Nephrolithiasis and Urolithiasis

Question 1

define nephrolithiasis

Answer 1

renal stones or calculi

Question 2

Where do stones usually form?

Answer 2

Most commonly develop in the renal pelvis or calyces

Question 3

What are stones usually composed of?

Answer 3

calcium oxalate or a combination of calcium and phosphate

Question 4

What demographic are stones seen in?

Answer 4

Male > Female 3rd/4th decades, equal in 6th/7th decades

Question 5

What type of stones are usually seen in middle aged males?

Answer 5

calcium

Question 6

True/false: stones rarely occur in children

Answer 6

true

Question 7

What is the most common type of stone composition for bladder calculi?

Answer 7

Most common is calcium oxalate followed by uric acid

Question 8

What demographic are bladder calculi most prevalent in?

Answer 8

Men w/ BPH

Question 9

What are predisposing factors for bladder calculi

Answer 9

1. Dehydration
2. Infection
3. Change in urine pH (nl 5.8-5.9)
   A. Calcium based stones in pH 5.5-6.8
   B. Uric acid & Cystine stones in pH < 5.5
   C. Struvite stones in pH>7.2
4. Obstruction to urine flow
5. Sedentary occupations
6. High temp/humidity

Question 10

What metabolic factors predisopse ppl to bladder stones?

Answer 10

Hyperparathyroidism
Renal tubular acidosis
Hyperuricemia
Dietary
-High protein/salt
Renal disease

Question 11

What is the pathophys of bladder stones?

Answer 11

1. Calculi form when substances that are normally dissolved in the urine precipitate
2. In appropriate conditions, stone forming substance forms crystal that becomes trapped in urinary tract
3. Trapped crystal attracts other crystals to form stone

Question 12

How large are bladder stones, on average?

Answer 12

<5mm

Question 13

What are 3 common sites for ureteral stones to form?

Answer 13

1. Ureteropelvic junction
2. Crossing of ureter at iliac vessels
3. Ureterovesicular junction

Question 14

Where are common places for stones to occur?

Answer 14

Stones may form in papillae, renal tubules, calyces, renal pelvis, ureter or bladder

Question 15

What type of composition of stones is most prevalent?

Answer 15

Calcium based stones

• Calcium oxalate
• Calcium phosphate

Question 16

What pH do calcium stones form at?

Answer 16

pH 5.5-6.8

Question 17

What is the cause of calcium based stones?

Answer 17

80% idiopathic

Question 18

What are some risk factors for calcium based stones?

Answer 18

Immobilization
Hyperparathyroidism
Renal tubular acidosis
Excessive intake of Vit. D and Calcium (rare)

Question 19

What comorbidity is often seen with calcium based stones?

Answer 19

hypercalciuria

Question 20

What are the 3 types of absorptive hypercalciuria?

Answer 20

1. Type I
   - Independent of calcium intake
2. Type II
   - Diet dependent (rare)
3. Type III
   - Secondary to renal phosphate leak
   - Increased Vit. D synthesis
   - Increases small bowel absorption of calcium

Question 21

What pH causes the formation of struvite stones?

Answer 21

pH >7.2

Question 22

What is the most common composition of staghorn shaped horns?

Answer 22

Struvite

Question 23

Who is more likely to develop struvite stones?

Answer 23

F > M, 10% of all stones

Question 24

What often precipitates struvite stones?

Answer 24

Often precipitated by infection:
Proteus, Klebsiella, Pseudomonas
-Breaks down urea, ↑ pH → precipitates magnesium + phosphate + ammonium crystals

Question 25

What are some complications of struvite stones?

Answer 25

Destroy renal parenchyma

Question 26

What pH precipitates the development of uriic acid stones?

Answer 26

pH <5.5

Question 27

What % of total kidney stones are uric acid?

Answer 27

5-10%

Question 28

Pathophys of uric acid stones

Answer 28

1. Results from breakdown of purines from protein 2. Uric acid enters bloodstream and kidneys 3. Usually occur with calcium stones 4. Poorly visible on KUB

Question 29

At what pH do Cystine stones form?

Answer 29

pH< 5.5

Question 30

Pathophys of cystine stones

Answer 30

Genetic mutation -Poor bowel absorption of amino acids -Cystine leaks into urine Due to excessive amounts of cystine

Question 31

Who gets cystine stones?

Answer 31

Due to excessive amounts of cystine 1% stones in adults 6-8% stones in children (avg 12 yr)

Question 32

What are the characteristics of cystine stones?

Answer 32

rapid growth and recurrence

Question 33

What are complications of cystine stones?

