Test ID: RSSAT
Supersaturation Profile, Pediatric, Random, Urine
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Diagnosis and management of patients with renal lithiasis:
-In patients who have a radiopaque stone, for whom stone analysis is not available, the supersaturation data can be used to predict the likely composition of the stone. This may help in designing a treatment program.
-Individual components of the supersaturation profile can identify specific risk factors for stones.
-During follow-up, changes in the urine supersaturation can be used to monitor the effectiveness of therapy by confirming that the crystallization potential has indeed decreased.
Profile Information A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| RRSUP | Supersaturation Random, U | No | Yes |
| NAUR | Sodium, Random, U | Yes, (order RNAUR) | Yes |
| KURR | Potassium, Random, U | Yes, (order RKUR) | Yes |
| CALRR | Calcium, Random, U | Yes, (order CAUR) | Yes |
| MGUR | Magnesium, Random, U | Yes, (order MGRU) | Yes |
| CLUR | Chloride, Random, U | Yes, (order RCHLU) | Yes |
| POUR | Phosphorus, Pediatric, Random, U | Yes, (order RPOU) | Yes |
| SULFR | Sulfate, Random, U | No | Yes |
| CITRR | Citrate Excretion, Peds, Random, U | Yes, (order RCITR) | Yes |
| OXUR | Oxalate, Pediatric, Random, U | Yes, (order ROXU) | Yes |
| UPHR | pH, Random, U | No | Yes |
| URCUR | Uric Acid, Random, U | Yes, (order RURCU) | Yes |
| CTURR | Creatinine, Random, U | Yes, (order RCTUR) | Yes |
| UOSMR | Osmolality, Random, U | No | Yes |
Method Name A short description of the method used to perform the test
RRSUP/57057: Not applicable
CITRR/31232: Enzymatic
OXUR/31233: Enzymatic Using Oxalate Oxidase
UOSMR/31237: Freezing Point Depression
SULFR/31231: High-Performance Liquid Chromatography (HPLC)
CALRR/31171, MGUR/31170: Inductively Coupled Plasma (ICP) Emission Spectroscopy
POUR/31230: Molybdic Acid
UPHR/31234: pH Meter
NAUR/31227, KURR/31228, CLUR/31229: Potentiometric, Indirect Ion-Selective Electrode (ISE)
CTURR/31236: Enzymatic Colorimetric Assay
URCUR/31235: Uricase
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Calcium Oxalate Crystal
Hydroxyapatite Crystal
Kidney Stone Disease
Kidney Stone Profile
Sodium Urate Crystal
Stone Risk Profile
Uric Acid Crystals
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: 6 plastic, 10-mL urine tubes (Supply T068)
Specimen Volume: 40 mL
Collection Instructions:
1. Collect a random urine specimen and divide the urine into 6 tubes
2. Specimen pH should be between 4.5 and 8 and will stay in this range if kept refrigerated. Specimens with pH >8 indicate bacterial contamination, and testing will be canceled. Do not attempt to adjust pH as it will adversely affect results.
Additional Information:
1. Patient's age is required.
2. A timed 24-hour urine collection is the preferred specimen for measuring and interpreting this profile to determine kidney stone risk factors. Random collections with individual analytes normalized to urinary creatinine may be of some clinical use in patients who cannot collect a 24-hour specimen, typically small children. Therefore, this test is offered on random collections for children <16 years old.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | Specimen must have a pH between 4.5 and 8.0 to be acceptable. |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | 7 days |
| Frozen | 7 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Urine is often supersaturated, which favors precipitation of several crystalline phases such as calcium oxalate, calcium phosphate, and uric acid. However, crystals do not always form in supersaturated urine because supersaturation is balanced by crystallization inhibitors that are also present in urine. Urinary inhibitors include ions (eg, citrate) and macromolecules but remain poorly understood.
Urine supersaturation is calculated by measuring the concentration of all the ions that can interact (potassium, calcium, phosphorus, oxalate, uric acid, citrate, magnesium, sodium, chloride, sulfate, and pH). Once the concentrations of all the relevant urinary ions are known, a computer program can calculate the theoretical supersaturation with respect to the important crystalline phases (eg, calcium oxalate).(1)
Since the supersaturation of urine has been shown to correlate with stone type (2), therapy is often targeted towards decreasing those urinary supersaturations that are identified. Treatment strategies include alterations in diet and fluid intake as well as drug therapy, all designed to decrease the urine supersaturation.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
No established reference values, with the exception of the following:
CALCIUM/CREATININE
0-12 months: <2,100 mg/g
13-24 months: <450 mg/g
25 months-5 years: <350 mg/g
6-10 years: <300 mg/g
11-18 years: <260 mg/g
> or =19 years: <220 mg/g
Interpretation Provides information to assist in interpretation of the test results
Delta G (DG), the Gibbs free energy of transfer from a supersaturated to a saturated solution, is negative for undersaturated solutions and positive for supersaturated solutions. In most cases, the supersaturation levels are slightly positive even in normal individuals but are balanced by an inhibitor activity.
