If there’s an infection or inflammation somewhere in the body besides the kidney, can we expect to see an increase in white blood cells in the urine? One of my clinical instructors said as much this week, but it seems to go against what I thought I knew.
As far as I was previously taught, the kidneys are pretty particular about what’s allowed to get through. Even albumin, a relatively small protein, isn’t normally in the urine unless there’s damage to the kidney tubules. But she seemed pretty sure about what she was saying, so now I’m a little confused. If there are a lot of white cells dying off, are they disposed of via the kidneys?
She also said that a high-protein diet will result in more protein being found in the urine. True?
I think you’re right to challenge your instructor.
The notion that a high circulating white blood cell count leads to pyuria (WBC’s in the urine) is simply wrong. One clear example is provided by patients with chronic lymphocytic leukemia where peripheral white blood cell counts are often in the hundred thousand range. Such individuals do not have pyuria in the absence of GU infection or inflammation. The same applies to people with chronic myelogenous leukemia, who have white counts in the thirty to fifty thousand ballpark. So, whether you’re talking about a high number of circulating mononuclear or PMN-type white cells, pyuria does not result.
In terms of protein, an acute load or intake of dietary protein has no effect on proteinuria although it will lead to an increase in urine urea (and blood urea, too). In the long run, however, a chronically high protein diet can contribute to both increased proteinuria and loss of renal function. Phrased differently, and in a more clinically relevant way, restriction of dietary protein will diminish proteinuria, slow down the progression of chronic renal insufficiency and delay end-points such as ESRD, dialysis, or transplant (cite - one of many, many reviews on the topic of the utility of low protein diets to slow the progression of renal insufficiency and cite - one of many reviews summarizing the effect of dietary protein restriction to cause diminution of proteinuria).
BTW, you said, “albumin, a relatively small protein, isn’t normally in the urine unless there’s damage to the kidney tubules”. Although tubular damage can lead to albuminuria solely due to the presence of tubular inflammation itself, the major clinical cause of albuminuria is glomerular damage.
I knew that, honest I did! Thanks for the correction, though.
I tried the leukemia argument with my instructor, actually, but she said I was missing the point: it’s just the dead cells that are being expelled by the kidneys. :rolleyes: It’s sort of frightening that she’s spreading misinformation to students, but there’s not much I can do about it. I questioned her, but I’m stopping here since she’s the one who’ll be signing my evaluation in a couple of weeks. She’d be likely to write a comment about questioning authority, and I’d like to avoid that sort of thing.