Answer 33

Renal failure

Question 34

Define Staghorn calculi

Answer 34

1. Branched stones A. Struvite >Calcium Oxalate 2. Stones of the calyceal and pelvic collecting system 3. Can continue to grow in renal pelvis and calyces 4. Forms a branching stone that can result in renal failure if not removed surgically

Question 35

sxs of nephrolithiasis

Answer 35

``` 1. Severe colicky flank pain A. Referred pain (males) 2. Nausea and vomiting 3. Diaphoresis 4. Fever & chills A. Infection 5. Hematuria A. When calculi abrade ureter 6. Urgency and frequency A. If stone lodged at UV junction ```

Question 36

What DS are indicated for stones?

Answer 36

``` 1. Urinalysis w/micro A. pH -7.2 suggests struvite stones -5.5-6.8 suggests calcium-based stones B. Hematuria & crystals 2. 24 hour urine collection A. Determines levels of calcium, oxalate, phosphorous, citrate, and uric acid excretion 3. Urine C&S if febrile/pyuria 4. Calculus analysis 5. Serum calcium, phosphate, BMP, CBC if febrile ```

Question 37

What imaging studies are indicated for stones?

Answer 37

1. Kidney-Ureter-Bladder (KUB) X-ray 2. Renal ultrasound A. Detects hydronephrosis and radiolucent stones not seen on KUB 3. Spiral CT A. Almost all stones visible on noncontrast CT B. Study of choice

Question 38

What is the Tx for stones?

Answer 38

``` 1. ↑ Fluids A. Double previous fluid intake 2. Stones < 6mm usually pass spontaneously 3. Antibiotics if UTI 4. Narcotic analgesics or NSAIDs A. Ketorolac (Toradal) 30-60 mg IM 5. Alpha-1-Antagonist A. Tamsulosin (Flomax) ```

Question 39

How are calcium based stones treated?

Answer 39

1. Restrict sodium (100 mEq/d) 2. Thiazide diuretic in Type I hypercalciuria A. HCTZ or clorthalidone 3. Avoid excessive animal protein* 4. ↓ dietary calcium* by 50% in Type II hypercalciuria 5. OTC orthophosphates (K-Phos, Neutra-Phos) in Type III hypercalciuria 6. ↑ potassium rich foods 7. +/- ↓ vit. C & oxalate rich foods (spinach, rhubarb, nuts, legumes) 8. Limit sucrose & fructose 9. Lemonade to ↑ urine citrate level

Question 40

How are uric acid stones treated?

Answer 40

1. Allopurinol 100-300 mg qd 2. Raise urine pH (goal 6.1-7) A. Potassium citrate or potassium bicarbonate B. Lemonade

Question 41

How are cystine stones treated?

Answer 41

1. Modest reduction in sodium & protein intake 2. Raise urine pH (goal >7) A. Potassium citrate or potassium bicarbonate B. Lemonade 3. Last resort A. Penicillamine (Cuprimine) (DMARD) Disease -Modifying Anti-Rheumatic Drug -Chelating effect

Question 42

What procedures can be used to tx stones?

Answer 42

1. Percutaneous ultrasonic lithotripsy 2. Extracorpeal shock wave lithotripsy 3. Laser Therapy A. Shatter calculi into small fragment B. Fragments removed by suction or natural passage w/ J-stent

Question 43

Describe Percutaneous Ultrasonic Lithotripsy

Answer 43

1. 1 cm incision in back or mid side of abdomen 2. Nephroscope passed to site of stone and shattered by ultrasound waves 3. Fragments can be manually removed

Question 44

Describe Extracorpeal Shock wave lithotripsy

Answer 44

1. Uses sound waves to break up stones in proximal or distal ureter 2. For stones < 3 cm in diameter 3. Shock waves crush stones into tiny sand-like pieces that usually pass easily through the urinary tract

Question 45

Describe Laser lithotripsy

Answer 45

1. General anesthesia 2. Flexible ureteroscope inserted through urethra and passed through the bladder and up the ureter to the stone 3. The light energy of the laser is transported through a light guide to the stone 4. Stone fragmentation occurs when pulses of intense laser light are applied 5. The fragments are then passed by the patient or removed with a basket

Question 46

How are stones that are too large to be passed treated?

Answer 46

1. Ureteroscopy and manipulation of calculus to remove stones too large for normal passage A. Used for proximal or distal ureteral stones

Question 47

What a re the indications for admission for stones?

Answer 47

1. Complete or high-grade unilateral urinary obstruction 2. Bilateral obstruction 3. Obstruction in a solitary kidney 4. Obstruction with fever or leukocytosis 5. Azotemia 6. Inability to tolerate PO 7. Uncontrollable pain

Question 48

What is the most important piece of pt education?

Answer 48

Hydration