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Test Code SUP24 Supersaturation Profile, 24 Hour, Urine


Ordering Guidance


 



Necessary Information


1. 24-Hour volume (in milliliters) is required.

2. Patient's height in centimeters and weight in kilograms are required if patient is younger than 18 years.



Specimen Required


Patient Preparation:

X-ray dyes and contrast media will affect uric acid test results.

-If a kidney X-ray with dye or computerized tomography (CT) scan with contrast has been performed, patient should wait a minimum of 1 day before starting collection.

-If a cholangiography (bile duct X-ray) has performed, patient should wait 7 days before starting collection.

-Urine must be collected before tablets have been taken for gallbladder X-ray, otherwise patient should wait 7 days before starting collection.

Supplies: Diazolidinyl Urea (Germall) 5.0 mL (T822)

Collection Container/Tube: 24-hour graduated urine container with no metal cap or glued insert

Submission Container/Tube: Plastic, 60-mL urine bottle

Specimen Volume: 35 mL

Collection Instructions:

1. Add 5 mL of diazolidinyl urea as preservative at start of collection or refrigerate specimen during and after collection.

2. Collect urine for 24 hours.

3. Specimen pH should be between 4.5 and 8 and will stay in this range if diazolidinyl urea is added at the beginning of the collection or kept refrigerated during the entirety of the collection. Specimens with pH above 8 indicate bacterial contamination, and testing will be canceled. Do not attempt to adjust pH as it will adversely affect results.

4. If not using Germall, the specimen must be kept refrigerated during the entirety of the collection and sent frozen.

Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.


Useful For

Diagnosis and management of patients with renal lithiasis:

-Predicting the likely composition of the stone, in patients who have a radiopaque stone, for whom stone analysis is not available

-May aid in designing a treatment program

 

 

Aiding in identification of specific risk factors for stones using a 24-hour urine collection

 

Monitoring the effectiveness of therapy by confirming that the crystallization potential has indeed decreased

 

Evaluating kidney excretion of acid and urine pH

 

Estimating a patient's protein intake

Profile Information

Test ID Reporting Name Available Separately Always Performed
SSINT Supersaturation, 24 HR, U 1 No Yes
NAUT Sodium, 24 HR, U Yes, (order NAU) Yes
KUT Potassium, 24 HR, U Yes, (order KUR) Yes
CALUT Calcium, 24 HR, U Yes, (order CALU) Yes
MAGT Magnesium, 24 HR, U Yes, (order MAGU) Yes
CLUT Chloride, 24 HR, U Yes, (order CLU) Yes
POUT Phosphorus, 24 HR, U Yes, (order POU) Yes
SULFT Sulfate, 24 HR, U Yes, (order SULFU) Yes
CITT Citrate Excretion, 24 HR, U Yes, (order CITR) Yes
OXUT Oxalate, 24 HR, U Yes, (order OXU) Yes
UPHT pH, 24 HR, U Yes, (order PHU_) Yes
URICT Uric Acid, 24 HR, U Yes, (order URCU) Yes
CTUT Creatinine, 24 HR, U Yes, (order URCU) Yes
OSMUT Osmolality, 24 HR, U Yes, (order UOSMU) Yes
AMMT Ammonium, 24 HR, U Yes, (order AMMO) Yes
UNT Urea Nitrogen, 24 HR, U No Yes
PCRUT Protein Catabolic Rate, 24 HR, U No Yes
DEMO9 Patient Demographics No Yes

Method Name

AMMT, CITT, OXUT: Enzymatic

OSMUT: Freezing Point Depression

SULFT: High-Performance Ion Chromatography (HPIC)

CALUT, POUT: Photometric

MAGT: Colorimetric Endpoint Assay

UPHT: pH Meter

NAUT, KUT, CLUT: Potentiometric, Indirect Ion-Selective Electrode (ISE)

CTUT: Enzymatic Colorimetric Assay

URICT: Uricase

UNT: Kinetic UV Assay

PCRUT, SSINT: Calculation

Reporting Name

Supersaturation, 24 HR, U

Specimen Type

Urine

Specimen Minimum Volume

25 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 14 days
  Frozen  14 days
  Ambient  72 hours

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 present in the 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 the urinary supersaturations 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 (Delta G: DG)

Men:

Calcium oxalate: 1.89 DG

Brushite: 0.46 DG

Hydroxyapatite: 4.19 DG

Uric acid: 1.18 DG

 

Women:

Calcium oxalate: 1.59 DG

Brushite: -0.11 DG

Hydroxyapatite: 3.62 DG

Uric acid: 0.89 DG

 

 

INDIVIDUAL URINE ANALYTES

 

OSMOLALITY, 24 HOUR, URINE

0-11 months: 50-750 mOsm/kg

≥12 months: 150-1,150 mOsm/kg

 

pH, 24 HOUR, URINE

4.5-8.0

 

SODIUM, 24 HOUR, URINE

≥18 years: 22-328 mmol/24 h

Reference values have not been established for patients who are younger than 18 years.

 

POTASSIUM, 24 HOUR, URINE

≥18 years: 16-105 mmol/24 h

Reference values have not been established for patients who are younger than 18 years.

 

CALCIUM, 24 HOUR, URINE

Males: <250 mg/24 h

Females: <200 mg/24 h

Reference values have not been established for patients who are younger than 18 years.

 

MAGNESIUM, 24 HOUR, URINE

51-269 mg/24 h

Reference values have not been established for patients who are younger than 18 years.

 

CHLORIDE, 24 HOUR, URINE

≥18 years: 34-286 mmol/24 h

Reference values have not been established for patients who are younger than 18 years.

 

PHOSPHORUS, 24 HOUR, URINE

≥18 years: 226-1,797 mg/24 h

Reference values have not been established for patients who are younger than 18 years.

 

SULFATE, 24 HOUR, URINE

7-47 mmol/24 h

 

CITRATE EXCRETION, 24 HOUR, URINE

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, 24 HOUR, URINE

0.11-0.46 mmol/24 h

9.7-40.5 mg/24 h

Reference values have not been established for patients who are younger than 16 years.

 

URIC ACID, 24 HOUR, URINE

Males: ≥18 years: 200-1,000 mg/24 h

Females: ≥18 years: 250-750 mg/24 h

Reference values have not been established for patients who are younger than 18 years.

 

CREATININE, 24 HOUR, URINE

Males: ≥18 years: 930-2,955 mg/24 h

Females: ≥18 years: 603-1,783 mg/24 h

Reference values have not been established for patients who are younger than 18 years.

 

AMMONIUM, 24 HOUR, URINE

15-56 mmol/24 h

Reference values have not been established for patients who are younger than 18 years or older than 77 years.

 

UREA NITROGEN, 24 HOUR, URINE

≥18 years: 7-42 g/24 h

Reference values have not been established for patients who are younger than 18 years.

 

PROTEIN CATABOLIC RATE, 24 HOUR, URINE

56-125 g/24 h

Day(s) Performed

Monday through Sunday

Report Available

2 to 5 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

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

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