Canadian Urological Association guideline: Evaluation and medical management of kidney stones Flashcards
1
Q
What is the kidney stone prevalence reported in the United States National Health and Nutrition Examination Survey (NHANES) published in 2020?
A
The prevalence of kidney stones was reported to be 12% in men and 10% in women.
2
Q
How has the incidence of stone formation changed between 2005 and 2015 according to U.S. data?
A
The incidence of stone formation increased from 0.6% to 0.9%.
3
Q
What trend has been observed in the male-to-female ratio of stone formation?
A
The male-to-female ratio of stone formation is decreasing.
4
Q
What systemic diseases are kidney stones associated with?
A
Kidney stones are associated with obesity, metabolic syndrome, and diabetes mellitus.
5
Q
Kidney stones are associated with obesity, metabolic syndrome, and diabetes mellitus.
A
The recurrence rates are reported to be 30–50%.
6
Q
What percentage of recurrent stone formers or those with more than one concurrent stone have a urinary metabolic abnormality?
A
Most recurrent stone formers or those with more than one concurrent stone (96.8%) have a urinary metabolic abnormality.
7
Q
What percentage of patients with a high risk of recurrent stone disease undergo metabolic evaluation?
A
Only 7% of patients with a high risk of recurrent stone disease undergo metabolic evaluation.
8
Q
What percentage of patients would prefer to take prophylactic medication to prevent future stones rather than undergoing surgery?
A
92% of respondents preferred medication to prevent future stones rather than undergoing surgery.
9
Q
What percentage of patients prescribed pharmacological prevention were non-compliant, especially those on potassium citrate?
A
Close to 50% of patients prescribed pharmacological prevention were non-compliant, especially those on potassium citrate.
10
Q
What are the estimated annual costs for patient care and lost work time related to recurrent stone disease?
A
The estimates of direct costs for patient care and the indirect costs related to lost work time exceed $5 billion USD annually.
11
Q
What were the search terms used for the literature review in the updated Canadian Urological Association guideline on the evaluation and medical management of kidney stones?
A
The search terms used were “nephrolithiasis,” “urolithiasis,” “kidney stone,” “renal stone,” and “urinary stone.”
12
Q
What was the time period for the literature review in the updated Canadian Urological Association guideline on kidney stones?
A
The literature review covered the period from January 1, 2015, to July 1, 2021.
13
Q
How many articles were initially identified in the literature review for the Canadian Urological Association guideline on kidney stones?
A
Initially, 11,640 articles were identified.
14
Q
How many articles were deemed potentially relevant for the literature assessment in the updated Canadian Urological Association guideline on kidney stones?
A
Out of 11,640 articles, 293 were identified as potentially relevant.
15
Q
How were the studies evaluated and recommendations made for the Canadian Urological Association guideline on kidney stones?
A
Studies were evaluated and recommendations made based on Oxford levels of evidence and grades of recommendation as per the CUA Guidelines Committee’s directive.
16
Q
When was the last guideline published before the current Canadian Urological Association guideline on kidney stones?
A
The last guideline was published in 2016. Recommendations in the current guideline were modified based on the most current literature since 2016.
17
Q
What are the recommended basic metabolic screenings for kidney stone evaluation?
A
Basic metabolic screenings should include urinalysis (with or without urine culture), serum electrolytes (Na, K, HCO3), calcium, creatinine, and a stone analysis when available.
18
Q
What systemic disorders should be ruled out for a first-time stone former without identifiable risk factors?
A
Potential systemic disorders such as hyperparathyroidism and renal dysfunction should be ruled out.
19
Q
Who should undergo an in-depth metabolic evaluation for kidney stones?
A
An in-depth metabolic evaluation is recommended for patients with risk factors for recurrent stone disease. This includes children (<18 years), those with bilateral or multiple stones, recurrent stones, non-calcium stones, pure calcium phosphate stones, any complicated stone episode, stones in the setting of a solitary kidney, patients with renal insufficiency, those with a history of systemic disease increasing the risk of stones, occupations where public safety is at risk, and a family history of kidney stones.
20
Q
What are the common conditions associated with struvite stones formation?
A
Struvite stones typically form in the setting of recurrent urinary infection, anatomical anomalies, and foreign bodies but occasionally are associated with metabolic abnormalities.
21
Q
What is the role of the urease inhibitor acetohydroxamic acid (AHA) in the management of kidney stones?
A
The urease inhibitor acetohydroxamic acid (AHA) has been used with limited success and with significant side effects in the management of kidney stones. However, it is not currently available in Canada.
22
Q
What is the recommended in-depth evaluation for patients with kidney stones?
A
The recommended in-depth evaluation includes serum tests, 24-hour urine tests, and a thorough dietary history.
23
Q
Which elements should be measured in serum tests during an in-depth evaluation for kidney stones?
A
Creatinine, sodium, potassium, calcium, albumin, uric acid, and bicarbonate. The parathyroid hormone (PTH) level should be checked if high or high-normal serum calcium is present, or in cases of idiopathic hypercalciuria with normocalcemia. Vitamin D levels should also be checked if PTH is elevated to rule out secondary hyperparathyroidism.
24
Q
What should be measured in a 24-hour urine collection during an in-depth evaluation for kidney stones?
A
Volume, creatinine, calcium, sodium, potassium, oxalate, citrate, uric acid, magnesium. Cystine should be measured if a cystine stone is known or suspected.
25
What is the relevance of PTH testing in an in-depth evaluation for kidney stones?
