Kidney Stone Analysis (Sendout)

Reference Values: The presence of a kidney stone is abnormal. A quantitative report will be provided after analysis.

Interpretation: The interpretation of stone analysis results is complex. Refer to Mayo's website for additional information.

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.

Send stone(s) in a clean, dry screw-capped container. The specimen source is required.

• Sources: Bladder, kidney, prostatic, renal, or urinary.

Instructions:

• Clean any blood or foreign material from the stone with deionized water.
• Send entire stone. Stone should be air dried thoroughly at room temperature on a tissue or towel and sent in screw-capped, plastic container. Any specimen received with residual moisture on the stone or in the container will result in a testing delay.
• Indicate source of specimen on outside of container (eg, left kidney, bladder, right ureter).
• 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.

Additional Resources:

• Patient Collection Instructions for Kidney Stones
• Kidney Stone Packaging Instructions

Outside Laboratories:

• Store and ship stone(s) in a clean, dry container at ambient temperature.
• Indicate the specimen source on the DLMP requisition.

Stability: Ambient (preferred): 2 years; Refrigerated: 365 days; Frozen: 365 days.

Upon arrival at Mayo, all stone specimens and the containers in which they are received will be inspected. Prior to analysis, stones must be clean and dry. Bladder, kidney, prostatic, renal, or urinary stones are accepted.

Store stone specimens at ambient temperature.

Result-at-Entry:

• STONS (Stone Source): <Enter the stone source at login. See list below for available codes.>

Sendouts:

• Order Mayo Test: KIDST
• Interfaced: Yes [Interface: 601; Department: MAAB]
• Specimen source is required for processing.

Stability: Ambient (preferred): 2 years; Refrigerated: 365 days; Frozen: 365 days.

Upon arrival at Mayo, all stone specimens and the containers in which they are received will be inspected. Prior to analysis, stones must be clean and dry. Bladder, kidney, prostatic, renal, or urinary stones are accepted.

Stone Source Codes: (If not listed, use free text.)