URINARY Section 5: CALCIFICATIONS

Question 1

Most common kidney stone

Answer 1

Calcium oxalate (75%)

Question 2

Kidney stone
common in women + associated with UTI

Answer 2

Struvite stone

Question 3

Kidney stone “unseen on x-ray”

Answer 3

Uric acid

Question 4

Rare kidney stone + associated with congenital disorders of metabolism

Answer 4

Cystine Stone

Question 5

the ONLY stones NOT seen on CT.

+ HIV

Answer 5

Indinavir

Question 6

What stones form Stahorns?

Answer 6

Struvite Stones form Staghoms.

Question 7

Kidney stone size = high likelihood of passing

Answer 7

< 5mm

Question 8

Kidney stone size = high likelihood of NOT passing

Answer 8

> 1 cm

Question 9

What kind of stone rarely require any invasive intervention?

Answer 9

Uric acid

Question 10

What population is uric acid stone more common

Answer 10

Big fat people and/or diabetics - acidic urine - increased uric acid

Question 11

Uric acid stone treatment

Answer 11

Uric acid stones very rarely will require any kind of invasive intervention (lithotripsy, etc…).

The reason is they are very pH dependent.

Potassium citrate or sodium bicarbonate = increases pH = melts stones

You can’t melt a calcium stone by messing with the pH.

Question 12

Uric acid stone attenuation

Answer 12

< 500 HU

Question 13

Non uric acid stone HU

Answer 13

higher HU at 80 kVp relative to 140 kVp.

Question 14

What kidney stone shows the biggest HU change between high and low energies?

Answer 14

Calcium

Question 15

a suspension of calcium crystals which frequently masquerades as renal calculi within a cyst or calyceal diverticulum

Answer 15

Milk of Calcium

Question 16

Answer 16

Milk of Calcium

Ultrasound showing the layering “fluid - debris level” that changes with positioning of the patient.

Question 17

Answer 17

Cortical Nephrocalcinosis

Question 18

This is typically the sequela of cortical necrosis

Answer 18

Cortical Nephrocalcinosis

which can be seen after an acute drop in blood pressure (shock, postpartum, bum patients, etc…).

Question 19

Answer 19

Cortical Nephrocalcinosis

a hypodense non-enhancing rim that later develops thin calcifications.

Question 20

Mimic of Cortical Nephrocalcinosis

Answer 20

Mimic is disseminated PCP.

Question 21

Answer 21

Medullary Nephrocalcinosis

Question 22

Hyperechoic renal papilla / pyramids which may or may not shadow on ultrasound.

Answer 22

Medullary Nephrocalcinosis

Question 23

Causes of Medullary Nephrocalcinosis

Answer 23

• Hyperparathyroidism - Most people say this is the most common.
• Medullary Sponge Kidney - Some people say this is the most common.
• Lasix - Common cause in children.
• Renal Tubular Acidosis (distal subtype - type 1)

Question 24

A congenital cause of medullary nephrocalcinosis (usually asymmetric)

Answer 24

Medullary Sponge Kidney

Question 25

The underlying mechanism in Medullary Sponge Kidney

Answer 25

a cystic dilation of the collecting tubules of the kidney

Question 26

Medullary Sponge kidney is associated with

Answer 26

Ehlers-Danlos syndrome (a group of hereditary connective tissue disorders that manifests clinically with skin hyperelasticity, hypermobility of joints, atrophic scarring, and fragility of blood vessels) and Carili's disease