Renal Tract Calculi Alex Papachristos

Overview Background Background Pathophysiology Pathophysiology Epidemiology Epidemiology Presentation Presentation Investigation Investigation Management Management

Background 1% of hospital admission are due to acute renal colic 1% of hospital admission are due to acute renal colic Excruciating pain > broken bones, childbirth, gunshot Excruciating pain > broken bones, childbirth, gunshot

Pathophysiology supersaturation of urine by stone- forming constituents (calcium, oxalate, uric acid) supersaturation of urine by stone- forming constituents (calcium, oxalate, uric acid) Crystals / foreign bodies act as nidi – ions from supersaturated urine can form microscopic crystalline structures Crystals / foreign bodies act as nidi – ions from supersaturated urine can form microscopic crystalline structures

Stone composition 80% calcium containing (oxalate/phosphate) 80% calcium containing (oxalate/phosphate) Struvite (10-15%) Struvite (10-15%) Uric acid (5-10%) Uric acid (5-10%) Rare – familial (homocysteinuria), Indinavir Rare – familial (homocysteinuria), Indinavir

Epidemiology Lifetime prevalence – 12% for men, and 7% for women (US data) Lifetime prevalence – 12% for men, and 7% for women (US data) Rates are doubled if there is a FMH Rates are doubled if there is a FMH Peak incidence years Peak incidence years Initial stone attack after 50yrs uncommon Initial stone attack after 50yrs uncommon Male:Female ratio: 3:1 Male:Female ratio: 3:1 More common in Anglo-Saxons and Asians than native Americans, African More common in Anglo-Saxons and Asians than native Americans, African

Risk factors Low fluid intake Low fluid intake Western diet Western diet Supplemental calcium Supplemental calcium

Presentation Symptoms Symptoms –Pain –Nausea and Vomiting –Haematuria –Fever

Diagnosis Xray KUB Xray KUB CT KUB (non-contrast) CT KUB (non-contrast) Xray IVP Xray IVP

Management Initial Mx: Initial Mx: –Pain relief –Hydration –Basic bloods –Is there an indication for urgent intervention?

Indications for Intervention Infected obstructed kidney Infected obstructed kidney Impaired renal function due to obstruction Impaired renal function due to obstruction Solitary kidney Solitary kidney Uncontrolled pain Uncontrolled pain

Emergency Intervention Immediate aim is relieving obstruction Immediate aim is relieving obstruction –Double-J stent insertion –Ureteroscopic stone extraction (if no active infection) –Nephrostomy

Definitive managment

Will the stone pass? Size of stone is inversely proportional to its chance of passing spontaneously Size of stone is inversely proportional to its chance of passing spontaneously Rule of thumb: Rule of thumb: –1mm stone - 90% chance of passing –4mm stone - 60% chance –8mm stone - 20% chance

Watchful Waiting Stones that have not passed in two month are unlikely to do so Stones that have not passed in two month are unlikely to do so Permanent damage to kidney occurs after ~4 weeks Permanent damage to kidney occurs after ~4 weeks Can try an alpha-1 blocker - smooth muscle relaxant Can try an alpha-1 blocker - smooth muscle relaxant

Treatment options Watchful waiting Watchful waiting ESWL ESWL Ureteroscopic stone extraction Ureteroscopic stone extraction Percutaneous nephrolithotomy Percutaneous nephrolithotomy

Long-term Management High fluid intake is most important High fluid intake is most important Stone analysis - alkalanise urine if uric acid stone Stone analysis - alkalanise urine if uric acid stone Low salt, high fibre diet Low salt, high fibre diet

Bladder Calculi Most common in men aged > 50 with bladder outlet obstruction Most common in men aged > 50 with bladder outlet obstruction –Stasis of urine leads to stone formation