26168 Kidney Stone Analysis (KIDST)

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

​Managing patients with recurrent renal calculi (kidney stones)

​Specimen source is required.

Upon arrival in the performing laboratory, all stone specimens and the containers in which they are received will be inspected. Prior to analysis, stones must be clean and dry.

1. Prepare stone by cleaning any blood or foreign material from the stone with deionized water.​

2. Place stone on a clean filter or paper towel and let dry at ambient temperature for a minimum of 24 hours.

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

Repeat steps 1 through 4 for each stone received

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 send filter.

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

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

​The composition of urinary stones may vary from a simple crystal to a complex mixture containing several different species of crystals. The composition of the nidus (center) may be entirely different from that of the peripheral layers.

Eighty percent of patients with kidney stones have a history of recurrent stone formation. Knowledge of stone composition can be useful to guide therapy of patients with recurrent stone formation.

Treatment of urinary calculi can be complex.(1) In an overly simplified format, the following patterns are often treated as follows:

-Hyperuricuria and predominately uric acid stones: Alkalinize urine to increase uric acid solubility

-Hypercalciuria and predominately hydroxyapatite stones: Acidify urine to increase calcium solubility

However, treatment also depends on urine pH and urine phosphate, sulfate, oxalate, and citrate concentrations.

-Hyperoxaluria and calcium oxalate stones: Increase daily fluid intake and consider reduction of daily calcium

However, daily requirements for calcium to maintain good bone formation complicate the treatment.

-Magnesium ammonium phosphate stones (struvite): Investigate and treat urinary tract infection.​

The interpretation of stone analysis results is complex and beyond the scope of this text. For more information see the second Clinical Reference.

Calcium oxalate stones:
-Production of calcium oxalate stones consisting of oxalate dihydrate indicates that the stone is newly formed, and current urine constituents can be used to assess the importance of supersaturation.
-Production of calcium oxalate stones consisting of oxalate monohydrate indicates 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 the formation of ephedrine/guaifenesin stones.