76
Indications for 24hr urine
Interested 1st time stone formers
| Recurrent stone formers
77
Initial dietary recommendations for ALL stone formers
```
>2.5L fluid intake daily
Na & oxalate restriction
Normal calcium intake (1000-1200mg/day)
Decrease animal protein
Increase citrus intake
```
78
Increased sodium intake leads to _____ in urinary calcium excretion
increase
79
Excess urinary ____ blocks hypocalciuric action of thiazies
sodium
80
Consumption of ____ enhances GI binding of Oxalate and decreased oxaluria
calcium
81
Clinicians should counsel patients with CaOx stones & hyperoxaluria to limit ____ rich food intake and maintain normal ___ consumption
limit oxalate rich foods
| normal calcium consumptions
82
Congenital, primary hyperoxaluria is due to a ____ deficiency. Only treatment option is ____
hepatic enzyme (alanine aminotransferase)
renal & liver transplant
83
Enteric hyperoxaluria is due to ____ malabsorption leading to limited calcium to bind to oxalate
fat
84
Clinicians should encourage patients with Calcium stones & hypocitraturia to increase intake of ____ & limit intake of ____
increase fruits & veggies
| limit animal protein
85
1st line therapy for hypercalciuria and recurrent stones
Thiazide diuretics
86
Thiazide diuretics work at the _____ to promote calcium resorption
Distal renal tubule
20% RR in stone formation
87
Side effects of thiazides
Hypokalemia
Hypocitraturia
High urine uric acid
88
Supplement thiazides with ___ to overcome hypokalemia
Potassium Citrate 40-60 mEq daily
89
1st line therapy for low urinary citrate and recurrent calcium stones
Potassium citrate
- alkalizes urine
- promotes citrate excretion
90
Citrate reduces stone formation by inhibiting ____
crystallization of calcium salts
91
RTA - low ___ levels in serum and low ___ levels in urine
Hypokalemia
| Hypocitraturia
92
Young female with calcium phosphate stones, nephrocalcinosis, urine pH >6.5, hypocitraturia, hypokalemia
Distal RTA
93
35 yo M with calcium oxalate stones, acidic urine, hypocalciruia, and hypocitraturia, and prior bowel surgery
Enteric hyperoxaluria
94
Contraindications to K Citrate
Hyperkalemia
Active gastric ulcer
Cr > 2.5
95
Cheaper alternative to K Citrate
Na Bicarbonate
96
Urine pH in uric acid stone formers
pH < 5.5
97
Obese patients have an independent increased risk of ___ stones
Uric acide
98
Offer ____ to patients with uric acid or cystine stones to raise urinary pH
K Citrate
99
To dissolve cystine stones, urine pH must be above ____
pH 7.5
100
Pharmaceutical therapy for struvite stones
Acetohydroxamuc acid (Lithostat)
101
Before PCNL, one must obtain ____
PCNL
102
ESWL contraindicated with skin to stone distance >___cm
10 cm
103
Alpha-blockers can be offered for patients with ureteral stones
10mm
104
Treatment for enteric hyperoxaluria
Oral Calcium & Mg
105
How to address thiazide-induced hypocitraturia?
Add potassium citrate
106
Contraindications to Potassium Citrate
____ Potassium
Active ____ disease
Cr > ____
High K
Active peptic ulcer disease
Cr >2
107
Uric Acid stones
pH < ____
pH < 5.5
108
UA with cystinuria - ____ Crystals
Hexagonal
109
Cystine stones rapidly dissolve at pH > ___
pH > 7.5
110
Urease producing bacteria
SHP
Staph Aureus
Hemophilus Influenza
Proteus
111
Obtain a repeat 24 hour after ____ of initiating pharmaceutical treatment
6 months
112
Optimal imaging prior to PCNL is a ____
CT A/P non-contrast
113
ESWL parameters
Hounsfield units < ____
Skin to stone distance
<1000 HU
<10 cm
114
If hydronephrosis or cortical thinning is seen on imaging, obtain ____ lab test
Cr, BUN, electrolytes aka BMP
115
____ should be offered after 1 month trial of MET or suspicious of stone passage
Repeat imaging (KUB, RBUS, or CT)
116
SWL has the ____ complication rate, but the ____ stone free rate
lowest..... worst
117
1st line treatment for mid & distal ureteral stones - ____
URS
118
Only proven therapy to reduce stent discomfort is ____
alpha-blocker
119
Only proven therapy to reduce stent discomfort is ____
alpha-blocker
120
In Symptomatic Patients With A Total Renal Stone Burden >20 mm, Clinicians Should Offer____ As First- line Therapy
PCNL
121
May Offer ___ or ____ to Patients With Symptomatic <10 mm Lower Pole Renal Stones
ESWL or URS
122
Pts With Lower Pole Stones >10 Mm Should Be Informed That ____ Has A Higher Stone-free Rate But Greater Morbidity
PCNL
123
____ should Not Be Offered As First-line Therapy To Pts With >10mm Lower Pole Stones
ESWL
124
In the absence of a UTI, SWL does not require ____
peri-op antibiotics
125
Prescribe ____ to facilitate stone passage after ESWL
alpha-blockers
126
If ESWL fails, next therapy should be ____
URS
127
____ is 1st line in patients on anti-platelet or anti-coag
URS
128
Vignette: A 45-year-old man presents with recurrent kidney stones. On further evaluation, you suspect primary hyperparathyroidism as the underlying cause.
Options:
A) 2–5%
B) 3–5%
C) 10–40%
D) 20–40%
Correct Answer: B) 3–5%
Explanation:
A) 2–5%: Incorrect, the prevalence of Resorptive hypercalciuria due to primary hyperparathyroidism is 3–5%.
B) 3–5%: Correct, Resorptive hypercalciuria, often linked to primary hyperparathyroidism, has a prevalence of 3–5%.
C) 10–40%: Incorrect, this prevalence rate is for Hyperuricosuric calcium nephrolithiasis and Hypocitraturic calcium nephrolithiasis.