Previously, it was suggested that PTH testing was only required if serum calcium was elevated. However, recent data suggest that normocalcemic hyperparathyroidism is an important clinical variant associated with a high prevalence of nephrolithiasis. Therefore, serum PTH should be measured if the patient has a high or high-normal serum calcium or in patients with idiopathic hypercalciuria and normocalcemia.
26
What is the role of measuring Vitamin D levels during an in-depth evaluation for kidney stones?
Vitamin D deficiency is common in North American populations and has an impact on stone disease. Therefore, if a patient has elevated PTH, Vitamin D levels should be measured to rule out secondary hyperparathyroidism.
27
What is the recommended number of 24-hour urine collections for kidney stone evaluation according to the Canadian Urological Association?
The Canadian Urological Association recommends two 24-hour urine collections when possible, but emphasizes the practicality and importance of obtaining at least one collection.
28
What percentage of patients had their clinical management changed by an abnormality identified only when two 24-hour urine samples were collected?
Approximately 47.6% of patients had their clinical management changed by an abnormality identified only when two 24-hour urine samples were collected.
29
What percentage of patients will have a 50% variation in at least one urinary parameter when two 24-hour urine samples are collected?
Close to 25% of patients will have a 50% variation in at least one urinary parameter when two 24-hour urine samples are collected.
30
What percentage of patients will have a 20% difference in three urine parameters when two 24-hour urine samples are collected?
25% of patients will have a 20% difference in three urine parameters when two 24-hour urine samples are collected.
31
What is the benefit of collecting two 24-hour urine samples and what should be considered?
The benefit of two collections is the potential for more accurate and comprehensive data, which can change the clinical management in nearly half of the cases. However, the practicality and importance of obtaining at least one collection should be considered.
32
What is the level of evidence and grade of the recommendation for submitting stones for analysis?
The level of evidence is 3, and it is a Grade C recommendation.
33
Why is the identification of stone composition important?
It aids in determining prevention and directing surgical options for future stones. Moreover, it alters the indication for in-depth metabolic evaluation based on the specific composition of the stone.
34
What should be done if a patient continues to form new stones?
: A repeat stone analysis should be performed, as this may change management.
35
How often does stone composition change in patients over time according to the provided data?
Stone composition changed in 21.2% of patients over time.
36
Which metabolic abnormalities are associated with hypercalciuria, and which types of stones are they commonly found with?
Hypercalciuria is associated with brushite and calcium oxalate dihydrate stones.
37
Which metabolic abnormalities are associated with hyperoxaluria, and which types of stones are they commonly found with?
Hyperoxaluria is most commonly found in calcium oxalate monohydrate stone formers.
38
Which metabolic abnormalities are associated with apatite stones?
Apatite stones were correlated with both hypercalciuria and hypocitraturia.
39
In which patients are uric acid stones typically found?
Uric acid stones are found in patients with low urinary pH.
40
How can stone composition be used for patients who are unable or unwilling to perform an in-depth medical evaluation?
Stone composition may be a useful tool to guide empiric medical therapy for these patients.
41
What level of evidence and grade of recommendation does the Canadian Urological Association assign to the involvement of a registered dietician in assessing and making dietary recommendations for kidney stone patients?
The Canadian Urological Association assigns a Level 3 evidence and Grade C recommendation to the involvement of a registered dietician in assessing and making dietary recommendations for kidney stone patients.
42
What impact does general dietary and fluid intake advice have on stone recurrence rates?
General dietary and fluid intake advice has been shown to be effective in reducing stone recurrence rates. This advice is beneficial even for first-time stone formers without identifiable risk factors.
43
What is the "stone clinic effect"?
The "stone clinic effect" refers to the significant reduction in stone recurrence seen when patients are counselled on appropriate fluid intake and dietary excesses.
44
In which circumstances is assessment with a registered dietician strongly suggested for patients with renal stones?
Assessment with a registered dietician is strongly suggested in cases where there is a history of compromised nutritional status, complex medical situations, or patients who need assistance implementing dietary recommendations.
45
What advantage does specific dietary advice based on comprehensive evaluation have over general dietary advice in managing kidney stones?
Patients who received specific dietary recommendations based on a comprehensive evaluation had fewer stone recurrences over three years than those who only received general dietary advice.
46
What is the recommended daily urine output for all stone formers?
The recommended daily urine output for all stone formers is 2.5 liters.
47
What is the reduction in the risk of stone formation when achieving a daily urine output of 2.5 L?
Achieving a daily urine output of 2.5 L can reduce the risk of stone formation by 60-80%.
48
How much does the risk of stones decrease with each 200 mL increase in fluid intake?
Each 200 mL increase in fluid intake reduces the risk of stones by 13%.
49
Which beverages may have a protective effect against stone formation?
Beverages such as orange juice, caffeinated beverages (or caffeine alone), coffee, wine, and beer may have a protective effect against stone formation. However, the effects must be weighed against other potential health effects.
50
How does low-calorie orange juice contribute to kidney stone prevention?
Low-calorie orange juice can increase urinary citrate levels, providing a protective effect against kidney stone formation.
51
What is the effect of milk on kidney stone formation?
Milk does not increase the risk of stones unless consumed in excess.
52
What is the role of smart technology in managing fluid intake for stone formers?
: Smart technology, including smart water bottles and digital applications, can accurately measure fluid intake. However, the impact on urine output is similar to counselling.
53
hat are some practical ways to increase fluid intake for stone formers?
Some practical ways to increase fluid intake include drinking at set times during the day, drinking hourly during working hours, keeping a water bottle in places where significant time is spent, and consuming foods high in water content like fruits and vegetables.
54
What should be considered when counselling patients with congestive heart failure or chronic renal insufficiency about fluid intake?
