Renal injuries are not very common, and the number of pediatric kidney injuries is even smaller. One potential complication after this injury is hypertension. As usual, there are many theories as to why this occurs. There are undoubtedly areas of the injured kidney that are under-perfused. The most popular theory is that this results in release of renin, upregulating the renin-angiotensin system.
But how much do we need to worry about this problem? Retrospective adult studies put the incidence at about 5%, and the onset generally occurs 2 to 8 weeks after injury.
And what about children? Are they just small adults when it comes to this problem? Primary Children’s Hospital in Salt Lake City designed a retrospective study to try to answer this question. They examined 11 years of their own registry data on children, defined as <18 years old. They focused on high grade injuries (grade III-V), as these should have the highest incidence of complications.
Here are the factoids:
- Hypertension was defined as elevated BP anytime after admission that required control with medication, but only after pain was controlled
- 62 children sustained high grade injury, with an average age of 10
- Most were grade III (21) and grade IV (40)
- Four (6.5%) developed hypertension while hospitalized
- Only two requiring ongoing medication months after discharge
- None of the non-hypertensive children became hypertensive later
Bottom line: Obviously, these numbers are small. The fact that it took over 10 years
at a pediatric hospital to accumulate this data demonstrates the difficulty in getting good, actionable information. It looks like that the incidence is similar to adults (about 5%). It does seem that some patients recover and don’t need long-term medication. I recommend that everyone (adult and child) with a significant renal injury (grade 3+) be monitored for hypertension while in the hospital, and for 2-3 months after discharge by their primary practitioner.
- How to grade renal injury
- Practical tip: how to evaluate hematuria
- Caution: IV contrast and trauma imaging
Reference: The incidence of long-term hypertension in children after high-grade renal trauma. J Ped Surg, in press June 2015.