Renal Stones Flashcards
What is the epidemiology of renal stones?
Common - 1/10
- Though many will remain asymptomatic
M>F at 3:1
Peaks 30-50yrs
Recurrence is common
What are some risk factors for developing renal stones?
Anatomical anomalies:
- In kidneys +/- tract e.g. horseshoe kidney, urethral stricture
Conditions:
- HTN
- Gout
- Hyperparathyroidism
- Chronic metabolic acidosis
Physiological states:
- Immobilisation
- Dehydration
- Hypercalciuria
- Hyperuricosuria
- Cystinuria
Drugs:
- Ca/Vit D supplements
- Diuretics
Indwelling Foley catheters
- More likely to develop bladder stones
FHx renal stones
What is the pathophysiology of renal stones?
Form when urine is supersaturated with salt + minerals e.g.
- Ca based stones = 80% of all stones
- Ca oxalate = most common, 80% of calcium stones
- Ca phosphate = 20% of calcium stones
- Uric acid = 10% of all stones
- Struvite (ammonium magnesium phosphate) = frequently present as staghorn calculi, secondary to infection with urea splitting organisms e.g. Proteus, Pseudomonas and Klebsiella (NOT E.coli)
- Cystine stones = 1%, from cystinuria - an inborn error of metabolism
Citrate and Mg are inhibitors of stone formation (so low levels can precipitate)
Low urinary volume and pH also contribute to the process
Vary in size:
- Tiny pebbles, a few mm across
- Large staghorn calculi that fill the renal calyces and whole pelvis sometimes
- > 5mm needed to obstruct
Can obstruct at any point along the urinary tract
- Large stones can form in the bladder when urine becomes stagnant through stasis = 5% of stones
