urolithiasis stones Flashcards
what are inhibitors of stone formation?
Magnesium
Citrate ( cuz it binds to calcium instead of oxalate )
Glycoseaminoglycans
what promotes stone formation?
Oxalate ( ca + oxalate = salt = crystallization )
Calcium
Foreign body or surface ( makes salts easily form a bubble )
what are the epideomolic risk factors for stone formation?
Male –> higher risk cuz higher oxalate due to testerone
Females—-> less risk cuz high lvl of citrate ( protect )
Age: Peak 30 to 50, uncommon before 20
Geography : More in warmer regions
Occupation : Jobs with heat exposure and dehydration , more common in people with sedentary jobs
BMI and Weight : More high in BMI and especially women
Water in take —> high incidence with decreased water intake
what are the etiological causes of stones?
Familial —> Renal tubular acidosis –> calcium phosphate stones —> cystineuria
Diet —>( high protein, more oxalate, low ph, low citrate ) ( vegetarians have dieteary oxalate ) , high sodium intake –> less sodium reabsorbtion –> less calcium reabsorption
Low water intake : Conc urine , Low pH,—> cystine and uric acid stones
Immobilization = bone resorption
Urinary system malformation -> PUJ stenosis, horse shoe kidney, calyx diverticulum - stasis
Metabolic disease—> hyperparathyroidism , cystinuria , renal tubular acidosis
Drug induced –> indinavir, ciprofloxacin
Short bowl –> Crohn disease–< hyperoxaluria
UTI —> protease –> ammonia –> alkaline
what is the crystallisation theory?
when conce of stone promoters like calcium and oxalate exceed conce of inhibitors like citrate and magnesium —-> this cause crystal formation
then
Crystal formation and aggregation leads to stone formation
what are the type of stones?
Calcium oxalate stones –> most common 80-85%
Uric acid stone —> 5-10%
Infection stone ( Strutive/triple stone )—> 2-20%
Calcium phosphate stone —> pure is rare
Calcium phosphate and calcium oxalate (mixed) = 10%
Cystine stone —> 1%
Others are rare :
Xanthine
Indinavir
matrix
which stones are radiolucent ?
Uric acid
Xanthine
Indinavir
Matrix
describe calcium oxalate stone?
80-85% of all stones
75% calcium oxalate —> MONOHYDRATE –> HARD STONE
25% calcium oxalate —> Dihydrate —> Softer stone
Radiopaque ( cuz calcium )
what are etiologies of calcium oxalate stone?
Hyper calciuria
Hyper oxaluria
Hypo Citraturia
what causes hyper calciuria ?
Increased intake of calcium or vitamin D
Increased calcium resorption from bone —> immobilization pr hyperparathyroidism
The increased calcium will go to urine
describe hyper oxaluria ?
Primary :
Increased liver production of oxalate –> autosommal recessive ( rare )
Secondary :
Diet : chocolate,black tee, beetroot, nuts , high protein diet
Short bowel syndrome —> Crohn’s disease —> Increased oxalate absorption cuz colon is exposed more to bile salts = increase permeability to oxalate
describe hypocitraturia ?
Citrate is an inhibitor for stone formation
15% to 50% of patients with calcium oxalate have hypocitraturia
what are 2 types of uric acid?
Uric acid —> Insoluble
Sodium urate —> Soluble ( Doesnt form stones )
at what ph does uric acid form stones?
Human uric acid is ACIDIC
end product of metabolism is acid
So acidic urine + uric acid in urine = uric acid stone formation
describe what causes uric acid stones?
Increase uric acid in urine from diet ( high protein )
Myeloproliferative disorder
Gout disease
Hemolytic anemia
20% of patients without gout have uric acid stone
what are the characteristics of uric acid stone ?
Radio-lucent stone —> can be seen as flling defect with IVP or CT scan regardless of plain or contrast
Can form staghorn stones
management of uric acid stones?
advise patient to take more fluid
Alkalinising agents may be needed- –> Potassium citrate , sodium carbonate
allopurinol in case of high serum uric acid
describe strutive stone?
2-20% of all stones
Formed by Magn - ammonium - phoshpate
can form staghorn stones
Formed by UTI –> Urease producing bacteria ( Protease, klebsiella, etc)
Urease will form ammonia
ammonia makes urine alkaline
this will help form the stones
For management we need to acidify the urine
Describe calcium phosphate stone?
RARE
form in high ph urine —> alkaline like ( sturivate )
caused by :
RTA : renal tubular acidosis —> autosomal dominant —> :
impaired kidney to acidify urine , so urine is high in ph and patient has metabolic acidosis ( cuz cant get rid of acids )
this high urine ph increases conc of calcium and phoshpate
its less common that the mixed calcium phosphate + calcium oxalate : 10% of all stones
describe cystine stones?
Very rare
Less than 1% of stones
Common pure metabolic stone disroder
Cystinuria :
Autosomal recessive defect in absorption of amino acids in proximal tubule of the kidney ( CYSTINE, ORTHININE, LYSINE , ARGININE ) –> COLA
Cystine is not soluble in urine and so precipitate and forms stone others are soluble so they dont form stones
Can form staghorn stone
what is the clinical presentation of renal stones?
Asymptomatic –> USUALLY ACCIDENTAL FINDING
Renal colic
Loain pain
Renal impairment
Recurrent attacks of infection
Pyelonephritis
Hematuria
Bladder output obstruction or urinary retention —> posterior urethral stone, intra mural stone
describe renal colic?
Abdominal pain –> spasmodic
Resulting from obstruction ( Either parietal or complete ) of the upper urinary tract ( usually stone )
Radiation : Loin to groin
Usually sudden onset
Rolling in pain, does not stay still
Hematuria
Nausea vomiting
Other symptoms include : Fever, dysuria
how do you assess renal colic?
History :
all questions of abd pain, previous episodes, known stone , similarity to previous pain, septic symptoms, comorbidities, drugs, family ,etc
Examination :
Tender loin, unable to settle , aortic abdominal aneurysm ,no peritonisms, temp, Bp
Urine analysis and culture :
Blood tests
Imaging
what could it be if you radiolucent stone on KUB? kidney, urter, bladder, xray?
Uric acid
xanthine
indinavir
Matrin
