Renal disease

A.  Serum urea and creatinine are usually done as part of a biochemistry profile.  Azotemia (elevated serum urea and creatinine) may be the result of pre-renal, renal, and post-renal causes.

B.  Urinalysis is an essential test.  Azotemia cannot be interpreted without a urine specific gravity.

C.  Urine protein:creatinine ratio (UPC).

The goal of a urine protein:creatinine ratio is to identify renal proteinuria having first ruled out pre-renal and post-renal causes.  Persistent proteinuria (ideally identified on the basis of at least 3 urine samples collected over a period of at least 2 wk) resulting in a UPC ratio > 0.4 in cats and  > 0.5 in dogs, is consistent with glomerular or tubulointerstitial disease.  UPC ratios > 2.0 are strongly suggestive of glomerular disease. 

UPC ratio

Canine

Feline

Non-proteinuric

< 0.2

< 0.2

Questionable

0.2 - 0.5

0.2 - 0.4

Proteinuric

> 0.5

> 0.4

Reference: Assessment and management of proteinuria in dogs and cats: 2004 ACVIM Forum Consensus Statement (Small Animal).  J Vet Intern Med 2005;19:377–385. www.iris-kidney.com

D.  Renal fine needle aspiration.  FNA may be useful in evaluation of generalized renal disease, e.g., lymphoma.