Caution should be exercised when counselling patients with congestive heart failure or chronic renal insufficiency, as excessive fluid intake may exacerbate their conditions.
55
What is the recommended daily intake of dietary calcium for individuals prone to kidney stones?
The recommended daily intake of dietary calcium for individuals prone to kidney stones is 1000–1200 mg/day.
56
What is a common misconception about dietary calcium intake and kidney stone formation?
A common misconception is that individuals prone to kidney stones should restrict their calcium intake. However, research shows that higher dietary calcium intakes are actually correlated with a lower risk of stone formation.
57
What is the suggested timing for calcium supplementation if required?
If calcium supplementation is required, it should ideally be taken at mealtimes. This helps maximize oxalate sequestration and does not increase the risk of hypercalciuria.
58
What is the potential risk associated with calcium supplementation?
Some studies suggest that calcium supplementation may increase cardiovascular risk. Therefore, obtaining calcium through diet is preferable.
59
What could be the impact of the timing of calcium supplement administration on stone formation risk?
The timing of calcium supplement administration could influence stone formation risk. One study suggested that calcium not consumed at mealtimes might have decreased its ability to chelate oxalate, possibly leading to an increased risk of stone formation.
60
What is the recommendation for calcium stone formers with Vitamin D deficiency?
In calcium stone formers with Vitamin D deficiency, repletion is appropriate. However, it is necessary to monitor Vitamin D levels and hypercalciuria on repeat testing.
61
When should bone mineral density (BMD) testing be considered in calcium stone formers?
BMD testing should be considered in calcium stone formers with evidence of hypercalciuria and/or distal renal tubular acidosis (dRTA).
62
What is the recommended treatment for calcium stone formers with documented low BMD?
Treatment with either a thiazide diuretic, alkali citrate, or ideally both. This has been shown to reduce stone recurrence risk and increase BMD.
63
What are the observed effects of Vitamin D deficiency in stone formers?
Vitamin D deficiency in stone formers often results in secondary hyperparathyroidism. Some studies note an association between higher Vitamin D levels and hypercalciuria, but this finding is not consistent across all studies.
64
What is the impact of Vitamin D supplementation on hypercalciuria and stone risk?
The impact is unclear. While some studies found no association between Vitamin D intake and urolithiasis, others have shown an increased risk of stone formation with Vitamin D supplementation, particularly when co-administered with calcium.
65
What is the relationship between BMD and calcium nephrolithiasis?
Several studies have demonstrated that calcium stone disease correlates with low BMD. The risk is higher with increasing levels of hypercalciuria and the prevalence of osteopenia or osteoporosis is higher in stone formers with concomitant Vitamin D deficiency.
66
What are the benefits of dietary recommendations for stone reduction and certain treatments like thiazide diuretics and alkali citrate therapy?
A low-sodium and normal-calcium diet can improve BMD. Thiazide diuretics can reduce urinary calcium levels, decrease stone recurrence, and improve BMD in stone formers. Alkali citrate therapy can positively affect both stone recurrence and bone health by reducing bone resorption and buffering acid production.
67
What is the recommendation regarding animal protein intake for patients with recurrent calcium or uric acid stones?
Patients with recurrent calcium or uric acid stones should moderate their animal protein intake and avoid purine-rich foods.
68
What is the level of evidence and grade of recommendation for the above advice?
Level of Evidence 2–3, Grade C recommendation.
69
How is high animal protein consumption associated with the risk of nephrolithiasis?
High animal protein consumption is associated with a slight increase in the risk of nephrolithiasis. In some populations, it's associated with a direct increase in the risk of stone formation and elevated urinary oxalate and calcium, alongside lower levels of urinary citrate.
70
How does a diet high in animal protein affect urinary excretion and pH levels?
Diets high in animal protein are associated with increased uric acid excretion and decreased urinary citrate and pH levels, predisposing individuals to uric acid nephrolithiasis.
71
How does a vegetarian diet compare to a typical Western diet in terms of the risk of uric acid crystallization?
A vegetarian diet has been demonstrated to reduce the risk of uric acid crystallization by 93% compared to a typical Western diet.
72
What is the recommended daily sodium intake for patients with recurrent calcium nephrolithiasis?
The recommended daily sodium intake for patients with recurrent calcium nephrolithiasis is limited to 1500 mg, and should not exceed 2300 mg. (Level of Evidence 1–2, Grade B recommendation)
73
What is the relationship between dietary sodium excess and hypercalciuria?
Dietary sodium excess is associated with hypercalciuria. High urinary sodium levels increase calcium excretion and decrease urinary citrate.
74
How does high sodium intake affect stone risk?
High sodium intake was associated with up to a 61% increase in stone risk in a large, prospective cohort of women.
75
How does reduction in dietary sodium affect stone recurrence and urinary parameters?
Reduction in dietary sodium can improve urinary parameters and decrease stone recurrence. In a study of hypercalciuric calcium stone formers, a low-sodium diet resulted in lower urinary sodium, calcium, and oxalate, and normalized urine calcium excretion for one-third of patients.
76
How does a low-sodium and animal protein diet compare to a low-calcium diet in terms of stone recurrences?
A randomized trial demonstrated that a low-sodium and animal protein diet resulted in fewer stone recurrences compared with a low-calcium diet.
77
What effect does a diet high in fiber, fruits, and vegetables have on kidney stone formation according to the Canadian Urological Association guidelines?
A diet high in fiber, fruits, and vegetables may offer a small protective effect against kidney stone formation. This is classified as a Grade C recommendation based on Level of Evidence (LE) 2-3.
