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Test Code RATO2 Protein/Creatinine, Random, Urine


Specimen Required


Only orderable as part of a profile. For more information see ORTHP / Orthostatic Proteinuria, Random, Urine.


Useful For

Calculation of total protein concentration per creatinine concentration

Method Name

Only orderable as part of a profile. For more information see ORTHP / Orthostatic Proteinuria, Random, Urine.

 

Calculation

Reporting Name

Protein/Creatinine Ratio

Specimen Type

Urine

Specimen Stability Information

Specimen Type Temperature Time Special Container
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 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

Only orderable as part of a profile. For more information see ORTHP / Orthostatic Proteinuria, Random, Urine.

 

≥18 years: <0.18 mg/mg creatinine

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.

 

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.

LOINC Code Information

Test ID Test Order Name Order LOINC Value
RATO2 Protein/Creatinine Ratio 2890-2

 

Result ID Test Result Name Result LOINC Value
RATO2 Protein/Creatinine Ratio 2890-2