Nephrotic syndrome
Definition
A condition where the kidneys are leaky, so they lose protein, leading to proteinuria (protein in your wee) and hypoalbuminaemia (low protein in your blood).
Epidemiology
Pretty rare in life, but much more common in exams. Generally happens in kids.
Pathophysiology
In more than 90% of cases, its due to minimal change disease. In other cases, it can be due to infection such as Hepatitis B or Group A strep, or from systemic inflammatory processes, such as lupus or Sjögren's.
In all there is a increase of space between the foot processes of the podocytes around the glomerulus. This means that larger molecules can get through, in this case, proteins.
Clinical Features
There is a classic triad:
- Proteinuria - sometimes the patient will complain of "frothy" urine.
- Hypoalbuminaemia - low serum albumin leads to...
- ...Oedema - the oedema will classically cause periorbital oedema (swelling round the eyes), although it can also occur just in the legs.
Some patients also get hyperlipidaemia, or lipiduria, but this is not always present. It's complicated, but in simple terms this is caused by the liver going into overdrive, trying to produce enough albumin, and it accidentally produces extra lipids as a by product.
Investigations
- Urine dipstick for protein
- Screen for UTI with MSC
- Serum albumin
- Look at lipid levels too
Management
If there is an underlying cause, such as infection, manage this, but most patients will require:
- ACE inhibitors to lower the pressure of blood reaching the podocytes,
- Steroids to counteract the damage to podocytes.
Prognosis
Most patients respond well to ACEis and steroids, but up to 80% relapse at some point.