Kidney Stones Flashcards
What are the modifiable risk factors for kidney stones?
Obesity
Chronic dehydration
High ambient temperatures
Diet high in oxalate, urate, sodium and animal protein
What is the most common stone?
Calcium oxalate which are Radiopaque
Can form in any urine pH
Associated with low urine volume and hypercalciuria
Which kidney stones are radiolucent?
Uric acid stones which Only form in acidic urine (pH < 5.5)
Associated with diabetes, obesity and gout
May occur due to malignancy (due to high cell turnover, especially due to chemotherapy)
When do calcium phosphate stones form?
Tend to form in alkaline urine
Associated with renal tubular acidosis types 1 and 3
Associated with primary hyperparathyroidism
What are struvite stones?
Composed of magnesium, ammonium and phosphate
Often occur due to urease-producing bacterial infection (e.g. Proteus, Enterobacter, Klebsiella)
Associated with alkaline urine
May form staghorn calculi (which involve the renal pelvis and extend into mulitple calyces)
What are cystine stones?
Faintly radiopaque
Occur due to cystinuria (an autosomal recessive condition affecting renal reabsorption of amino acids)
More likely to form in alkaline urine
Often occur in young patients
What is the presentation for renal stones?
Sudden onset of
renal or ureteric colic - There is severe, spasmodic pain that often starts in one flank (or ““loin””) - It may then radiate to the groin (i.e. ““loin to groin”” pain) - It may also radiate to the scrotum, labia or anterior thigh
Which imaging should be performed for kidney stones?
Non-contrast CT KUB should be done urgently in patients with suspected renal colic
Ultrasound KUB is an alternative that should be offered to pregnant women and under 16 year olds
Abdominal X-ray also has a role e.g. to follow up radio-opaque stones that are being managed conservatively
What is the first line analgesic for kidney stones?
First line is NSAIDs
What are the radiopaque stones?
Calcium phosphate
Struvite
What is considered for patients with distal ureteric stones?
Using an alpha blocker like tamsulosin to relax smooth muscle and promote passage of stones
What is first line for stones over 1cm?
Extracorporeal shockwave lithotripsy for stones which is first line
What is first line for retrieving stones 1-2cm in size
Ureteroscopy for retrieving scones endoscopicaly
What is first line for renal stones over 2cm?
Percutaneous nephrolithotomy to remove stones through a puncture wound in the skin
Which stones are acidic?
Uric acid stones
-> calcium oxolate stones can form in any urine pH
Which stones form in alkaline urine?
Calcium phosphate
Struvite
Cystine stones can form
Which stones are linked to diabetes and obesity?
Uric acid
Which stones are linked to renal tubular acidosis type 1 and 3?
Calcium phosphate which is also associated with primary hyperparathyoridism
What stone causes stag horn calculi?
Struvite stones
What are the medication induced causes of stones?
zonisamide
Allopurinol
Ceftriaxone
indinavid
What is the ideal imaging for renal colic suspected?
Non-contrast CT KUB
What imaging should be offered for pregnan women and under 16s?
Ultrasound KUB
What is the role of abdominal X-ray?
For radio-opaque stones
