08 septembre 2015

Comment prévenir l'apparition d'une prochaine pierre au rein?

Tiré du Canadian Pharmacist's Letter

Prevention of Recurrent Kidney Stones
Up to 50% of patients with a symptomatic kidney stone will have another episode within five years. Eighty percent of stones are comprised of calcium oxalate and/or calcium phosphate.  Risk factors for kidney stones include obesity, diabetes, hypertension, and gout. Treatment options include dietary changes and pharmacotherapy. 

Intervention (stone type)Comments
Dietary Interventions
Increase fluid intake
(any stone type)

Drink 3 L of fluid throughout the day, or enough to produce at least 2 to 2.5 L of urine daily.
Patients with cystine stones may need to drink 4 L of fluid daily to adequately dilute urinary cystine.
Increase fluid intake when needed to replace fluid loss through sweat.
The majority of fluid intake should be water.
Also consider sugar-free real lemonade, a natural citrate source (see potassium citrate, below). (Epidemiologic data suggest sugar may increase stone risk.)
Limit colas, especially sugar-sweetened

(any stone type) 
Citric acid sodas (e.g., sugar-free lemon-lime sodas as opposed to phosphoric acid-containing colas) are probably okay to consume.
Ensure 1000 to 1200 mg of calcium intake daily from food/supplements

(calcium stones)
Calcium binds dietary oxalate. Consume calcium with meals.

Limit oxalate-rich foods
(calcium oxalate stones)
Many oxalate-containing foods are healthy foods (e.g., spinach, nuts), so moderation, or eating oxalate-containing foods at the same time as calcium-containing foods (so calcium can bind oxalate in the gut), rather than complete avoidance, may be the best option.
Evidence of benefit is lacking for this intervention; recommendation is based on the association between high urinary oxalate levels and kidney stones.
Oxalate content of foods often varies from list-to-list due to differences in testing methods, soil content, and fruit/vegetable ripeness.
Avoid high-dose vitamin C supplements

(oxalate, uric acid, and cystine stones)
Vitamin C may cause urate, oxalate, or cystine stones. Hyperoxaluria, hyperuricosuria, hematuria, and crystalluria have occurred in people taking 1000 mg or more per day. In people with a history of oxalate kidney stones, supplemental vitamin C 1000 mg per day appears to increase stone risk by 40%.
Limit sodium to
2300 mg (100 mEq) daily
(calcium and cystine stones)
Lower dietary sodium is associated with lower urinary calcium and cystine excretion.
2300 mg of sodium is about one teaspoonful of table salt. Due to larger crystal size, kosher and sea salt may have less sodium per teaspoon (i.e., fewer crystals fit into the spoon).
Limit meat, cheese, and eggs
(calcium and uric acid stones)
Meats, cheese, and eggs make urine acidic.
Meat is a source of purines, which are converted to uric acid.
Limit animal protein

(cystine stones)
Animal protein is a source of cystine and its precursors.
Increase fruits and vegetables

(calcium, uric acid, and cystine stones)
Fruits and vegetables provide citrate and make urine more alkaline.
Pharmacotherapy: for patients with recurrent stones despite increased fluid intake
Potassium citrate (Urocit-K, generics [U.S.])
(calcium, uric acid, and cystine stones)
First-line for most patients, especially those with no identified risk factors. Well-tolerated.
Reduces urinary acidity (i.e., urinary alkalinizing agent) and provides citrate, which inhibits calcium stone formation. Good choice for patients with lower urine citrate levels.
Thiazide diuretic 

(calcium-containing stones)

Reduces urinary calcium. Good choice for patients with higher urine calcium levels.
Can combine with calcium citrate.
Daily doses studied include hydrochlorothiazide 50 mg, chlorthalidone 25 to 50 mg, and indapamide 2.5 mg. Lower doses may have fewer side effects, but no proof they work.

(calcium oxalate stones in patients who are hyperuricosuric and/or hyperuricemic; uric acid stones in patients who fail urinary alkalinization)
Reduces uric acid in the urine.
Not first-line, even for uric acid stones. Most patients with uric acid stones have low urine pH, not hyperuricosuria, so using potassium citrate to raise urine pH is first-line.
200 to 300 mg once daily or divided

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