78
How does a low dietary intake of fiber, fruit, and vegetables impact the risk of kidney stones in women?
A low dietary intake of fiber, fruit, and vegetables increases the risk of kidney stones in women.
79
In stone-forming patients with hypocitraturia, what happens when the diet is supplemented with foods high in fiber, fruits, and vegetables?
Introducing foods high in fiber, fruits, and vegetables results in increased excretion of citrate, potassium, and magnesium, and a reduction in the supersaturation of calcium oxalate and calcium phosphate crystals.
80
What is the recommended daily limit for Vitamin C supplementation according to the Canadian Urological Association, and why?
The Canadian Urological Association recommends not exceeding 1000 mg of Vitamin C supplementation daily. This is due to the associated risk of hyperoxaluria and nephrolithiasis. Excess vitamin C can be converted to oxalate, potentially increasing the risk of stone formation. In population-based studies, intake of over 1000 mg of Vitamin C daily has been shown to cause a slight increase in the risk of nephrolithiasis. Furthermore, Vitamin C supplementation of 1–2 g was associated with increased urinary oxalate in stone-forming patients.
81
What is the relationship between stone disease and metabolic syndrome?
Stone disease is highly correlated with obesity, diabetes, and metabolic syndrome. Patients with metabolic syndrome have 2.13 times increased odds of developing stones. The risk of stone disease increases with the number of metabolic syndrome traits present.
82
What lifestyle modifications should be recommended to patients with metabolic syndrome and stones?
Patients should be counselled to adopt healthier lifestyles, including dietary practices that promote low sodium intake and consumption of fresh fruit and vegetables. The Dietary Approaches to Stop Hypertension (DASH) diet has been shown to be effective in reducing both cardiovascular risks and kidney stone recurrence.
83
How do obesity and diabetes contribute to stone formation?
Obesity and diabetes have been shown to be independent risk factors for stone formation, likely secondary to the development of acidic urine promoting uric acid crystal formation. The underlying insulin resistance in these patients leads to impaired glutamine metabolism, ammonia production, and ammonium excretion. This results in unbuffered hydrogen ions and a lowering of the urinary pH.
84
How might pioglitazone, a thiazolidinedione, be beneficial in patients with type 2 diabetes and stone disease?
Pioglitazone can reduce insulin resistance, leading to increases in ammonium excretion and more alkaline urinary pH values, which may be protective against stone disease.
85
What is the recommendation for patients with hyperoxaluria?
Patients with hyperoxaluria should minimize their intake of high-oxalate foods. Vitamin B6 supplementation can be considered to lower urinary oxalate levels when dietary modification has been unsuccessful.
86
What is the recommended treatment for patients with enteric hyperoxaluria?
Elemental calcium or calcium citrate should be given with meals to bind with dietary oxalate to reduce its intestinal absorption.
87
What is hyperoxaluria and what is it associated with?
Hyperoxaluria can result from dietary, enteric, or idiopathic causes and is associated with an increased risk of calcium oxalate stone formation.
88
What is the result of the treatment of dietary and idiopathic hyperoxaluria with a low-oxalate diet?
Most studies have shown that a low-oxalate diet reduces urinary oxalate levels; however, this did not consistently result in a decrease in calcium oxalate crystal supersaturation.
89
What has research shown about the effectiveness of Vitamin B6 or pyridoxine supplementation in treating hyperoxaluria?
Multiple studies, including several prospective cohort studies and a randomized controlled trial, have shown that vitamin B6 or pyridoxine supplementation (25 mg daily) are effective in reducing urinary oxalate levels.
90
What is enteric hyperoxaluria and which patients is it most commonly found in?
Enteric hyperoxaluria is due primarily to the malabsorption of intestinal fats in the ileum. This condition is most frequently found in patients with inflammatory bowel disease with small bowel involvement, short gut syndrome, and after bariatric surgery (not including restrictive bariatric procedures, such as vertical banded gastroplasty and sleeve gastrectomy).
91
What are the typical laboratory findings in conditions associated with enteric hyperoxaluria?
Typical laboratory findings include low urine volume and pH, hypocitraturia, hypocalciuria (unique to malabsorptive disease), and hyperoxaluria.
92
What is the treatment for conditions associated with enteric hyperoxaluria?
Treatment includes reduction of dietary oxalate, increased fluid intake, and calcium consumption. The calcium can be elemental calcium or calcium citrate, as this will help correct the hypocitraturia and low urinary pH as well. Importantly, the calcium should be taken with meals for it to bind to the dietary oxalate.
93
What is the recommended approach for children with stone disease according to the Canadian Urological Association guidelines?
All children with stone disease should undergo an in-depth medical evaluation and may benefit from a multidisciplinary approach with urology and nephrology.
94
What is the incidence of pediatric stone disease per 100,000 person-years in the U.S.?
59.5 cases.
95
What is the recurrence rate of pediatric stone disease?
50% of patients form a recurrent stone within three years of the index stone.
96
What dietary and environmental factors are associated with an increased risk of pediatric stone disease?
Sodium and purine intake, low urine volume, and climate.
97
What type of medical evaluation is recommended for toilet-trained children with stone disease?
An in-depth evaluation with a 24-hour urine collection.
98
What are the recommended fluid intake targets for children with stone disease, based on their age?
: >750 ml/day in infants, >1 L/day in children under age five, >1.5 L/day in children ages 5–10, and >2 L in children over age 10.
99
What is the most common metabolic abnormality in children with stone disease?
Hypercalciuria.
100
Hypercalciuria.
Increasing fluid intake, reducing sodium intake, and using thiazide diuretics if refractory.