D) 20–40%: Incorrect, this prevalence rate corresponds to Absorptive hypercalciuria.
Memory Tool: Think "Resorp-three-five" to remember the prevalence of Resorptive hypercalciuria.
Reference Citation: Modified from Pearle MS, Pak CY, in "International yearbook of nephrology," 1996, Table 91.2, paragraph 1.
Rationale: Knowing the prevalence of different types can help guide diagnostic evaluations.
129
Topic: Metabolic/Environmental defect causing Renal Hypercalciuria
Vignette: A 37-year-old woman experiences her third episode of renal stones within a year. A metabolic evaluation indicates impaired renal calcium reabsorption.
Options:
A) Absorptive hypercalciuria
B) Renal hypercalciuria
C) Renal phosphate leak
D) Hyperuricosuric calcium nephrolithiasis
Correct Answer: B) Renal hypercalciuria
Explanation:
A) Absorptive hypercalciuria: Incorrect, this condition is due to increased gastrointestinal calcium absorption.
B) Renal hypercalciuria: Correct, impaired renal calcium reabsorption leads to Renal hypercalciuria.
C) Renal phosphate leak: Incorrect, this is characterized by impaired renal phosphorus absorption.
D) Hyperuricosuric calcium nephrolithiasis: Incorrect, this is due to dietary purine excess or uric acid overproduction.
Memory Tool: "Hyper-calciu-‘Renal’-ya" to remember that renal calcium problems relate to Renal hypercalciuria.
Reference Citation: Modified from Pearle MS, Pak CY, in "International yearbook of nephrology," 1996, Table 91.2, paragraph 1.
Rationale: Understanding the metabolic cause can inform targeted treatment.
130
Topic: Prevalence of Cystinuria in Nephrolithiasis
Vignette: A 24-year-old man presents with painful renal colic. You diagnose him with Cystinuria.
Options:
A) <1%
B) 5–10%
C) 15–30%
D) 20–40%
Correct Answer: A) <1%
Explanation:
A) <1%: Correct, Cystinuria is a rare cause of nephrolithiasis, with a prevalence of less than 1%.
B) 5–10%: Incorrect, this prevalence range is for Hypomagnesiuric calcium nephrolithiasis.
C) 15–30%: Incorrect, this corresponds to Idiopathic low urine pH.
D) 20–40%: Incorrect, this is the prevalence of Absorptive hypercalciuria.
Memory Tool: Think "Cysti-nu-ria, <1 rare-ia" to remember its rarity.
Reference Citation: Modified from Pearle MS, Pak CY, in "International yearbook of nephrology," 1996, Table 91.2, paragraph 1.
Rationale: Recognizing rare causes is crucial for an accurate diagnosis.
131
opic: Prevalence of Hypomagnesiuric Calcium Nephrolithiasis
Vignette: A 52-year-old woman is experiencing repeated bouts of kidney stones. Her lab results show decreased intestinal magnesium absorption.
Options:
A) 2–15%
B) 3–5%
C) 5–10%
D) 10–50%
Correct Answer: C) 5–10%
Explanation:
A) 2–15%: Incorrect, this is the prevalence range for Hyperoxaluric calcium nephrolithiasis.
B) 3–5%: Incorrect, this corresponds to Resorptive hypercalciuria.
C) 5–10%: Correct, the prevalence of Hypomagnesiuric calcium nephrolithiasis is 5–10%.
D) 10–50%: Incorrect, this prevalence range is for Hypocitraturic calcium nephrolithiasis and Low urine volume.
Memory Tool: Think of "Hypo-magnesiuric, mag-5-10" for easy recall.
Reference Citation: Modified from Pearle MS, Pak CY, in "International yearbook of nephrology," 1996, Table 91.2, paragraph 1.
Rationale: Knowing the prevalence of a condition aids in diagnosis and management.
132
Topic: Metabolic/Environmental defect causing Hyperuricosuric Calcium Nephrolithiasis
Vignette: A 60-year-old male has been diagnosed with Hyperuricosuric calcium nephrolithiasis. He is a known meat lover.
Options:
A) Oxalate overproduction
B) Dietary purine excess
C) Impaired renal phosphorus absorption
D) Gastrointestinal alkali loss
Correct Answer: B) Dietary purine excess
Explanation:
A) Oxalate overproduction: Incorrect, this corresponds to Primary hyperoxaluria.
B) Dietary purine excess: Correct, Hyperuricosuric calcium nephrolithiasis often occurs due to dietary purine excess or uric acid overproduction.
C) Impaired renal phosphorus absorption: Incorrect, this leads to Renal phosphate leak.
D) Gastrointestinal alkali loss: Incorrect, this is related to Chronic diarrheal syndrome in Hypocitraturic calcium nephrolithiasis.
Memory Tool: Remember "Hyper-‘uric’-osuric = excess purine" to keep the link in mind.
Reference Citation: Modified from Pearle MS, Pak CY, in "International yearbook of nephrology," 1996, Table 91.2, paragraph 1.
Rationale: Dietary modification may be key in treating this form of nephrolithiasis.
133
opic: Prevalence of Low Urine Volume as a Cause of Nephrolithiasis
Vignette: A 38-year-old woman presents with kidney stones. She confesses to consuming very little water daily.
Options:
A) <1%
B) 5–10%
C) 10–50%
D) 15–30%
orrect Answer: C) 10–50%
Explanation:
A) <1%: Incorrect, this is the prevalence of Cystinuria.
B) 5–10%: Incorrect, this corresponds to Hypomagnesiuric calcium nephrolithiasis.
C) 10–50%: Correct, low urine volume due to inadequate fluid intake can cause nephrolithiasis in 10–50% of cases.
D) 15–30%: Incorrect, this is the prevalence for Idiopathic low urine pH.
Memory Tool: "Low urine? High chance! 10–50%" to remember the prevalence range.
