Week 7

Question 1

What is urolithiasis

Answer 1

Formation of stones in the urinary tract

Question 2

Most common location of urolithiasis

Answer 2

Renal pelvis

Question 3

Where can uroliths be found

Answer 3

Renal pelvis and calyces
Ureter (usually from kidney)
Bladder

Question 4

Causes of bladder stones

Answer 4

Bladder outflow obstruction - urethral structure, prostate obstruction, neurogenic bladder
Foreign body e.g catheter or non absorbable sutures
Passed down form upper tract

Question 5

Symptoms of bladder stones

Answer 5

Anuria

Painful bladder distension (urinary retention)

Question 6

What are nephroliths

Answer 6

Solid materials formed in kidneys from minerals and urine

Question 7

Types of nephroliths

Answer 7

99% calcium stones - calcium oxolate, calcium phosphate, uric acid, struvite
1% other - drug, cysteine, ammonium acid urate

Question 8

Causes of nephrolithiasis

Answer 8

Urine supersaturation
Urine stasis
Drugs
Congenital e.g polycystic kidney

Question 9

What are Randall’s plaques

Answer 9

Calcium oxolate stones growing on interstitial deposits of calcium phosphate e.g renal papillae, ducts of Bellini, free in solution

Question 10

What is urine supersaturation

Answer 10

Solvent contains more solute than it can hold so crystals form by nucleation

Question 11

Broad cause of urine supersaturation

Answer 11

Low water content - dehydration
High mineral content
Low solubility of solute

Question 12

What alters solubility of solute in urine

Answer 12

Urine pH

Question 13

Consequences of acidic or alkaline urine

Answer 13

Acid - favours calcium oxolate and uric acid stone formation

Alkaline - favours calcium phosphate stone formation

Question 14

What is renal tubular acidosis

Answer 14

Persistently alkaline urine and increased citrate excretion

Leads to calcium phosphate stone formation

Question 15

What senses serum Ca

Answer 15

Parathyroid glands
Kidneys
Brain

Question 16

Actions of PTH

Answer 16

Stimulates osteoclasts
Increases renal reabsorption of Ca
Increases phosphate excretion
Increases calcitriol synthesis

Question 17

Actions of calcitriol

Answer 17

Stimulates osteoclasts
Increases renal reabsorption of Ca
Increases intestinal absorption of Ca

Question 18

Actions of calcitonin

Answer 18

Inhibits osteoclasts

Increase excretion of Ca

Question 19

Causes of hypercalciuria

Answer 19

Hypercalcaemia
Excessive dietary Ca
Excessive breakdown of bone e.g prolonged immobilisation
Increased gut absorption (idiopathic)

Question 20

Causes of hypercalcaemia

Answer 20

Hyper secretion of PTH
Increased bone destruction
Excessive dietary Vitamin D and Ca
Thiazides diuretics
Sarcoidosis - macrophages activate vitamin D precursor

Question 21

Causes of hyper secretion of PTH

Answer 21

Parathyroid hyperplasia/tumour
Secondary to renal failure - retention of phosphate reduces Ca in serum
Ectopic secretion of PTHrP by a malignant tumour

Question 22

Reasons for increased bone destruction

Answer 22

Immobilisation
Bone marrow tumour
Diffuse skeletal metastases
Paget’s disease

Question 23

Clinical signs of hypercalcaemia

Answer 23

Severe muscle weakness
Fractures or bone pain
Renal stones
Gallstones
Constipation
Depression
Seizures

Question 24

Causes of hyperoxaluria

Answer 24

Type 1/2 primary hyperoxaluria - autosomal recessive disorder of oxolate synthesis
Increased intestinal absorption - secondary to GI disease e.g Chron’s
High dietary oxolate intake - tea, rhubarb, spinach, nuts
Low Ca intake - stimulates oxolate absorption in gut

Question 25

What are struvite stones

Answer 25

Magnesium ammonium phosphate stones with variable amounts of Ca

Question 26

What causes struvite stones

Answer 26

Secondary to infection by microorganisms that produce: Urease enzyme - produce ammonium hydroxide Mucoprotein - provides organic matrix for stone formation

Question 27

What is the usual type of struvite stone

Answer 27

Staghorn calculi - cast of renal collecting system

Question 28

Risk factors for struvite stones

Answer 28

``` Risk factors for UTIs: Spinal cord injury Neurogenic bladder Vesicoureteric reflux Urinary tract obstruction ```

Question 29

Risk factors for uric acid stones

Answer 29

Hyperuricaemia | Urine pH <5.5

Question 30

What is uric acid

Answer 30

Endpoint of purine metabolism

Question 31

Causes of hyperuricaemia

Answer 31

Idiopathic gout | Increased cell turnover - lympho/myelo-proliferative disorders, following chemotherapy

Question 32

Which renal stone is hardest to detect

Answer 32

Uric acid | It is radiolucent (need CT)

Question 33

Symptoms of renal stones

Answer 33

``` Asymptomatic Renal colic Recurrent UTI Loin pain Haematuria Renal failure Urinary tract obstruction ```

Question 34

Where is renal colic pain referred to

Answer 34

Flank to iliac fossa Inner thigh Labia/scrotum

Question 35

How do you investigate renal stones

Answer 35

Mid stream urine sample - culture, detect RBCs and crystals Serum sample - urea, electrolytes, creatinine, minerals AXR CT (ideally during pain) Examine calculi

Question 36

Complications of renal stones

Answer 36

Acute pyelonephritis Pressure necrosis of renal parenchyma Urinary obstruction Ulceration through wall of collecting system

Question 37

Treatment for renal stones

Answer 37

Analgesia Ureteroscopy Percutaneous nephrolithotomy - remove renal stones by cutting into back Shock wave lithotripsy - focused ultrasonic energy to fragment stones so they can be passed spontaneously (<5mm)

Question 38

Prevention of renal stones

Answer 38

Keep hydrated to reduce urine supersaturation Increase Ca excretion (diuretics) Potassium citrate to alkalinise urine - reduces risk of calcium oxolate, uric acid and cysteine stones