Treatment
Treatments to reduce kidney stone recurrence have common and stone-specific aspects. All stone formers should be advised to maintain a high fluid intake, night and day, sufficient to result in straw-coloured urine.
Calcium Oxalate and Phosphate Stones (not Primary or Enteric Hyperoxaluria)
Restrict animal protein.
Restrict sodium chloride intake (notably sodium chloride increases calciuria, whereas sodium bicarbonate does not).
Thiazide-type diuretics halve recurrence rate,[6] with or without amiloride (adds a weak anti-calciuretic action and may reduce adverse effects of potassium depletion).
Citrate supplementation [either dietary (e.g. citrus juices)[6] or potassium citrate] should be considered, particularly in hypocitraturia.[7]
Allopurinol reduces stone recurrence among patients with calcium oxalate stones and high 24-h urine uric acid excretion; Febuxostat has similar effects but has not been tested in outcome trials. Higher urine uric acid concentrations reduce calcium oxalate solubility.[8]
Enteric Hyperoxaluria
No RCT evidence exists, but the following are logical:[9]
Restriction of dietary oxalate.
Use of oxalate binders with meals (most phosphate binders also bind oxalate).
Bile acid sequestrants (reduce colonic permeability to oxalate; colestyramine and colestipol may also bind oxalate).
Pancreatic enzyme replacement, if indicated.
Restoration of normal bowel anatomy after malabsorptive bariatric surgery.
Primary Hyperoxaluria
Correct hypercalciuria, hyperuricosuria and hypocitraturia.
No proven role for dietary oxalate restriction.
High-dose pyridoxine supplementation is effective in some Type 1 patients, depending on the causative mutation;[10] watch for neuropathy.
Consider liver transplant in patients with severe phenotypes (typically Type 1, some Type 2), particularly if stone formation has caused kidney failure and the patient also needs a kidney transplant.
Cystinuria
Restrict animal protein (reduces acid load and methionine intake).
Restrict sodium intake.
Use potassium citrate to achieve urine pH ≥ 7; if not tolerated, use sodium bicarbonate (effects on urine pH outweigh effects of sodium load on cystine excretion).
Cystine-chelating drugs—penicillamine and tiopronin. Both require careful counselling about potential adverse effects.[7] Titrate to keep urine cystine concentration <1000 μmol/L.
Uric Acid Stones
Treat diarrhoea/high ileostomy output.
Restrict animal protein intake (reduces acid load).
Weight loss (probably restores urine buffering capacity).
Sodium bicarbonate, adjust dose to achieve pre-meal urine dipstick pH >7.
Allopurinol/Febuxostat contribute very little if urine remains acid.[4]
Nephrol Dial Transplant. 2017;32(12):1984-1986. © 2017 Oxford University Press
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