Reference Citation: Modified from Pearle MS, Pak CY, in "International yearbook of nephrology," 1996, Table 91.2, paragraph 1.
Rationale: Emphasizing hydration may prevent future episodes.
134
Question 1: A patient is found to have struvite stones and you suspect the presence of a urease-producing bacteria. Which of the following gram-negative bacteria is most likely (>90% of isolates) to produce urease?
Options:
A. Haemophilus influenzae
B. Proteus mirabilis
C. Pseudomonas aeruginosa
D. Klebsiella pneumoniae
Correct Answer:
B. Proteus mirabilis
Explanation:
A. Haemophilus influenzae: Occasional urease-producer (5%-30% of isolates).
B. Proteus mirabilis: Usually produces urease (>90% of isolates).
C. Pseudomonas aeruginosa: Occasional urease-producer (5%-30% of isolates).
D. Klebsiella pneumoniae: Occasional urease-producer (5%-30% of isolates).
Memory Tool:
Remember the phrase "Proteus Mira-Bliss" to recall that Proteus mirabilis is blissfully (>90%) urease-positive.
Reference Citation:
Gleeson MJ, Griffith DP: Infection stones. In Resnick MI, Pak CYC, editors: Urolithiasis: a medical and surgical reference, Philadelphia, 1990, Saunders, p 115. (Table 91.3)
Rationale:
Knowing the urease-producing capacity of bacteria is essential for accurate diagnosis and treatment of struvite stones.
135
Question 2: Which gram-positive organism is LEAST likely to produce urease based on the given table?
Options:
A. Corynebacterium ulcerans
B. Bacillus species
C. Peptococcus asaccharolyticus
D. Staphylococcus aureus
Correct Answer:
D. Staphylococcus aureus
Explanation:
A. Corynebacterium ulcerans: Listed as a urease-producer.
B. Bacillus species: Listed as a urease-producer.
C. Peptococcus asaccharolyticus: Listed as a urease-producer.
D. Staphylococcus aureus: Listed as a urease-producer, but unlike the others, it is well-known to produce urease occasionally rather than usually.
Memory Tool:
Remember "Staph Aure-LEAST" to remember that Staphylococcus aureus is least likely among the options to produce urease.
Reference Citation:
Gleeson MJ, Griffith DP: Infection stones. In Resnick MI, Pak CYC, editors: Urolithiasis: a medical and surgical reference, Philadelphia, 1990, Saunders, p 115. (Table 91.3)
Rationale:
Identifying organisms least likely to produce urease can help in differential diagnosis and in directing antibiotic therapy.
136
Question 3: A patient presents with suspected infection stones, and Mycoplasma is being considered as a causative agent. Which Mycoplasma species should be suspected as a urease-producer?
Options:
A. T-strain Mycoplasma
B. Mycoplasma genitalium
C. Ureaplasma urealyticum
D. Mycoplasma pneumoniae
Correct Answer:
C. Ureaplasma urealyticum
Explanation:
A. T-strain Mycoplasma: Listed as a urease-producer, but it's not typically associated with urological issues.
B. Mycoplasma genitalium: Not listed in the table.
C. Ureaplasma urealyticum: Specifically listed as a Mycoplasma species that usually produces urease.
D. Mycoplasma pneumoniae: Not listed in the table.
Memory Tool:
"Urea-plasma, Urea-lytic!"—Ureaplasma urealyticum is the Mycoplasma species concerned with urea breakdown.
Reference Citation:
Gleeson MJ, Griffith DP: Infection stones. In Resnick MI, Pak CYC, editors: Urolithiasis: a medical and surgical reference, Philadelphia, 1990, Saunders, p 115. (Table 91.3)
Rationale:
Differentiating between Mycoplasma species is vital for accurate diagnosis and treatment of infection stones.
137
uestion 4: You suspect an infection stone caused by yeast in a patient. Which of the following yeasts is NOT listed as a urease-producer?
Options:
A. Cryptococcus
B. Candida albicans
C. Rhodotorula
D. Sporobolomyces
orrect Answer:
B. Candida albicans
Explanation:
A. Cryptococcus: Listed as a urease-producing yeast.
B. Candida albicans: Not listed as a urease-producer in the table; Candida humicola is listed instead.
C. Rhodotorula: Listed as a urease-producing yeast.
D. Sporobolomyces: Listed as a urease-producing yeast.
Memory Tool:
Remember "Candida Albi-GONE" to help remember that Candida albicans is gone from the list of urease-producers.
Reference Citation:
Gleeson MJ, Griffith DP: Infection stones. In Resnick MI, Pak CYC, editors: Urolithiasis: a medical and surgical reference, Philadelphia, 1990, Saunders, p 115. (Table 91.3)
Rationale:
Knowing which yeasts don't produce urease could guide treatment choices and further diagnostics.
138
Clinical Vignette:
You are consulting for a patient who reports having sharp, intermittent pain in the lower abdomen. Upon microscopic examination of a collected urinary calculus, you observe an "envelope, tetrahedral" appearance.
Multiple-Choice Options:
A) Calcium oxalate monohydrate
B) Calcium oxalate dihydrate
C) Calcium phosphate-apatite
D) Uric acid
Correct Answer:
B) Calcium oxalate dihydrate
In-Depth Explanation:
A) Calcium oxalate monohydrate: Incorrect. This type of urinary calculus usually has an "hourglass" appearance under the microscope.
B) Calcium oxalate dihydrate: Correct. The "envelope, tetrahedral" microscopic appearance is characteristic of calcium oxalate dihydrate crystals.
C) Calcium phosphate-apatite: Incorrect. This typically appears "amorphous" under microscopic examination.
D) Uric acid: Incorrect. These crystals usually appear as "amorphous shards, plates" microscopically.
139
Clinical Vignette:
A patient has chronic kidney issues and upon examination, you observe urinary calculi with a needle-shaped appearance.
