Nephrolithiasis Flashcards
Where do renal calculi usually form?
Pelviureteric junction
Pelvic brim
Vesicoureteic junction
What are renal calculi commonly made of?
Calcium oxalate 75%
Magnesium ammonium phosphate 15%
Urate 5%
How do renal stones present?
Renal colic
Loin to groin pain
Nausea/vomoiting
Cannot lie still
Infection can coexistE.g. UTI, pyelonephritis, (fevers, riggers, loin pain, nausea, vomiting)
Haematuria
Proteinuria
Sterile puria
Anuria
What tests for renal stones? Diagnostic?
Bedside:
Urine dip
MSU - MC&S
Blood:
FBC, U&E, Calcium, phosphate, glucose, bicarbonate, urate
Imaging:
Non-contrast CT
- also helps exclude differential causes of acute abdomen
80% also visible on KUB XR - look along ureters for calcification over transverse processes of vertebral bodies
What are differentials?
Ruptured abdominal aortic aneurysm Puelonephritis Ruptured ectopic pregnancy Tubo=ovarian abscess Apeendicitis Salpingitis
What is initial conservative management?
Analgesia NSAIDs or if CI, opioids
IV fluids if unable to tolerate PO
Antibiotics if infection - tazocin
What is management for stones depending on size?
<5mm in lower ureter - pass spontaneously, increase fluid intake
>5mm/pain not resolving - medical expulsion therapy
Nifedipine or alpha-blockers (tamsulosin) promote expulsion and reduce analgesia requirements
Extracorporeal shockwave lithotripsy - US waves shatter stone
Percutaneous nephrolithotomy: keyhole surgery to remove stones when large, multiple or complex
What are indications for urgent intervention:
Presence of infection and obstruction Percutaneous nephrostomy or ureteric stent may be needed to relieve obstruction Urosepsis Intractable pain or vomtiing Impending AKI Obstruction in solitary kidney Bilateral obstructing stones
What advice to prevent tones?
Drink plenty
Normal dietary calcium intake low
What can be given to prevent stones?
Calcium stones - thiazide is used to reduce calcium excretion
Oxalate - reduce oxalate intake, or use pyridine
Urate - allopurinol, urine alkalisation as urate is more soluble at higher pH
What foods are high in oxalate?
Chocolate Tea Rhubarb Strawberries Nuts Spinach
What are risk factors for urinary sonnets?
Recurrent UTI
REduced hydration
Metabolic abnormalities - hypercalclaemia, hyperparathyroidism, neoplastic,
Hyperuricosuria, hyperuricaemia
Hyperoxaluria
Drugs: diuretics, antacids, acetazolamide, corticosteroids, theophylline, aspirin
Urintary tract abnormalities - pelviuretierc junction obstruction
Foreign bodies - stents, catheters
Family history
