Urine Protein to Creatinine Ratio

Protein in urine is normally composed of a combination of plasma-derived proteins that have been filtered by glomeruli and have not been reabsorbed by the proximal tubules and proteins secreted by renal tubules or other accessory glands.

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Increased amounts of protein in the urine may be due to:

• Glomerular proteinuria: caused by defects in permselectivity of the glomerular filtration barrier to plasma proteins (eg, glomerulonephritis or nephrotic syndrome)
• Tubular proteinuria: caused by incomplete tubular reabsorption of proteins (eg, interstitial nephritis)
• Overflow proteinuria: caused by increased plasma concentration of proteins (eg, multiple myeloma, myoglobinuria)

Why get tested:

To detect excess protein in the urine, to help evaluate and monitor kidney function, and to detect kidney damage.

When to get tested:

• As part of a routine physical exam, often as part of a urinalysis
• Urine total protein and urine protein / creatinine ratio (UPCR) have traditionally been used as important indicators of kidney disease and as a follow-up test to monitor the disease.
• The albumin to creatinine ratio (ACR) is now the preferred test for these purposes.
• Even so, UPCR should be ordered to identify preeclampsia in pregnant women and when excess total protein in urine is suspected to be different from albumin.

Sample Required:

Patient Preparation: Collect specimen either prior to fluorescein administration or wait to collect for at minimum of 24 hours after administration.

• Supplies: Aliquot Tube, 5 mL
• Container/Tube: Plastic, 5-mL tube
• Specimen Volume: 4 mL

Sample Collection Instructions :

• Collect a random urine specimen.
• No preservative.
• Invert well before taking 4 mL aliquot.
• Do not overfill aliquot tube, maximum 4 mL.

Reference Values 

<0.18 mg/mg creatinine

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

Causes of Abnormal Results:

Some examples of these causes include:

• Urinary tract infection
• Preeclampsia
• Lupus
• Multiple myeloma
• Amyloidosis
• Bladder cancer
• Congestive heart failure
• Drug therapies that are potentially toxic to the kidneys
• Goodpasture syndrome
• Heavy metal poisoning

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