Renal stones/Nephrolithiasis & Urinary Tract Trauma Flashcards
Renal stones aka nephrolithiasis are a cause of unilateral ureteric obstruction
What are other causes of unilateral ureteric obstruction?
- PUJ obstruction,
- extrinsic/intrinsic tumour,
- retroperitoneal fibrosis,
- AAA,
- calculi,
- ureteric stricture,
- congenital a-peristaltic segment
Renal stones aka nephrolithiasis are a cause of unilateral ureteric obstruction, there is also bilateral ureteric obstruction
What are other causes of bilateral ureteric obstruction?
- urethral stricture,
- BPH,
- prostate cancer (locally advanced),
- large bladder tumuor,
- gravid uterus
What is the definition of renal stones?
renal calculi consist of crystal aggregates - stones form in collecting ducts,
classically deposit at:
- pelvi-ureteric junction,
- pelvic brim,
- vesico-ureteric junction…
Which patient groups are more likely to get renal stones?
- hotter climates (dehydration)
- high protein & salt diets
- peak incidence 20-50yrs,
- M:F 3:1 (women have more citrate & less testosterone which may increase oxalate levels)
- 10% men by 70yrs,
- Women better at passing stones spontaneously
- Caucasians & Asians,
What types of renal stones are there & how prevalent are they?
Pathophysiology os stones = supersaturation –> cyrstallization –> aggregation / especially if abnormal surface
- calcium oxalate (85%)
- struvite (up to 20%)
- uric acid (5-10%)
- calcium phosphate (10%)
- cysteine (10%)
Calcium oxalate stones make 85% of renal stones AKA the most common type
where does the hypercalciruia / oxalate come from?
Oxalate
- in strawberries, rhubarb, tea, leafy veg, nuts,
- also hyperparathyroidism & IBD
Hypercalciuria but not hypercalcaemia (serum Ca - so don’t cut out diet); causes of hypercalciuria:
- Absorption: over absorption of Ca from gut
- Renal hypercalciura: defect in renal tubules impairing renal tubular absorption of calcium in proximal tubule
- Hypercalcaemia: usually due to primary hyperparathyroidism
STRUVITE renal stones make 20% of renal stones AKA the 2nd most common type
where do these come from?
- proteus infection (g-ve UTI, particularly from LT catheterisation)
- –> urease produced
- struvite = from –> urea + water –> ammonia + CO2 under effect of urease
- ammonia causes alkaline urine = mg, ammonium and phos precipitant
- –> struvite renal stones = radio-opaque!
Uric acid causes 5-10% of renal stones
how?
myeloproliferative disorders, acidic urine, gout & chemo
–> increase DNA breakdown = increase nulceic acid –> uric acid = stones
calcium phosphate causes 10% of renal stones.
How do these form?
- renal tubular acidosis,
- hyperchloraemic metabolic acidosis,
- hypokalaemia (assoc with alkalosis)
- alkaline urine (as acid is retained in kidneys?)
- [overall idk as both acid and alkalosis seem to cause this..]
cysteine causes 10% of renal stones.
How do these form?
associated with inherited metabolic disorders
cysteine renal stones are difficult to treat due to hard consistency
[- they are radioopaque]
What condition can kidney stones cause that gives
- reduced renal function and atrophy due to pressue
- –> development of UTI
hydronephrosis
What predisposing factors to renal stones are there and why?
- diet (Ca, oxylate, urate)
- dehydration (bus/taxi drivers)
- sedentary lifestyle seasons e.g. winter (vitamin D- PTH, hypercalcuria & ca oxalate stones)
- drugs (diuretics, antacids)
- recurrent UTIs (in Mg ammonium phosphate calculi akak Struvite)
- urinaty tract abnormalities (horseshoe kidney)
- foreign bodies
- family hx
- metabolic abnormalities
hyper - uric acid (gout), ca, oxylate (rhubarb, strawberries, tea , chocolate)
hypo = citrate
What are the SSx of renal stones?
- colicky loin pain (worst pain ever, stabbing, can’t get comfortable, loin to groin),
- N&V,
- tachycardia,
- fever,
- haematuria,
- PMH stones,
- comorbidities
- But often no signs on just renal angle tenderness
- Can predispose development of UTI
What are the RFs for renal stones?
- high protein/sald/oxalate diet (ca oxalate is commonest stone - formed with black tea & milk)
- infection (urease to breakdown urea + water–> ammonia)
- hot climate
- abnormal anatomy, foreign body
- poor mobility
- IBD
- chemotherapy
- gout
- high PTH
- low fluid intake, low citrate
What problems/complications can renal stones cause (if not treated etc)?
- infection/sepsis
- AKI
- obstruction
- hydronephrosis
- chronic inflammation & ulceration (viscus perforation, malignancy)
What Ix are used in renal stones for bloods?
(bloods, urine, imaging)
- FBC
- U&E
- Ca (ca oxalate)
- PO4 (ca phosphate / mg ammonium phosphate (struvite)
- glucose
- bicarb (renal rubular acidosis -> Ca phosphate)
- urate (uric acid stones from nucleic acids e.g. MPDs and chemo too)
- is there an infection above the stone?
What Ix are used in renal stones for urine?
(bloods, urine imaging)
- Urine dip (+ve for blood in 90%);
- MSU,
- MC&S
- Urine:
- urine pH, - alkaline urine
- 24h urine (ca, oxalate, urate, citrate, Na, creatiine),
- Stone biochem (sieve urine)
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What Ix are used in renal stones for imaging?
(bloods, urine imaging)
- plain radiograph KUB,
- CT KUB (non-contrast, thick slices to reduce radiation),
- CT urogram (contrast);
- Intavenous Urogram, (Contrast w/XR)
- MRU (if pregnant) - magnetic resonance urography
- sometimes DMSA (radionuclide scan for split renal function, morphology & structure)
- renal US (hydronephrosis)
What is the Rx for renal stones?
There are conservative, medical expulsion therapy and surgical options, overall you should give:
- analgesia for the pain - PR diclofenac 100mg
- anti-emetic for N&V - metoclopramide 10mg
- fluid intake
- suveillance (95% stones <5mm pass spontaneously)
When is the conservative managment for stones appropriate?
stones <5mm
in the lower ureter
as up to 95% pass spontaneously
What is the medical expulsion therapy for renal stones?
- tamsulosin (alpha blocker)
- Calcium channel blockers
- (stops contraction of ureters/relaxes them on the stone –> reduce pain & pass them quicker)