101
Figure 1. Specific dietary and medical treatments for patients with calcium oxalate or mixed calcium oxalate/calcium phosphate stones. *Calcium intake 1200 mg daily (with meals), moderation of foods high in oxalate, pair oxalate and calcium-containing foods.
102
What are the main recommendations for medical management of calcium oxalate or mixed calcium oxalate/calcium phosphate stones?
Thiazide diuretics and alkali citrates are recommended as they decrease urinary calcium and increase urinary citrate, respectively. Allopurinol is effective in patients with hyperuricemia but doesn't provide benefits in patients with normal serum uric acid levels. Empiric treatment with thiazide diuretics and/or alkali citrates can reduce stone recurrence in patients with active stone disease who have normal metabolic evaluations.
103
What are potential urinary abnormalities in patients with calcium oxalate or mixed calcium oxalate/calcium phosphate stones?
These patients may have normal 24-hour urine testing, hypercalciuria, hyperoxaluria, hypocitraturia, hyperuricosuria, low urine volume, or a combination of these features.
104
Why should dietary sodium intake be reduced before initiating thiazide therapy in patients with calcium stones?
Elevated urinary sodium can result in hypercalciuria, which can contribute to stone formation.
105
What dosages of thiazide diuretics are typically used in the clinical management of calcium stones?
Hydrochlorothiazide (25 mg orally twice daily or 50 mg orally once daily), chlorthalidone (25 mg orally once daily, can be increased to 50 mg), and indapamide (1.25 mg orally once daily, can be increased to 2.5 mg).
106
What are the potential side effects of thiazide diuretics?
Hypokalemia, hyperglycemia, hyperlipidemia, hyperuricemia, hypomagnesemia, and hypocitraturia. These can be mitigated by combining thiazide diuretics with potassium citrate or potassium chloride.
107
How does alkali citrate assist in the prevention of calcium nephrolithiasis?
Alkali citrate increases urinary citrate levels and decreases the risk of recurrent nephrolithiasis.
108
What is the most studied alkali citrate agent and its typical dosage for calcium stone prevention?
Potassium citrate is the most studied agent with dosages in clinical trials ranging from 30–60 mEq in two to three divided doses daily.
109
Why is potassium citrate preferred over sodium citrate for calcium nephrolithiasis prevention?
Sodium citrate might increase urinary calcium excretion, which could exacerbate stone formation.
110
What is the role of allopurinol in managing calcium stone disease?
Allopurinol is a xanthine oxidase inhibitor used to treat hyperuricemia. It reduces stone recurrence in calcium oxalate stone formers with elevated uric acid levels.
111
What is the rationale behind empiric preventative treatment with thiazide diuretics and/or alkali citrate in calcium stone formers?
Even in patients with normocalciuria, thiazide diuretics have been shown to be effective in reducing stone recurrence. Similarly, alkali citrate can decrease stone events in calcium stone patients without hypocitraturia.
112
What are potential underlying conditions for patients who form pure calcium phosphate stones?
Distal Renal Tubular Acidosis (dRTA) and primary hyperparathyroidism.
113
What is the recommended treatment for patients with incomplete or complete dRTA?
Alkali citrate therapy.
114
What are the potential presentations of patients with dRTA?
Recurrent calcium phosphate stones, nephrocalcinosis, systemic acidosis, osteoporosis, failure to thrive, or sensorineural hearing loss.
115
How does potassium citrate affect patients with dRTA?
It corrects systemic acidosis, improves urinary parameters, reduces stone formation, and increases bone mineral density (BMD). It has superior effects on urinary indices compared to sodium citrate in patients with dRTA.
116
What is incomplete dRTA, and how does it differ from complete dRTA?
Incomplete dRTA is a condition characterized by defective urinary acidification similar to complete dRTA, without systemic metabolic acidosis. It results in recurrent stone formation and increased bone turnover.
117
When should incomplete dRTA be suspected?
In patients with persistently alkaline urine (pH>5.3), low urinary citrate, and low-normal serum potassium and bicarbonate levels.
118
What is the mainstay of treatment for incomplete dRTA?
Alkali citrate therapy, which improves urinary citrate and reduces stone formation.
119
What is the impact of primary hyperparathyroidism on renal stone disease?
Patients with primary hyperparathyroidism have a significantly increased risk of renal stone disease. Even with normal serum calcium levels, an elevated parathyroid hormone (PTH) can increase stone risk and result in decreased BMD.
120
What is the result of surgery for primary hyperparathyroidism?
Surgery for primary hyperparathyroidism results in decreased serum calcium, reduced stone formation, and improved BMD.
121
Figure 2. Specific dietary and medical treatments for patients with uric acid stones.
122
What are the underlying disorders associated with uric acid stones?
Uric acid stones may form as a result of several underlying disorders, including obesity, diabetes mellitus, gout, excessive bicarbonate loss due to high output bowel disease, myeloproliferative disorders, and tumor lysis syndrome.
123
What is the first-line therapy for patients with uric acid stones?
The first-line therapy in patients with uric acid stones is urinary alkalization to a pH of 6.5.
124
What is the main focus of prevention for uric acid stones?
The focus of prevention should be to correct urine pH above 5.5 and increase urine volume.
125
When can allopurinol be used as an adjunctive therapy in the treatment of uric acid stones?
Allopurinol, a xanthine oxidase inhibitor, can be used as an adjunctive therapy in patients with demonstrated hyperuricemia, hyperuricosuria, or a history of gout after the correction of urinary pH.
126
What is the success rate of dissolving uric acid stones using potassium citrate therapy, according to recent studies?
