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In the urinary stone disease case, what lab values were abnormal?
- Citrate= low
- Specific gravity= high
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The patient in the kidney stone disease case had what pertinent medical history issues?
- renal stones at 35, 43, and 52 yo
- zenker diverticulum
- IgG immunodeficiency disorder
- Non-Hodgkin's lymphoma
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Why is the patient in the kidney stone case zenker diverticulum significant?
- prevents him from swallowing caps or tabs
- also leads to him not drinking enough water
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What symptoms did the kidney stone patient have?
- left flank pain (most common symptom)-- most likely means that he is passing the stone through the ureter
- radio-opaque stone in left ureter
- radio-opaque stone in inferior calyx of right kidney
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How are kidney stones classified?
- by location: kidney, ureter, or bladder
- by composition: calcium, struvite, uric acid, or cystine
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Has the incidence of kidney stones increased or decreased in last 10-15 years?
- increased by 40%
- not sure why
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Are kidney stones more common in males or females?
males
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Most cases of kidney stones have what type of composition (75%)?
calcium oxalate or calcium phosphate
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What race is more commonly affected by kidney stones?
caucasians
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What are the major causes of calcium kidney stones?
- idiopathic hypercalciuria
- hyperuricosuria
- hyperparathyroidism
- distal renal tubular acidosis
- dietary, enteric, or primary hyperoxaluria
- hypocitraturia
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What are the causes of uric acid kidney stones?
- gout
- metabolic syndrome
- idiopathic
- dehydration
- Lesch-Nyhan syndrome
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What are the risk factors that the patient in the kidney stone case had?
- male
- caucasian
- sedentary lifestyle
- previous stones
- dehydration
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What are dietary risk factors for developing a kidney stone?
- increased sodium and protein
- excess oxalates or purines
- low citrates
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What are metabolic acidosis risk factors associated with kidney stone development?
- prolonged fasting
- hypomagnesemia
- hypokalemia
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Diet alterations, metabolic acidosis, genetics, and sleeping on one side are all risk factors for what?
kidney stones
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What are some drugs that might induce a kidney stone?
- triameterene
- sulfadiazine
- antivirals
- antibacterials (cipro, amoxicillin, nitrofurantoin)
- ephedrines
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What signs and symptoms did the kidney stone patient present with?
- inability to remain still
- nausea/vomiting
- excruciating side and back pain/flank pain
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Which diagnostic test did kidney stone patient have done?
spiral computed tomography (CT scan)
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Which type of stones are radio-opaque in imaging?
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What does a radio-opaque kidney stone tell you about the stone?
it obstructs the passage of radiant energy
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What color do calcium or struvite stones appear on x-ray or CT scan?
light in color
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What color do uric acid or cystine stones appear on x-rays?
black, near black
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What type of kidney stones are radiolucent?
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What does radiolucent mean?
permitting the passage of radiant energy
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What is the best method for diagnosing a kidney or ureter stone?
CT scan (spiral computed tomography)
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What is the problem with the Intravenous Pyelogram (IVP)?
- it is invasive
- it can't be used on kidney failure patients
- there is an allergy risk with the dyes
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What type of stones will a regular x-ray identify?
- calcium
- not uric acid or indinavir stones
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Does ultrasound detect both calcium and non-calcium kidney stones?
yes
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What is normal urine pH?
5.9
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What does persistent urinary pH below 5.5 suggest?
uric acid or cystine stone
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What does persistent pH above 7.2 suggest?
struvite or calcium phosphate stone
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What is a stone analysis?
- done on recovered stones
- identifies the components and underlying cause of the stone
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What is the underlying cause of a cystine stone?
congenital cystinuria
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What is the underlying cause of a struvite or carbonate stone?
UTI with urease + organism
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What is the underlying cause of a calcium phosphate stone?
acidification defects
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What type of test is performed on recurrent kidney stone formers?
non-restricted diet and 24 hour urine collection
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Where are staghorn stones located?
major and minor calyces (deep within the kidney)
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Where are non-staghorn stones located?
in the renal pelvis or sometimes in the calyces
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What is the order of kidney stones listed by prevalence?
- calcium: 70-80%
- struvite: 15%
- uric acid: 7%
- cystine: less than 1%
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How is a calcium kidney stone formed?
- calcium increases ionic activity and saturation of crystallizing calcium salts (oxalate and phosphate)
- calcium binds to stone inhibitors like citrate and glycosaminoglycans
- chronic metabolic acidosis and protein load causes HYPERCALCIURIA and HYPOCITRATURIA
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What amount defines hypercalciuria?
more than 200 mg of calcium excreted in the urine in 24 hours
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What are the 3 types of hypercalciuria?
- Absorptive
- Resorptive
- Renal
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This type of hypercalciuria is due to increased calcium absorption in the small intestine?
absorptive
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Which type of absorptive hypercalciuria is independent of calcium intake?
Type I
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What type of absorptive hypercalciuria is diet dependent?
Type II
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What type of absorptive hypercalciuria is caused by low levels of urinary phosphate resulting in increased vitamin D synthesis?
Type III
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What type of hypercalciuria is due to hyperparathyroid disease, an increase in PTH, and an increase in calcium reabsorption from bones?