While the DG of urine is often positive, even in the urine of nonstone formers, on average, the DG is even more positive in those individuals who do form kidney stones. The "normal" values are simply derived by comparing urinary DG values for the important stone-forming crystalline phases between a population of stone formers and a population of nonstone formers. Those DG values that are outside the expected range in a population of nonstone formers are marked "abnormal."
A normal or increased citrate value suggests that potassium citrate may be a less effective choice for treatment of a patient with calcium oxalate or calcium phosphate stones.
If the urine citrate is low, secondary causes should be excluded including hypokalemia, renal tubular acidosis, gastrointestinal bicarbonate losses (eg, diarrhea or malabsorption), or an exogenous acid load (eg, excessive consumption of meat protein).
An increased urinary oxalate value may prompt a search for genetic abnormalities of oxalate production (ie, primary hyperoxaluria). Secondary hyperoxaluria can result from diverse gastrointestinal disorders that result in malabsorption. Milder hyperoxaluria could result from excess dietary oxalate consumption, or reduced calcium (dairy) intake, perhaps even in the absence of gastrointestinal disease.
The results can be used to determine the likely effect of a therapeutic intervention on stone-forming risk. For example, taking oral potassium citrate will raise the urinary citrate excretion, which should reduce calcium phosphate supersaturation (by reducing free ionic calcium), but citrate administration also increases urinary pH (because it represents an alkali load) and a higher urine pH promotes calcium phosphate crystallization. The net result of this or any therapeutic manipulation could be assessed by collecting a 24-hour urine and comparing the supersaturation calculation for calcium phosphate before and after therapy.
Important stone-specific factors:
-Calcium oxalate stones: Urine volume, calcium, oxalate, citrate, and uric acid excretion are all risk factors that are possible targets for therapeutic intervention.
-Calcium phosphate stones (apatite or brushite): Urinary volume, calcium, pH, and citrate significantly influence the supersaturation for calcium phosphate. Of note, a urine pH <6 may help reduce the tendency for these stones to form.
-Uric acid stones: Urine pH, volume, and uric acid excretion levels influence the supersaturation. Urine pH is especially critical, in that uric acid is unlikely to crystallize if the pH is >6.
-Sodium urate stones: Alkaline pH and high uric acid excretion promote stone formation.
A low urine volume is a universal risk factor for all types of kidney stones.
The following reference means for calculated supersaturation apply to 24-hour timed collections. No information is available for random collections.
Brushite: 0.21
Hydroxyapatite: 3.96
Uric acid: 1.04
Sodium urate: 1.76
Values for individual analytes that are part of this panel on a random urine collection are best interpreted as a ratio to the creatinine excretion. Following are pediatric reference ranges for the important analytes for which pediatric data is available.
Oxalate/Creatinine (mg/mg)
| Age (year) | 95th Percentile |
| 0-0.5 | <0.175 |
| 0.5-1 | <0.139 |
| 1-2 | <0.103 |
| 2-3 | <0.08 |
| 3-5 | <0.064 |
| 5-7 | <0.056 |
| 7-17 | <0.048 |
Matos V, Van Melle G, Werner D et al: Urinary oxalate and urate to creatinine ratios in a healthy pediatric population. Am J Kidney Dis 1999;34:e1
Uric Acid/Creatinine (mg/mg)
| Age (year) | 5th Percentile | 95th Percentile |
| 0-0.5 | >1.189 | <2.378 |
| 0.5-1 | >1.040 | <2.229 |
| 1-2 | >0.743 | <2.080 |
| 2-3 | >0.698 | <1.932 |
| 3-5 | >0.594 | <1.635 |
| 5-7 | >0.446 | <1.189 |
| 7-10 | >0.386 | <0.832 |
| 10-14 | >0.297 | <0.654 |
| 14-17 | >0.297 | <0.594 |
Matos V, Van Melle G, Werner D et al: Urinary oxalate and urate to creatinine ratios in a healthy pediatric population. Am J Kidney Dis 1999;34:e1
Phosphate/Creatinine (mg/mg)
| Age (year) | 5th Percentile | 95th Percentile |
| 0-1 | >0.34 | <5.24 |
| 1-2 | >0.34 | <3.95 |
| 2-3 | >0.34 | <3.13 |
| 3-5 | >0.33 | <2.17 |
| 5-7 | >0.33 | <1.19 |
| 7-10 | >0.32 | <0.97 |
| 10-14 | >0.22 | <0.86 |
| 14-17 | >0.21 | <0.75 |
Matos V, van Melle G, Boulat O et al: Urinary phosphate/creatinine, calcium/creatinine, and magnesium/creatinine ratios in a healthy pediatric population. J Pediatr 1997;131:252-257
Magnesium/Creatinine (mg/g)
| Age (year) | 95th Percentile |
| 0-1 | <0.48 |
| 1-2 | <0.37 |
| 2-3 | <0.34 |
| 3-5 | <0.29 |
| 5-7 | <0.21 |
| 7-10 | <0.18 |
| 10-14 | <0.15 |
| 14-17 | <0.13 |
Matos V, van Melle G, Boulat O et al: Urinary phosphate/creatinine, calcium/creatinine, and magnesium/creatinine ratios in a healthy pediatric population. J Pediatr 1997;131:252-257
Citrate/Creatinine (mg/mg)
| Age (yr) | 95th Percentile |
| 5-18 | <1.311 |
Srivastava T, Winston MJ, Auron A et al: Urine calcium/citrate ratio in children with hypercalciuric stones. Pediatr Res 2009;66:85-90
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
The urine is often supersaturated with respect to the common crystalline constituents of stones, even in nonstone formers.