Multiple-Choice Options:
A) Brushite
B) Cystine
C) Magnesium ammonium phosphate (struvite)
D) Uric acid
Correct Answer:
A) Brushite
In-Depth Explanation:
A) Brushite: Correct. The "needle-shaped" appearance is characteristic of Brushite calculi.
B) Cystine: Incorrect. Cystine calculi would have a "hexagonal" appearance.
C) Magnesium ammonium phosphate (struvite): Incorrect. These typically appear as "rectangular, coffin-lid" shapes.
D) Uric acid: Incorrect. Uric acid crystals appear as "amorphous shards, plates."
Memory Tool:
"Brushite is like a needle in a haystack" can help you remember the needle-shaped appearance of Brushite.
Reference Citation:
Table 92.2: Microscopic Appearance of Common Urinary Calculi
Rationale for Question Importance:
Recognizing the microscopic appearance of various calculi allows for better treatment planning, especially for patients with chronic kidney issues.
140
Clinical Vignette:
A young patient presents with a history of recurrent urinary tract stones. A microscopic evaluation reveals a hexagonal-shaped urinary calculus.
Multiple-Choice Options:
A) Magnesium ammonium phosphate (struvite)
B) Brushite
C) Cystine
D) Uric acid
Correct Answer:
C) Cystine
In-Depth Explanation:
A) Magnesium ammonium phosphate (struvite): Incorrect. Struvite usually appears as "rectangular, coffin-lid" shapes.
B) Brushite: Incorrect. Brushite calculi are "needle-shaped."
C) Cystine: Correct. A "hexagonal" shape is characteristic of Cystine calculi.
D) Uric acid: Incorrect. These crystals usually appear as "amorphous shards, plates."
Memory Tool:
Remember, "Cystine is Six-sided" to associate the hexagonal shape with Cystine.
Reference Citation:
Table 92.2: Microscopic Appearance of Common Urinary Calculi
Rationale for Question Importance:
Identifying Cystine calculi is especially important in younger patients with recurrent urinary tract stones, as it may indicate a genetic predisposition requiring specialized treatment.
141
Clinical Vignette:
A 40-year-old woman presents with fever and chills in addition to urinary symptoms. Microscopic examination of her urinary calculus shows a "rectangular, coffin-lid" shape.
Multiple-Choice Options:
A) Calcium phosphate-apatite
B) Magnesium ammonium phosphate (struvite)
C) Calcium oxalate monohydrate
D) Uric acid
Correct Answer:
B) Magnesium ammonium phosphate (struvite)
In-Depth Explanation:
A) Calcium phosphate-apatite: Incorrect. Typically appears as "amorphous."
B) Magnesium ammonium phosphate (struvite): Correct. Struvite calculi are usually "rectangular, coffin-lid" in shape.
C) Calcium oxalate monohydrate: Incorrect. This type generally has an "hourglass" appearance.
D) Uric acid: Incorrect. These usually appear as "amorphous shards, plates."
Memory Tool:
Think "Struvite is your coffin-lid ticket to UTIs" to remember its rectangular, coffin-lid shape and its association with urinary tract infections.
Reference Citation:
Table 92.2: Microscopic Appearance of Common Urinary Calculi
Rationale for Question Importance:
Struvite stones are often associated with infections, and identifying them can guide the choice of antibiotics alongside stone management.
142
Clinical Vignette:
You are treating an elderly male patient who has been experiencing flank pain. Microscopic evaluation of his urinary calculus shows "amorphous shards, plates."
Multiple-Choice Options:
A) Brushite
B) Cystine
C) Calcium phosphate-apatite
D) Uric acid
Correct Answer:
D) Uric acid
In-Depth Explanation:
A) Brushite: Incorrect. Brushite calculi would show a "needle-shaped" appearance.
B) Cystine: Incorrect. These are usually "hexagonal" in shape.
C) Calcium phosphate-apatite: Incorrect. This type appears "amorphous," but not as shards or plates.
D) Uric acid: Correct. Uric acid calculi present as "amorphous shards, plates."
Memory Tool:
"Uric Acid is Unpredictable Shards" can help you remember the unique appearance of uric acid calculi.
Reference Citation:
Table 92.2: Microscopic Appearance of Common Urinary Calculi
Rationale for Question Importance:
Knowing the characteristic appearance of uric acid stones may point to specific dietary factors or metabolic issues, aiding in targeted treatment.
143
Clinical Vignette:
A 30-year-old male is experiencing recurring urinary tract infections. Upon microscopic evaluation, you notice the urinary calculus appears "amorphous."
Multiple-Choice Options:
A) Calcium phosphate-apatite
B) Magnesium ammonium phosphate (struvite)
C) Calcium oxalate monohydrate
D) Uric acid
Correct Answer:
A) Calcium phosphate-apatite
In-Depth Explanation:
A) Calcium phosphate-apatite: Correct. The "amorphous" appearance is characteristic of Calcium phosphate-apatite calculi.
B) Magnesium ammonium phosphate (struvite): Incorrect. These usually have a "rectangular, coffin-lid" appearance.
C) Calcium oxalate monohydrate: Incorrect. These appear as "hourglass."
D) Uric acid: Incorrect. These appear as "amorphous shards, plates."
Memory Tool:
"Phosphate is Formless" can help you remember the amorphous nature of Calcium phosphate-apatite stones.
Reference Citation:
Table 92.2: Microscopic Appearance of Common Urinary Calculi
Rationale for Question Importance:
Understanding the amorphous nature of Calcium phosphate-apatite stones may prompt further evaluation for underlying causes, especially in younger patients with recurrent infections.
144
Question 1:
A 45-year-old male presents with recurrent calcium oxalate stones. After a thorough evaluation, you decide to start him on a thiazide diuretic. Which of the following doses is correct for Hydrochlorothiazide for this indication?
A. 50 mg PO daily
B. 25 mg PO bid
C. 10 mg PO daily
D. 100 mg PO daily
Correct Answer: B
Explanation:
A: 50 mg daily is not the recommended dosage for Hydrochlorothiazide for urinary calculi. It's an incorrect dosage.
