Kidney Stones/Nephrolithiasis (1*)

Question 1

How does it present?

What are its differentials?

What are its complications?

Answer 1

➊ • Renal colic - Excruciating, colicky loin to groin pain
• Restlessness (differentiates it from peritonitis, where they’re still)
• Haematuria
• N+V
• Oliguria

➋ • Pyelonephritis
• Other ureteric obstructions (e.g. stricture, clot, tumour)
• MSK pain

➌ • Obstruction
• Infection with obstructive pyelonephritis

Question 2

Types:
What is its most common type?
→ What is it usually made of?
→ What are its risk factors?

What are its other types?

Answer 2

➊ Calcium (80%)
→ Calcium Oxalate (more common) and Calcium Phosphate
→ Hypercalcaemia and Oliguria

N.B. Thiazide diuretics can be given to prevent calcium phosphate stones.

➋ * Uric acid - Radiolucent so aren’t seen on XR, but on CT
* Struvite (ammonium magnesium phosphate) - Associated with proteus infection, and often leads to Staghorn calculi
* Cystine - Due to cystinuria, which is an autosomal recessive disease
* Indinavir - Due to ART

N.B. Only the Uric acid and Indinavir stones are radiolucent, therefore won’t be seen on XR.

Question 3

What’s the main investigation to do?

What are other investigations to do?

Answer 3

➊ Non-contrast CT KUB

N.B. US KUB good alternative in pregnant women and children

➋ • Urine dip - Shows haematuria and rules out infection
• Bloods - FBC, U&E, Ca, Uric acid

Question 4

What are the lifestyle changes to make?

What is given as analgesia?

What is done for stones < 5mm?

What can be done for the larger stones (> 1cm)?

What should be done if the pt presents septic?

Answer 4

➊ • Stay hydrated
• Add fresh lemon juice to water (citric acid binds to urinary calcium for excretion)
• Avoid fizzy drinks
• Allopurinol or potassium citrate (decrease uric acid)

➋ NSAIDs (e.g. Diclofenac) better option for colicky, spasmic pains - One-off IM dose shown to best option in the acute setting

➌ • Watchful waiting if no signs of obstruction
• Tamsulosin (expuslive therapy) if stone is in distal ureter

➍ • Shock wave lithotropsy - high energy shock waves break up the stone, allowing them to pass naturally
• Ureteroscopy - option for distal/middle ureteric stones and pregnant women - stents can be left to prevent obstruction
• Percutaneous nephrolithotomy - used for very large (> 2cm) stones or staghorn calculi
• Open surgery - last option

➎ Nephrostomy - This allows for decompression and immediate drainage of the kidney