Urinary calculi

Clinical Use: To determine the composition of a renal stone
Background: Kidney stones (ureterolithiasis) result from stones or renal calculi in the ureter. The stones are solid concretions or calculi formed in the kidneys from dissolved urinary minerals. Nephrolithiasis refers to the condition of having kidney stones. Urolithiasis refers to the condition of having calculi in the urinary tract (which also includes the kidneys), which may form or pass into the urinary bladder. Ureterolithiasis is the condition of having a calculus in the ureter, the tube connecting the kidneys and the bladder. Kidney stones typically leave the body by passage in the urine stream, and many stones are formed and passed without causing symptoms. If stones grow to sufficient size before passage (usually at least 2-3 millimeters), they can cause obstruction of the ureter. The resulting obstruction causes dilation or stretching of the upper ureter and renal pelvis as well as muscle spasm of the ureter, trying to move the stone.

There are several types of kidney stones based on the type of crystals of which they consist. The majority are calcium oxalate stones, followed by calcium phosphate stones. More rarely, struvite stones are produced by urea-splitting bacteria in people with urinary tract infections, and people with certain metabolic abnormalities may produce uric acid stones or cystine stones.

Preventive lifestyle measures are often advised such as drinking sufficient amounts of water and milk although the effect of many dietary interventions has not been rigorously studied.

Reference Ranges: Test code CALC incorporates the following test codes:-
ORIGST – Origin of stone
FRAGSI – Size of largest fragment
CALWT – (Weight of calculus in mg)
SURAPP – Surface Appearance
SHAPE – Shape
COLOUR – Colour
CAOX – (% Calcium Oxalate)
CALP – (% Calcium phosphate)
URICA – (% Urate)
MGAP – (% Magnesium Ammonium Phosphate)
CYSC – (% Cysteine)
MATRIX – (% Matrix (unknown matter, usually protein))
Associated Diseases:
Patient Preparation: None required
Specimen Requirements: Stone in white top universal container
Turnaround Time: 2 weeks
Additional Information:
Referred Test: Referred test
Location: Sunderland Royal Hospital