Kidney Stones

Question 1

What is urolithiasis?

Answer 1

Formation of stones in the urinary tract

Question 2

What is the commonest site of renal stone formation?

Answer 2

Renal pelvis

Question 3

What percentage of kidney stones occur as unilateral?

Answer 3

80%

Question 4

How can bladder stones form?

Answer 4

Can descend from the kidneys

Can form in the bladder

Question 5

Give some dietary conditions that increase a patient’s risk of kidney stones

Answer 5

Low protein diet 
Chronic diarrhoea 
Dehydration 
Increase oxalate consumption 
Vitamin A, B1, B6 deficiencies 
Magnesium deficiency

Question 6

What is a lithotomy?

Answer 6

Surgical removal of a calculus

From bladder, kidney or urinary tract

Question 7

What are the complications of kidney stones?

Answer 7

Haemorrhage 
Infection 
Fistulae
Incontinence
Erectile dysfunction

Question 8

Is it easier for men or women to pass stones?

Answer 8

Women

Have a shorter urethra

Question 9

Name some causes of bladder stones

Answer 9

Bladder outflow obstruction (stricture, BPH)
Presence of a foreign body
Some are passed down from upper urinary tract

Question 10

What are 2 other names of a kidney stone?

Answer 10

Renal calculus

Nephrolith

Question 11

Are stones more common in men or women?

Answer 11

Men (2:1)

Question 12

Which kidney stones are the only type commoner in women?

Answer 12

Struvite stones

Question 13

What percentage of kidney stones are a type of calcium stone?

Answer 13

99%

Question 14

Name the different types of calcium stones starting from the most prevalent

Answer 14

Calcium oxalate (with calcium phosphate)
Calcium phosphate
Struvite (infection)
Uric acid

Question 15

Name some kidney stones that are not calcium based

Answer 15

Cysteine stones
Drug stones
Ammonium and urate stones
Urine stones

Question 16

When do urine stones form?

Answer 16

When there is a supersaturation of the urine with minerals

Minerals start to crystallise out of solution

Question 17

What pathologies can lead to increased mineral content in the urine?

Answer 17

Hypercalcaemia -> hypercalciuria
Hyperoxaluria
Hyperuricaemia -> hyperuricosuria
Cysteinuria

Question 18

Acidic urine favours the formation of which stones?

Answer 18

Calcium oxalate

Uric acid

Question 19

Alkaline urine favours the formation of which stones?

Answer 19

Calcium phosphate

Question 20

How do the majority of calcium oxalate stones seem to form?

Answer 20

Appear to grow like stalactites
Attached to exposed interstitial deposits of calcium phosphate
(Randall’s plaque)
Core of calcium phosphate surrounded by calcium oxalate

Question 21

55% of calcium oxalate stones are associated with which plasma/urine abnormalities?

Answer 21

Hypercalcuria

Without hypercalcaemia

Question 22

Name the 3 substances that control calcium levels

Answer 22

PTH
Calcitriol (activated vit D)
Calcitonin

Question 23

In which organs are the most calcium sensing receptors located?

Answer 23

Parathyroid glands
Kidney
Brain

Question 24

Describe the effects of PTH

Answer 24

Increased osteoclastic resorption of bone
Increased intestinal absorption
Increased synthesis of calcitriol 
Increased tubular reabsorption 
Increased excretion of phosphate

Question 25

Describe the effects of calcitriol

Answer 25

Increased calcium absorption in gut | Increased calcification and resorption of bone - keeps bone turning over

Question 26

Describe the effects of calcitonin

Answer 26

Inhibits osteoclastic resorption of bone | Increased renal excretion of calcium and phosphate

Question 27

What is the most common metabolic abnormality in calcium stone formers?

Answer 27

Hypercalcuria

Question 28

Name some causes of hypercalcuria

Answer 28

Idiopathic Hypercalcaemia Increased dietary intake of calcium Excessive resorption of calcium from skeleton

Question 29

Name some causes of hypercalcaemia

Answer 29

Hypersecretion of PTH Destruction of bone tissue Excessive vit D ingestion Thiazides

Question 30

Describe primary hypersecretion of PTH

Answer 30

Parathyroid hyperplasia | Tumour

Question 31

Name some reasons for destruction of bone tissue

Answer 31

Primary tumour of bone marrow Diffuse skeletal metastases Paget's disease of bone Immobilisation

Question 32

Give some clinical signs of hypercalcaemia

Answer 32

Severe muscle weakness Painful bones Renal stones Abdominal groans - constipation, ulcers, gallstones etc Psychic moans - depression, lethargy, seizures

Question 33

Give some causes of hyperoxaluria

Answer 33

Rare autosomal recessive genetic disorder of oxalate synthesis Increased intestinal absorption of oxalate High oxalate diet Low calcium intake

Question 34

Describe struvite stones

Answer 34

More common in women Mixed infective stones Composed of magnesium ammonium phosphate Usually secondary to infection of organisms with urease Often large

Question 35

Why are uric acid stones difficult to diagnose?

Answer 35

Radiolucent | Cannot see them on an xray

Question 36

Uric acid is the end point of which molecule metabolism?

Answer 36

Purine

Question 37

Give some causes of hyperuricaemia

Answer 37

Gout | Secondary consequence of increased cell turnover (malignancy, chemotherapy)

Question 38

Describe the presentation of kidney stones

Answer 38

``` Asymptomatic (most) Renal colic Dull ache in loins Recurrent UTIs Haematuria Renal failure UT obstruction ```

Question 39

Why does drinking water often make the pain in real stones worse?

Answer 39

Fluid is increased in kidneys | Increased pressure on stones

Question 40

What is renal colic?

Answer 40

Excruciating pain Bouts of 20-60 minutes Peristaltic contractions/spasms Loin to groin pain

Question 41

What symptoms often accompany renal colic?

Answer 41

``` Nausea/vomiting Pallor Sweating Restlessness (Haematuria) ```

Question 42

What investigations would you do for renal stones?

Answer 42

Mid stream urine: blood, culture etc Serum: urea, creatinine, electrolytes, calcium Plain abdominal x-ray (can see 60% of stones) CT of kidneys, ureter and bladder

Question 43

Stones under which diameter are usually passed?

Answer 43

< 5mm

Question 44

What are some severe complications of renal stones?

Answer 44

``` Acute pyelonephritis Pressure necrosis of renal parenchyma Urinary obstruction Hydronephrosis Ulceration ```

Question 45

Describe the treatment of urinary stones

Answer 45

Analgesia, warmth to site and bed rest Ureteroscopy Percutaneous nephrolithotomy ESWL (extracorporeal shock wave lithotripsy)