In a recent prospective study, potassium citrate therapy was successful in dissolving 83% of stones (mean 1.4 cm^3) after six months of treatment.
127
How is uric acid stone formation most commonly associated with urinary pH and urine volume?
Uric acid stone formation is most associated with low urinary pH and low urine volume rather than hyperuricosuria.
128
What is an underused treatment strategy for uric acid stones?
: In-situ uric acid stone dissolution with alkali citrate is an underused treatment strategy.
129
What is the index patient 4 stone composition in the Canadian Urological Association guidelines on kidney stones?
Cystine stones.
130
What is the first-line recommendation for managing cystine stone formation?
Patients should aim for a daily urine output of 3 L, restrict their sodium intake, and moderate their protein intake. The initial therapy involves urinary alkalization, targeting a urine pH of 7–7.5.
131
What is cystinuria and who is commonly affected?
Cystinuria is a common genetic disorder caused by a deficiency in reabsorbing dibasic amino acids, affecting 1/7000 individuals. Cystine stone formers often present in childhood or as teenagers.
132
Why is maintaining a daily urine output of at least 3 L crucial for patients with cystinuria?
This is a key part of prevention as even with adjunctive medical therapy, the success of stone prevention will be poor in patients who do not comply with increased fluid intake.
133
How does restricting sodium and moderating protein intake help manage cystine stones?
Sodium restriction decreases cystine excretion, reflecting the coupling of cystine to parallel sodium transport in the kidney. Elevated dietary protein is associated with increased urinary cystine, and reducing protein intake can decrease urinary cystine levels.
134
What is the target urine pH for cystine stone formers and why?
The target urine pH is 7–7.5. The solubility of cystine significantly increases within this pH range. However, a urinary pH greater than 7.5 should be avoided as it may promote calcium phosphate stone formation.
135
What are thiol-binding agents and when are they used in the management of cystine stones?
Thiol-binding agents, such as penicillamine (1–2 g daily) or tiopronin (800–1200 mg daily), may be used if alkalizing agents fail to adequately control cystine stone formation. However, they are considered second-line therapy due to potential side effects.
136
Why should tiopronin be prioritized over penicillamine, if available?
Tiopronin should be prioritized due to its better side effect profile compared to penicillamine, which can cause significant side effects such as fever, arthralgias, rash, dysgeusia, leukopenia, and proteinuria.
137
What is the role of captopril in managing cystine stones?
Captopril was evaluated in a small study, but it did not achieve a significant reduction in stone formation and is therefore no longer recommended.
138
What considerations should be made for long-term management of patients with cystinuria?
Long-term compliance can be difficult to achieve in patients with cystinuria. Therefore, consideration should be given to managing these patients at specialized multidisciplinary clinics with close follow-up.
139
Figure 3. Specific dietary and medical treatments for patients with cystine stones.
140
What are the suggestive features of primary hyperparathyroidism?
High or high-normal serum calcium, high or high-normal serum parathyroid hormone (PTH), hypercalciuria, calcium oxalate or calcium phosphate stones, and decreased bone mineral density.
141
What investigations are needed for primary hyperparathyroidism?
Serum calcium, PTH, and Vitamin D tests.
142
What is the treatment for primary hyperparathyroidism?
Treat Vitamin D deficiency and consider referral to endocrinology.
143
What are the suggestive features of secondary hyperparathyroidism?
High serum PTH, low Vitamin D, low or normal serum calcium, hypercalciuria, and decreased bone mineral density.
144
What investigations are needed for secondary hyperparathyroidism?
Serum calcium, PTH, and Vitamin D tests.
145
What is the treatment for secondary hyperparathyroidism?
Treat Vitamin D deficiency and consider referral to endocrinology.
146
What are the suggestive features of complete distal renal tubular acidosis?
Urine pH greater than 5.8, low serum bicarbonate, low serum potassium, pure apatite stone, hypocitraturia, hypercalciuria, and decreased bone mineral density.
147
What investigations are needed for complete distal renal tubular acidosis?
Serum electrolytes, urine pH, and 24-hour urine collection.
148
What is the treatment for complete distal renal tubular acidosis?
Alkali citrate and thiazide.
149
What are the suggestive features of incomplete distal renal tubular acidosis?
Urine pH greater than 5.3, low-normal serum bicarbonate, low-normal serum potassium, pure apatite stone, hypocitraturia, hypercalciuria.
150
What investigations are needed for incomplete distal renal tubular acidosis?
Serum electrolytes, urine pH, and 24-hour urine collection.
151
What is the treatment for incomplete distal renal tubular acidosis?
Alkali citrate and thiazide.
152
What is the prevalence of nephrolithiasis?
8. 8% overall
10. 6% in men
7. 1% in women
153
With health conditions are associated with nephrolithiasis?
Obesity
HTN
Diabetes
154
What diet has been shown to be potentially beneficial for recurrent stone forming men?
High fluid
Low sodium
Low animal protein
Normal Ca
155
What dietary factors may enhance stone formation?
Low calcium
Low fluid
Sugary drinks
High animal protein
156
What medical conditions should be asked about during evaluation of a stone patient?
```
Obesity
Hyperthyroidism
Gout
RTA type I
Diabetes
Hyperparathyroidism
Bowel or pancreatic dz
```
157
What medications are associated with stone formation?
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Probenacid
Protease inhibitors
Lipase inhibitors
Triamterene
Chemotherapy
Vitamins C/D
Topiramate
Acetazolamide
Zonisamide
```
158
What laboratory workup should be included in the evaluation of a stone patient?
