Q. I have a question. Why do you see a decreased glomerular filtration rate in nephritic syndrome? I read on your blog and other places that it’s due to “hemodynamic changes”– from Robbins I’m assuming this is compensatory stuff- but wouldn’t that increase GFR?
A. It’s because of what’s going on in the glomerulus! In a normal glomerulus, the capillaries are all nice and open and patent. Blood flows through the capillaries like a little river, fluid gets filtered out into the urinary space, and the GFR is normal. But in nephritic syndrome, the glomeruli are stuffed full of cells, and blood flow slows way down.
Take a look at post-streptococcal glomerulonephritis, a common cause of nephritic syndrome. In that disorder, the glomeruli are huge and hypercellular, with tons of neutrophils in there (and probably some other proliferating glomerular cells as well). The poor capillaries are compressed by all that extra stuff, and you can imagine how hard it is for the poor blood to flow through there! If the blood can’t flow through at the same rate, then the filtration of fluid from blood into urine is decreased (and the GFR slows down to a sad little dribble).
thank you dr. I loved your explanation!
love from saudi arabia!
You’re welcome. Glad it helped!
Thank you very much! I don’t understand how what is supposedly the best pathology textbook in the world can make vague statements like this without further explanation. My school basically teaches us nothing so I am relying almost 100% on robbins to teach myself pathology but I can’t tell you what a pain it is to read through pages and pages of things like this trying to figure it out.
The sad part is that there really aren’t any better pathology textbooks. Not that I’ve seen anyway. I hope this isn’t blasphemy for a pathology website.
Whew – that’s coming close to blasphemy! (not really) I know – there are these nagging questions that nobody seems to answer. It takes a while to even articulate the question sometimes – and then finding the answer is difficult. I still maintain that Robbins is the best pathology textbook – even compared to big residency tomes. Sorry your path is lacking at your school! I’m sure you’re not alone – going through Robbins will definitely help. 🙂
that really helped,thank you
Well at this rate I am gonna have to bookmark this website. I am finding your straightforward answers to difficult questions extremely easy to understand. The problem with most pathology books is that they concentrate a lot more on pathoanatomy than the pathophysiology aspect and this is causing quite a bit of grief but thanks to you guys at pathologystudent.com, we are finding our answers.
Thanks so much, Hamim! I agree – it’s hard to find straightforward discussions in regular textbooks 🙂 I’m so glad you’ve found some answers here!
HAHA what a vivid explanation XDDD
Thank you so much. Didn’t expect for such an interesting tone in a medical topic. Love it! It helps me a lot.
I’ve researched for about an hour and I finally find the answer here. It’s a very important puzzle piece of my academic progress.
nice