Stones: Evaluation, Prevention, and Non-Surgical Management

ROKS nomogram for predicting recurrent stone episodes, from Rule 2014

Evaluation after first stone episode, from Campbell's

Reasons to get a 24hr urine collection, from Campbell's

Stone management, from Campbell's

Risk factors

Epidemiology

Factors increasing stone formation

Factors decreasing stone formation

Anatomic risk factors

Medication

Stone Prevention

Dietary recommendations

Choosing fluids

Juice options

Calcium balance

Mineral Metabolism Workup

Patient history

Components

Hypercalciuria

24hr Urine Collection

Measured variables

Tips for Collection

Management based on metabolic workup parameters

Dehydration Hypercalcuria Hypercalcemia Hypernatruria Hyperuricosuria Low urinary pH Hypocitraturia Hyperoxaluria Stone composition Other findings Management
Yes - Increase fluid intake to 2-3L
No Yes Yes No - CaPhos HyperPTH Parathyroidectomy
No - Thiazide diuretic
Yes Limit sodium intake
No Yes Yes - Calcium - Hydration
Alkalinization
Uric acid
No - Hyperuricosemia Treat underlying cause
Allopurinol
No No Yes - KCit supplement
No (increased) - CaPhos Hypokalemia/Hypochloremia KCit + Hydration (RTA I)
No Yes - Limit dietary oxalate
Consider B6 supplement
No Struvite Urease-splitting bacteria Complete stone removal
Acetohydroxamic acid
Cystine Cystinuria Hydration
Alkalinization
Thiola
Ammonium acid urate Radiolucent Check for chronic diarrhea
Xanthine Check for mutation vs allopurinol use
Calcium Otherwise normal KCit supplements

Medications

Class Mechanism Indication Side effects Dosing
Thiazide diuretics distal tubule calcium resorption, sodium excretion Hypercalciuria, calcium stones Hypokalemia (may need supplements), hyperuricosuria, hypercalcemia, hyperglycemia, hypocitraturia (secondary to intracellular acidosis), tachyphylaxis HCTZ 25mg BID
Chlorthalidone 25mg QD
Indapamide 2.5mg QD
Potassium citrate (KCit) Increases urinary citrate, alkalinizes urine, binds urinary calcium Calcium stones, low urinary citrate, Type I RTA, chronic diarrhea (use liquid form), thiazide-induced hypocitraturia GI symptoms, hyperK (requires regular monitoring), increased CaPhos risk, wax coating passes in stool 20mg BID-TID
Calcium supplements Prevents oxalate absorption, maintains normocalcemia Hypocalcemia, hyperoxaluria - test on and off supplementation Increases calcium stone risk 500-600mg CaCarb BID
Sodium bicarbonate
Sodium citrate
Increases urinary citrate, alkalinizes urine KCit replacement if hyperkalemia risk Hypernatremia
Allopurinol (Zyloprim) Inhibits uric acid production Calcium stones in setting of hyperuricosuria (> 800/day) and normal calcium, do not give for uric acid stones Transaminitis, rash, myalgias 300mg daily
Alpha-mercaptopropionylglycine (Thiola) Inhibits formation of insoluble cystine bond Cystinuria Transaminitis, anemia, asthenia, GI distress, rash 300mg BID, titrate up PRN
Acetohydroxamic acid Urease inhibitor Struvite stones that cannot be managed surgically Phlebitis/DVT, hemolytic anemia (3-15%), hypercoagulable state, tremor, headache, rash, palpitations, GI distress, alopecia 250mg BID-TID

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