Nephrolithiasis II Flashcards
Approach to renal colic/nephrolithiasis
nephrolithiasis can be broken down into two stone types: __ containing stones (90%) and _ __ stones (10%).
Calcium containing stones can be broken down into hard and soft types. The hard types are made of _ _, and soft stones are made of _.
Hard calcium sontes are often caused by 3 broad reasons: 1. incresaed solute due to ___ or __, 2. decreased solubility due to low __ ___ or ___, or an 3. anatomical problem like ___ ___ ___.
NON-calcium sontes (10% of stones) can me made of either ___ (in cysteinuria) or __ __ (due to high ___ intake or hyperuricosuria)
Approach to renal colic/nephrolithiasis
nephrolithiasis can be broken down into two stone types: Calcium containing stones (90%) and non calcium stones (10%).
Calcium containing stones can be broken down into hard and soft types. The hard types are made of calcium oxalate, and soft stones are made of struvite.
Hard calcium sontes are often caused by 3 broad reasons: 1. incresaed solute due to hypercalciuria or hyperoxaluria, 2. decreased solubility due to low urine volume or hypocirtraturia, or an 3. anatomical problem like medullar sponge kidney.
NON-calcium sontes (10% of stones) can me made of either cysteine (in cysteinuria) or uric acid (due to high protein intake or hyperuricosuria)
rare causes of “renal colic” that should be rued out
- clot
- sloughed papilla
- renal mass
- ectopic pregnancy
- aortic aneurysm
scoring system for diagnosing nephrolithiasis
- Flank pain (1pt)
- Acute onset pain (1 point)
- hematuria (2 points)
- positive KUB (2 points)
- Likelihood of stones (4 points for 90%, 5 points for 96%, and 6 points for 98.5%)
3 ways you can determine clues to the stone type
- stone analysis – the deifnitive test
- radiology
- urine microscopy
Type of calculus and typical composition
Typically these stones are composed of “struvite” AKA “triple phosphate” (Magnesium Ammonium Phosphate)
STAGHORN CALCULUS
type of crystla
Calcium oxalate crystals
type of crystal?
Brushite (CaHPO4) crystals
Type of crystal?
Struvite (MgNH4 PO4) crystals
Type of crystal
Uric acid crystal
Type of crystal?
Cystine crystals
Stones form because of conditions leading to ___
Stones form because of conditions leading to supersaturation
Types of stones that form in the tubular lumen
struvite, uric acid, brushite, cysteine
NOT CA OXALATE USUALLY
types of crystals that form in the kidney interstitium
Ca Oxalate
In the LOH cells, Positive luminal charge facilitates paracellular __, ___ reabsorption
Positive luminal charge facilitates paracellular Ca, Mg reabsorption
___ calculi made of ____ are associated with chronic infection of urine, particular by ___ and ___ containing urease
STRUVITE calculi made of MhNH4PO4 are associated with chronic infection of urine, particular by KLEBISELLA and PROTEUS containing urease
___ ____ calculi is associated with gout and is very ___ sensitive
uric acid calculi. very pH sensitive, forms in acid urine
T/F women are more likely to develop recurrent stones
false. men
Management of first stone or asymptomatic stones
Investigation:
• stone analysis, serum creatinine, [Ca] and/or [urate] • Radiological follow-up @ 6 - 12months
Treatment: • High fluid intake (urine output >2 L/day) ↓ risk by ~ 50% @ 5
years (but not soda)
• Normal calcium intake (vs. low) ↓ risk by ~ 50% @ 5 years
T/F during the treatment of your first stone, you should lower the amount of calcium in your diet to prevent it from growing larger or for recurring
false • Normal calcium intake (vs. low) ↓ risk by ~ 50% @ 5 years
investigations of recurrent calcium oxalate stone formers
urine: look at volume, Ca2+, oxalate, sodium, cirate.
Management of recurrent calcium oxalate stone formers:
- Hypercalciuria
- hyperoxaluria
- hypocituria
- no abnormality?
- radiological follow up in ___ year if remains asymptomatic
- Hypercalciuria: DO NOT REDUCE DIETARY CA2+. Limit Na+ intake. Thizide diuretics
- hyperoxaluria: low oxalate diet
- hypocituria: K+ citrate
- no abnormality? decrease urinary ca2+ and increase urinary citrate?
- radiological follow up in 1 year if remains asymptomatic
80 – 90% of stones passed without intervention. What are the 5 Ps requiring referral to urology?
- pyrexia (pyonephrosis)
- post-renal failure
- persistent symptoms
- previous problems
- pretty big stone >5 mm
most common stone in kids
cystine crystals
why does crohns predispose someone to stone formation?
crohns disease; problematic ileum that is involved in bile salt and probiotic excretion. resection due to chrogns disease resutls in decresaed bile salt reabosrption. as a consequence, other positively charged ions will attract fatty acids, speciifically calcium. when they bind, there is less calcium to bind to oxalate. there is free oxalate in the gut, which then gets absorbed into the blood, and then gets into the urine.
therefore crohsn causes creation of calcium oxalate stones.This also explains why people with a low calcium diet arre at higher risk to developing calcium oxalate stones too.
most common sites of stone formation
form in collecting tubules (proximal usually). anatomically, stones form at sites where theeyre more liekyl to achieve supersaturation; 1 in the tubular lumen of distal nephron, and 2. interstitium
at the heart of the of a calcium stone is a bud of calcium called ___ plaque– typically develop just outside the basolateral membrane of the cells of the ___.
at the heart of the of a calcium stone is a bud of calcium called randal’s plaque– typically develop just outside the basolateral membrane of the cells of the LOH.
why does LOH have a predisposition for stone formation? (recall randal plaque starting)
because it is a site of supersaturation. facilitated by excess Ca2+ and Mg2+ reabsorption.there is also little water in the interstitium, causing a higher likely hood of supersaturation
