Urinary Tract Calculi

Question 1

what is urinary tract calculi AKA

Answer 1

nephrolithiasis

Question 2

def of nephrolithiasis

Answer 2

presence of crystalline stones (calculi) in the urinary system (kidneys and ureter)

Question 3

what are renal stones made of

Answer 3

varying amounts of crystalloid and organic matrix

Question 4

where do ureteric stones come from

Answer 4

they almost always originate in the kidney and then pass into the ureter

Question 5

epi

Answer 5

common in middle age

males>females

Question 6

risk factors

Answer 6

heat exposure
dehydration
increased BMI

Question 7

what are renal stones made out of

Answer 7

crystalline mineral deposition which forms microscopic crystals

Question 8

where do microscopic crystals (formed from crystalline mineral deposition) form

Answer 8

in the loop of Henle, distal tubules, collecting duct

Question 9

why is there crystalline mineral deposition

Answer 9

elevated levels of urinary solutes such as calcium, uric acid, oxalate, sodium
decreased levels of stone inhibitors such as citrate and magnesium

Question 10

what is urine supersaturation

Answer 10

occurs when there are too many solutes dissolved into a fluid, this leads to microscopic crystal formation

Question 11

how does microscopic crystal formation lead to renal stones

Answer 11

these crystals are retained in the kidneys and grow to form renal stones

Question 12

what are common types of renal stones

Answer 12

calcium stones (most common)
-calcium oxalate
-calcium phosphate
uric acid stones

Question 13

how are UTC prevented

Answer 13

hydration

reduce sodium

Question 14

risk factors

Answer 14

middle aged white men
obesity
dehydration
high protein and high salt

Question 15

history

Answer 15

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)

Question 16

what colour are calcium oxalate stones

Answer 16

black/dark brown

Question 17

what colour are calcium phosphate stones

Answer 17

dirty white

Question 18

what colour are uric acid stones

Answer 18

yellow/reddish brown

Question 19

examination

Answer 19

tender flank

medications which may increase risk of renal stones

Question 20

what drugs increase risk of renal stones

Answer 20

antacids
Na+Ca containing medicines
Vit C+D

Question 21

investigations

Answer 21

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

Question 22

what should be excluded in nephrolithiasis

Answer 22

ectopic pregnancy

Question 23

what does a urine pH >7 indicate

Answer 23

urea-splitting organisms such as proteus, pseudomonas, klebsiella

Question 24

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

Answer 24

renal colic by nephrolithiasis

Question 25

what is the initial management for nephrolithiasis

Answer 25

conservative management 1 hydration (crystalloids) 2 pain control (morphine) 3 anti-emetics (ondansetron)

Question 26

what is the acute management for nephrolithiasis

Answer 26

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

Question 27

what antibiotics are used for treatment of confirmed stones with no obstruction causing bacteriuria

Answer 27

trimethoprim or nitrofurantoin

Question 28

what is surgical drainage as applied to confirmed stones with no obstruction causing bacteriuria

Answer 28

renal drainage by a ureteric stent past the obstructing stone or percutaneous nephrostomy

Question 29

what is medical expulsive therapy

Answer 29

medication therapy to increase passing of the stone using a-blockers such as tamsulosin or alfuzosin

Question 30

when is surgical removal of nephrolithiasis indicate

Answer 30

failure of medical expulsive therapy in smaller stones and larger stones (>10mm)

Question 31

what treatments are used for surgical removal of nephrolithiasis

Answer 31

extracorporeal shock wave lithotripsy and uretoscopy are first line

Question 32

what antibiotics are used for treatment of confirmed stones WITH obstruction causing infection

Answer 32

ampicillin or piperacillin AND gentamicin

Question 33

what is the ongoing management for nephrolithiasis

Answer 33

in all cases, patients should increase fluid intake, decrease protein and salt intake this is about controlling hyperuricosuria, hypercalcaemia, hyperoxaluria

Question 34

what would be used to control hyperuricosuria

Answer 34

alkalinisation with potassium citrate or allopurinol

Question 35

what would be used to control hypercalcaemia

Answer 35

diuretics (thiazide diuretics such as chlortalidone or hydrochlorothiazide)

Question 36

what would be used to control hypocitraturia

Answer 36

potassium citrate

Question 37

what is citrate used for in renal stone formation

Answer 37

a renal stone inhibitor

Question 38

what would be used to control hyperoxaluria

Answer 38

oxalate chelator such as calcium carbonate or calcium citrate or potassium citrate

Question 39

complications

Answer 39

bleeding post-Percutaneous nephrolithotomy (removal of gallstones through the skin)

Question 40

prognosis

Answer 40

recurrence is common