Calculus Disease Flashcards
Do men or women tend to get calculus disease (kidney stones) more often?
- MEN
What are some risk factors for calculus disease (nephrolithiasis; kidney stones)?
- family hx (genetics)
- increased weight
- previous stone
- diet (salt)
- climate (warm)
- gender (male)
- water supply (calcium, magnesium)
- occupation/stress
What diet components contribute to nephrolithiasis?
- oxalate (binds to calcium and precipitates out)
- animal proteins (nitrogen contributing to uric acid stones)
- animal fat
- vitamin D
- fish oils
- vitamin C (converted to oxalate)
- calcium (binds to oxalate and precipitates out)
- phosphorus (phosphorous stones).
What is the most common type of stone?
- CALCIUM OXALATE MONOhydrate= hard
- CALCIUM OXALATE DIhydrate= less hard.
What is important to know about calcium PHOSPHATE stones?
- less common and often contain calcium oxalate.
- may be associated with hyperparathyroidism and renal tubular acidosis.
What are the effects of animal protein from the diet on nephrolithiasis?
- increased calcium
- increased sulfate
- increased uric acid
- decreased pH (can’t form stones above 5.5).
- decreased citrate (citrate such as from orange juice or lemonade actually helps to prevent stones).
What is associated with URIC ACID STONES?
- GOUT
* more people will form uric acid stones before gout, bc the kidneys are good at excreting serum uric acid.
What causes uric acid stones?
- uric acid is the end product of purine metabolism.
- increased dietary purine intake
- uricosuric drugs (allopurinol), which impair uric acid reabsorption from proximal tubule.
- obesity and alcohol
- myelo- and lymphoproliferative diseases
- inborn metabolic disorders
- chronic diarrheal syndromes
What are some clinical characteristics of uric acid stones?
- renal colic
- hematuria
- low urinary pH (less than 5.5)
- NEGATIVE plain x-rays (radiolucent)
- CT or US confirmation
What are STRUVITE CALCULI? (staghorn)
- referred to as “infection,” “urease,” and “triple phosphate stones”
- composed of magnesium ammonium phosphate and carbonate apatite.
- more FEMALES than males bc women get UTIs more than men.
- most prevalent form in those with supravesical diversions and neurogenic bladders.
What is essentially a prerequisite for struvite calculi?
- urinary infection with urease-synthesizing organism.
Are bacteria contained within the interstices of struvite calculi?
- YES and are protected from antibiotic therapy (aka antibiotics won’t work).
What is the urine pH for struvite calculi?
- greater than 7.5
What are the most common bacteria in struvite calculi (urease producers)?
- proteus vulgaris
- proteus mirabilis
- you will NEVER see E. coli bc it does NOT produce urease.
What are the clinical manifestations of struvite calculi?
- often asymptomatic bc the stones are so large to fit in the ureters.
- often associated with indwelling catheters.
Can stuvite calculi recurr?
YES in patients who do not undergo complete removal.
What is cystinuria?
- rare inborn error of metabolism characterized by a disturbance in renal and intestinal handling of cystine.
- result is an excessive excretion of cystine (usually in teens).
- urinalysis reveals HEXAGONAL CRYSTALS.
What are xanthine stones?
- gene mutation results in xanthine oxidase enzyme deficiency.
- inability to convert xanthine into uric acid.
Is there a difference in the way we treat a first-time stone former vs a recurrent stone former?
- no difference
Who should we absolutely work up for medical management of stones?
- bilateral stones
- recurrent stones
- family history
- children
- solitary kidney (emergency bc this is the only kidney)
- African Americans
- skeletal diseases (Paget’s…)
- bowel disease
- bowel surgery
- any stones other than calcium oxalate.
What is the conservative management for kidney stones?
- high fluid intake (more than 3 L per day).
- sodium restriction
- oxalate restriction (tea, nuts, chocolate, green leafy vegetables).
- avoid purine gluttony
- increase citrus fruit intake
- moderate calcium restriction in hypercalciuric patients.
How do we treat hyperuricosuria (lots of uric acid in the urine)?
- Allopurinol (really used to treat gout)= reduces uric acid synthesis (meaning less in the serum) and thus reducing the amount that ends up in the urine.
- POTASSIUM CITRATE= effective alternative to Allopurinol. Reduces urinary saturation of calcium oxalate and increases urine pH (above 5.5) to prevent uric acid from precitating out of solution and inhibit urate induced crystallization of calcium oxalate.
What else can we use to raise the urinary pH?
sodium bicarb
How do we treat enteric hyperoxaluria?
- oral calcium or magnesium, which will bind to oxalate in the GI tract, preventing its absorption, thus decreasing urinary oxalate.
- restrict dietary oxalate (duh).
- high fluid intake
- calcium citrate
