Week 109 - Renal Colic

Question 1

In L/min what is the approximate Renal blood flow?

Answer 1

1.5L/min

Question 2

Fluid and electrolyte balance takes place by the glomerulus and tubular resorption, what are the four controlling mechanisms?

Answer 2

ADH, Aldosterone, Macula Densa and Renin.

Question 3

How does ADH control resorption of water?

Answer 3

• ADH is secreted by the posterior pituitary gland.
• It binds to Vasopressin II receptors on the wall of the collecting duct.
• This triggers a cascade; Adenylate Cyclase converts ATP>cAMP, the increased levels of cAMP trigger aquaporin-2 channels to move into the membrane allowing for greater reabsoprtion.

Question 4

What triggers the secretion of ADH and where from?

Answer 4

• From the posterior pituitary gland, due to an increase in plasma osmolality or a decrease in plasma volume. And stimulation by Angiotensin II.

Question 5

Where are the pressure receptors that detect reduced plasma volume?

Answer 5

In the carotids, veins and atria.

Question 6

What receptors detect change in plasma osmolality and where are they located?

Answer 6

Osmoreceptors in the hypothalamus.

Question 7

Where is Aldosterone secreted from and what causes it’s secretion?

Answer 7

Adrenal Cortex, Increased plasma levels of Angiotensin II and III and stretch receptors in the atria of the heart.

Question 8

What does Aldosterone do?

Answer 8

It is the principle regulator of salt and water balance in the body. It binds to receptors in the distal tubule and collecting duct and upregulates the Na/K pumps, pumping K into the urine and Na into the blood, it causes a retention of water.

Question 9

Where is the macula densa and what does it detect?

Answer 9

Specialised cells in the walls of the distal tubule, detect Na levels in the distal tubule.

Question 10

When macula densa detects a low Na level what two actions does it take?

Answer 10

• Dilates afferent arterioles, decreasing resistance of the afferent arterioles, causing greater flow to the glomerulus.
• Releases prostaglandins that cause juxtaglomerular cells to release Renin.

Question 11

Where is Renin synthesised, stored and secreted?

Answer 11

Juxtaglomerular cells that are mainly in the walls of the afferent arterioles of the nephron.

Question 12

Renin is secreted for juxtaglomerular cells in response to which 3 stimuli?

Answer 12

1) A decrease in arterial blood pressure detected by baroreceptors.
2) Protaglandins secreted by the macula densa.
3) Sympathetic stimulation.

Question 13

What does Renin do?

Answer 13

Renin, also known as angiotensinogenase, hydrolyses angiotensinogen into angiotensin I.

Question 14

What converts angiotensin I into angiotensin II?

Answer 14

Angiotensin-converting Enzyme (ACE)

Question 15

What is ACE and what does it do?

Answer 15

Angiotensin-converting Enzyme, converts angiotensin I into angiotensin II.

Question 16

Where is ACE secreted from?

Answer 16

Mainly from the lungs but also the kidneys.

Question 17

What are the five actions of Angiotensin II?

Answer 17

1) Increase in sympathetic activity.
2) Tubular Na,Cl resorption; K excretion; water retention.
3) Increased secretion of Aldosterone.
4) Vasoconstriction > Increased blood pressure.
5) Increased ADH secretion.

Question 18

There are three types of significant Haematuria what are they?

Answer 18

1) Visible haematuria
2) Symptomatic non-visible haematuria (sNVH)
3) Persistant asymptomatic non-visible haematuria.

Question 19

What are the initial investigations for Haematuria?

Answer 19

1) Exclude UTI or other transient causes.
2) Plasma creatinine/ eGFR
3) Proteinurea

Question 20

There are three types of patient that should have a urological referral with haematuria, what are they?

Answer 20

1) Any patient with visible haematuria.
2) Any patient with sNVH.
3) Patient >40yrs with aNVH.

Question 21

What are some of the causes of haematuria?

Answer 21

Stones, UTI, Trauma, Urothelial Malignancy, Benign prostate hypertrophy, Bladder Tumour, Prostate cancer, Kidney tumours, Nephrological causes.

Question 22

What is the most common type of Kidney cancer and how much does it account for?

