Tubular Proteinuria and Focal Segmental Glomerulosclerosis (FSGS)

00:01 Let’s switch gears now to the second category of proteinuria which is tubular proteinuria.

00:07 These patients usually have a low fixed level of proteinuria.

00:12 Usually, the protein to creatinine ratio is less than 1.

00:15 It’s not in the nephrotic range.

00:18 There are many causes of tubular proteinuria.

00:22 We can’t possibly go through them all and here’s a list if you’re interested, but the one I want to focus on and the most important one is acute tubular necrosis, which is the most common cause of this problem.

00:36 So decreased renal perfusion results in acute tubular necrosis.

00:42 It causes a decreased glomerular filtration rate and this is from an acute injury.

00:49 Acute tubular necrosis occurs as a result of underperfusion of the kidney.

00:56 So there are many causes, one of them is simply hypovolemia or hypovolemic shock.

01:02 So patients who are in the ICU with severe dehydration, for example, may suffer an acute tubular necrosis.

01:10 It may come from hypoxemia.

01:12 The hypoxemia has to be very significant.

01:16 It may come as a result of sepsis or septic shock.

01:20 But one area where we see it that’s interesting is drugs.

01:25 and in particular, there are few drugs that are most likely to cause this.

01:29 Those include NSAIDs like ibuprofen which even when you use that in appropriate dose can cause an acute tubular necrosis.

01:38 Other drugs include aminoglycosides, amphotericin, lithium, the list goes on.

01:46 So, let’s switch now to the higher loss of protein category which is true glomerular proteinuria.

01:55 This is usually a very high rate of protein loss in the urine.

02:00 So these patients have a high grade fixed proteinuria and usually that ratio of protein to creatinine is greater than 1, actually, usually greater than 2.

02:11 This can happen, additionally, in patients who have a proteinuria but have another symptom from renal dysfunction.

02:21 An example would be hypertension, hematuria and addition to proteinuria, generalized edema or renal failure.

02:30 If a patient has any of these things, it’s most likely to be a glomerular proteinuria.

02:37 So switching to glomerular proteinuria, there are once again many different causes of glomerular proteinuria.

02:46 These include minimal change disease, focal segmental glomerulosclerosis, mesangial proliferative glomerulonephritis, membranous nephropathy, amyloidosis, diabetic nephropathy or sickle cell disease, tubulointerstitial disease, heavy metal poisoning again which can cause both tubular or glomerular, et cetera.

03:08 I want to focus on some of the more common ones that might show up on exam.

03:13 Let’s start with FSGS or focal segmental glomerulosclerosis.

03:19 This is a disease that affects focal areas of the kidney.

03:24 So here, you can see a picture or both normal and abnormal glomeruli.

03:30 This one is the abnormal one.

03:32 You can see it’s infiltrated and abnormal.