Download Urine Protein/Creatinine Ratio Interpretive Summary

Urine Protein/Creatinine Ratio
Interpretive Summary
Description: Urine protein/creatinine ratio (UPC) gives a quantitative measurement of protein in the urine adjusted for urine
concentration. It can be used to determine the magnitude of glomerular disease in the absence of pre-renal and post-renal
proteinuria.
Decreased Urine Protein/Creatinine Ratio
Common Causes
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Clinically normal
Increased Urine Protein/Creatinine Ratio
Common Causes
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Pre-renal proteinuria
o Overflow/overload pre-glomerular proteinuria
 Bence Jones proteins, hyperglobulinemia
 Post-colostral proteinuria (foal)
 Hemoglobinuria, myoglobinuria
o Systemic hypertension
o Transient mild proteinuria
 Shock
 Fever
 Increased physical exercise
Renal proteinuria
o Glomerular proteinuria
 Glomerulonephritis
 Amyloidosis
o Tubular proteinuria
 Acute and chronic renal failure
 Defects in proximal renal tubular function
 Congenital disorders
o Functional – transient
 Fever, shock, cardiac disease, exercise (horse), seizures
Post-renal proteinuria
o Inflammation or infection in the upper or lower urinary tract (or reproductive tract in voided specimen)
o Hemorrhage into the urinary or reproductive tract
o Neoplasia of the urinary tract
Cushing’s disease
Related Findings
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Pre-renal proteinuria
o Increased globulins
o Positive Bence Jones proteins in urine
o Hemoglobinuria
 Anemia
 Increased bilirubin
o Myoglobinuria
 Increased CK, AST
Renal proteinuria
o Decreased albumin
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Secondary systemic hypertension
Increased BUN, creatinine, phosphorus with secondary renal tubular damage
Increased cholesterol, ascites/pulmonary edema in severe nephrotic syndrome
Positive serologic/PCR testing if glomerulonephritis secondary to infectious agents
 Heartworm, Lyme, leptospirosis, rickettsial, fungal, protozoal, or viral (in some cases)
o Positive antinuclear antibody titer if associated with systemic immune-mediated disease
o Consistent renal biopsy and electron microscopy results
Post-renal proteinuria
o Active urine sediment (RBC, WBC, bacteria, abnormal epithelial cells)
o Positive urine culture
o Positive bladder tumor analyte test
o Urinary calculi visualized on radiographs or ultrasound
Cushing’s disease
o Increased ALP
o Decreased urine specific gravity
o Adrenal function tests consistent with Cushing’s disease
Additional Information
Physiology
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The UPC is calculated by dividing the urine protein concentration (mg/dL) by the urine creatinine concentration (mg/dL).
The ratio has no units.
Urinary creatinine excretion is constant and is not affected by glomerular filtration rate, therefore, a change in the UPC is
due to a change in the urine protein excretion.
The UPC correlates with the 24-hour urine protein measurement.
The UPC is not affected by gender or time of day.
The collection method (cystocentesis vs free catch) does not affect the UPC as long as there is no trauma or
hemorrhage with the cystocentesis, and as long as there is no lower urinary tract disease detected by the free catch.
A urinalysis with urine sediment should be performed on the same sample as a UPC to evaluate for post-renal causes of
proteinuria.
If the UPC shows significant proteinuria, then two more UPCs should be done within two weeks to evaluate for transient
causes of proteinuria.
In dogs, persistent renal proteinuria with UPC values >2.0 usually is due to glomerular disease.
In cats, persistent renal proteinuria with UPC values >1.0 usually is due to glomerular disease.
The UPC can decrease with severe chronic renal disease, because, there is a decrease in functional nephrons and a
decrease in the amount of protein lost.
References
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Beatrice L, Zatelli A, et al. Comparison of urine protein-to-creatinine ratio in urine samples collected by cystocentesis
versus free catch in dogs. JAVMA June 2010;236(11):1221-1224.
Latimer KS, Mahaffey EA, Prasse KW, eds. Duncan and Prasse's Veterinary Laboratory Medicine: Clinical Pathology,
4th ed. Ames, IA: Blackwell; 2003.
Lees GE, Brown SA, et al. Assessment and management of proteinuria in dogs and cats: 2004 ACVIM Forum
Consensus Statement (small animal). J Vet Intern Med 2005;19:377-385.
Stockham SL, Scott MA. Fundamentals of Veterinary Clinical Pathology, 2nd ed. Ames, IA: Blackwell; 2008.
Last updated 11/1/2013
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