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HelpTest ID SAT24 Supersaturation Profile, 24 Hour, 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.
-The protein catabolic rate, calculated from the urine urea nitrogen, can be used to estimate a patient's protein intake.
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| SUPST | Supersaturation, U | No | Yes |
| NAUP | Sodium, U | Yes, (order NAU) | Yes |
| KUP | Potassium, U | Yes, (order KUR) | Yes |
| CALCP | Calcium, U | Yes, (order CALU) | Yes |
| MAGP | Magnesium, U | Yes, (order MAGU) | Yes |
| CLUP | Chloride, U | Yes, (order CLU) | Yes |
| POUP | Phosphorus, U | Yes, (order POU) | Yes |
| SULFP | Sulfate, U | Yes, (order SULFU) | Yes |
| CITP | Citrate Excretion, U | Yes, (order CITR) | Yes |
| OXUP | Oxalate, U | Yes, (order OXU) | Yes |
| UPHP | pH, U | Yes, (order PHU_) | Yes |
| URCP | Uric Acid, U | Yes, (order URCU) | Yes |
| CTUP | Creatinine, U | Yes, (order CTU) | Yes |
| UOSMP | Osmolality | Yes, (order UOSMU) | Yes |
| AMMP | Ammonium, 24 Hr, U | Yes, (order AMMO) | Yes |
| UNP | Urea Nitrogen, U | No | Yes |
| PCTR | Protein Catabolic Rate, U | No | Yes |
Special Instructions
Method Name
CITP: Enzymatic
OXUP: Enzymatic using Oxalate Oxidase
USOMP: Freezing Point Depression
SULFP: High-Performance Liquid Chromatography (HPLC)
CALCP: Photometric, NM-BAPTA Reaction
MAGP: Colorimetric Endpoint Assay
POUP: Molybdic Acid
UPHP: pH Meter
NAUP, KUP, CLUP: Potentiometric, Indirect Ion-Selective Electrode (ISE)
CTUP: Enzymatic Colorimetric Assay
URCP: Uricase
AMMP: Enzymatic Assay
UNP: Kinetic UV Assay
Reporting Name
Supersaturation, USpecimen Type
UrineContainer/Tube: Plastic, 60-mL urine bottle
Specimen Volume: 35 mL
Collection Instructions:
1. Collect urine for 24 hours.
2. Add 30 mL of toluene as preservative at start of collection, or refrigerate specimen during and after collection.
3. 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 cancelled. Do not attempt to adjust pH as it will adversely affect results.
Additional Information:
1. 24-Hour volume is required.
2. Patient's height in centimeters and weight in kilograms are required if patient is <18 years old.
3. See Urine Preservatives in Special Instructions for multiple collections.
Forms: If not ordering electronically, submit a General Request Form (Supply T239) with the specimen.
Urine Preservative Collection Options
|
Ambient |
No |
|
Refrigerated |
Yes |
|
Frozen |
Yes |
|
6N HCl |
No |
|
50% Acetic Acid |
No |
|
Na2CO3 |
No |
|
Toluene |
Preferred |
|
6N HNO3 |
No |
|
Boric Acid |
No |
|
Thymol |
No |
Specimen Minimum Volume
25 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
SUPERSATURATION REFERENCE MEANS (DG)
Calcium oxalate: 1.77
Brushite: 0.21
Hydroxyapatite: 3.96
Uric acid: 1.04
Sodium urate: 1.76
INDIVIDUAL URINE ANALYTES
OSMOLALITY
0-11 months: 50-750 mOsm/kg
≥12 months: 150-1,150 mOsm/kg
pH
4.5-8.0
ALL REFERENCE RANGES BELOW ARE BASED ON 24-HOUR COLLECTIONS.
SODIUM
41-227 mmol/24 h
Reference values have not been established for patients <16 years of age.
POTASSIUM
17-77 mmol/24 h
Reference values have not been established for patients <16 years of age.
CALCIUM
Males: <250 mg/24 h
Females: <200 mg/24 h
Reference values have not been established for patients <18 years and >83 years of age
MAGNESIUM
51-269 mg/24 h
Reference values have not been established for patients <18 years and >83 years of age
CHLORIDE
40-224 mmol/24 h
Reference values have not been established for patients <16 years of age.
PHOSPHORUS
<1,100 mg/24 h
SULFATE
7-47 mmol/24 h
CITRATE EXCRETION
0-19 years: not established
20 years: 150-1,191 mg/24 h
21 years: 157-1,191 mg/24 h
22 years: 164-1,191 mg/24 h
23 years: 171-1,191 mg/24 h
24 years: 178-1,191 mg/24 h
25 years: 186-1,191 mg/24 h
26 years: 193-1,191 mg/24 h
27 years: 200-1,191 mg/24 h
28 years: 207-1,191 mg/24 h
29 years: 214-1,191 mg/24 h
30 years: 221-1,191 mg/24 h
31 years: 228-1,191 mg/24 h
32 years: 235-1,191 mg/24 h
33 years: 242-1,191 mg/24 h
34 years: 250-1,191 mg/24 h
35 years: 257-1,191 mg/24 h
36 years: 264-1,191 mg/24 h
37 years: 271-1,191 mg/24 h
38 years: 278-1,191 mg/24 h
39 years: 285-1,191 mg/24 h
40 years: 292-1,191 mg/24 h
41 years: 299-1,191 mg/24 h
42 years: 306-1,191 mg/24 h
43 years: 314-1,191 mg/24 h
44 years: 321-1,191 mg/24 h
45 years: 328-1,191 mg/24 h
46 years: 335-1,191 mg/24 h
47 years: 342-1,191 mg/24 h
48 years: 349-1,191 mg/24 h
49 years: 356-1,191 mg/24 h
50 years: 363-1,191 mg/24 h
51 years: 370-1,191 mg/24 h
52 years: 378-1,191 mg/24 h
53 years: 385-1,191 mg/24 h
54 years: 392-1,191 mg/24 h
55 years: 399-1,191 mg/24 h
56 years: 406-1,191 mg/24 h
57 years: 413-1,191 mg/24 h
58 years: 420-1,191 mg/24 h
59 years: 427-1,191 mg/24 h
60 years: 434-1,191 mg/24 h
>60 years: not established
OXALATE
0.11-0.46 mmol/24 h
URIC ACID
Diet-dependent: <750 mg/24 h
CREATININE
Normal values mg per 24 hours:
Males: 955-2936 mg/24 hours
Females: 601-1689 mg/24 hours
Reference ranges for male and female patients <18 and >83 years of age have not been established.
The expected urine creatinine excretion per 24 hours:
Males: 13-29 mg/kg of body weight/24 hours
Females: 9-26 mg/kg of body weight/24 hours
Reference ranges for male and female patients <18 and >83 years of age have not been established.
Note: To convert to mg/kg of body weight/24 hours, divide the mg/24 h result by body weight in kg.
AMMONIUM
15-56 mg/24 hour
Reference values have not been established for patients <18 years and >77 years of age.
UREA NITROGEN
5.0-16.0 mg/24 hour
PROTEIN CATABOLIC RATE
56-98 g/kg/24 hour
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.Performing Laboratory
Mayo Medical Laboratories in Rochester
CPT Code Information
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
82140-Ammonium
84540-Urea Nitrogen