26168 Kidney Stone Analysis (KIDST)

​Calculi Stone Analysis, Calculus (Stone) Analysis, Prostatic Stones, Renal  Calculi, Urinary Calculi

​Managing patients with recurrent renal calculi

​Specimen source is required.

1.  Clean any blood or foreign material from the stone with water.

2.  Send entire stone.  Stone should be air dried thoroughly at room temperature for 24 hours on a tissue or towel and sent in a screw-capped, plastic container.

3.  Indicate source of specimen on outside of container (eg, left kidney, bladder, right ureter).

4.  If multiple stones are collected and individal testing is desired for each stone, place each stone into its own container.  Testing must be ordered separately on each stone.  Each order will be charged separately.

5.  Important:  Any specimen received with residual moisture on the stone or in the container will result in a testing delay.

 -A dry stone will not stick to the walls of the container.

 -Do not send stone in formalin, surgical gel, or any other liquid as it interferes with the analytical procedure.

 -Do not tape specimen to anything.  Tape interferes with the analytical procedure.

 -Do not place stone directly in a bag.  If specimen is received in a bag, either transfer stone into a screw-capped, plastic container or place bag containing stone in a screw-capped, plastic container. 

 -Do not send filter.

​Stone from bladder, kidney, prostatic, renal or urinary

​All specimens will be evaulated at Mayo Clinic Laboratories for test suitability.

​The interpretation of stone analysis is complex, and beyond the scope of this text.  We refer you to chapter 25 of Smith LH:  Diseases of the Kidney. Vol 1. Fourth edition.  Edited by RW Schrier, CW Gottscholk.  Boston, MA, Little, Brown and Company, 1987.

Calcium oxalate stones:

-Production of calcium oxalate stones consisting of oxalate dihydrate indicate that the stone is newly formed and current urine constituents can be used to assess the importance of supersaturation.

-Producation of calcium oxalate stones consisting of oxalate monohydrate indicate an old (>2 months since formed) stone and current urine composition may not be meaningful.

Magnesium ammonium phosphate stones (struvite): 

-Production of magnesium ammonium phosphate stones (struvite) indicates that the cause of stone formation was infection.

-Treatment of the infection is the only way to inhibit further stone formation.

Ephedrine/guaifenesin stones:

-Certain herbal and over-the-counter preparations (eg, Mah Jung) contain high levels of ephedrine and guaifenesin.  Excessive consumption of these products can lead to formation of ephedrine/guaifenesin stones.