Synopsis
Translate stone composition and biochemical risk into an individual fluid, dietary and drug plan, with measured response, prescribing safeguards and appropriate infection-stone surveillance.
- For adults, NICE advises 2.5–3 L water daily, salt no more than 6 g/day and normal calcium intake 700–1200 mg/day. EAU uses a 4–5 g/day salt target and recommends enough fluid to achieve urine volume above 2.5 L/day; tailor intake when heart or kidney disease limits fluid.
- Match prevention to the phenotype: consider potassium citrate for recurrent predominantly calcium-oxalate stones, particularly with hypocitraturia; consider a thiazide for recurrent calcium-oxalate disease with hypercalciuria after salt reduction, and allopurinol for appropriate hyperuricosuria.
- Prevention is monitored treatment, not a promise of no further stones. Check formulation-specific contraindications, baseline renal function and electrolytes, early drug safety and a repeat 24-hour urine profile eight to twelve weeks after pharmacological prevention begins.
Reasoning priorities
Choose a targeted medicine and establish whether it can be prescribed safely.
Review stone analysis, serum calcium, potassium, sodium and renal function, with hepatic tests and other drug-specific measures where needed. Use appropriate 24-hour urine calcium, citrate, oxalate, urate, sodium, pH and volume. An unverified numerical renal cutoff from another formulation must not replace the selected product’s restriction.
Worked reasoning
A fifty year old woman has recurrent stones containing 70% calcium oxalate and low citrate in two stable 24-hour collections.
- Her daily urine volume is 1.6 L and citrate 1.2 mmol/day, with normal serum calcium, potassium 4.2 mmol/L and normal renal function. The clinician reviews food, fluids and interacting medicines. She agrees practical measures to increase water intake and reduce salt while maintaining normal dietary calcium, with output and tolerability reviewed rather than an unmeasured instruction to drink more.
- The stone specialist selects the local SW London off-label potassium-citrate-mixture schedule:10 mL orally twice daily, using the chosen 1.5 g/5 mL product, so each dose contains 3 g potassium citrate. She shakes and dilutes the mixture and takes it after food. Renal dysfunction, hyperkalaemia, ventricular arrhythmia and Addison’s disease are excluded, and the prescription includes potassium/renal monitoring and illness advice; the licensed cystitis dose is not silently transferred into long-term stone prevention.
- The initiating team checks tolerance and blood results during its initial eight-week responsibility period. She reports no gastrointestinal intolerance; potassium is 4.4 mmol/L and renal function remains normal. At twelve weeks, repeat urine volume is 2.6 L/day and citrate 2.5 mmol/day. The team reviews urine pH alongside those improvements to avoid unnecessary excess alkalinisation.
- The recorded response supports continuing the agreed dose and habits with an owned monitoring plan. At the supplied six-month review she has had no symptomatic recurrence, but the clinician explains that this observation does not prove permanent protection. Future urine tests, imaging and prescribing review remain matched to her risk and any new symptoms.
Key medicines
Potassium citrate mixture 1.5 g/5 mL, selected Thornton and Ross productSelected SW London specialist stone-prevention schedule, off-label:10 mL orally twice daily, equivalent to 3 g per dose and 6 g/day of this product. Shake, dilute well with water and take after meals. Review and individualise to biochemical response and tolerance; the specialist retains care for at least 8 weeks under that local protocol. This is long-term reviewed prevention, not a short cystitis course.The selected SmPC contraindicates renal dysfunction, hyperkalaemia, ventricular arrhythmias and Addison’s disease; do not reinterpret the local protocol’s eGFR thresholds as permission to ignore these product restrictions. The worked patient has normal renal function. Check potassium/renal function and review potassium supplements, potassium-sparing diuretics, ACE inhibitors, ciclosporin and aliskiren; cardiac glycosides also need review. Urinary alkalinisation reduces activity of nitrofurantoin and methenamine. Monitor pH to avoid excess alkalinisation and calcium-phosphate risk. Gastrointestinal irritation may limit use. The mixture contains sucrose and is unsuitable in the stated hereditary fructose/glucose-galactose/sucrase-isomaltase disorders. Under the local illness advice, withhold during acute gastroenteritis and restart only after 24–48 hours of recovery with normal eating/drinking and an appropriate safety assessment. Long-term stone use in pregnancy is not established by the short-term cystitis label.
Indapamide 2.5 mg immediate-release tablets, selected Strides productSpecialist-selected off-label stone prevention for persistent hypercalciuria:2.5 mg orally once daily in the morning, as included in the EAU calcium-oxalate algorithm. Do not exceed 2.5 mg/day under this selected product schedule or assume interchangeability with 1.5 mg modified-release tablets. Review early safety and urine response at 8–12 weeks; continuation depends on benefit and tolerance.Contraindicated in severe renal failure, including CrCl below 30 mL/min, severe hepatic impairment or hepatic encephalopathy, hypokalaemia, hyponatraemia or hypercalcaemia, porphyria, Addison’s disease and relevant sulfonamide/product hypersensitivity. Use only when renal function is normal or minimally impaired; review exact renal assessment in older people. Measure sodium before starting and regularly, potassium during the first week and more often if at risk; follow magnesium, renal function, pressure, glucose and urate as appropriate. Correct electrolyte disturbance and stop for increasing renal insufficiency or hepatic encephalopathy. Avoid routine lithium combination; check QT-prolonging drugs, digoxin, ACE inhibitors, NSAIDs and other potassium-lowering drugs. Acute eye pain or visual loss needs immediate cessation and urgent assessment for angle closure; stop for photosensitivity and assess. Avoid during pregnancy and do not use while breastfeeding. Do not use this lactose/sucrose-containing product in the listed hereditary galactose or fructose intolerance, total lactase deficiency, glucose-galactose malabsorption or sucrase-isomaltase insufficiency.