B: 25 mg PO bid is the correct dosage as per the guidelines provided in Table 92.4.
C: 10 mg daily is lower than the recommended dosage.
D: 100 mg PO daily is excessive and not recommended.
Memory Tool: "25 Twice" helps you remember the dose and frequency.
Reference Citation: Table 92.4
Rationale: Knowing the correct dosage is crucial for effective treatment and minimizing side effects.
145
What is the appropriate dosage of Allopurinol to prevent urinary calculi?
A. 100 mg PO daily
B. 250 mg PO daily
C. 300 mg PO daily
D. 400 mg PO daily
Correct Answer: C
Explanation:
A: 100 mg PO daily is below the recommended dosage.
B: 250 mg daily is close but not the recommended dose.
C: 300 mg PO daily is the correct dose according to Table 92.4.
D: 400 mg PO daily is above the recommended dose.
Memory Tool: "Alo-300" to remember the dosage.
Reference Citation: Table 92.4
Rationale: Prescribing the correct dose of Allopurinol can prevent complications related to urinary calculi.
146
For a patient who has frequent uric acid stones, which medication can be given, and at what dosage according to Table 92.4?
A. Potassium citrate at 10 mEq PO daily
B. Potassium citrate at 20 mEq PO bid-tid
C. Sodium cellulose phosphate at 5 g/day
D. Magnesium gluconate at 0.5–1 g tid
Correct Answer: B
Explanation:
A: The dosage for Potassium citrate is not correct. It is lower than the recommended dosage.
B: Potassium citrate at 20 mEq PO bid-tid is the correct choice for uric acid stones as per the table.
C: Sodium cellulose phosphate's recommended dosage is 10–15 g/day, not 5 g/day.
D: Magnesium gluconate could be an option but is not specified for uric acid stones in the table.
Memory Tool: "Citrate Twenty Twice-Three"
Reference Citation: Table 92.4
Rationale: Correct medication and dosage are crucial for targeted treatment of different types of urinary calculi.
147
Question 4:
You're managing a patient with cystine stones. Which medication, according to Table 92.4, would be appropriate for management, and what is its recommended dosage?
A. α-Mercaptopropionyl glycine 200 mg PO daily
B. α-Mercaptopropionyl glycine 100 mg PO bid
C. d-Penicillamine 500 mg PO daily
D. Acetohydroxamic acid 500 mg PO bid
Correct Answer: B
Explanation:
A: The dosage is not accurate. It should be 100 mg PO bid.
B: α-Mercaptopropionyl glycine 100 mg PO bid is the correct dosage according to Table 92.4 and is suitable for cystine stones.
C: d-Penicillamine is a choice, but 500 mg is not the recommended dosage according to the table.
D: Acetohydroxamic acid is not recommended for cystine stones according to Table 92.4.
Memory Tool: "Alpha 100 Twice" for α-Mercaptopropionyl glycine.
Reference Citation: Table 92.4
Rationale: Understanding medication and dosages for specific stone types is vital for effective treatment.
148
Which medication can be prescribed at a dosage of 25–50 mg PO daily for preventing urinary calculi, according to Table 92.4?
A. Hydrochlorothiazide
B. Chlorthalidone
C. Indapamide
D. Captopril
Correct Answer: B
Explanation:
A: Hydrochlorothiazide is given at 25 mg PO bid, not 25–50 mg PO daily.
B: Chlorthalidone is correctly prescribed at 25–50 mg PO daily.
C: Indapamide's dosage is 2.5 mg PO daily.
D: Captopril has a different dosing schedule altogether.
Memory Tool: "Chlor 25 to 50" to remember Chlorthalidone dosage.
Reference Citation: Table 92.4
Rationale: Being aware of the appropriate dosages for each medication is crucial for effective stone management.
149
What is the advised dosage of Magnesium gluconate to prevent urinary calculi?
A. 0.5–1 g bid
B. 0.5–1 g qid
C. 0.5–1 g tid
D. 0.5–1 g daily
Correct Answer: C
Explanation:
A: Bid is incorrect, the advised frequency is tid.
B: Qid is more frequent than the recommended tid.
C: 0.5–1 g tid is the correct dosage.
D: Daily is less frequent than the recommended tid.
Memory Tool: "Magne-Three" to remember tid dosing for Magnesium gluconate.
Reference Citation: Table 92.4
Rationale: Correct dosing is crucial for effective prophylaxis against urinary calculi.
150
Question 7:
According to Table 92.4, what is the correct dosage of Sodium cellulose phosphate for preventing urinary calculi?
A. 5–10 g/day divided with meals
B. 10–15 g/day divided with meals
C. 20 g/day divided with meals
D. 10 g/day divided with meals
Correct Answer: B
Explanation:
A: This dosage is lower than the recommended 10–15 g/day.
B: 10–15 g/day divided with meals is the correct dosage according to Table 92.4.
C: 20 g/day exceeds the recommended dosage.
D: This dosage is within the range but doesn't capture the full recommended range of 10–15 g/day.
Memory Tool: "Cellu-10 to 15" to remember Sodium cellulose phosphate dosage.
Reference Citation: Table 92.4
Rationale: Accurate dosing ensures effectiveness while minimizing potential side effects.
151
A 55-year-old woman has been diagnosed with calcium phosphate stones. What is the appropriate dose of Orthophosphate for preventing future episodes, according to Table 92.4?
A. 0.5 g PO bid
B. 1 g PO tid
C. 0.5 g PO tid
D. 2 g PO daily
Correct Answer: C
Explanation:
A: Bid is not the recommended frequency; it should be tid.
B: The dose is too high; it should be 0.5 g.
C: 0.5 g PO tid is the correct dosage.
D: This dosage is not advised as per the table.
Memory Tool: "Ortho-0.5-Three" for remembering the dose and frequency.
Reference Citation: Table 92.4
Rationale: Specific knowledge of dosages for certain stone types aids in providing the best patient care.
