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Stone Former, Urine 24-Hour

Stone Former Workup

Test Codes

Antrim #15840, EPIC: LAB5457, SOFT: STFRU

Department

Special Chemistry

Instructions

Please refer to the Specimen Collection Manual for instructions on 24-Hour Urine Collection:

• Urine 24-Hour Collection - Inpatient
• Urine 24-Hour Collection - Outpatient/Outreach
• Random Urine

Specimen Collection Criteria

Collect: 24-hour urine specimen with no preservatives.

• Keep 24-hour urine specimen iced or refrigerated during collection.
• Include start and end dates and times for the collection period on the specimen container.

Urine Preservative Options
No Preservative	6N Hydrochloric Acid	Boric Acid (10g)	Sodium Carbonate	50% Acetic Acid
REQUIRED	Unacceptable	Unacceptable	Unacceptable	Unacceptable

Physician Office/Draw Specimen Preparation

Maintain specimens refrigerated (2-8°C or 36-46°F) prior to transport.

Preparation for Courier Transport

Transport: Entire 24-hour urine collection, refrigerated (2-8°C or 36-46°F).

Rejection Criteria

• Random urine specimens.
• Samples collected with any preservative.
• Samples not kept refrigerated (2-8°C or 36-46°F).
• Samples not collected and processed as indicated.

In-Lab Processing

Measure total volume of 24-hour urine specimen. Record total volume and collection start and end dates and times in the LIS system.

For Chemistry: Aliquot a minimum of 5.0 mL from the well-mixed 24-hour urine collection and centrifuge.

For Special Testing: Prepare 2 aliquots. Aliquot 1: Aliquot a minimum of 10 mL from the well-mixed 24-hour urine collection and centrifuge. Refrigerate aliquot prior to analysis. Aliquot 2: Aliquot a minimum of 10 mL from the well-mixed 24-hour urine collection. 

Adjust the pH of the aliquot to between 1.0 and 3.0. Heat the aliquot to 56°C for 15 minutes prior to storage. Refrigerate aliquot prior to analysis. The sample will, again, be heated to 56°C in Special Testing, prior to analysis, to re-dissolve the oxalate. 

 

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): Unacceptable
Refrigerated (2-8°C or 36-46°F): 4 Days
Frozen (-20°C/-4°F or below): 3 weeks

Specimen Storage in Department Prior to Disposal:

Chemistry Assays: Refrigerated (2-8°C or 36-46°F): 30 days
Urine Citrate and Oxalate: Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Automated Chemistry Laboratory
Royal Oak Special Testing Laboratory

Performed

Varies, once per week.
Results available within 7 days.

Reference Range

See individual assays for reference range.
This assay includes: Urine Calcium, Urine Citric Acid, Urine Creatinine, Urine Magnesium, Urine Na/K, Urine Oxalate, Urine Phosphorus, Urine Urea, and Urine Uric Acid.

Test Methodology

Potentiometry and Spectrophotometry.

Interpretation

This assay includes: Urine Calcium, Urine Citric Acid, Urine Creatinine, Urine Magnesium, Urine Na/K, Urine Oxalate, Urine Phosphorus, Urine Urea, and Urine Uric Acid.

Elevated levels of calcium, oxalate, magnesium, and uric acid or decreased levels of citric acid may increase the risk of renal calculi formation.

Clinical Utility

The stone former panel is useful in evaluating the likelihood of renal calculus formation and the type of calculus that may be formed. For definitive stone analysis, order Calculi Analysis. See individual tests for further details of their clinical significance.

CPT Codes

Please see individual assays for CPT codes.

This assay includes: Urine Calcium, Urine Citric Acid, Urine Creatinine, Urine Magnesium, Urine Na/K, Urine Oxalate, Urine Phosphorus, Urine Urea, and Urine Uric Acid.

Contacts

Last Updated

1/13/2023