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HelpTest ID SSATR Supersaturation Profile, Pediatric, Random, Urine
Useful For
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
-Urine ammonium can be used to evaluate renal excretion of acid and urine pH.
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| RRSUP | Supersaturation Random, U | No | Yes |
| NAUR | Sodium, Random, U | Yes, (order KNAUR) | Yes |
| KURR | Potassium, Random, U | Yes, (order RKUR) | Yes |
| CACR2 | Calcium, Random, U | Yes, (order CACR1) | Yes |
| MAGR | Magnesium, Random, U | Yes, (order MAGNR) | 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 |
| RAMCN | Ammonium, Random, U | Yes, (order RAMBO) | Yes |
Method Name
CITRR, RAMCN: Enzymatic
OXUR: Enzymatic Using Oxalate Oxidase
UOSMR: Freezing Point Depression
SULFR: High-Performance Liquid Chromatography (HPLC)
MAGR: Colorimetric Endpoint Assay
CACR2: Photometric, NM-BAPTA Reaction
POUR: Molybdic Acid
UPHR: pH Meter
NAUR, KURR, CLUR: Potentiometric, Indirect Ion-Selective Electrode (ISE)
CTURR: Enzymatic Colorimetric Assay
URCUR: Uricase
Reporting Name
Supersaturation, Peds, Random, USpecimen Type
UrineContainer/Tube: 2 plastic, 10-mL urine tubes (Supply T068) and 4 plastic, 5-mL urine tubes (Supply T465)
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
30 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | 14 days |
| Frozen | 14 days |
Clinical Information
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
pH: 4.5-8.0
OSMOLALITY:
0-11 months: 50-750 mOsm/kg
≥12 months: 150-1,150 mOsm/kg
Ammonium:
18-77 years: 3-65 mmol/L
No reference values established for <18 years and >77 years of age
Calcium:
Random Calcium/Creatinine Ratio:
18-83 years: <0.20 mg/mg
No reference values established for <18 years and >83 years of age
Magnesium:
Random Magnesium/Creatinine Ratio:
18-83 years: ≤ 0.035 mg/mg
No reference values established for <18 years and >83 years of age
Cautions
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.
Day(s) Performed
Monday through Friday; 8 a.m.-4 p.m.
Report Available
2 days; Excess capacity for this test is limited. Therefore, if sample volume exceeds analyzer and staff capacity, the turnaround time will increase. Please contact the lab supervisor for an estimate.Performing Laboratory
Mayo Medical Laboratories in Rochester
CPT Code Information
82310-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
82140-Ammonium