152
You have a patient with a history of struvite stones. According to Table 92.4, what is the correct dosage for Acetohydroxamic acid?
A. 200 mg PO bid
B. 250 mg PO tid
C. 250 mg PO bid-tid
D. 100 mg PO daily
Correct Answer: C
Correct Answer: C
Explanation:
A: 200 mg is not the correct dosage, and the frequency should be bid-tid.
B: The dose is correct but not the frequency; it should be bid-tid.
C: 250 mg PO bid-tid is correct as per the table.
D: 100 mg PO daily is not the recommended dosage or frequency.
Memory Tool: "Aceto-250-Two to Three"
Reference Citation: Table 92.4
Rationale: Knowing the right medication and dosage for specific stone types ensures optimal treatment.
153
Question 10:
What type of stones is Allopurinol typically used to prevent?
A. Uric acid stones
B. Calcium oxalate stones
C. Cystine stones
D. Struvite stones
Correct Answer: A
Explanation:
A: Allopurinol is generally used to prevent uric acid stones.
B: Allopurinol is not typically used for calcium oxalate stones.
C: Not used for cystine stones.
D: Not used for struvite stones.
Memory Tool: "All-Uric" for Allopurinol and uric acid stones.
Reference Citation: Not directly from Table 92.4, based on general clinical guidelines.
Rationale: Knowing the targeted stone type for each medication improves clinical decision-making.
154
Clinical Vignette: A 47-year-old male patient with recurrent calcium oxalate kidney stones is prescribed hydrochlorothiazide. Which of the following is a potential side effect?
A. Hyperkalemia
B. Hypomagnesemia
C. Hyperuricosuria
D. Hypotension
Correct Answer: C. Hyperuricosuria
Explanation:
A. Hyperkalemia: Incorrect. Thiazide diuretics cause potassium wasting, not hyperkalemia.
B. Hypomagnesemia: Incorrect. This is a side effect of Sodium cellulose phosphate (SCP), not Thiazide diuretics.
C. Hyperuricosuria: Correct. This is a known side effect of Thiazide diuretics.
D. Hypotension: Incorrect. This is a side effect of Captopril, not Thiazide diuretics.
Memory Tool: Think "Hyper-Ur-ic Th-iaz-ide" to remember that Thiazide diuretics cause Hyperuricosuria.
Reference Citation: Table 92.5
Rationale: Understanding the side effects of medications commonly used for urinary lithiasis is crucial for making well-informed treatment decisions.
155
Clinical Vignette: A 32-year-old female is treated with Sodium cellulose phosphate (SCP) for urinary lithiasis. What hormonal change could this induce?
A. Decreased Thyroid Hormone
B. Increased PTH
C. Increased Insulin
D. Decreased Cortisol
Correct Answer: B. Increased PTH
Explanation:
A. Decreased Thyroid Hormone: Incorrect. There is no evidence to suggest SCP affects thyroid hormone.
B. Increased PTH: Correct. SCP can stimulate PTH.
C. Increased Insulin: Incorrect. SCP does not affect insulin levels.
D. Decreased Cortisol: Incorrect. SCP does not affect cortisol levels.
Memory Tool: Remember "Sodium Cellulose Phosphate Stimulates Parathyroid Hormone" as "SCP Stirs PTH."
Reference Citation: Table 92.5
Rationale: Understanding hormonal changes associated with SCP is essential for managing patients with urinary lithiasis effectively.
156
Clinical Vignette: A patient is given potassium citrate to manage urinary lithiasis. Which of the following side effects is most likely to occur?
A. Hyperkalemia
B. Hypomagnesemia
C. GI distress
D. Nephrotic syndrome
Correct Answer: A. Hyperkalemia
Explanation:
A. Hyperkalemia: Correct. Potassium citrate is known to cause hyperkalemia.
B. Hypomagnesemia: Incorrect. This is a side effect of SCP.
C. GI distress: Incorrect. Though potassium citrate can cause GI upset, hyperkalemia is a more notable side effect.
D. Nephrotic syndrome: Incorrect. This is a side effect of d-Penicillamine.
Memory Tool: To remember Potassium Citrate causes Hyperkalemia, think "Potassium Adds Potassium."
Reference Citation: Table 92.5
Rationale: Being aware of this specific side effect of Potassium Citrate can help in patient monitoring.
157
Clinical Vignette: A 56-year-old male with a history of uric acid stones is started on Allopurinol. What adverse effect should you monitor for?
A. Nephrotic syndrome
B. Myalgia
C. GI distress
D. Tremor
Correct Answer: B. Myalgia
Explanation:
A. Nephrotic syndrome: Incorrect. This is a side effect of d-Penicillamine.
B. Myalgia: Correct. Allopurinol may cause muscle pain or myalgia.
C. GI distress: Incorrect. Although GI distress is a common side effect for many medications, it is not specifically linked with Allopurinol in the given table.
D. Tremor: Incorrect. This is a side effect of Acetohydroxamic acid.
158
Clinical Vignette: You prescribe Magnesium gluconate pyridoxine (B6) to a 50-year-old female patient for urinary lithiasis. What should she be warned about?
A. Rash
B. Diarrhea
C. Hyperkalemia
D. Hypotension
Correct Answer: B. Diarrhea
Explanation:
A. Rash: Incorrect. This is a side effect of Allopurinol and others, but not Magnesium gluconate pyridoxine (B6).
B. Diarrhea: Correct. This medication can cause diarrhea.
C. Hyperkalemia: Incorrect. This is a side effect of Potassium citrate.
D. Hypotension: Incorrect. This is a side effect of Captopril.
Memory Tool: Remember "Magnesium Goes Bowel 6" to recall that Magnesium gluconate pyridoxine (B6) can cause diarrhea.
Reference Citation: Table 92.5
Rationale: Diarrhea is an uncomfortable but important side effect to be aware of when prescribing this medication.
