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HelpTest Code OPTU Orthostatic Protein, Timed Collection, Urine
Reporting Name
Orthostatic Protein, UUseful For
Diagnosis of orthostatic proteinuria
As a second-order test for additional characterization of proteinuria of less than 3 grams/24 hours, particularly in children or adolescents
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| DOPTU | Daytime Orthostatic Protein, U | No | Yes |
| NOPTU | Nighttime Orthostatic Protein, U | No | Yes |
Method Name
Turbidimetry
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
UrineOrdering Guidance
This collection process requires 2 separate urine collections within a 24-hour period.
Collect specimen per instructions in Orthostatic Protein Measurement 24-Hour Urine: Collection Site Instructions (T546) in Special Instructions.
Necessary Information
This collection process requires 2 separate urine collections within a 24-hour period.
-Submit start and end times for collection and 16-hour volume (required).
-Submit start and end times for collection and 8-hour volume (required).
Specimen Required
Specimens should be collected before fluorescein is given or not collected until at least 24 hour later.
Supplies: 2 Sarstedt 5 mL Aliquot Tube (T914)
Daytime Collection
Container/Tube: Plastic, 5-mL tube
Specimen Volume: 4 mL
Collection Instructions:
1. Collect a 16-hour (daytime) urine specimen.
2. No preservative.
3. Invert well before taking 4-mL aliquot.
4. Do not over fill aliquot tube 4 mL at most.
5. Collect specimen per instructions in Orthostatic Protein Measurement 24-Hour Urine: Collection Site Instructions (T546) in Special Instructions.
Nighttime (Supine) Collection
Container/Tube: Plastic, 5-mL tube
Specimen Volume: 4 mL
Collection Instructions:
1. Collect an 8-hour (nighttime) urine specimen.
2. No preservative.
3. Invert well before taking 4-mL aliquot at most.
Specimen Minimum Volume
1 mL from 16-hour (daytime) urine collection/1 mL from 8-hour (nighttime) urine collection
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 14 days | |
| Frozen | 30 days | ||
| Ambient | 24 hours |
Reject Due To
| All specimens will be evaluated at Mayo Clinic Laboratories for test suitability. |
Special Instructions
Reference Values
Nighttime (supine) collection: <68 mg/8 hours
Reference values have not been established for patients <18 years of age.
Daytime collection: <197 mg/16 hours
Reference values have not been established for patients <18 years of age
Day(s) Performed
Monday through Sunday
CPT Code Information
84156 x 2
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| OPTU | Orthostatic Protein, U | 1755-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| DPTU | Total Protein, 16 HR, U | 49002-9 |
| NPTU | Total Protein, 8 HR, U | 50209-6 |
| DUR7 | Nighttime collection duration | 13362-9 |
| DUR4 | Daytime collection duration | 13362-9 |
| DVOL | Day volume | 19153-6 |
| VL | Night volume | 19153-6 |
| NPRO | Total Protein Conc, 8 HR, U | 35663-4 |
| DPRO | Total Protein Conc, 16 HR, U | 35663-4 |
Clinical Information
Orthostatic proteinuria refers to the development of increased proteinuria that develops only when the person is upright and resolves when recumbent or supine. This condition is usually seen in children, adolescents, or young adults, and accounts for the majority of cases of proteinuria in childhood.
Orthostatic proteinuria usually does not indicate significant underlying renal pathology, and is usually not associated with other urine abnormalities such as hypoalbuminemia, hematuria, red blood cell casts, fatty casts, etc. Orthostatic proteinuria typically resolves over time.
This test characterizes this condition by obtaining 2 urine collections within a 24-hour time frame, one collection obtained while the person is recumbent or supine, the other when upright.
Interpretation
A supine 8-hour urine protein excretion of less than 68 mg/8 hours together with either 1) an elevated upright (16-hour) excretion of greater than 197 mg/16 hours, or 2) a 24-hour urine protein excretion of greater than 228 mg/24 hours is considered consistent with orthostatic proteinuria.
Cautions
It is not unusual for urine protein excretion derived from supine collections to be somewhat lower than protein excretion derived from upright collections. However, orthostatic or postural proteinuria is characterized by a supine excretion rate of less than 50 mg/8 hours.
False-proteinuria may be due to contamination of urine with menstrual blood, prostatic secretions, or semen.
The urinary protein concentration may rise to 300 mg/24 hours in healthy individuals after vigorous exercise.
Normal newborn infants may have higher excretion of protein in urine during the first 3 days of life.
The presence of hemoglobin elevates protein concentration.
Protein electrophoresis and immunofixation may be required to characterize and interpret the proteinuria.
Method Description
The sample is preincubated in an alkaline solution containing EDTA, which denatures the protein and eliminates interference from magnesium ions. Benzethonium chloride is then added, producing turbidity.(Package insert: Total Protein Urine/CSF. Roche Diagnostics; V13.0 11/2018)