Pathophysiology Exam 3
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In the urinary stone disease case, what lab values were abnormal?
- Citrate= low
- Specific gravity= high
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
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
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
How are kidney stones classified?
- by location: kidney, ureter, or bladder
- by composition: calcium, struvite, uric acid, or cystine
Has the incidence of kidney stones increased or decreased in last 10-15 years?
- increased by 40%
- not sure why
Are kidney stones more common in males or females?
Most cases of kidney stones have what type of composition (75%)?
calcium oxalate or calcium phosphate
What race is more commonly affected by kidney stones?
What are the major causes of calcium kidney stones?
- idiopathic hypercalciuria
- distal renal tubular acidosis
- dietary, enteric, or primary hyperoxaluria
What are the causes of uric acid kidney stones?
- metabolic syndrome
- Lesch-Nyhan syndrome
What are the risk factors that the patient in the kidney stone case had?
- sedentary lifestyle
- previous stones
What are dietary risk factors for developing a kidney stone?
- increased sodium and protein
- excess oxalates or purines
- low citrates
What are metabolic acidosis risk factors associated with kidney stone development?
- prolonged fasting
Diet alterations, metabolic acidosis, genetics, and sleeping on one side are all risk factors for what?
What are some drugs that might induce a kidney stone?
- antibacterials (cipro, amoxicillin, nitrofurantoin)
What signs and symptoms did the kidney stone patient present with?
- inability to remain still
- excruciating side and back pain/flank pain
Which diagnostic test did kidney stone patient have done?
spiral computed tomography (CT scan)
Which type of stones are radio-opaque in imaging?
What does a radio-opaque kidney stone tell you about the stone?
it obstructs the passage of radiant energy
What color do calcium or struvite stones appear on x-ray or CT scan?
light in color
What color do uric acid or cystine stones appear on x-rays?
black, near black
What type of kidney stones are radiolucent?
What does radiolucent mean?
permitting the passage of radiant energy
What is the best method for diagnosing a kidney or ureter stone?
CT scan (spiral computed tomography)
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
What type of stones will a regular x-ray identify?
- not uric acid or indinavir stones
Does ultrasound detect both calcium and non-calcium kidney stones?
What is normal urine pH?
What does persistent urinary pH below 5.5 suggest?
uric acid or cystine stone
What does persistent pH above 7.2 suggest?
struvite or calcium phosphate stone
What is a stone analysis?
- done on recovered stones
- identifies the components and underlying cause of the stone
What is the underlying cause of a cystine stone?
What is the underlying cause of a struvite or carbonate stone?
UTI with urease + organism
What is the underlying cause of a calcium phosphate stone?
What type of test is performed on recurrent kidney stone formers?
non-restricted diet and 24 hour urine collection
Where are staghorn stones located?
major and minor calyces (deep within the kidney)
Where are non-staghorn stones located?
in the renal pelvis or sometimes in the calyces
What is the order of kidney stones listed by prevalence?
- calcium: 70-80%
- struvite: 15%
- uric acid: 7%
- cystine: less than 1%
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
What amount defines hypercalciuria?
more than 200 mg of calcium excreted in the urine in 24 hours
What are the 3 types of hypercalciuria?
This type of hypercalciuria is due to increased calcium absorption in the small intestine?
Which type of absorptive hypercalciuria is independent of calcium intake?
What type of absorptive hypercalciuria is diet dependent?
What type of absorptive hypercalciuria is caused by low levels of urinary phosphate resulting in increased vitamin D synthesis?
What type of hypercalciuria is due to hyperparathyroid disease, an increase in PTH, and an increase in calcium reabsorption from bones?
What type of hypercalciuria is due to inefficient reabsorption of filtered calcium in the renal tubules?
What type of stones are aka infectious stones?
These stones are composed of magnesium, ammonia, phosphate, and carbonate apatite?
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)
In uric acid kidney stones, the concentration of _______is greater than that of ______?
undissociated uric acid >> urate
What type of stone is caused by inherited defects of renal transport and renal leakage of basic amino acids?
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
What contributes the formation of a crystalline nidus?
surfaces on the renal tubules and papillae have attractive properties
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)
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
What urine volume per day and osmolarity would contribute to forming a kidney stone?
- < 1 liter/day
- > 600 mOsm/kg
What are some inhibitors of stone formation?
- Tamm-Horsfall protein
- Potassium citrate
What is Type I hyperoxaluria?
- mutation/polymorphism in gene that codes for alanine-glyoxylate aminotransferases
- most common
What is Type II hyperoxaluria?
- inactivating mutations in genes coding for glyoxylate reductase and hydroxypyruvate reductase
- less common
What is the genetic cause of cystinuria?
multiple inactivating mutations in genes SLC3A1 and SLC7A9
How is Non-Hodgkin's Lymphoma thought to cause kidney stones?
lymphoma = cell death = increase in DNA = increase in purines = increase in uric acid
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
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
What is stone reoccurrence without treatment?
14, 35, 52% within 1, 5, and 10 years
What majority of kidney stones pass spontaneously?
What size of stone did the kidney stone patient have?
Why did kidney stone patient pass his stone in 3 hours?
- previous stone passage = dilated ureter
- easier to pass subsequent stones
What % of stones under 5 mm pass spontaneously?
< 5 mm
Do you treat asymptomatic stones?
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
The 3 surgical treatments are used only when....?
- stone is causing obstruction
- stone is growing even during treatment
Who is shock wave lithotripsy contraindicated for?
- stone > 2 cm
- cystine stone > 1 cm
What are the hardest kidney stones to destroy?
Who is PCNL contraindicated for?
- irreversible coagulopathy
Which type of stones respond well to PCNL?
staghorn because they are soft (even though they are usually large)
What is a drug that has an off-label use for passing stones?
What meds can be used to prevent uric acid kidney stones?
- allopurinol: decrease uric acid
- citric acid, potassium citrate: increase urine pH
What meds are used to prevent calcium stones (like the patient)?
- hydrochlorithiazide: off-label, decreases renal calcium excretion
- cellulose sodium phosphate: decreases calcium
What should we do to prevent new stones?
- increase fluid intake
- decrease oxalate intake
- increase exercise
- potassium citrate supplement
Why was kidney stone patient's specific gravity high?
- Zenker diverticulum
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%
- Manage source of Increased PTH: remove parathyroid tumor
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