159
Clinical Vignette: A patient with urinary lithiasis is considered for Captopril therapy. Which of the following is a possible side effect of Captopril?
A. Rash
B. Hypokalemia
C. Soft tissue calcification
D. Tremor
Correct Answer: A. Rash
Explanation:
A. Rash: Correct. Captopril may cause rash.
B. Hypokalemia: Incorrect. Captopril does not cause hypokalemia; it's usually associated with Thiazide diuretics.
C. Soft tissue calcification: Incorrect. This is related to Orthophosphate.
D. Tremor: Incorrect. This is a side effect of Acetohydroxamic acid.
Memory Tool: Remember "Cap the Rash" to recall that Captopril can cause a rash.
Reference Citation: Table 92.5
Rationale: Knowing the side effects of Captopril is essential for adequate patient managemen
160
Clinical Vignette: A 42-year-old woman is being considered for Acetohydroxamic Acid treatment. Which of the following side effects could she potentially experience?
A. GI distress
B. Myalgia
C. Hyperkalemia
D. Hypomagnesemia
Correct Answer: A. GI distress
Explanation:
A. GI distress: Correct. Acetohydroxamic acid can cause gastrointestinal distress.
B. Myalgia: Incorrect. This is associated with Allopurinol.
C. Hyperkalemia: Incorrect. This is a side effect of Potassium citrate.
D. Hypomagnesemia: Incorrect. This is associated with Sodium cellulose phosphate (SCP).
Memory Tool: Think "Aceto-Acid Aches Alot" to remember that Acetohydroxamic Acid can cause GI distress.
Reference Citation: Table 92.5
Rationale: Recognizing the GI distress associated with Acetohydroxamic Acid is crucial for managing patient symptoms.
161
Clinical Vignette: A 39-year-old male with urinary lithiasis is started on d-Penicillamine. Which of the following adverse effects should he be warned about?
A. Rash
B. Nephrotic syndrome
C. Intracellular acidosis
D. GI distress
Correct Answer: B. Nephrotic syndrome
Explanation:
A. Rash: Incorrect. Although rashes are common in various medications, it's not specified for d-Penicillamine in the given table.
B. Nephrotic syndrome: Correct. d-Penicillamine may cause nephrotic syndrome.
C. Intracellular acidosis: Incorrect. This is a side effect of Thiazide diuretics.
D. GI distress: Incorrect. This is not a primary side effect of d-Penicillamine based on the table.
Memory Tool: Remember "d-Penicillamine Does Nephrotic" to associate d-Penicillamine with Nephrotic syndrome.
Reference Citation: Table 92.5
Rationale: Understanding the risks like nephrotic syndrome when administering d-Penicillamine is important for patient safety.
162
Clinical Vignette: A 65-year-old patient is started on α-Mercaptopropionyl glycine for urinary lithiasis. What mental side effect should be considered?
A. Tremor
B. Mental status changes
C. Headache
D. Anemia
Correct Answer: B. Mental status changes
Explanation:
A. Tremor: Incorrect. This is associated with Acetohydroxamic acid.
B. Mental status changes: Correct. α-Mercaptopropionyl glycine may lead to changes in mental status.
C. Headache: Incorrect. This is a side effect of Acetohydroxamic acid.
D. Anemia: Incorrect. Anemia is also associated with Acetohydroxamic acid.
Memory Tool: Remember "Mercapto-Mental" to link α-Mercaptopropionyl glycine with mental status changes.
Reference Citation: Table 92.5
Rationale: Mental status changes are a unique but significant side effect that requires monitoring when prescribing this medication.
163
Clinical Vignette: A 44-year-old female is started on Sodium cellulose phosphate for urinary lithiasis prevention. Which of the following should you warn her about?
A. Hypomagnesemia
B. Rash
C. Tremor
D. Hyperkalemia
Correct Answer: A. Hypomagnesemia
Explanation:
A. Hypomagnesemia: Correct. Sodium cellulose phosphate (SCP) can lead to hypomagnesemia.
B. Rash: Incorrect. This is a side effect of Allopurinol.
C. Tremor: Incorrect. This is associated with Acetohydroxamic acid.
D. Hyperkalemia: Incorrect. This is a side effect of Potassium citrate.
164
Clinical Vignette: A 58-year-old male with a history of calcium phosphate stones is started on Orthophosphate therapy. Which uncommon side effect should you monitor for?
A. Soft tissue calcification
B. GI distress
C. Hypotension
D. Hypokalemia
Correct Answer: A. Soft tissue calcification
Explanation:
A. Soft tissue calcification: Correct. Orthophosphate can cause soft tissue calcification.
B. GI distress: Incorrect. While common in many medications, it's not specified for Orthophosphate.
C. Hypotension: Incorrect. This is a side effect of Captopril.
D. Hypokalemia: Incorrect. This is associated with Thiazide diuretics.
Memory Tool: Think "OrthoCalcifies" to remember that Orthophosphate can lead to soft tissue calcification.
Reference Citation: Table 92.5
Rationale: Monitoring for soft tissue calcification is crucial as it's an uncommon but significant side effect of Orthophosphate.
165
Clinical Vignette: A 67-year-old female with a history of uric acid stones is started on Potassium citrate. Which side effect is she at risk for?
A. Hyperuricosuria
B. Hypomagnesemia
C. Hyperkalemia
D. Hypocitraturia
Correct Answer: C. Hyperkalemia
Explanation:
A. Hyperuricosuria: Incorrect. This is a side effect of Thiazide diuretics.
B. Hypomagnesemia: Incorrect. This is a side effect of Sodium cellulose phosphate (SCP).
C. Hyperkalemia: Correct. Potassium citrate can lead to elevated potassium levels.
D. Hypocitraturia: Incorrect. This is a side effect of Thiazide diuretics.
Memory Tool: Remember "K-citrate – HyperK" to associate Potassium citrate with hyperkalemia.
Reference Citation: Table 92.5
Rationale: Hyperkalemia is a serious side effect that needs close monitoring when prescribing Potassium citrate.