Individual interpretation of the supersaturation values in light of the clinical situation is critical. In particular, treatment may reduce the supersaturation with respect to one crystal type, but increase the supersaturation with respect to another. Therefore, the specific goals of treatment must be considered when interpreting the test results.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Werness PG, Brown CM, Smith LH, Finlayson B: EQUIL2: a BASIC computer program for the calculation of urinary saturation. J Urol 1985;134:1242-1244
2. Parks JH, Coward M, Coe FL: Correspondence between stone composition and urine supersaturation in nephrolithiasis. Kidney Int 1997;51:894-900
3. Finlayson B: Calcium stones: Some physical and clinical aspects. In Calcium in Renal Failure and Nephrolithiasis. Edited by DS David. New York, John Wiley & Sons, 1977, pp 337-382
Method Description Describes how the test is performed and provides a method-specific reference
The major analytes evaluated are potassium, calcium, phosphorus, oxalate, uric acid, citrate, magnesium, sodium, chloride, sulfate, and pH. Given the measured urine concentrations of these analytes and the known affinity constants of the ions for each other at the given pH, a computer program (EQUIL2) calculates a supersaturation for each ion pair of interest (eg, calcium oxalate).(1) Results are expressed as a delta G (DG) value for each ion pair. DG is the Gibbs free energy of transfer from a supersaturated to a saturated solution. (Werness PG, Brown CM, Smith LH, Finlayson B: EQUIL2: a BASIC computer program for the calculation of urinary saturation. J Urol 1985;134:1242-1244)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; 8 a.m.-4 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
82340-Calcium
82436-Chloride
82507-Citrate excretion
82570-Creatinine
83735-Magnesium
83935-Osmolality
83945-Oxalate
83986-pH
84105-Phosphorus
84133-Potassium
84300-Sodium
84392-Sulfate
84560-Uric acid
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| SULFR | Sulfate, Random, U | 2975-1 |
| UOSMR | Osmolality, Random, U | 2695-5 |
| UPHR | pH, Random, U | 2756-5 |
| 31171 | Calcium, Random, U | 17862-4 |
| RCHLU | Chloride, Random, U | 2078-4 |
| RCTUR | Creatinine, Random, U | 2161-8 |
| RKUR | Potassium, Random, U | 2828-2 |
| 31170 | Magnesium, Random, U | 19124-7 |
| RNAUR | Sodium, Random, U | 2955-3 |
| OXCON | Oxalate, Pediatric, Random, U | 15086-2 |
| CITR1 | Citrate Concentration, Peds, Random, U | 2128-7 |
| POCON | Phosphorus, Pediatric, Random, U | 2778-9 |
| 31241 | Calcium Oxalate Crystal | 5774-5 |
| URCO2 | Uric Acid, Random, U | 3086-6 |
| RATO6 | Uric Acid/Creatinine Ratio | 3089-0 |
| 31242 | Brushite Crystal | In Process |
| RATO5 | Phosphorus/Creatinine Ratio | 11141-9 |
| RATO8 | Citrate/Creatinine Ratio | 13722-4 |
| OXCO2 | Oxalate Concentration | 2700-3 |
| 31248 | Magnesium/Creatinine Ratio | 13474-2 |
| 31247 | Calcium/Creatinine Ratio | 9321-1 |
| RATO7 | Oxalate/Creatinine Ratio | 13483-3 |
| 31243 | Hydroxyapatite Crystal | In Process |
| 31244 | Uric Acid Crystal | 5817-2 |
| 31245 | Sodium Urate Crystal | 60341-5 |
| 31246 | Interpretation | 69051-1 |
External
link
PDF
document
Excel
document
Word
document