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Test Code ORTHP Orthostatic Proteinuria, Random, Urine


Specimen Required


Patient Preparation: Specimens should be collected before fluorescein is given or not collected until at least 24 hour later.

Container/Tube: Plastic, 5-mL tube

Specimen Volume: 4 mL

Collection Instructions:

1. This is a nighttime (supine) collection.

2. Void immediately prior to lying down to sleep.

3. Collect an 8-hour (nighttime) urine specimen.

4. Upon awaking in the morning, the patient should immediately void into the specimen cup.

4. No preservative.

5. Invert well before taking 4-mL (maximum) aliquot.


Useful For

Diagnosis of orthostatic proteinuria

Profile Information

Test ID Reporting Name Available Separately Always Performed
PRCON Protein, Total, Random, U No Yes
RATO2 Protein/Creatinine Ratio No Yes
CRETR Creatinine, Random, U No Yes

Method Name

PRCON: Turbidimetry

CRETR: Enzymatic Colorimetric Assay

RATO2: Calculation

Reporting Name

Orthostatic Proteinuria, Random, U

Specimen Type

Urine

Specimen Minimum Volume

1 mL

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.

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 evaluates for this condition by demonstrating either significant proteinuria, even while supine, or normal protein excretion. Significant proteinuria, even while supine, suggests that the patient does not have orthostatic proteinuria while normal protein excretion supports the diagnosis. This test is typically done on three consecutive mornings to provide more robust support for the diagnosis.

Reference Values

PROTEIN/CREATININE RATIO:

≥18 years: <0.18 mg/mg creatinine

 

CREATININE:≥18 years = 16-326 mg/dL

Reference values have not been established for patients younger than 18 years of age.

Interpretation

First-morning urine protein-to-creatinine ratio below 0.20 mg/mg creatinine supports the diagnosis of orthostatic proteinuria, while a result above 0.20 mg/mg creatinine does not support this diagnosis.

 

Further investigation into other etiologies for proteinuria may be warranted.

Cautions

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 day

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

CRETR- 82570

PRCON- 84156

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ORTHP Orthostatic Proteinuria, Random, U 87434-7

 

Result ID Test Result Name Result LOINC Value
CRETR Creatinine, Random, U 2161-8
PRCON Protein, Total, Random, U 2888-6
RATO2 Protein/Creatinine Ratio 2890-2