BMP
Ca
Uric acid
UA
159
What is the AUA guideline for a stone patient with high serum Ca?
PTH
| Vit D
160
When should one suspect hyperparathyroidism in a Stone patient?
High serum Ca
CaP stones
Elevated urinary Ca
161
High Ca with normal mid range PTH?
Primary hyperparathyroidism
162
Potential causes of CaP stones?
RTA type 1
Primary hyperPTH
Medullary sponge
Carbonic anhydrase i
163
What can nephrocalcinosis indicate?
RTA type 1
Primary HyperPTH
Primary hyperoxaluria
Medullary sponge
164
When should a 24 urine analysis be obtained?
Recurrent stone formers
Interested first timers
High risk formers
165
What makes high risk stone formers?
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Family history
Solitary kidney
Intestinal malabsorption
rUTIs
Obesity/diabetes
Type 1 RTA
Primary hyperPTH
```
166
What are the AUA guidelines for metabolic testing for nephrolithiasis?
one or two 24-hour urine collections obtained on a random diet
167
What should a 24 hour urine analysis include at minimum?
Total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium and creatinine.
168
What are the roles of fasting calcium and calcium load testing?
They should not be used.
169
What is the recommended daily fluid volume to prevent stones?
fluid intake that will achieve a urine volume of at least 2.5 liters daily
170
What is the recommended calcium intake for stone formers?
Normal Ca intake
1000-1200 mg/day
Low Ca intake may lead to increased oxalate absorption.
171
What is the recommended sodium intake for stone formers?
2300 mg/day
172
What are the diet recommendations for Ca oxalate stones?
Limit oxalate rich foods and keep normal calcium consumption
173
Calcium stone and lower urinary citrate diet recommendations?
increase fruits and vegetables. Limit non dairy animal protein.
174
Uric acid/calcium stones with high uric acid diet recommendations?
Limit non dairy protein.
175
Cysteine stones, diet recommendations?
Limit sodium and protein intake.
176
Medical tx options for patient with high urine calcium and recurrent calcium stones?
HCTZ 25mg BID, 50mg qd
Chlorthalidone 25mg qd
Indapamide 2.5mg qd
177
What additional medication may be needed when on thiazides?
Potassium supplementation.
178
Tx for patient with recurrent calcium stones and low urinary citrate?
Clinicians should offer potassium citrate therapy to patients with recurrent calcium stones and low or relatively low urinary citrate.
179
Medical treatment for a patient with recurrent calcium oxalate stones, hyperuricosuira, and normal urinary calcium?
Allopurinol
180
What is the cutoff for hyperuricosuria?
>800mg/day
181
Medical treatment for a patient with recurrent calcium stones in which 24 hour urine analysis failed to identify an abnormality?
Thiazide diuretics
| Potassium citrate
182
What medical therapy is available for uric acid or cysteine stones?
Alkalinization of the urine with potassium citrate to 6 for uric acid and 7 for cysteine
183
Role of allopurinol in uric acid stones?
Do not use as first line tx. Alkalinization is the first line treatment. Allopurinol can only be considered if patient continues to form uric acid stones on adequate alkaliniztion therapy.
184
What is the first line medical therapy for Cysteine stones?
irst-line therapy for patients with cystine stones is increased fluid intake, restriction of sodium and protein intake, and urinary alkalinization.
185
What are the second and third line treatments for Cysteine stones?
2nd line: Tiopronin
| 3rd line: d-penicillamine, captopril
186
What is the medical treatment for patients with struvite stones that are recurrent and not treated adequately with surgical therapy?
acetohydroxamic acid (AHA), it is a urease inhibitor.
187
What are the notable adverse effects of Acetohydroxamic acid?
Patients taking this medication should be closely monitored for phlebitis and hypercoagulable phenomena.
188
How should patients on medical therapy for stones be followed up?
linicians should obtain a single 24-hour urine specimen for stone risk factors within six months of the initiation of treatment to assess response to dietary and/or medical therapy. Then annually thereafter. Blood testing should be tailored to specific medication.
189
What does the screening evaluation consistent of in a patient newly diagnosed with kidney or ureteral stones?
Guideline 1: A thorough history and physical examination, dietary history, close look at their medications, serum chemistries and UA (both macro and micro)/UC
190
What are stone provoking medications and dietary supplements?
probenecid, some protease inhibitors, lipase inhibitors, triamterene, chemotherapy, vitamin C, vitamin D, calcium and carbonic anhydrase inhibitors such as topiramate, acetazolamide, and zonisamide
191
What health conditions are associated with an increased risk of stones?
Increased risk of stones: obesity, hyperthyroidism, gout, renal tubular acidosis (RTA) type 1, diabetes mellitus type 2, bone disease, primary hyperparathyroidism
malabsorptive gastrointestinal states due to bowel resection, bariatric surgery or bowel or pancreatic disease
192
When should you obtain serum intact parathyroid hormone (PTH)?
Guideline 2: when serum calcium is high or high normal.
Note: Measurement of vitamin D levels may additionally be helpful as low vitamin D levels may mask primary hyperparathyroidism, or contribute to secondary hyperparathyroidism
193
What different stone analysis should clue you into different etiologies?
Guideline 3: Stone composition of uric acid, cystine or struvite implicates specific metabolic or genetic abnormalities
Calcium phosphate stone composition is more likely to be associated with certain medical conditions or medications, such as RTA Type 1, primary hyperparathyroidism, medullary sponge kidney and the use of carbonic anhydrase inhibitors.
194
How do you access for stone burden?
