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Test ID OPTU Orthostatic Protein, Timed Collection, Urine


Ordering 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.


Forms

1. Orthostatic Protein Measurement 24-Hour Urine: Patient Collection Instructions in Special Instructions

2. If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.

Secondary ID

614360

Useful 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

Reporting Name

Orthostatic Protein, U

Specimen Type

Urine

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
Urine Refrigerated (preferred) 14 days
  Frozen  30 days
  Ambient  24 hours

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.

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

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.

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 to 4 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

84156 x 2

NY State Approved

Yes