A urine P:C ratio, or a urine protein-creatinine ratio, is a laboratory test used to detect or monitor renal disease. The urine P:C ratio allows to detect abnormalities earlier than blood tests. For blood tests to be abnormal, 70% of the kidney function is generally lost.
A urine P:C ratio test is indicated for screening patients for early renal disease, monitoring the course of renal disease, evaluating response to therapy and/or to determine renal disease progression. It may be used for evaluating pets with urinary abnormalities such as increased urine production, increased water consumptions, frequent urination or abnormal color to the urine. It may also be used to assess vague nonspecific signs of renal disease such as anorexia, dehydration, or vomiting.
A urine P:C ratio test may be recommended in any geriatric pet or when indicated by the results of an X-ray, results of blood tests that indicate a problem with the urinary system or as a follow-up to physical examination when abnormalities are detected. It also may be preformed on pets at risk for renal disease or that are on long-term medications that can have renal side effects.
There is no real contraindication to performing this test. Even normal results help determine health or exclude certain diseases.
What Does a Urine P:C Ratio Reveal?
The urine P:C ratio test evaluates the urine for the presence of protein and creatinine that can be associated with early renal disease.
A urine P:C ratio test helps to evaluate the function of the kidneys. Values greater than 0.5 with blood abnormalities (such as increased blood urea nitrogen or creatinine) are suggestion of kidney disease with proteinuria. Values greater than 0.5 and less than 1.0 with normal blood values will generally be repeated and monitored for progression of disease. Patients with urine P:C ratio values greater than 1.0 with normal blood values should be worked up for diseases such as glomerulonepthritis or interstitial nephritis.
In most cases, additional tests such as a complete blood count, biochemical profile and urinalysis will also be recommended. Additional procedures such as X-rays, abdominal ultrasound, X-rays with contrast (IVP or cystogram) or even exploratory surgery may be needed to diagnose a problem.
How Is a Urine P:C Ratio test Done?
A urine P:C ratio test is performed with the collection of a urine sample. Urine can be obtained by three methods:
Catheterization consists of inserting a flexible plastic tube into the urethra, then up into the bladder (the reservoir inside the body where urine is stored until the pet urinates).
Cystocentesis is a very common method to obtain urine from dogs and cats. This procedure involves introducing a needle directly into the bladder through the body wall. This is a relatively painless and quick procedure. The pet can be lying or standing. The bladder is palpated (felt) and a needle is inserted into the bladder.
Free catch urine samples are obtained by catching a sample when the pet urinates. This is easy in some pets and quite difficult in others. Plastic containers, ladles, scoops and various objects can be used. The container should be as clean as possible for the most accurate of results. This method is the least "sterile" and is associated with the most lab error.
Most veterinary hospitals have the equipment to perform a urine P:C ratio test although some choose to submit samples to outside laboratories.
A urine P:C ratio test generally takes about 30 to 40 minutes to complete.
Is a Urine P:C Ratio Painful?
Whether a urine P:C ratio test is painful or not depends on the method by which urine is obtained. Catheterization is "uncomfortable" in most pets although many male pets tolerate the procedure well. Females are more difficult to catheterize due to the anatomical location of their urethra.
If urine is obtained by cystocentesis, the needle insertion through the skin can be associated with brief pain, just as any injection.
Is Sedation or Anesthesia Needed for a Urine P:C Ratio test?
Neither sedation nor anesthesia is needed in most patients; however, some pets resent positioning for a catheter placement (especially females) and may need tranquilization or ultrashort anesthesia.