Kidney stones

Demographics

Incidence 0.5% M:F 3:1 (but equal after menopause and at autopsy)

Risk factors

  1. Abnormal anatomy
  2. Supersaturation
  3. Lack of inhibition (organic & inorganic)
  4. Matric initiation (LMW protein released by injured kidney)
  5. Epitaxy (e.g., oxalate on urate but not cystine)
Inhibitors: organic (Tamm-Horsfall protein), inorganic (citrate).

Pathology

oxalate 80% struvite 13% urate 5% cystine 1% xanthine/matrix 1%

Treatment

Conservative: phosphate, thiazindes, MgO, citrate (sherbet), dietary restriction (↓Ca ↓oxalate &uarrfluid (except tea, milk) until colourless urine)

Urate: acidify urine, allopurinol.

Cystine: ↑fluid

Matric calculi: mucolytic drugs

Management

  1. Analgesia (diclofenac)
  2. CT or IVU
  3. MAG3 renal function
  4. Urine MCS
  5. Bloods: U&E Ca PO4 PTH
  6. Urine biochemistry (cystine Ca PO4 oxalate citrate)
Underlying pathology: Intervention if:
  1. Fail conservative measures
  2. stone >5mm
  3. Functional impairment on renogram
  4. Proximal infection (nephrostomy)
  5. Structural abnormality
Treatment:
  1. ESWL
  2. PCNL
  3. other
ESWL: ESWL contraindicated in pregnancy, warfarin treatment, weight >300 lb. Complications: Give up after 3 sessions. Stone >2 cm → double pigtail ureteric stent.