Urinary Tract Calculi Flashcards
Define urinary tract calculi
Presence of stones in the urinary tract • Calcium oxalate (radiopaque) – 65% • calcium phosphate (radiopaque) – 15% • Uric acid (radiolucent) – 10% • Cystine (semi-radiopaque) – 1% • Struvite – 1%
What are the causes/risk factors of urinary tract calculi?
• Idiopathic • Dehydration • UTIs • Alkaline urine – calcium stones • Acidic urine – cystine, urate stones • Hypercalciuria – drugs • Hypercalcaemia – malignancy, sarcoidosis, myeloma • Hyperoxaluria – diet • Hyperuricaemia – tumour lysis syndrome, high cell turnover • Cystinuria • Anatomical abnormalities e.g. horseshoe kidneys
Risk Factors • Male • Heat exposure • Dehydration • Obesity • High protein and salt intake • Proteus, Klebsiella, Pseudomonas – staghorn calculi
What are the signs and symptoms of urinary tract calculi?
- Asymptomatic
- Loin pain
- Renal colic – colicky or constant severe pain, can’t keep still
- Nausea
- Vomiting
- Frequency
- Strangury – slow, painful spasmodic discharge of urine drop by drop
- Haematuria
no signs
What investigations are carried out for urinary tract calculi?
• Bloods
o U&Es – calcium, phosphate, albumin, PTH, vit D, urate, bicarbonate, serum
ACE, TFTs
• Urinalysis – haematuria, proteinuria, nitrites
• Urine MC&S – exclude infection
• Non-contrast CT helical KUB – gold standard
• Stone analysis once passed
Other tests
• 24h urine collection - calcium, phosphate, oxalate, urate, cystine, glyoxalate, citrate
• Plain KUB
• IVU
• Renal USS – hydronephrosis
What is the management of urinary tract calculi?
Conservative • Hydration (oral/IV) • Analgesia e.g. NSAIDs, opiates • Antiemetics e.g. metoclopramide • Antibiotics if infection • Wait for stone to pass
Stones <10mm – medical expulsive therapy
• Alpha-blockers e.g. tamsulosin
• CCBs e.g. nifedipine
Stones >10mm or failed MET
• Extracorporeal shockwave lithotripsy (ESWL)
• Percutaneous anterograde ureteroscopy – visualise stone and break up with laser
• Percutaneous nephrostolithotomy>20mm
• Laparoscopic/open stone removal
Prevention
• Increase fluid intake (>3l/day)
• Calcium stones – reduce calcium and vitamin D intake
• Oxalate stones – reduce oxalate containing foods
• Uric acid stones – allopurinol and urinary alkalinisation (oral sodium bicarbonate)
• Cystine stones – urinary alkalinisation (oral sodium bicarbonate)
What are the complications of urinary tract calculi?
- Obstruction
- Hydronephrosis
- Infection
