Sign in →

Test Code SSH24 Supersaturation Profile, Self-Collect, 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.

3. Patient's street address, city, state, ZIP (postal) code, country, and home phone are required (post-office [PO] boxes are not acceptable delivery locations)



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, the patient should wait at least 24 hours before starting collection.

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

-If patient has taken tablets for a gallbladder X-ray, the patient should wait 7 days before starting collection.

Supplies: SSH24 Home Collection Kit (T921)

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. Order test each time the patient is to collect a 24-hour urine specimen at home and mail the specimen directly to Mayo Clinic Laboratories.

2. Order should be placed a minimum of 3 days prior to desired date of collection.

3. Enter patient's address information for each order created, including street address (post office [PO] boxes are not acceptable delivery locations), city, state abbreviation, zip code, country, and home phone number.

4. For each order, the SSH24 Home Collection kit will be mailed directly to the patient for self-collection (delivery to a PO box will not occur). This kit contains instructions for how to properly collect and transport the specimen after collection.


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
SSIN1 Supersaturation, 24 HR,Home Kit,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 CTU) 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, SSIN1: Calculation

Reporting Name

Supersaturation, 24 HR, Home Kit, 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

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

 

OSMOLALITY, 24 HOUR, URINE

0-11 months: 50-750 mOsm/kg

≥12 months: 150-1,150 mOsm/kg

 

pH, 24 HR, U

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

≥18 years: 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 of.

 

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

 

URIC ACID, 24 HOUR, URINE

Male: ≥18 years: 200-1,000 mg/24 h

Female: ≥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

Male: ≥18 years: 930-2,955 mg/24 h

Female: ≥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 than18 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

Interpretation

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 non-stone formers, on average, the DG is more positive in those individuals who do form kidney stones. The reference values were derived by comparing urinary DG values for the important stone-forming crystalline phases between a population of stone formers and a population of non-stone formers. DG values that are outside the expected range in a population of non-stone formers are marked abnormal.

 

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).

 

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.

 

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.

 

High urine ammonium and low urinary pH suggest ongoing gastrointestinal losses. Such patients are at risk of uric acid and calcium oxalate stones.

 

Low urine ammonium and high urine pH suggest renal tubular acidosis. Such patients are at risk of calcium phosphate stones.

 

Patients with calcium oxalate and calcium phosphate stones are often treated with citrate to raise the urine citrate (a natural inhibitor of calcium oxalate and calcium phosphate crystal growth). However, since citrate is metabolized to bicarbonate (a base), this drug can also increase the urine pH. If the urine pH gets too high with citrate treatment, one may unintentionally increase the risk of calcium phosphate stones. Monitoring the urine ammonium concentration is one way to titrate the citrate dose and avoid this problem. A good starting citrate dose is about one-half of the urine ammonium excretion (in mEq of each). One can monitor the effect of this dose on urine ammonium, citrate, and pH values and adjust the citrate dose based upon the response. A fall in urine ammonium levels should indicate whether the current citrate is enough to partially (but not completely) counteract the daily acid load of that given patient.

 

The protein catabolic rate is calculated from urine urea. Under routine conditions, the required protein intake is often estimated as 0.8 g/ kg body weight.

 

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), which 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 of calcium phosphate. Of note, a urine pH below 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 above 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.

Clinical Reference

1. Werness PG, Brown CM, Smith LH, Finlayson B. EQUIL2: a BASIC computer program for the calculation of urinary saturation. J Urol. 1985;134(6):1242-1244

2. Parks JH, Coward M, Coe FL. Correspondence between stone composition and urine supersaturation in nephrolithiasis. Kidney Int. 1997;51(3):894-900

3. Finlayson B. Calcium stones: Some physical and clinical aspects. In: David DS, ed. Calcium Metabolism in Renal Failure and Nephrolithiasis. John Wiley and Sons; 1977:337-382

4. Burtis CA, Bruns DE. Tietz Fundamentals of Clinical Chemistry and Molecular Diagnostics. 7th ed. Saunders, 2014

5. Tiselius HG, Daudon M, Thomas K, Seitz C. Metabolic work-up of patients with urolithiasis: indications and diagnostic algorithm. Eur Urol Focus. 2017;3(1):62-71. doi: 10.1016/j.euf.2017.03.014

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

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SSH24 Supersaturation, 24 HR, Home Kit, U 81232-1

 

Result ID Test Result Name Result LOINC Value
CRU24 Creatinine, 24 HR, U 2162-6
AMU24 Ammonium, 24 HR, U 25308-8
CAU24 Calcium, 24 HR, U 6874-2
CIT24 Citrate Excretion, 24 HR, U 6687-8
CLU24 Chloride, 24 HR, U 2079-2
KU24 Potassium, 24 HR, U 2829-0
MGU24 Magnesium, 24 HR, U 24447-5
NAU24 Sodium, 24 HR, U 2956-1
UOSMT Osmolality, 24 HR, U 2694-8
PCRUT Protein Catabolic Rate, 24 HR, U 93746-6
POU24 Phosphorus, 24 HR, U 2779-7
SUL24 Sulfate, 24 HR, U 26889-6
UNU24 Urea Nitrogen, 24 HR, U 3096-5
UPHT pH, 24 HR, U 27378-9
URC24 Uric Acid, 24 HR, U 3087-4
BSA1 Patient Surface Area 8277-6
OXM24 Oxalate, 24 HR, U (mmol/24 HR) 14862-7
616217 Calcium Oxalate Crystal 81623-1
616218 Brushite Crystal 101825-8
OXG24 Oxalate, 24 HR, U (mg/24 HR) 2701-1
HT6 Height (cm) 3137-7
WT6 Weight (kg) 29463-7
616219 Hydroxyapatite Crystal 81622-3
616220 Uric Acid Crystal 101827-4
SSDUR Collection Duration 13362-9
SSVOL Volume 3167-4
21060 Interpretation 69051-1
CS001 Patient Street Address No LOINC Needed
CS002 Patient City No LOINC Needed
CS003 Patient State No LOINC Needed
CS004 Patient Zip Code No LOINC Needed
CS005 Patient Country No LOINC Needed
CS006 Patient Home Phone No LOINC Needed