Urinary Stones - Types and Prevention Flashcards Preview

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Flashcards in Urinary Stones - Types and Prevention Deck (21)
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1
Q

General risk factors for stones

A

Too little water leads to too concentrated urine

Solid objects act as nuceli to start process

2
Q

Randalls plaque

A

Ca phosphate concretion in renal tubule

Plaque erodes through urothelium

Stone deposits onto the exposed plaque

3
Q

Risk factors for calcium oxalate stones

A

High levels of Ca (hypercalcemia or excess in urine only) or oxalate

Low urine levels of inhibitor (citrate or Mg)

High urine levels of uric acid…Ca Ox form on uric acid crystals

4
Q

Causes of hypercalcuria

A

Excess absorption of Ca from intestine (Blood Ca only birefly or idiopathic)

Renal leak of Ca (blood abs same bc of increase absorption)

Met acidosis - bone demineralization

5
Q

Causes of increase urine oxalate

A

Excess absorption ——most common

Vitamin C turns to oxalate in alkaline urine

Primary hyperoxaluria - rare auto rec…enzyme defect

6
Q

Causes of increase oxalate absorption

A

Excess intake of foods

Dec levels of oxalobacter formigenes that degrades oxalate

Dec binding of oxalate in gut so more free to be absorbed

7
Q

Oxalate binding in gut

A

Normal - oxalate binds to Ca and Mg and eliminated in feces…free is absorbed

If less calcium then more absorbed

8
Q

Oxalate biding in colon clinical implications

A

Enteric hyperoxaluria (Celiac, crohn’s, CF)

Fat malabsorption - more fat in colon

Fatty acids bind Ca

More free oxalate

9
Q

Ca oxalate vs Ca phopshate stones

A

High urine Ca is risk for both

Low pH - oxalate
High pH - phos

10
Q

If stone over 20 20% Ca Phos

A

HyperPTH - Bone resorption means more HCO3 and phosphate

Excess Ca, HCO3 and phos excreted in urine

Urine has high pH, Ca, and phos

Distal RTA - imparied excreted of acid into the urine by the distal neprhon…high pH and urine Ca

11
Q

Purine degradation - Humans

A

Adenosine and guanosine to xanthine

Xanthine to uric acid

No uricase enzyme so path ends with uric acid

12
Q

Uric acid risk factors

A

Too much uric acid in the ruine

pH too Low –most important

Uric acid pKa 5.35
Low pH means more free uric acid and more precipitates
At pH 6.5, over 90% of uric acid is lowuble

13
Q

Too much uric acid in the urine

A

Excess production

Uricosurics - decrease serum uric acid levels but increase urine uric acid levels

Red meat

Other random disorders

14
Q

Struvite

A

Mg, ammonium phosphate

Solubility according to pH - more soluble in low

Some also contain calcium phosphate (also not soluble at high pH)

15
Q

How do struite stones form

A

UTI with specific bacteria that have uease

Urease hydrolyzes urea into ammonium

Ammonium - 1 of 3 stone constituents…increased urine pH, hydrogen phspphate dissociated and leads to phsophate

ABove + Mg in urine —–srtuvite

16
Q

Most common urea splitters

A

Proteus - P mirabillis is most common

Klebsiella

Pseudomonas

E coli (rarely)

17
Q

Struvite stones Risk factors

A

UTI with urea splitting

UTI risks - female postmenopausal, catheter

Infection stones are likely to grow fast and fill colecting system (staghorn stone)

18
Q

Cystinuria

A

Autosomala rec defecti n intestine and kideny tubule transport of cystine, ornithine, lysine and argiinine

Dec tubular reabsorpotion of cystine —-high urine levels —-stones

Can form multiple stones nad staghonrs

19
Q

Cysitnuria dx

A

Urine cysteine level

Stone analysis

Classic hexagonal crystals in the urine

20
Q

Tx of cystinuria

A

Keep cystine in solution

Drink h2O to have at least 1X nocturia

Drugs with SH replace 1 cystine…drug-cystine dimer more soluble

Tiopronin and D.penicillamine

21
Q

General diet recommendations

A

Drink moe H2O
Drink more lemonade and OJ

LEss animaal protein because it increases Ca absorption and has purines (uric acid)

Dec sodium…less Na means less reabsorption of both Na and Ca