Guideline 4: Clinicians should obtain and review available imaging studies to quantify stone burden
195
Who should get additional metabolic testing (24H urine study)?
Guideline 5: recurrent stone formers, interested first time stone formers, pediatric stone formers
Also "high risk" stone formers: family history of stone disease, malabsorptive intestinal disease or resection, recurrent urinary tract infections, obesity or medical conditions predisposing to stones and solitary kidney persons
196
What is "metabolic testing" for recurrent and high risk stone formers?
Guideline 6: one or two 24-hour urine collections obtained on a random diet and analyzed for total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium and creatinine
197
Should you do a fast and oral calcium load test to distinguish among types of hypercalciuria
Guideline 7: NO
198
What minimum urine output volume should be the target for all stone formers?
Guideline 8: At least at least 2.5 liters (85 oz) per day (note: this is urine output- intake needs to be higher in order to achieve this). This can be easily monitored on a 24 hour urine study.
199
What dietary changes should you counsel patients with calcium stones and relatively high urinary calcium?
Guideline 9: limit sodium intake and consume 1,000-1,200 mg per day of dietary calcium- this is a normal amount of dietary calcium (not on supplements but also not shying away from calcium food)
Sodium increases urinary calcium excretion. The Panel supports a target of ≤100 mEq (2,300 mg) sodium intake daily. This goal is difficult to achieve.
200
What dietary changes should you counsel patients with calcium oxalate stones and relatively high urinary oxalate to make?
Guideline 10: limit intake of oxalate-rich foods (and stop vitamin C supplements) and maintain normal calcium consumption (however, persons with enteric hyperoxyalate absorption such as gastric bypass should be counseled to increase their calcium intake with meals to absorb the oxalate and poop it out)
201
What dietary changes should you counsel patients with calcium stones and relatively low urinary citrate to make?
Guideline 11: increase their intake of fruits and vegetables and limit non-dairy animal protein
202
What dietary changes should you counsel patients with cystine stones to make?
Guideline 13: Oral intake of at least 4L of water a day and limit sodium and protein intake
203
What dietary changes should you counsel patients with calcium or uric acid stones and relatively high urinary uric acid to make?
Guideline 12: limit intake of non-dairy animal protein (fish, seafood, poultry and red meats, "Anything with a face")
204
Who should you offer thiazide diuretics?
Guideline 14: high or relatively high urine calcium and recurrent calcium stones
Note: these are: hydrochlorothiazide (25mg orally, twice daily; 50mg orally, once daily), chlorthalidone (25mg orally, once daily), and indapamide (2.5mg orally, once daily)
check potassium and calcium while on this medication (BMP)- causes hypokalemia and glucose intolerance
Note- this only works if the patient also does sodium restriction
will cause hypercalcemia if a person has an undiagnosed hyperparathyroidism
205
To whom should you offer potassium citrate?
Guideline 15: patients with recurrent calcium stones and low or relatively low urinary citrate
Check potassium- frequent abdominal side effects with hyperkalemia
Alternatives to increase urinary pH: sodium bicarbonate, sodium citrate
206
To whom should you offer allopurinol?
Guideline 16: recurrent calcium oxalate stones who have hyperuricosuria and normal urinary calcium
NOT uric acid stones- remember, they need urinary alkalization with K citrate instead. In fact, guideline 19 says do not offer allopurinol routinely to uric acid stone formers
Causes elevated LFTs
207
What pharmacotherapy should you offer a person with recurrent calcium stones in whom other metabolic abnormalities are absent or have been appropriately addressed and stone formation persists?
Guideline 17: Clinicians should offer thiazide diuretics and/or potassium citrate
208
What pharmacotherapy should you try to give someone with uric acid and cystine stones to try to raise their urinary pH?
Guideline 18: potassium citrate
209
To whom should you offer cystine-binding thiol drugs, such as alpha-mercaptopropionylglycine (tiopronin, Thiola)
Guideline 20: patients with cystine stones who are unresponsive to dietary modifications and urinary alkalinization, or have large recurrent stone burdens.
Side effects: Elevated LFTs, anemia and other myelosuppression
210
To whom should you offer acetohydroxamic acid (AHA)?
Guideline 21: patients with residual or recurrent struvite stones only after surgical options have been exhausted. Remember this is like a last hope effort.
Side effects: anemia, phlebitis and hypercoagulable phenomena
211
When should you get a 24H urine test after initiation of treatment to assess response to dietary and/or medical therapy?
Guideline 22: You should get a single 24H urine test within 6 months
212
When should you consider getting a repeat stone analysis?
Guideline 25: When patients are not responding to treatment
213
What are some pharmacotherapy adverse events that you should think about when monitoring people on these meds?
Guideline 24: obtain periodic testing to access for this:
Thiazides: hypokalemia and glucose intolerance
allopurinol and tiopronin may cause an elevation in liver enzymes
AHA and tiopronin may induce anemia and other hematologic abnormalities
potassium citrate may result in hyperkalemia
214
What should you monitor patients with struvite stones for?
Guideline 26: reinfection with urease-producing organisms and utilize strategies to prevent such occurrences
215
What are some urease producing bacteria?
Klebsiella, proteus, and pseudomonas
216
What are some general medications that are stone-provoking?
Topiramate, acetazolamide, zonisamide (carbonic anhydrase inhibitor- causes RTA)
Triamterene (potassium sparing diuretic- causes medication crystals)
Vitamin C (coverts to oxalate)
Vitamin D and high levels of calcium (> 1200 mg/day)
Lipase inhibitors
Probenecid
chemotherapy (tumor lysis)
certain protease inhibitors (indinivir)- not able to see on CT
