Urinary Tract Calculi Flashcards
what is urinary tract calculi AKA
nephrolithiasis
def of nephrolithiasis
presence of crystalline stones (calculi) in the urinary system (kidneys and ureter)
what are renal stones made of
varying amounts of crystalloid and organic matrix
where do ureteric stones come from
they almost always originate in the kidney and then pass into the ureter
epi
common in middle age
males>females
risk factors
heat exposure
dehydration
increased BMI
what are renal stones made out of
crystalline mineral deposition which forms microscopic crystals
where do microscopic crystals (formed from crystalline mineral deposition) form
in the loop of Henle, distal tubules, collecting duct
why is there crystalline mineral deposition
elevated levels of urinary solutes such as calcium, uric acid, oxalate, sodium
decreased levels of stone inhibitors such as citrate and magnesium
what is urine supersaturation
occurs when there are too many solutes dissolved into a fluid, this leads to microscopic crystal formation
how does microscopic crystal formation lead to renal stones
these crystals are retained in the kidneys and grow to form renal stones
what are common types of renal stones
calcium stones (most common)
-calcium oxalate
-calcium phosphate
uric acid stones
how are UTC prevented
hydration
reduce sodium
risk factors
middle aged white men
obesity
dehydration
high protein and high salt
history
acute severe flank pain (renal colic)
radiates to the back and the groin
N+V
increased urinary frequency/ urgency which is associated with haematuria
Hx of previous nephrolithiasis (renal stones causing renal colic)
what colour are calcium oxalate stones
black/dark brown
what colour are calcium phosphate stones
dirty white
what colour are uric acid stones
yellow/reddish brown
examination
tender flank
medications which may increase risk of renal stones
what drugs increase risk of renal stones
antacids
Na+Ca containing medicines
Vit C+D
investigations
1 urinalysis -microhaematuria is very common 2 bloods -FBC (raised WCC may indicate infection) -UEs 3 non-contrast helical CT scan -good sensitivity and specificity for nephrolithiasis -identifies calcification (presence, size, location of stones) in kidneys and ureter
what should be excluded in nephrolithiasis
ectopic pregnancy
what does a urine pH >7 indicate
urea-splitting organisms such as proteus, pseudomonas, klebsiella
a 45y/o man presents with a 1hr history of sudden onset left-sided flank pain which radiates to his groin. The pt is writhing in agony and complains of N+V
renal colic by nephrolithiasis
what is the initial management for nephrolithiasis
conservative management
1 hydration (crystalloids)
2 pain control (morphine)
3 anti-emetics (ondansetron)
what is the acute management for nephrolithiasis
confirmed stones with no obstruction:
1 bacteriuria
-first line is hydration, pain control, anti-emetics with antibiotic therapy and surgical decompression
2 stones <10mm
-swap antibiotic therapy and surgical decompression for medical expulsive therapy
3 if stones >10mm
-swap antibiotic therapy and surgical decompression for surgical removal
confirmed stones with obstruction:
1 with infection
-first line is hydration, pain control, anti-emetics with antibiotic therapy, surgical removal and surgical decompression
what antibiotics are used for treatment of confirmed stones with no obstruction causing bacteriuria
trimethoprim or nitrofurantoin
what is surgical drainage as applied to confirmed stones with no obstruction causing bacteriuria
renal drainage by a ureteric stent past the obstructing stone or percutaneous nephrostomy
what is medical expulsive therapy
medication therapy to increase passing of the stone using a-blockers such as tamsulosin or alfuzosin
when is surgical removal of nephrolithiasis indicate
failure of medical expulsive therapy in smaller stones and larger stones (>10mm)
what treatments are used for surgical removal of nephrolithiasis
extracorporeal shock wave lithotripsy and uretoscopy are first line
what antibiotics are used for treatment of confirmed stones WITH obstruction causing infection
ampicillin or piperacillin
AND
gentamicin
what is the ongoing management for nephrolithiasis
in all cases, patients should increase fluid intake, decrease protein and salt intake
this is about controlling hyperuricosuria, hypercalcaemia, hyperoxaluria
what would be used to control hyperuricosuria
alkalinisation with potassium citrate or allopurinol
what would be used to control hypercalcaemia
diuretics (thiazide diuretics such as chlortalidone or hydrochlorothiazide)
what would be used to control hypocitraturia
potassium citrate
what is citrate used for in renal stone formation
a renal stone inhibitor
what would be used to control hyperoxaluria
oxalate chelator such as calcium carbonate or calcium citrate or potassium citrate
complications
bleeding post-Percutaneous nephrolithotomy (removal of gallstones through the skin)
prognosis
recurrence is common