Resorptive hypercalciuria
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What type of hypercalciuria is due to inefficient reabsorption of filtered calcium in the renal tubules?
renal hypercalciuria
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What type of stones are aka infectious stones?
struvite
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These stones are composed of magnesium, ammonia, phosphate, and carbonate apatite?
struvite
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Women are at higher risk for developing which type of stones and why?
struvite because of increased incidence of UTIs (these stones are associated with infections)
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In uric acid kidney stones, the concentration of _______is greater than that of ______?
undissociated uric acid >> urate
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What type of stone is caused by inherited defects of renal transport and renal leakage of basic amino acids?
cystine stone
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How does a kidney stone develop?
- begins with a nidus (nucleus): in the presence of saturated urine with stone forming substances like calcium oxalate via a process called crystallization
- increased aggregation of crystals around the nidus = stone formation
- stone gradually increases in size on the renal tubules or in renal pelvis
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What contributes the formation of a crystalline nidus?
surfaces on the renal tubules and papillae have attractive properties
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What are some contributine factors to retention of kidney stones?
- urinary stasis
- anatomical abnormalities
- inflamed epithelium in the urinary tract
- stone size (greater than 1 cm = almost no chance of spontaneous passage)
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Why is citrate important?
- helps to solubilize precipitating agents that might cause a kidney stone
- most abundant organic anion in human urine
- permits base excretion without raising urine pH
- facilitates calcium excretion in a soluble form
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What urine volume per day and osmolarity would contribute to forming a kidney stone?
- < 1 liter/day
- > 600 mOsm/kg
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What are some inhibitors of stone formation?
- Tamm-Horsfall protein
- Potassium citrate
- Pyrophosphate
- Magnesium
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What is Type I hyperoxaluria?
- mutation/polymorphism in gene that codes for alanine-glyoxylate aminotransferases
- most common
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What is Type II hyperoxaluria?
- inactivating mutations in genes coding for glyoxylate reductase and hydroxypyruvate reductase
- less common
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What is the genetic cause of cystinuria?
multiple inactivating mutations in genes SLC3A1 and SLC7A9
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How is Non-Hodgkin's Lymphoma thought to cause kidney stones?
lymphoma = cell death = increase in DNA = increase in purines = increase in uric acid
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What type of lymphoma does the kidney stone patient have?
- Diffuse Large B-Cell Lymphoma: defect in B-cell development in germinal center (IgV mutation)
- treat with chemo and rituximab
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What are the complications of kidney stone formation?
- decrease of loss of function
- hydro ureter: complete renal obstruction, accumulation of urine, dilated ureter, increased pressure, decreased GFR, kidney injury leading to ischemia and hypoxia
- hydro nephrosis: partial ureter obstruction, less renal impairment
- kidney damage/scarring: due to urine retention, tissue inflammation, distended kidney for extended time
- UTI: urinary stasis, obstruction, distention
- Pyelonephritis: septicemia and shock
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What is stone reoccurrence without treatment?
14, 35, 52% within 1, 5, and 10 years
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What majority of kidney stones pass spontaneously?
80-85%
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What size of stone did the kidney stone patient have?
6 mm
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Why did kidney stone patient pass his stone in 3 hours?
- previous stone passage = dilated ureter
- easier to pass subsequent stones
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What % of stones under 5 mm pass spontaneously?
< 5 mm
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Do you treat asymptomatic stones?
no
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What are the 3 invasive surgical treatments for kidney stones?
- SWL: shock wave lithotripsy
- PCNL: percutaneous nephrolithotomy
- Open Operative Intervention: only use when other two fail, there is an anatomical abnormality, or the stone is too extensive
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The 3 surgical treatments are used only when....?
- pain
- infection
- hematuria
- stone is causing obstruction
- stone is growing even during treatment
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Who is shock wave lithotripsy contraindicated for?
- pregnant
- infection
- stone > 2 cm
- cystine stone > 1 cm
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What are the hardest kidney stones to destroy?
cystine
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Who is PCNL contraindicated for?
- pregnant
- irreversible coagulopathy
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Which type of stones respond well to PCNL?
staghorn because they are soft (even though they are usually large)
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What is a drug that has an off-label use for passing stones?
Tamsulosin (Flomax)
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What meds can be used to prevent uric acid kidney stones?
- allopurinol: decrease uric acid
- citric acid, potassium citrate: increase urine pH
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What meds are used to prevent calcium stones (like the patient)?
- hydrochlorithiazide: off-label, decreases renal calcium excretion
- cellulose sodium phosphate: decreases calcium
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What should we do to prevent new stones?
- increase fluid intake
- decrease oxalate intake
- increase exercise
- potassium citrate supplement
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Why was kidney stone patient's specific gravity high?
- dehydration
- Zenker diverticulum
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How do you treat hypercalciuria?
- Type I Absorptive-
- Calcium chelating agent: cellulose phosphate
- Decrease renal calcium excretion: thiazide diuretic
- Type III Absorptive-
- Decrease Vitamin D synthesis: orthophosphate
- Type II Absorptive-
- Decrease Calcium intake by 50%
- Resorptive-
- Manage source of Increased PTH: remove parathyroid tumor
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