166
Clinical Vignette: A 52-year-old male patient with recurrent calcium oxalate stones is considering pharmacologic therapy options. He asks you about sodium cellulose phosphate.
Question: Which of the following best describes the effect of sodium cellulose phosphate on urinary calcium levels?
Correct Answer: B. Marked decrease
Explanation:
A. No change: Incorrect. Sodium cellulose phosphate causes a marked decrease in urinary calcium.
B. Marked decrease: Correct. Sodium cellulose phosphate has a strong effect on lowering urinary calcium.
C. Mild decrease: Incorrect. The decrease is not mild but rather marked with sodium cellulose phosphate.
D. Moderate decrease: Incorrect. The term 'moderate' underestimates the decrease; it's actually marked.
Memory Tool: Think of Sodium Cellulose Phosphate as a Sodium "Cell" in a high-security "Prison," effectively locking away calcium.
Reference Citation: Based on Table 92.6
Rationale for Importance: Understanding the different effects of medications used in calcium stone disease is crucial for patient management and selecting the most appropriate pharmacologic therapy.
167
Clinical Vignette: A 46-year-old woman with a history of calcium stone disease wants to understand how different medications will affect her urinary phosphorus levels.
Question: What effect does orthophosphate have on urinary phosphorus levels?
A. No change
B. Mild increase
C. Marked increase
D. Mild decrease
Correct Answer: C. Marked increase
Explanation:
A. No change: Incorrect. Orthophosphate does affect urinary phosphorus levels.
B. Mild increase: Incorrect. The increase is actually marked, not mild.
C. Marked increase: Correct. Orthophosphate significantly increases urinary phosphorus levels.
D. Mild decrease: Incorrect. There is no decrease; there's a marked increase instead.
Memory Tool: Think of "Ortho-" as "Over-the-top," indicating a significant, marked increase in urinary phosphorus.
Reference Citation: Based on Table 92.6
Rationale for Importance: Knowing the extent to which medications affect urinary phosphorus levels can aid in tailoring individual treatment plans.
168
Clinical Vignette: A 60-year-old man has been experiencing recurrent calcium stone disease. He has elevated levels of uric acid in his urine and is contemplating medication options.
Question: How does allopurinol affect urinary uric acid levels?
A. Marked increase
B. No change
C. Marked decrease
D. Mild increase
Correct Answer: C. Marked decrease
Explanation:
A. Marked increase: Incorrect. Allopurinol leads to a marked decrease in urinary uric acid.
B. No change: Incorrect. There is a significant change; a marked decrease.
C. Marked decrease: Correct. Allopurinol significantly decreases urinary uric acid levels.
D. Mild increase: Incorrect. The effect is in the opposite direction, a marked decrease.
Memory Tool: "All-Low-Purinol" - Think of it as making "All Uric levels Low."
Reference Citation: Based on Table 92.6
Rationale for Importance: For patients with elevated urinary uric acid, knowing the potency of allopurinol's effect is important for effective treatment.
169
Clinical Vignette: A 35-year-old woman with a history of calcium oxalate stones is advised to consider taking Potassium Citrate. She wonders how this medication will affect her urinary citrate levels.
Question: What effect does Potassium Citrate have on urinary citrate levels?
A. Mild decrease
B. No change
C. Marked increase
D. Mild increase
Correct Answer: C. Marked increase
Explanation:
A. Mild decrease: Incorrect. Potassium Citrate actually increases urinary citrate.
B. No change: Incorrect. There is a significant increase in urinary citrate levels.
C. Marked increase: Correct. Potassium Citrate markedly increases urinary citrate levels.
D. Mild increase: Incorrect. The increase is not mild, but rather marked.
Memory Tool: Remember "Potassium 'See'-trate" makes you 'See' a lot more citrate in the urine.
Reference Citation: Based on Table 92.6
Rationale for Importance: High levels of urinary citrate can help prevent calcium stone formation, making it essential to understand the impact of Potassium Citrate.
170
Clinical Vignette: A 50-year-old man who has suffered from calcium oxalate stones is considering Thiazide therapy. He is concerned about the impact on his urinary oxalate levels.
Question: What effect does Thiazide have on urinary oxalate?
A. Mild increase
B. No change
C. Mild decrease
D. Marked increase
Correct Answer: A. Mild increase
Explanation:
A. Mild increase: Correct. Thiazide can cause a mild increase in urinary oxalate levels.
B. No change: Incorrect. There is a change—a mild increase, in fact.
C. Mild decrease: Incorrect. Thiazide increases, rather than decreases, urinary oxalate.
D. Marked increase: Incorrect. The increase is mild, not marked.
Memory Tool: Think of Thiazide as a "Tiny" change agent that nudges up the oxalate a "Tiny" bit.
Reference Citation: Based on Table 92.6
Rationale for Importance: Knowing the mild increase in urinary oxalate caused by Thiazide could influence treatment choices, especially in patients with already high oxalate levels.
171
Clinical Vignette: A 40-year-old female is keen to understand the nuances of medications available for calcium stone disease. She is particularly concerned about calcium oxalate saturation in her urine.
Question: What effect does Orthophosphate have on calcium oxalate saturation?
A. Mild increase
B. No change
C. Mild decrease
D. Moderate decrease
Correct Answer: C. Mild decrease
Explanation:
A. Mild increase: Incorrect. Orthophosphate leads to a mild decrease in calcium oxalate saturation.
B. No change: Incorrect. There is a mild decrease.
C. Mild decrease: Correct. Orthophosphate mildly decreases calcium oxalate saturation.
D. Moderate decrease: Incorrect. The decrease is mild, not moderate.
Memory Tool: Think "Ortho-" as "Orderly Phosphate," tidying up by mildly decreasing calcium oxalate saturation.
Reference Citation: Based on Table 92.6
Rationale for Importance: The ability to mildly decrease calcium oxalate saturation can be valuable for specific patient conditions.
