Urinary tract calculi

Last updated: Thursday, 20, January, 2011
CausesAppropriate Tests

Investigation is usually only indicated in those patients with recurrent calculi.
Urine microscopy and culture; early morning specimen for pH (to assess predisposition for uric acid crystals);
Urine: calcium, phosphate, urate, creatinine, electrolytes.
Calculus analysis, if specimen available.
Plasma: Creatinine, urea, urate, calcium, phosphate, protein (total), albumin; FBC, blood film.

Calcium stones

Stones may have a uric acid nidus.

Hypercalciuria, especially

Hyperoxaluria

Oxalate - urine.

Renal tubular acidosis

Idiopathic

Uric acid stones

Hyperuricaemia, especially

  • Hyperuricosuria

Dehydration

Struvite stones

Urinary tract infection

Cystine stones

Cystinuria

Amino acids - urine.

Xanthine stones

Xanthinuria

Urine xanthine - consult pathologist.

Allopurinol

Factitious stones

Usually insoluble in acid.