Answer 22

Renal Cell Carcinoma, 85%.

Question 23

What is a definition of Renal Colic?

Answer 23

‘Kidney Pain’ begininning in the abdomen and often radiating to the hypochondrium or groin. Is often ‘colicky’ due to peristalsis but can be constant.

Question 24

What initial investigations (excluding imaging) should be performed for renal colic?

Answer 24

Urine dipstick, Midstream urine for microscopy and culture, Blood tests, Pregnancy test (if of reproducing age.)

Question 25

What is the gold standard of imaging for renal colic?

Answer 25

Non-contrast CT.

Question 26

Non-contrast CT is the gold standard for investigating Renal Colic, what are the advantages?

Answer 26

• Quick
• Almost all stones are visible
• High sensitivity and specificity
• Can identify non-urological pathology.

Question 27

What imaging tests are recommended for investigation of Renal Colic?

Answer 27

• KUB X-ray - simple but 10% of stones are radiolucent.
• IVU - Intravenous Urogram - Depends on renal function and allergy may occur to dye (interaction with metformin)
• USS - Ultrasound - Quick and widely available but easy to miss stones.

Question 28

Referral to the metabolic clinic is recommended in some patients, what six types of patient?

Answer 28

1) All recurrent stones.
2) All non-calcium stones.
3) Family History.
4) Age <25 years
5) Disease associated with stones.
6) Single kidney and any stone event.

Question 29

For uncomplicated stone disease, what will the metabolic clinic look at?

Answer 29

Stone analysis, blood analysis and urine dipstick.

Question 30

In complicated stone disease the metabolic clinic looks at the same as uncomplicated stone disease (stone analysis, blood analysis and urine dipstick) and which additional test?

Answer 30

Urine analysis; Ca, oxalate, citrate, urate, magnesium, phosphate, urea, sodium, potassium, creatinine, volume.

Question 31

What are the three common sites of obstruction for renal stones?

Answer 31

1) Pelviureteric junction.
2) As the ureter arches over the iliac vessels.
3) Vesicoureteric junction.

Question 32

If a patient had a urinary stone but with no sign of obstruction what would the management be?

Answer 32

NSAIDS, depends on size of stone.

6mm 10% pass spontaneously, intervention likely.

Question 33

If a patient had an obstructed ureter but no sign of sepsis what would the management be?

Answer 33

NSAIDS, Admission, may be allowed home for trial passing. Depends on size of stone.
6mm - 10 % pass spontaneously.

Question 34

If a patient had an obstructed ureter and signs of sepsis, what would the management be?

Answer 34

• NSAIDS
• 1g IV ampicillin
• IV Gentamicin
• Nephrostomy or uteric stent.

Question 35

Removing a stone (Renal): What method is used for 85% of stone removals?

Answer 35

Extracorporeal shock wave Lithotrpisy.

Question 36

Removing a stone (Renal): What type of removal is ideal for distal stones?

Answer 36

Ureteroscopy.

Question 37

Removing a stone (Renal): What type of procedure is used for removing calyceal, staghorn/large renal stones?

Answer 37

Percutaneous Neprolithotomy (PCNL) - keyhole procedure, a nephrostomy is needed afterwards.

Question 38

Urgent drainage via a stent or nephrostomy is sometimes needed in which four cases?

Answer 38

1) Acute obstruction.
2) Infected obstructed kidney.
3) Non-progression on conservative management.
4) Persistant pain.

Question 39

Which type of stone accounts for 70% of all urinary stones?

Answer 39

Calcium oxalate.

Question 40

Accounting for 15-20% of stones what is the second most common type of urinary stone?

Answer 40

Infective stones - Struvite (Magnesium Ammonium Phosphate) caused by infectious agents converting urea to ammonia.

Question 41

What are the four types of stone, what is their prevalence and what is their cause?

Answer 41

1) Calcium Oxalate (70%) - Higher calcium concentration in urine, but unclear.
2) Struvite - (15-20%) Magnesium Ammonium Phosphate - caused by infective agents converting urea into ammonium.
3) Uric Acid (5-10%) - 50% caused by hyperuricaemia)
4) Cystine (1-2%) - Caused by a genetic defect.