This transcript has been edited for clarity.
Jessica Hane, MD: Welcome back to The Cribsiders. This is a Medscape video recap of one of our most recent podcast episodes. Justin, what topic are we reviewing today?
Justin L. Berk, MD, MPH, MBA: We have a great topic that was part of the Neph Madness event on social media: chronic kidney disease (CKD) in the pediatric population. We had an amazing fellow who came on to teach us all about CKD. She is AC Gomez. She was a superstar and a really great guest.
Hane: First question, what is CKD?
Berk: This is actually a tougher question than it may first appear. In training, we learn that an estimated glomerular filtration rate (eGFR) less than 60 is considered CKD. And that if you have poor renal function, that can be CKD. But there's another entire category of CKD, especially in the pediatric population, that is defined by any type of structural or other abnormality in the kidney. That can be a horseshoe kidney, a transplanted kidney, or something like Alport syndrome, where there's a basement membrane defect. This can be IgA nephropathy or some other glomerular nephropathy, where the creatinine level may still actually be normal but there are some kidney issues.
Hane: So, the definition of CKD is a little more inclusive than just having an eGFR less than 60. How do these kids present?
Berk: This was also something that seemed a very simple question, but the answer came with a lot of different presentations. We learned that something like Alport syndrome can present with a speech delay, and the child has a hearing test and is diagnosed with sensorineural hearing loss and ultimately with the X-linked condition of Alport syndrome, which is not that uncommon. Other kids with CKD might present with hematuria or proteinuria with some foamy urine.
A big takeaway was that many of the chronic kidney diseases in pediatrics are inherited, so it's important to take a good family history. One of the anecdotes that Dr Gomez shared with us was that as a pediatric nephrologist, she is often collecting urine not only from the patient but also from the parents and other family members, to look for signs of hereditary forms of pathology in the kidneys. Another pearl is that you might see hematuria or even proteinuria in the inpatient setting, but any abnormality needs to be repeated in the outpatient setting. That's where we need a valid urine test to see if there's a problem.
Hane: Speaking of urine samples and proteinuria, when you are looking for proteinuria, is a spot test adequate, or do we always need to get a 24-hour urine test?
Berk: This was a question that we asked her, and then everyone kind of braced for the answer, hoping that she would say a spot urine was fine. It's confirmed. Nephrologists approve the spot urine as being very accurate, with some exceptions. For example, if a patient has a known acute kidney injury in the hospital, that's when a 24-hour urine might be a little bit more accurate. But the spot urine is okay for the rest of the time.
Hane: That is great news — it's a lot easier to collect. So if we have a patient with CKD, what should we be monitoring?
Berk: Much of what we do for kids with CKD is close monitoring, and how often to monitor depends on the stage of kidney disease. If it's stage 1 or 2 CKD, we're going to be checking basic labs annually. But if it's stage 3 CKD, we might do it every 6 months; for CKD stage 4, every 3 months, and for stage 5 it might be monthly.
That's the frequency, but what are we looking for? It's really the core electrolyte complications of CKD. One major clinical complication of CKD is hyperkalemia, so we are monitoring the child's serum potassium level at these intervals. In pediatrics, a level above 5.5 mEq/L is when we get worried, and we think about starting the child on potassium binders and doing some dietary guidance.
We also look at phosphorus, although the upper limit of normal with phosphorus is very age dependent. But if it's too high, phosphate binders come into play, and as treatment for acidosis of hyperphosphatemia, bicarbonate supplementation might be needed. Anemia and iron deficiency are both common complications of CKD. Erythropoietin might be needed if the hemoglobin level drops below 10 g/dL, and in iron-deficiency anemia, we might start the child on an iron supplement (although intravenous iron works better in kids with CKD). But these are the conditions we are monitoring these patients for to see if intervention is needed.
Hane: What about bone health in patients with CKD?
Berk: First and foremost, there are always some growth issues in people with pretty significant CKD because of growth hormone resistance, and the child may even need growth hormone supplementation. One of my favorite questions for medical students is, why might the alkaline phosphatase level be elevated in a patient with CKD? The answer is that it can be a sign of bone resorption. We went through the pathophysiology of how the kidneys activate vitamin D, and that can help increase calcium. And basically, if the kidney function prevents this calcium absorption, PTH will increase to try to balance out the calcium, and that leads to an increase in bone resorption and some bone mineral disease. Acting on the phosphate level can help balance the increase in PTH and help prevent some of these complications.
Hane: Let's move away from the pathophysiology for a minute and chat about how pediatric CKD goes on to affect adults.
Berk: We took advantage of having a dual-specialized guest and talked about how children with CKD are four times more likely to develop end-stage renal disease, and that the need for dialysis often occurs earlier in life. We talked about the transition in care from a pediatric to an adult nephrologist and how important that is to prevent progression of CKD. One of the cool pearls that she shared with us is the website called Got Transition, which can help with care transitions for these complex patients.
Hane: I think that's all we have time for today. Thanks for joining us for another Medscape video recap of The Cribsiders pediatric podcast. To listen to the full episode, you can download CKD and Transitions of Care on any podcast player or check it out on our website, https://thecurbsiders.com/cribsiders.
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Cite this: Justin L. Berk, Jessica Hane. When a Spot Urine Will Suffice: Kids With Kidney Disease - Medscape - May 15, 2023.
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