Kidney stones and calcium

Question 1

What are the 3 principle organs calcium is found

Answer 1

bone, gut, kidneys

Question 2

After which surgery should you closely monitor calcium levels?

Answer 2

Thyroidectomy

*may accidentally remove parathyroid

Question 3

Which hormone increases the intestinal absorption of calcium?

Answer 3

Calcitriol/Vit D

Question 4

Explain how Vitamin D goes from the sun/food to active calcitriol

Answer 4

7-dehydrocholesterol in skin -> D3 cholecalciferol with UV

D3 travels through circulation bound to transcalciferin, (small free fraction)

2 hydroxylations:

1. -> 25 hydroxyl Vit D in the liver
2. -> calcitriol in kidney

D2 from yeast and fungi is converted into calcitriol in liver/kidney

Question 5

Where does calcitonin come from?

Answer 5

Parafollicular cells in thyroid

Question 6

What does calcitonin do? (3)

Answer 6

Decreases blood calcium:

1. Inhibits osteoclasts
2. Decreases kidney resorption
3. Ensures calcium from diet being incorporated into bone

Question 7

Define the following terms:

a) urolithiasis
b) nephrolithiasis
c) renal colic

Answer 7

a) urolithiasis: stones anywhere in upper urinary tract
b) nephrolithiasis: stones in kidney
c) renal colic: pain due to stone not being passed

Question 8

Try to name 9 risk factors for developing a kidney stone

Answer 8

Dehydration

Kidney problems: renal failure, anatomical anomalies

Drugs causing hypercalcemia: Vit D supplements, diuretics (i.e spironolactone, amiloride)

Diseases causing hypercalcemia or affecting absorption in bowels; gout, Crohn’s, hypertension

Age and gender, FH, obesity, urine pH

Question 9

What are the 5 types of stones? What features are associated with each type?

Answer 9

1. Calcium salts (80%): low urine volume, calcium, phosphate, oxalate in urine, raised urine pH (and low concentration of natural inhibitors keeping urine pH normal, i.e citrate and magnesium)
2. Uric acid: hyperuricosuria
3. Struvite stones: Mg, phosphate, ammonium (bacterial infections hydrolyzed urea - ammonia, raised urine pH)
4. Cystine stones: cystinuria (genetic)
   * other substances, i.e xanthene

Question 10

Describe the pain associated with renal colic

Answer 10

Radiates up loins and flanks, fluctuates in intensity

Question 11

List 4 other possible symptoms of kidney stones other than pain

Answer 11

Hematuria, infection, vomiting, restlessness

Question 12

List the 3 main locations where a kidney stone can get stuck

Answer 12

1. Ureteropelvic junction: leaving kidney
2. Mid ureter/pelvic inlet
3. Ureterovesical junction: entrance to bladder

Question 13

What is the differential diagnosis for kidney stones?

Answer 13

Ruptured AAA, appendicitis (if loin pain R sided), diverticulitis (if pain L sided)

Question 14

What 2 investigations might you do in someone presenting with symptoms alike to a kidney stone?

Answer 14

Urinalysis: hematuria, nitrites and leukocytes

Blood test: urea, creatinine, electrolytes FBC, CRP, Blood cultures

Question 15

When would you admit a patient for kidney stones? (5 things)

Answer 15

Systemic infection, AKI, pregnant, dehydrated and can’t take oral fluids (i.e vomiting), not responding or worsening pain after an hour of treatment

Question 16

What is the golden standard for imaging a kidney stone?

Answer 16

CT KUB

Question 17

What should you equip a patient with kidney stones with when sending them home?

Answer 17

NSAIDs, antiemetic, tell them to pee with sieve

*7 day follow up

Question 18

Which stone commonly leads to hydronephrosis and why? What can you do if this develops?

Answer 18

Struvite stones (tend to stick together)

Can do a nephrostomy *drains urine from kidney

Question 19

What can you insert after a procedure has been done to remove kidney stones to stabilize the ureters?

Answer 19

Ureteric stent

Question 20

What drugs may help facilitate a spontaneous passage of stones? What are the criteria for giving these?

Answer 20

Alpha-blockers, Ca2+ channel blockers

Recently diagnosed, no systemic infection, adequate renal function, stone <10 mm

Question 21

What is the name of the non-invasive outpatient treatment that focuses shock waves to break up the stone until particles are small enough to be passed

Answer 21

Extracorporeal shock wave lithotripsy

Question 22

What is the most surgical option there is to remove a kidney stone?

Answer 22

Percutaneous nephrolithotomy:

*pass scope through back of kidney to break up the stone which can be extracted through the nephroscope or removed

Question 23

What makes a stone more likely to spontaneously passage through?

Answer 23

Small and distal

Question 24

What are some complications of having a kidney stone

Answer 24

Urinary obstruction: reduced GFR, AKI, infection

Ureteric stricture can damage endothelia -> sepsis

Question 25

What can you do to prevent a kidney stone from reoccurring?

Answer 25

Calcium - avoid oxalate rich foods (i.e strawberry, rhubarb

Uric acid stones: avoid excessive dietary intake of urate rich foods like fish