Crr Week 8: Nephrolithiasis

Front 1

During which season is the occurrence of renal stones the greatest?

Back 1

Summer
(insufficient fluid intake)

Front 2

What are the causes of renal stones?

Back 2

1. Hypercalciuria in the absence of hypercalcemia
2. Decreased urine volume (dehydration)
3. Reduced urine citrate
4. Primary HPTH
5. Diets high in dairy products or oxalates
6. Urinary infections due to UREASE producers (Proteus)

Front 3

What normally chelates calcium?

Back 3

Citrate

Front 4

List 5 types of renal stones

Back 4

1. Calcium oxalate
2. Calcium phosphate
3. Magnesium ammonium phosphate (MAP)
4. Uric acid
5. Cystine

Front 5

What are the most common stones in adults?

Back 5

Calcium oxalate

Front 6

Which stones have an increased incidence in Vegans?

Back 6

Calcium oxalate

Front 7

Which stones have an increased incidence in patients with malabsorptive disorders like Crohn's disease?

Back 7

Calcium oxalate

Front 8

What are the most common renal stones in children?

Back 8

Calcium phosphate

Front 9

Which renal stones are associated with dairy products?

Back 9

Calcium phosphate

Front 10

Which renal stones are associated with renal tubular acidosis?

Back 10

Calcium phosphate

Front 11

"Staghorn calculus" refers to which type of stone?

Back 11

Magnesium ammonium phosphate (MAP)

Front 12

Which type of stone forms "struvite" stones?

Back 12

Magnesium ammonium phosphate

Front 13

Which type of stone is associated with urease producers?

Which bacterium is the common agent?

Back 13

Magnesium ammonium phosphate

*Proteus

Front 14

Describe the clinical presentation of renal stones

Back 14

1. Sudden onset of flank pain
2. Nausea and vomiting
3. Colicky pain radiating into groin
4. Patient constantly moving, trying to relieve pain
5. Gross hematuria (may be present)

Front 15

If a patient has hypercalcemia along with renal stones, what would you consider the cause to be?

Back 15

Primary hyperparathyroidism

Front 16

List 4 ways to diagnose kidney stones

Back 16

1. Plain film (kidney-ureter-bladder-- KUB)
2. Spiral (helical) CT
3. Ultrasound
4. Strain urine to collect stone

Front 17

Which stones cannot be seen by plain film radiography?

Back 17

Uric acid stones
(radiolucent)

Front 18

List 2 treatments for Ca2+ stones

Back 18

1. Hydrochlorothiazide (increases renal reabsorption of Ca2+)
2. Cellulose phosphate (binds Ca2+ in intestine)

Front 19

List 2 treatments for uric acid stones

Back 19

1. Allopurinol
2. Increase urinary pH (makes uric acid soluble in urine)

Front 20

List 2 treatments for struvite stones

Back 20

1. Surgical removal because of size
2. Antibiotic to eliminate urease producer

Front 21

If urine is alkaline and smells like ammonia, which type of renal stone is present?

Back 21

Magnesium ammonium phosphate (MAP)

Front 22

List 2 types of surgical techniques for removing stones

Back 22

1. Extracorporeal shock wave lithotripsy
2. Ureteroscopic stone extraction

Front 23

What kind of pH do uric acid stones and phosphate stones form in?

Back 23

uric acid --> forms in acidic pH
PO4 --> forms in alkaline pH

Front 24

What are the only 2 renal stones that can be dissolved?

Back 24

1. Cystine
2. Xanthine

Front 25

Which stone inhibitor is low in RTA?

Back 25

Citrate

Front 26

Cystinuria can form from the leakage of which compounds?

Back 26

1. Cystine
2. Ornithine
3. Arginine
4. Lysine

Front 27

The presence of crystals resembling benzene rings, is indicative of which renal stone?

Back 27

Cystine

Front 28

What is the qualitative test that can be used to diagnose cystinuria?

Back 28

Cyanide nitroprusside test (>300 mg/day)

Front 29

What is the treatment for cystine stones?

Back 29

1. Fluids (> 4.5 L/day)
2. Alkali and acetazolamide till urine pH >8
3. Penicillamine
4. Captopril

Front 30

Are cystine stones formed in an alkaline or acidic environment?

