Kidney stones (R1) Flashcards
Clinical anatomy
- Name the 3 sites of constriction within the ureter
- Which point is the narrowest?
Ureteropelvic junction
Pelvic inlet (where ureter enters the pelvis)
Ureterovesicular junction (narrowest)
Aetiology
- Why do kidney stones form? (In terms of solutes/solvents)
- What 2 ions inhibit crystal formation?
Urine becomes too concentrated (↑ solutes, ↓solvent/water) –> supersaturation of urine –> solute precipitates out to form the stone.
Magnesium and citrate
Aetiology
- Types of stones, from most to least common?
Calcium oxalate stones
Calcium phosphate stones
Uric acid stones
Struvite stones
Cystine stones
Xanthine stones
Aetiology
- Calcium oxalate stones form in [acidic/basic] urine, while calcium phosphate stones from in [acidic/basic] urine
- Reasons why each can from?
Calcium oxalate: acidic (oxalate is an acid)
Calcium phosphate: basic (phosphate is a base)
Too much calcium
- Hyperparathyroidism
- Increased calcium absorption in GIT
- Decreased renal tubular calcium reabsorption
Too much oxalate
- Genetics
- Liver metabolism defect
- Diet: rhubarb, spinach, chocolate, nuts, beer (oxalate rich)
Aetiology: uric acid stones
- Uric acid is formed from the breakdown of which substance?
- What foods are high in this substance –> promote uric acid stone formation?
- Seen in what condition?
Purines
Red meat, organ meat, anchovies, shellfish
Gout.
Aetiology: struvite stones
- Produced by which bacteria? Hence, risk factor?
- What shape?
Urease producing bacteria (eg. proteus) - UTI’s
Staghorn
Aetiology
- Cystine stones are produced in which condition?
- Xanthine stones: xanthine is a breakdown product of which substance, hence has similar properties to which stones?
- Cystinosis
- Purines: hence, uric acid stones
Applied biomedical sciences
- Where in the nephron do stones tend to form?
- Where do the stones tend to lodge? Implications for the site of pain?
- Describe size of stones
- Is true urinary retention common with kidney stones?
Loop of Henle –> collecting duct
The three constriction sites - lon to groin pain.
Size
- 90 to 95% of stones are 5mm or less, and pass on their on
- 6-7 mm stones are borderline
- Stones 8mm and bigger will not pass on their own
Rare, can only happen if both ureters are blocked.
3 complications?
Urinary obstruction –> hydronephrosis
Obstructive pyelonephritis
AKI
Complications
- Describe how obstructive pyelonephritis occurs
- Do individuals with obstructive pyelonephritis get sick quickly?
Ureter is obstructed by a stone.
Leads to urinary stasis in the kidney –> bacteria multiply –> pyelonephritis.
Infection has nowhere to go but the kidney - BAD
Yes
Risk factors for kidney stones?
- Personal and family history of kidney stones
- Demographics: obese, white, male
- Dehydration, high salt diet
Prevention
- 3 ways?
Most important: hydration
Decrease sodium intake
Optimal BMI
Clinical features
- History?
Clinical features
- Exam?
Abdomen: while kidney tenderness may be present, it is more often absent (not -itis positive)
Investigation
- Bedside?
Investigation
- Labs?
Investigation
- Imaging?
CT KUB (non contrast) is gold standard.
For pregnant individuals and young people: ultrasound
Investigation
- Why is CT KUB non contrast?
- Jon’s 4 indications?
Non contrast means nothing else is bright except the stone.
- Impaired eGFR
- Signs of infection
- Reaching ceiling of analgesia
- Serious/equally likely diagnosis to rule out (eg. AAA)
Treatment
- Principles of management?
Manage symptoms
Conservative treatment: medical expulsive therapy
OR interventional management
Treatment
- Symptom management?
Analgesia: NSAIDs –> opioids
Antiemetics
Hydration: IV fluids
Treatment
- When is conservative treatment vs interventional treatment indicated?
Conservative treatment for small stones <=5mm, interventional management for large stones >=8mm
Treatment: conservative treatment/medical expulsive therapy
- How does it work?
- First and second line medications?
Helps relax the ureteral SMC to help the stones pass
First line: tamsulosin (alpha blocker)
Second line: nifedipine (CCB) - currently not routinely recommended
Treatment: interventional management
- What are the 3 procedures?
Shockwave lithotripsy: shockwaves break up stones so they can pass.
Ureteroscopy (endoscopic removal of the stone) +- stent placement (allows urine drainage)
Large stones >=20mm: percutaneous nephrolithotomy: tube into kidney to remove the stone.
Treatment
- Treating obstructive pyelonephritis
Patient explanation
- What are kidney stones?
- What are the symptoms?
When stones form in your kidneys.
Stones leave the kidneys, go into the tubes.
Tubes contract on the stone, causing the tube to become irritated –> pain, blood in urine.
Can become generally unwell –> N&V
