Kidney Stones Flashcards
How are kidney stones formed?
A lot of solute compared to the amount of filtrate.
Formed from the combination of excreted/secreted ions whiting the glomerular filtrate
Name the three most common locations kidney stones get stuck.
Kidney (nephrolithiasis)
Ureter (ureterolithiasis)
Bladder (cystolithiasis)
What are the risk factors for kidney stones?
Genetic - male, familial risk (2.5x more likely)
Environmental - BMI >27, vegetarian, high fruit and high fibre diet (decreased risk)
Obesity
Metabolic syndromes - diabetes, hypertension (uric acid stones)
What are the most common type of kidney stones?
Calcium (80%)
What kind of calcium stones are there and how are they formed?
Calcium oxalate and calcium phosphate
Calcium complexes with phosphate of oxalate to form a central nucleus. The minerals in the supersaturated urine aggregate around it to form a crystal
What are struvite stone made from?
Magnesium
Ammonium
Phosphate
(5-10% of kidney stones)
What is the most common cause of struvite stones?
H.Pylori.
Because it breaks down urea into ammonium and carbon dioxide, this means ammonium will now be present in the urine. This reacts with the magnesium and phosphate already present in urine to make the stones
What are the main problems with struvite stones?
They commonly cause UTIs
They usually get stuck in the renal pelvis and grow into the major calyces - staghorn stone
Normally need surgical removal
What normally causes the formation of uric acid stones?
Conditions of gout or other reasons for high uric acid in the urine
Not visible on X-ray
Low density
Normally forms in pH of 5.1-5.9, so are treated with potassium alkali salts
The least common kidney stone is cysteine (1-2%). When do these occur?
Genetic defect in renal transport of cystine
Resemble struvite stones, with a smaller chance of infection because they are passed more often.
What solutes can kidney stones be made from?
Calcium
Oxalate
Urate
Cysteine
