Urolithiasis Flashcards
What are the classic locations for urinary tract stones to occur?
- Pelviureteric junction
- Pelvic brim
- Vesicoureteric junction
What is the most common type of kidney stone?
Calcium oxalate
What are the different types of stones the can occur in the urinary tract?
- Calcium oxalate/phosphate
- Cystine
- Magnesium ammonium phosphate (struvite)
- Urate
- Hydroxyapatite
- Brushite
What are causes of urinary tract stones?
- Dehydration
- Hypercalcaemia
- Hypercalciuria
- Hyperparathyroidism
- Neoplasia
- Hyperthyroidism
- Recurrent UTI’s
- Hyperuricosuria
- Cystinuria
- Renal tubular acidosis
- PKD
- Drugs
What are the common causes of hypercalcaemia leading to stone formation?
- Primary hyperparathyroidism
- Vitamin D ingestion
- Sarcoidosis
What are causes of hypercalciuria?
- Hypercalcaemia
- Excess dietary calcium
- Excess resorption
- Idiopathic
What can cause uric acid stones to form?
- Gout
- Myeloproliferative disorders
- Dehydration
How does renal tubular acidosis cause stone formation?
Caused, in part, by the production of a persistently alkaline urine and reduced urinary citrate excretion.
What drugs can cause bladder stones?
- Calcium - Loop diuretics, antacids, glucocorticoids, theophylline, Vitamin D, acetazolamide
- Uric acid - Thiazides, salicylates
How do those with urinary tract calculi present?
Can be asymptomatic:
- Pain - excruciating spasm; loin to groin pain; often in area where stone is affecting
- Nausea + Vomiting
- Signs of infection
- Haematuria
- Proteinuria
- Sterile pyuria
- Can be anuric
If someone had an obstruction of the kidney due to stones, where might the pain be?
Felt in the loin, between rib 12 and lateral edge of lumbar muscle
Where might someone experience pain if they had an obstruction caused by a stone of the mid-ureter?
May mimic appendicitis/diverticulitis in terms of location
What features might indicate that a stone is obstructing the lower ureter?
- Symptoms of bladder irritability
- Pain in scrotum/penile tip/labia majora
What features might you see in someone who has obstruction of the the bladder/urethra?
- Pelvic pain
- Dysuria
- Strangury
- Interrupted flow
What is strangury?
Desire but inability to void
What are people at increased risk of developing if they have urinary stones?
Infection
What is the character of pain experienced in urinary stones?
Colicky pain - tube contracting against obstruction.
Patient is very restless, unable to find comfortable position
What nerve root distribution is implicated in the loin to groin pain experienced in renal colic?
L1 - First lumbar nerve root
What might you find on examination of someone with urinary tract stones?
Usually no tenderness on palpation, however may have:
- Costovertebral angle and ipsilateral flank tenderness
- Signs of sepsis - fever, tachycardia, and hypotension
What investigations would you consider doing in someone with urinary stones?
- Bloods - FBC, U+E’s, Ca2+, PO43-, glucose, bicarbonate, urate, PTH, coag screen
- Urine dipstick
- MSU + culture
- Plain abdo x-ray/ Non-contrast CT-KUB
-
Consider
- Renal ultrasound
- Urine pH
- 24hr urine collection
- Stone biochemistry
What is a CT-KUB?
CT of kidney, ureter and bladder - best diagnostic test available
What may present similarly to renal stones?
Ruptured AAA
What proportion of stones are visible on X-ray KUB?
80%
Why might you do a urine dipstick?
Check for blood in urine
Which sex does urinary stones occur more commonly in?
Males
What might signs of sepsis in someone with renal colic indicate?
Obstruction with overlying infection
How would you manage someone with acute renal colic?
- Analgesia - IV/IM diclofenac
- Hydration - crystalloids
- Anti-emetics - ondansetron
- If infection - Trimethoprim
What would you do if someone had stones confirmed at <5mm diameter in the lower ureter?
Increase fluid intake with supportive therapy - 90-95% of stones will pass
How long does it take for most stones treated with alpha-blockers/nifedipine to pass?
Most pass within 48hrs
If stones are failing to pass/>5mm, what else would you consider doing?
- Extracorporeal shockwave lithotripsyy (if <1cm diameter)
- Percutaneous Ureteroscopy
- Percutaneous Nephrolithotomy - with large, multiple, complex stones
When is percutaneous nephrolithotomy used to treat urinary stones?
- Renal/proximal ereteric stones
- Those >20mm
- Failed medical expulsion therapy/ESWL + uteroscopy
What are indications for urgent intervention?
- Presence of infection and obstruction - may need percutaneous nephrostomy/ureteric stent to relieve obstruction
- Urospesis
- Intractable pain/vomiting
- Impending AKI
- Obstruction in a solitary kidney
- Bilateral stones
What general advice would you give someone to prevent urinary stones?
- Drink plenty
- Normal dietary calcium
What secondary prevention measures would you employ in someone who had had calcium stones?
In hypercalciuria - Thiazide diuretics
What secondary prevention measures would you employ in someone who had had urate stones?
- Allopurinol
- Urine alklainisation - sodium bicarb/potassium citrate
What secondary prevention measures would you employ in someone who had had cystine stones?
- Vigorous hydration - >3L/day urine output
- Urinary alkalinisation
- Penicillamine + pyroxidine
What might significant bacteruira indicate?
Mixed infective stone formation
Why might you look at serum albumin in someone with kidney stones?
To correct serum calcium concentration
Why might you look at plasma bicarbonate?
This is low in renal tubular acidosis. The finding of a urine pH that does not fall below 5.5 in the face of metabolic acidosis is diagnostic of this condition
Why might you do a 24 hour urine collection?
To measure urinary calcium, oxalate and uric acid output
Why might you do a coag screen in someone with urinary stones?
Incase there is need for nephrostomy insertion
What would you initially do to manage someone with infection and obstruction due to urinary stone?
- ABCDE and Sepsis 6
- Drain the kidney - Nephrostomy/stent
What is the best form of pain medication for urinary stones?
IM/IV/PR diclofenac
What investigations would you consider doing to investigate the cause of urinary stones?
- Bloods - Ca2+, PO43-, Albumin, PTH, urate, bicarbonate
- Specific - urinary spot cystine, 24 hr urine collection
