Urology: Nephrolithiasis Flashcards Preview

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Flashcards in Urology: Nephrolithiasis Deck (108)
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1

What % of kidney stones are radio-opaue and can be seen on KUB or clean Abd. X-ray?

90%

2

What % of patients with stones have a metabolic abnormality (hypercalciuria- Excreting too much Ca)?

Over 95%

3

What is the most common type of stone in industrialized countries?

Calcium oxalate

4

What is the most common cause of urolithiasis?

Dehydration (spike in summer and fall...sweating)

5

Is there a family inheritance with stones?

Yes... there is a 3 fold increase among family members

6

Who gets more stones, men or women?

Men (1.3:1)

7

What is the peak age for stone formation?

30-60

8

Where is the stone belt?

In the southern US... hotter, more dehydrated, less fluids

9

Does body size obesity increase the risk of stones?

Yes

10

What kind of diet increases stones and why?

High in aminal protein: Nucleic acids lead to uric acid stones which are not seen on KUB X-ray

11

What season are more stones seen in and why?

Summer...there is an increase in insensible water loss (sweating) and an increase in light exposure which results in increased calcium absorption due to increased vitamin D production

12

What are 10 Etiologies of Stone Formation?

1. Anatomic
2. Urine composition
3. Urine volume
4. Diet
5. Metabolic
6. Disease states
7. Medications
8. UTI (Staghorn stones
9. Sedentary lifestyle
10, Supersaturation point (If decreased, need fluids)

13

What are the anatomic features associated with stone formation?

Stasis v. obstruction
-Poor ureter drainage (kidney stones)
-BPH: Can't empty bladder...urine is stagnant and warm and it can crystallize

14

What are the urine composition features associated with stone formation?

-pH, crystal inhibitors, stone forming substances
-Ex. Uric acid stones can only form in acidic urine (pH 5.), so if you alkalize the urine to 6.5-7.0 you can dissolve the stone

15

What are the 2 stones you can dissolve?

Uric acid and cysteine

16

What are the urine volume features associated with stone formation?

Smaller urine volume, more likely to form stones (decrease suprasaturation of urine)
-2.5 L of urine per day = Stone former

17

What type of diet can decrease stone formation?

Vegetarian (decrease protein)
-High protein diets have lots of nucleic acid and can lead to uric acid stones

18

What are the metabolic features associated with stone formation?

-Hypercalciuria
-Hypocitraturia
-Hyperoxaluria
-Hyperuricouria
-Hypomagnesuira
-Hypokalemia

19

What disease states lead to stone formation?

-DM
-Type I RTA
-Chronic diarrhea: Dehydrated
-Medullary sponge kidney
-Hyperparathyroidism: Increase Ca excretions (remove PTH, fixes stones)
-PCKD
-IBD
-Sarcoidosis
-Obesity
-Metabolic acidosis

20

What medications lead to stone formation?

-Vitamin C: Metabolized to oxalate (this binds to Ca and forms stones)...only need 500mg a day of C
-Vitamin D: Increases calcium absorption (in kidney)
-Triamterene: Precipitates in the urine (crystalizes)..This is an old BP medication
-Protease Inhibitors: Used in HIV...crystallizes in urine
-Lasix: Increases Ca++ excretion
-Acetazolamide
-Agents that increase uric acid in urine (i.e. salicylates and probenicid)

21

What are some organic inhibitors of stone formation?

1. Citrate: Directly inhibits Ca crystalization*
2. Urea
3. Nephrocaclcin
4. Tamm-Horsfall Protein (native)
5. Glycosaminoglycans

22

What are some inorganic inhibitors of stone formation?

1. Phosphate
2. Mg
3. Trace elements: Zinc?

23

What is the recurrence after 1st stone in year 1?

10-15%

24

What is the recurrence after 1st stone in year 5?

50-50%

25

What is the recurrence after 1st stone in year 10?

70-80%

26

What should we do about stones?

PREVENT THEM!

27

What are the 5 types of stones and their incidence?

1. Calcium containing stones: 70%
-Calcium Oxalate: 27%
-Calcium Phosphate: 7%
-Mixed: 36%
2. Infection stones (Struvite, Magnesium ammonium phosphate, matrix): 15-20%
3. Uric Acid Stones: 5-10%
4. Cystine Stones: 1-5%
5. Protease Inhibitor Stones (Indinavir): Rare

28

What is the number 1 type of stone?

Calcium oxalate

29

What is the only stone to form in alkaline urine (pH 6.7-7)?

Calcium Phosphate

30

Are uric acid stones radio-opaque?

NO...they are radiolucent