Canadian Urological Association guideline: Evaluation and medical management of kidney stones Flashcards
What is the kidney stone prevalence reported in the United States National Health and Nutrition Examination Survey (NHANES) published in 2020?
The prevalence of kidney stones was reported to be 12% in men and 10% in women.
How has the incidence of stone formation changed between 2005 and 2015 according to U.S. data?
The incidence of stone formation increased from 0.6% to 0.9%.
What trend has been observed in the male-to-female ratio of stone formation?
The male-to-female ratio of stone formation is decreasing.
What systemic diseases are kidney stones associated with?
Kidney stones are associated with obesity, metabolic syndrome, and diabetes mellitus.
Kidney stones are associated with obesity, metabolic syndrome, and diabetes mellitus.
The recurrence rates are reported to be 30–50%.
What percentage of recurrent stone formers or those with more than one concurrent stone have a urinary metabolic abnormality?
Most recurrent stone formers or those with more than one concurrent stone (96.8%) have a urinary metabolic abnormality.
What percentage of patients with a high risk of recurrent stone disease undergo metabolic evaluation?
Only 7% of patients with a high risk of recurrent stone disease undergo metabolic evaluation.
What percentage of patients would prefer to take prophylactic medication to prevent future stones rather than undergoing surgery?
92% of respondents preferred medication to prevent future stones rather than undergoing surgery.
What percentage of patients prescribed pharmacological prevention were non-compliant, especially those on potassium citrate?
Close to 50% of patients prescribed pharmacological prevention were non-compliant, especially those on potassium citrate.
What are the estimated annual costs for patient care and lost work time related to recurrent stone disease?
The estimates of direct costs for patient care and the indirect costs related to lost work time exceed $5 billion USD annually.
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?
The search terms used were “nephrolithiasis,” “urolithiasis,” “kidney stone,” “renal stone,” and “urinary stone.”
What was the time period for the literature review in the updated Canadian Urological Association guideline on kidney stones?
The literature review covered the period from January 1, 2015, to July 1, 2021.
How many articles were initially identified in the literature review for the Canadian Urological Association guideline on kidney stones?
Initially, 11,640 articles were identified.
How many articles were deemed potentially relevant for the literature assessment in the updated Canadian Urological Association guideline on kidney stones?
Out of 11,640 articles, 293 were identified as potentially relevant.
How were the studies evaluated and recommendations made for the Canadian Urological Association guideline on kidney stones?
Studies were evaluated and recommendations made based on Oxford levels of evidence and grades of recommendation as per the CUA Guidelines Committee’s directive.
When was the last guideline published before the current Canadian Urological Association guideline on kidney stones?
The last guideline was published in 2016. Recommendations in the current guideline were modified based on the most current literature since 2016.
What are the recommended basic metabolic screenings for kidney stone evaluation?
Basic metabolic screenings should include urinalysis (with or without urine culture), serum electrolytes (Na, K, HCO3), calcium, creatinine, and a stone analysis when available.
What systemic disorders should be ruled out for a first-time stone former without identifiable risk factors?
Potential systemic disorders such as hyperparathyroidism and renal dysfunction should be ruled out.
Who should undergo an in-depth metabolic evaluation for kidney stones?
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.
What are the common conditions associated with struvite stones formation?
Struvite stones typically form in the setting of recurrent urinary infection, anatomical anomalies, and foreign bodies but occasionally are associated with metabolic abnormalities.
What is the role of the urease inhibitor acetohydroxamic acid (AHA) in the management of kidney stones?
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.
What is the recommended in-depth evaluation for patients with kidney stones?
The recommended in-depth evaluation includes serum tests, 24-hour urine tests, and a thorough dietary history.
Which elements should be measured in serum tests during an in-depth evaluation for kidney stones?
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.
What should be measured in a 24-hour urine collection during an in-depth evaluation for kidney stones?
Volume, creatinine, calcium, sodium, potassium, oxalate, citrate, uric acid, magnesium. Cystine should be measured if a cystine stone is known or suspected.
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.
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.
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.
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.
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.
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.
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.
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.
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.
What should be done if a patient continues to form new stones?
: A repeat stone analysis should be performed, as this may change management.
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.
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.
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.
Which metabolic abnormalities are associated with apatite stones?
Apatite stones were correlated with both hypercalciuria and hypocitraturia.
In which patients are uric acid stones typically found?
Uric acid stones are found in patients with low urinary pH.
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.
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.
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.
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.
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.
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.
What is the recommended daily urine output for all stone formers?
The recommended daily urine output for all stone formers is 2.5 liters.
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%.
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%.
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.
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.
What is the effect of milk on kidney stone formation?
Milk does not increase the risk of stones unless consumed in excess.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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.
What is the level of evidence and grade of recommendation for the above advice?
Level of Evidence 2–3, Grade C recommendation.
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.
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.
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.
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)
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Figure 2. Specific dietary and medical treatments for patients with uric acid stones.
Figure 3. Specific dietary and medical treatments for patients with cystine stones.
