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Test Code CASA Kidney Stone Analysis

Reporting Name

Kidney Stone Analysis

Useful For

Managing patients with recurrent renal calculi

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Stone


Shipping Instructions


1. Transport specimen per Kidney Stone Packaging Instructions in Special Instructions.

2. Specimen must be sent clean and dry.



Necessary Information


Specimen source is required.



Specimen Required


Supplies: Stone Analysis Collection Kit (T550)

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

Specimen Volume: Entire dried calculi specimen

Collection Instructions: 

1. Prepare specimen per Patient Collection Instructions for Kidney Stones in Special Instructions.

2. 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.


Specimen Minimum Volume

Entire stone

Specimen Stability Information

Specimen Type Temperature Time
Stone Ambient (preferred)
  Frozen  365 days
  Refrigerated  365 days

Reference Values

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

Day(s) and Time(s) Performed

Monday through Friday; 8 a.m.-8 p.m.

Saturday; 8 a.m.-3 p.m. Continuously

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

82365

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CASA Kidney Stone Analysis 74446-6

 

Result ID Test Result Name Result LOINC Value
8596 Kidney Stone Analysis 40787-4
SRC1 Source: 31208-2
2440 1st Constituent: 9795-6
2441 2nd Constituent: 9795-6
2442 3rd Constituent: 9795-6
2443 Nidus, Major 9795-6
2444 Nidus, Minor 9795-6
2445 Shell, Major 9795-6
2446 Shell, Minor 9795-6
2447 Comment 48767-8

Clinical Information

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 is 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.

Interpretation

The interpretation of stone analysis results 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.

-Production 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 the formation of ephedrine/guaifenesin stones.

Clinical Reference

1. Lieske JC, Segura JW: Evaluation and medical management of kidney stones. In Essential Urology: A Guide to Clinical Practice. Edited by JM Potts. Totowa, NJ, Humana Press, 2004, pp 117-152

2. Lieske JC: Pathophysiology and evaluation of obstructive uropathy. In Smith's Textbook of Endourology. Second edition. Edited by AD Smith, B Gopal Badlani, D Bagley, et al. Hamilton, Ontario, Canada, BC Decker Inc., 2007, pp 101-106

Analytic Time

2 days

Reject Due To

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

Embedded in tissue, sent with collection devices, sent in fluid-filled containers, or sent with significant nonstone debris

 

Method Name

Infrared Spectrum Analysis

Forms

If not ordering electronically, complete, print, and send a General Request Form (T239) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/general-request-form.pdf).