Renal Case: 28-year-old Man with Cola-colored Urine

00:01 Let's move on to our next clinical case.

00:03 A 28-year-old man presents to his primary care provider for new onset cola-colored urine.

00:09 In questioning him further, he recalls a terrible sore throat a few weeks ago that resolved with some antibiotics he was given at the urgent care center.

00:19 On physical exam, he's noted to have an elevated blood pressure at 147/90 mmHg which is new for him.

00:25 He was lower-extremity edema and periorbital edema.

00:28 His serum creatinine is high at 1.9 mg/dL and his urine analysis shows numerous red blood cells and he also has white blood cells in there as well.

00:39 Nearly all of those red blood cells, when looking underneath the microscope, showed dysmorphic features and he actually has 2-3 red blood cell cast per high power field.

00:48 On a urinary spot albumin-to-creatinine ratio, it estimates about 2 g per gram of albumin.

00:54 So, estimating about 2 g of protein excretion with a 24-hour period of time.

00:59 He has a low serum complement C3 but he has a normal serum complement C4.

01:05 So, what is the etiology of this patient's renal presentation? Let's see if we can find some clues in our case.

01:13 So, one of the things that is important to note, he has cola-colored urine.

01:17 When people describe tea or cola-colored urine, remember, that really is a symptom or sign of gross hematuria.

01:26 Hematuria or blood cell seen with a naked eye.

01:29 The other thing that's really important is he's describing an infection, an upper respiratory infection, in particular, a sore throat.

01:38 But that happened weeks ago before the onset of the tea-colored urine.

01:42 So, that temporal correlation is important.

01:44 It's not synpharyngitic like it was with our IgA nephropathy.

01:48 He had the sore throat first, treated with antibiotics, and now, he's manifesting with a tea-colored urine.

01:56 That's more indicative of a post-infectious glomerulonephritis.

02:01 The other thing which is important, he's got some signs of nephritic syndrome with his elevated blood pressure.

02:07 Again, those dysmorphic RBCs. He is volume overloaded or hypertensive.

02:13 Again, he's got that periorbital edema. And his laboratory values.

02:19 So, he's got an elevated creatinine, he's got those dysmorphic-looking red blood cells, and I think the clincher here is we have a low C3 complement and a normal C4.

02:30 That is an alert to us telling us that the alternative pathway of complement activation is being turned on and there's only a couple of things that we need to think about with that.

02:38 We're either thinking about complement mediated MPGN or something like infection-associated GN and in fact, that's what this gentleman has, post-infectious or infection-associated GN.