Back 30

Acidic

(however; alkalinization of the urine is not practical for therapy)

Front 31

Why is captopril useful for treating cystine stones?

Back 31

Captopril has a disulfide ring that allows it to combine with cysteine to make a heterodimer. This molecula has a much higher solubility, thereby decreasing stone formation

Front 32

Why can uric acid stones be dissolved?

Back 32

1. Uric acid solubility increases with increasing pH
2. Urate (basic form) is more soluble than uric acid

Front 33

What can cause acidic urine and what factors can concentrate it?

Back 33

Acid urine:
1. Small bowel disease/ bypass
2. Protein-sparing ketogenic diet
3. Gouty patients

Concentration:
1. Dehydration
2. Hyperuicosuria due to increased purine intake or neoplasma and chemotherapy

Front 34

Can phosphate stone be treated by acidifying the urine?

Back 34

No
(there is no way to acidify the blood enough to acidify the urine)

Front 35

Which kind of phosphate stones are formed above pH 5.6? > 6.3? >7.3?

Back 35

pH > 5.6 = Brushite stones

pH > 6.3 = Apatite stones

pH > 7.3 = Struvite

Front 36

Do oxalate stones form in alkaline urine?

Back 36

No

(Alkaline urine does, however, predispose to phosphate stones)

Front 37

Hyperoxalaturia is quantified as urine oxalate >____ mg/day

Back 37

>40 mg/day

Front 38

Which metabolic condition results in nephrocalcinosis and progressive renal insufficiency in childhood, and is associated with a defect in metabolism of glyoxylic acid?

Back 38

Primary hyperoxalaturia

Front 39

What can cause secondary hyperoxalaturia?

Back 39

Small bowel bypass or malabsorption
(fatty acid Ca2+ complexes results in free excessive dietary oxalate for absoprtion by the colon)

Front 40

What is the treatment for hyperoxalaturia?

Back 40

1. Low fat diet (decrease fatty acids, which bind Ca2+)
2. High Ca2+ diet (allowing more Ca2+ to complex with oxalate)
3. Low oxalate diet
4. High fluid intake

Front 41

Explain how malabsorption can lead to hyperoxaluria.

Back 41

Normally fatty acids are absorbed by the intestines and Ca2+ can bind oxalate, forming insoluble Ca2+-oxalate complexes that are eliminated in the stool.

*In a malabsorption disorder, the fatty acids are not absorbed. They bind Ca2+, preventing Ca2+ from forming insoluble complexes with oxalate. Therefore, oxalate is absorbed in excessive quantities.

Fatty acids steal Ca2+!

Front 42

Patients with inflammatory bowel disease are more likely to form which renal stones?

Why?

Back 42

1. Calcium oxalate
2. Uric acid

IBD causes:
1. Dehydration from diarrhea (and patients are discouraged from drinking fluids)
2. Loss of alkali in stool-> metabolic acidosis (uric acid formation)
3. Absorptive hyperoxaluria

Front 43

High doses of Vitamin C can form which type of renal stones?

Back 43

Oxalate stones

Front 44

List 4 causes of hypercalciuria

Back 44

1. RTA (decreases citrate, which normally chelates Ca2+)
2. Thyrotoxicosis
3. Vit. D
4. Sarcoidosis

Front 45

Which urine Ca2+ levels correspond to idiopathic hypercalciuria in men, women, and kids?

Back 45

Men: >300 mg/day
Women: >250 mg/day
Kids: >4 mg/kg/day

Front 46

What is Type I Renal Tubular Acidosis?

Does this form stones?

Back 46

Distal RTA
Inability to generate and/or sustain H+ gradient

*Forms stones

Front 47

What is Type II RTA?

Does this form stones?

Back 47

Proximal RTA
Reduced reabsoprtion threshold for HCO3- (less HCO3- can be reabsorbed)

*This does not form stones

Front 48

List the risk factors for developing stones due to distal RTA

Back 48

(things that increase Ca2+ and PO4)

1. decreased urine citrate
2. increased urine calcium --> secondary hyperparathyroidism --> increased urine PO4
3. Persistently alkaline urine (favors PO4 crystal formation)

Front 49

Why is it so important to diagnose distal RTA?

Back 49

1. It is often familial
2. It is easily treatable, and you want to avoid injurious consequences like stone formation and bone complications