One of the things we talked about last week in our Renal Path lecture was nephritic and nephrotic syndromes. I thought it might help to review them a bit, since they can be maddeningly frustrating if you don’t understand the underlying principle in each one.
So here are the four main characteristics of each:
- Massive proteinuria
How do you make these lists hang together in a way that you can remember?
First, let’s take nephrotic syndrome. The thing to remember for this one is massive proteinuria. You might do this by remembering that nephrotic and protein both have an “o” in them. The massive proteinuria in these patients leads to hypoalbuminemia (they are peeing out albumin!), which results in edema (the oncotic pressure in the blood goes down, and fluid leaks out of the vasculature into the surrounding tissue). So right there, you have three of the four features, just by remembering one. The hyperlipidemia/hyperlipiduria occurs because as the liver is trying to make more albumin (to make up for the albumin loss in the urine), it also ends up making more lipids. As an aside, nephrotic syndrome is often more dangerous than nephritic syndrome, so you might want to think of this syndrome as the “oh sh*t” syndrome (again – nephrotic has an o in it, nephritic does not). Crude, but if it works, who cares?
In nephritic syndrome, there is some proteinuria and edema, but it’s not nearly as severe as in nephrotic syndrome. The thing with nephritic syndrome is that the lesions causing it all have increased cellularity within the glomeruli, accompanied by a leukocytic infiltrate (hence the suffix “-itic”). The inflammation injures capillary walls, permitting escape of red cells into urine. Hemodynamic changes cause a decreased glomerular filtration rate (manifested clinically as oliguria and azotemia). The hypertension seen in nephritic syndrome is probably a result of fluid retention and increased renin released from ischemic kidneys.
If you really want to pare it down – if you only have enough brain space to remember one feature for each disorder – remember that nephrotic syndrome is characterized by massive proteinuria (the “o” in nephrotic), and nephritic syndrome is characterized by inflammation (the “-itic” in nephritic). Then at least you’ll have a shot at remembering the other features.