Pediatric Proteinuria (Protein in Urine)

00:01 In this lecture, we’re going to discuss proteinuria and the nephrotic syndrome.

00:06 We have another lecture where we discussed hematuria and glomerulonephritis.

00:11 So here’s a typical case for you, a 7-year-old girl presents with complaints of, say, dysuria.

00:18 She has been taking bubble baths and you suspect, this a simple case of vaginitis.

00:23 On exam, your suspicions are confirmed and as she’s leaving, the nurse pulls you inside and says, "Wait, wait, wait not so fast." "We have dipped her urine to check for UTI and she doesn’t have UTI but we did notice she has +3 protein in her dipstick." Now what? Here’s an asymptomatic child who has some protein in her urine.

00:45 What do we do? Well, let’s look at proteinuria.

00:50 This is when you have protein in your urine and it's technically defined as more than 100 mg per square meter per day, very challenging to make that calculation.

01:01 So this translates roughly to a dipstick value of +3 or +4 on the dipstick.

01:08 Around 10% of children will dip positive for urine, but only 0.1% have true proteinuria.

01:17 So remember that a mild positive urine dip for protein is probably nothing to worry about.

01:23 So here’s a comparison where you can refer for how much protein is on the dipstick and approximately how much that actually works out to be in terms of concentration of protein in the urine.

01:37 The idea here is that point +3 and +4 tend to correlate to more than 1 gram of protein per day lost in the urine which is usually pathologic.

01:49 Okay, so if you want to test for proteinuria, one way we classically have taught people to do is to obtain a 24-hour urine protein.

02:01 This might be feasible in adults, but in children this is just practically very challenging.

02:06 They forget to pee in the cup or they go to school, it’s a little bit harder.

02:11 So what we usually use for children is a protein to creatinine ratio.

02:16 The protein-creatinine ratio allows us to correct for the concentration of the urine to give an estimation on whether there is too much protein or not in that urine sample.

02:29 It’s common for children under twp years of age to have a higher protein to creatinine ratio.

02:35 So we consider an abnormal value more than 0.5.

02:40 The reason is that children and babies do tend to spill a little bit more protein because of immature glomeruli.

02:49 In children over two years of age, we consider more than 0.2 to be abnormal.

02:56 For patients with frank nephrotic syndrome, this value is usually more than 2.

03:01 So a value more than 2 tells you something is substantially going wrong.

03:07 So when we think of the pathology of proteinuria, we think of 3 major types.

03:14 Patients may have benign transient proteinuria.

03:17 They may have a tubular source of proteinuria.

03:20 Or they may have a glomerular source of proteinuria.

03:24 I want to look at these three categories separately.

03:27 Let’s start with benign transient causes of proteinuria.

03:32 Among these, there are two types: Transient and orthostatic.

03:37 Transient proteinuria is common in patients who are having fever, in patients who had seizure, in patients who are stressed, and patients who are dehydrated or in patient who have a lot of exercise.

03:50 All of these things can cause a transient proteinuria.

03:53 This is a benign condition and will resolve when the stressor is resolved.

03:59 Orthostatic proteinuria is a phenomenon that's most specific to school aged children.

04:06 This is an asymptomatic proteinuria such as our case at the beginning of this talk.

04:12 There are no comorbidities.

04:13 These children have no other problems.

04:16 And if you obtain a first morning void, right when they wake up, it will not have protein.

04:23 These patients had protein from having stood up all day; hence, the word orthostatic proteinuria.