A quick post on an important topic. It’s one of my soapbox topic, and when it was brought up in a rounds session today – I was reminded that I didn’t have this information online.
One of the early steps in investigating proteinuria and kidney disease is to evaluate for urinary tract infection. Urinalysis combined with urine culture are recommended to evaluate for bacterial infection. We know that blood and bladder infection (bacterial cystitis) can increase the urine protein/creatinine ratio (UP/C). However, vets often ask – by how much?
Don’t ignore proteinuria just because there are red blood cells or bacteria in the urine.
A few things to keep in mind:
- Simple bacterial cystitis generally does not cause severe proteinuria. If there is evidence of a bladder infection, proteinuria should not be ignored. Kidney infection (pyelonephritis), however, can cause significant proteinuria.
- In the absence of lower urinary tract symptoms (ie: straining to urinate, small/frequent urinations), bacterial infection is an uncommon cause of proteinuria.
- Microscopic hematuria generally does not significantly increase the UP/C, however visibly blood-tinged urine may have an increased UP/C.
- Pyuria (white blood cells in the urine) does not always increase the UP/C. In one study, 81% of dogs with pyuria had normal UP/Cs.
- Don’t ignore proteinuria! If the UP/C is significantly increased in the face of blood-tinged urine or bladder infection, it should be rechecked after treatment. In some situations (ie: severe proteinuria), treatment may be initiated concurrently with treatment of lower urinary tract disease.