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59 Cards in this Set
- Front
- Back
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Urinary Stone prevelance?
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3% overall, 12% of population at some point in their lifetime.
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recurrance rate?
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50% at 10 years
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What is the "stone belt" and why?
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SE and Southern US. Probably dehydration and hot weather.
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Types of Kidney stones from most to least frequent
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1. Ca oxalate
2. uric acid 3. struvite (Mg, Ammonium, Phos) 4. Ca phosphate 5. cysteine 6. less common such as xanthine or drug related |
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How are most Ca Oxalate stones formed?
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From the initial Ca phosphate concretion (Randall's plaque) that erodes through urothelium, is exposed to urine, nad forms a nidus for Ca oxalate deposition with time. The Ca Ox stone grows until it breaks off its urothelial "anchor" and can flow through the system
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Factors that promote Ca oxalate supersaturation (and deposition)
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dehydration, hyperCa, hyperoxaluria, hyperNa, hyperuricosuria, hypocitraturia
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What is an important inhibitor of Ca Oxalate stone formation?
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urinary citrate - so low levels is a risk factor for formation
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At what pH is uric acid more soluble?
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>6
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What are most common risk factors for uric acid stones?
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dehydration, persistently acidic urine (pH < 5.5) including lack of post-prandial alkaline tide.
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What are diseases that could put a pt at higher risk for uric acid stones?
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distal RTA (persistent acidosis), gout (hyperuricemia)
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Why are pts treated with chemo for lymphoma and leukemia more at risk of uric acid stones?
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sudden lysis of millions of cells releases PURINES into the circ and urine- uric acid is a product of purine metabolism
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What causes struvite stones?
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urinary infections with urease producing organisms.
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What is the most common urease producing organism? What are others?
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Proteus. Others are:
Klebsiella Enterobactor Pseudomonas (NOT e. coli) |
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How does urease from the urease containing organisms cause stones?
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Urease cleaves each mole of urea into 2 moles of ammonium
-> causing an H from H20 to bind to NH3 to make NH4, and leaving OH which makes the urine more alkaline. Phosphate is less soluble in alkaline, so it precipitates onto the insoluble ammonium, yielding Magnesium, ammonium, phosphate. |
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Why do staghorn stones get so big?
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The bacteria that cleave urease remain in urine and in the stone and continue to produce urease and add onto the stone and fill the calyceal spaces of the kidney.
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Who gets cystine stones?
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Pts with homozygous recessive gene for cystine transport, producing excess urinary transport.
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What are the 4 dibasic AA's?
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COLA- cystine, ornithine, lysine, arginine
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At what pH is cystien more soluble?
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9.6 and higher (dissolves in alkaline pH's- opposite of uric acid)- almost impossible to achieve a pH that high with oral agents
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With acute unilateral obstruction, how does the obstructed kidney react in the first 2 hours?
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There is increased renal pelvic pressures and renal blood flow. As pressure increases, GFR decreases.
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At 6-24 hours of obstruction?
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renal pelvic pressures remain elevated, but blood flow diminishes
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At >24 hours of obstruction?
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Renal pelvic pressures trend down (but remain high), and blood flow continues to decrease. If persistent, obstruction leads to renal ischemia.
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With high-grade obstruction, renal impairment will occur within ___
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2 weeks
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How does the pain change as a stone descends from the kidney to the ureter?
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It goes from colicky flank/scrotal/groin pain to possible localizing to the abdomen overlying that part of the ureter.
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Where is the stone most likely if the pt has lower quadrant pain, urinary urgency, frequency, dysuria?
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Uretovesicle junction
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What is a major difference bw stones and acute abdomen?
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Stones: writhing in pain, trying to find comfortable position. Maybe CVa tenderness.
AA: can't move, rigid abdomen |
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What % of ppl with stones have gross or microscopic hematuria?
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90%. but the absence does not preclude stone, as there could be complete obstruction.
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N/V with stones is usually caused by...
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hydronephrosis and capsular distension
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DDx for acute renal colic in adults
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1. urinary stone
2. hydronephrosis (uretopelvic junction obstruction) 3. bacterial cystitis or pyelonephritis 4. acute abdomen 5. gyn (ectopic, torsion) 6. radicular pain 7. referred pain (orchitis) |
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What is the gold standard for dx of stones?
