RENAL - Kidney stones

Question 1

Types of kidney stones

Answer 1

–Calcium oxalate (70%)
–Uric acid (radio-lucent)
–Magnesium ammonium phosphate (struvite/infection stones)
–Cystine (cystinuria- autosomal recessive disorder)
–Other: matrix, proteases inhibitor stones (radiolucent)

90% are radio-opaque

Question 2

Risk factors of kidney stones

Answer 2

–Dehydration

–Diet (high animal protein & sodium)

Question 3

Mx of kidney stones

Answer 3

•Pain relief
–NSAIDS
–Opioids
–Paracetamol
•Hydration

See if pt needs acute intervention 
•Infection/Sepsis
•Renal Impairment
•Bilateral obstructing calculi
•Solitary kidney (anatomical or functional)
•Inability to control Sx
–Refractory pain (repeat presentations)
•Prolonged obstruction
•Unlikely to pass spontaneously

Question 4

Describe obstructive polynephrosis

• causative organism
• Mx

Answer 4

• Urological emergency
• Usually GNB (E.Coli)
• High rates of SIRS/shock

–IV Abs (G-ve AND Enterococcus coverage)
–Urgent decompression (nephrostomy, stent)
–Supportive care (fluids, monitoring, ICU if necessary)

Question 5

Discuss medical expulsive therapy for kidney stones

Answer 5

α-blockers relax ureteric wall

Tamsulosin 0.4 mg OD x 2/52

Question 6

Surgical options for kidney stones

Answer 6

•JJ stent and delayed management

•Ureteroscopy and lithotrospsy
–Laser
–Pneumatic

•Shock wave lithotripsy
–ESWL

Question 7

Describe radiolucent stones

• type of stone
• pH of urine
• Rx

Answer 7

Usually uric acid (or cystine)

Form in acidic urine (pH less than 6.0)

Dissolve with urinary alkalinisation
–Target pH > 6.5
–Potassium citrate / sodium bicarbonate
–Allopurinol if serum uric acid levels elevated

High fluid intake

Question 8

Prevention of stone recurrence in kidneys

Answer 8

•Adequate fluid intake
•Dietary modification
•Urinary alkalinization
•Medical therapy
–Allopurinol
–Thiazide diuretics
•Cystinuria