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Unenhanced (non-contrast?) helical CT of abdomen and pelvis (surpasses IVP in sensitivity and specificity)
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How often can KUB detect stones?
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75-90%
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What is the first imaging test in pregnant women?
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U/S (but vastly inferior to the others)
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What are indication for urgent intervention with urinary stones?
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1. obstructed upper tract WITH infection
2. impending renal failure 3. pain refractory to analgesics 4. intractable N/V 5. patient preference |
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In general, how are fully obstructed or infected collecting systems treated?
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Decompression with either Percutaneous nephrostomy or ureteral stent placement.
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In the absence of obstruction, how are most struvite stones treated?
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Abx w/o decompression
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What are examples of impending renal deterioration?
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High-grade obstruction (moderate or severe hydronephrosis) or a solitary or transplant kidney
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What is usually used for analgesia?
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NSAIDS or narcotics (NSAIDS shown to be better in study).
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Reasons you might not want to use NSAIDs for analgesia?
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1. May pose a threat to renal function with decreased blood flow from obstruction, esp in pts with preexisting renal impairment
2. If pt may go to surgery, NSAIDs would cause unwanted platelet inhibition leading to increased surgical bleeding. |
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What is a drug that can be used to treat renal colic?
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DDAVP
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How is intractable pain treated?
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DECOMPRESSION!
(percutaneous nephrostomy or stent) |
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What are main determinants of whether or not stone can be passed spontaneously?
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Size and location
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List the chance of passing ureteral stones based on different sizes and how many days it will take to pass stone
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Size (mm) Days % interven
=/< 2 8 3 3 12 14 4-6 22 50 >6 -- 99% |
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What % of stones will pass spontaneously within 4 weeks?
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2/3
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What are 2 drugs that can help with expulsion of stones? (MET - medical expulsion therapy)
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1. alpha-blockers
2. Calcium channel blockers Both typically used with NSAIDs |
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What is the fear of using corticosteroids with MET?
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avascular necrosis of the hip
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What should pts do with a stone when passed?
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Collect it for w/u to help prevent and treat future stones.
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What are treatment options for stone intervention, from least to most invasive?
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1. oral stone dissolution
2. extracorporeal Shock Wave Lithotripsy (SWL) 3. Ureteroscopy (Laser) 4. Percutaneous nephrolithotomy (PCNL) 5. open or laparoscopic lithotomy |
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How are uric acid stones managed?
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Unique in that they can be managed medically.
-urine alkalinization with K citrate (or Na citrate or Na bicarb) |
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When is Shock Wave lithotripsy good? When is it not as effective?
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Good for stones <3 cm.
Less successful for stones in the lower pole of kidney, probably because of gravity. |
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What is best treatment for stones in the lower pole of the kidney?
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Percutaneous nephrolithotomy
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When is Percutaneous nephrolithotomy most useful
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1. lower pole stones
2. all stones >3 cm (maybe with adjunctive SWL) |
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What are some of the side effects/risk factors for using PCNL over SWL?
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more invasive with higher likelihood of narcotic use significant bleeding and transfusion rates.
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What is the most common method for proximal stones? Why is it different for more distal stones?
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SWL. For distal stones located over the bony pelvis, it may be difficult to image and target them with shock waves.
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What is the w/u for patients with recurrent stones?
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Metabolic evaluation, consisting of:
1. stone composition analysis 2. 24 hour urine collection 3. serum studies |
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What do we measure in the 24 hour urine collection?
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total volume, pH, Ca, Oxalate, Na, Uric acid, Citrate, phosphate, Mg, sulfate, Cr, quantitative cystine (optional)
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What serum studies are part of the w/u?
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serum Ca
Phos uric acid HCO3 BUN Cr Albumin Alk phos intact PTH (optional) vit D (optional) |
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What are the most common metabolic identifiers found?
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1. Low urine volume
2.Hypercalciuria 3. Hypocitraturia |
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What are some methods of stone prophylaxis?
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1. increase fluid intake
2. Dietary restriction of animal protein (oxalates) and salt ((think ox is an animal) 3. |
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What to do when hypercalciuria is found?
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Don't need to restrict oral ca intake. Just restrict animal protein and salt like the others
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What medications/supplements can be used for prophylaxis?
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Thiazide diuretics, citrate
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