Sometimes the most logical thing to do is to stop being logical
One particular recommendation regarding kidney protection by Psooy, 2009 reads as follows:
Parents should try to keep things in perspective: If they are not going to restrict a child from an activity based on the child having only one “head,” then they should not restrict the child from that activity based on having only one kidneyEvidence – Level 3: Those activities most associated with high-grade renal trauma (bicycling, sledding, downhill skiing, snow boarding and equestrian), have more than a 5 × relative risk of head injury compared to renal injury
This is all very logical but perhaps it is a little too logical. It might be so logical that it is in fact an insensitive perspective.
What is missing from the doctor's evidence-based recommendation is consideration of the journey that parents might be on relating to coping with a child's chronic illness.
Why would a child only have one functioning kidney? There are many reasons. The child could have renal agenesis. The child could have renal scarring from undetected vesicoureteral reflux. The child could have polycystic kidney disease. The child could have had the other kidney removed because of cancer. Any of these conditions are potentially frightening for a family. Let's extrapolate some more. Maybe the mother had preeclampsia and now has end stage renal disease. Maybe a grandparent is on dialysis. Maybe the parent is just frightened because it is their child and there is only one kidney left and it does not matter if the child also only has one brain and one spine and one heart.
The point is that not everything can be managed with logic. I am just as fond of a Spock-like orientation as anyone, but I am not foolish enough to believe that you can present a logical piece of evidence to a parent who is frightened and expect a good outcome.
And what are parents to think anyway? Prior to all this 'evidence' about the questionable value of avoiding contact sports it was relatively standard fare for doctors to tell parents that they needed to PROTECT THE REMAINING KIDNEY AT ALL COSTS!!!!1! In fact, many doctors still tell this to their patients despite the evidence.
Anyone who has spent any time in a children's hospital understands the twisted perspective one gets by working in that environment. That twisted perspective occurs because even if something tragic happens rarely, when it does finally happen they will show up at the children's hospital. I assure you all that your mothers were correct. You should not run with a lollipop in your mouth and you can put out your brother's eye by swinging around a toy golf club. This stuff all really does happen. Listen to your mother.
Despite the studies, despite the statistics, despite any evidence - the fact is that some child with one functioning kidney will in fact take a hockey or lacrosse stick to their remaining kidney and they will be hospitalized and there will be some level of medical disaster associated with the event. Even though the odds of it happening to any single child are infinitesimally small, it is at this point of singularity that the recommendations of the AAP all go out the window because the event will achieve instant Internet fame as it is posted on Facebook and Twitter for everyone to see. People all over the world will see the tragic story and they will all quietly think to themselves, "Wow, that person DID NOT listen to their mother."
I know, none of it is likely. Even less of it is logical. But there is nothing logical about a child receiving a traumatic injury. In fact it is the most illogical thing in the world. Kids are not supposed to be hurt. Ever. When they do it is illogical and tragic and horrendous. Statistics be damned.
Parents actually know how to deal with this. There are two solutions.
Solution one is to be logical and follow the advice of the doctor. If you have a logical orientation then it is all good. Your logic might even be so good that even in the face of an unmitigated disaster that no one expected, you can still be saved by your logical analysis that you are the unfortunate recipient of an absolutely unlikely event.
Solution two is to tell the doctor to shove their logic, go on Amazon.com or some other site, and just order the relatively inexpensive kidney belt for yourself. If you want you can go order a helmet and some bubble wrap too. It is your child, and you can do whatever you want - even if someone else states that it is illogical. In time you might come to change your mind. Or you might not. Either is OK.
In my experience, kids tend to survive either approach. Well, as long as nothing illogical happens.
So I say let parents order the kidney guard. It really is not that big a deal. It is not a surgery. It is not a medication. There is no damage caused by wearing a kidney guard in gym. It is benign - and it might actually make a parent feel like they are doing something. Or having some control.
In an illogical world where unexpected things happen at rates that are almost too small to measure it might even save a child's life. Who knows?
In the long run parents can make choices about the risks they are willing to incur, but it is important to remember that families are on a journey when they are dealing with chronic illness. Not everyone will be at the same point of logical understanding as everyone else at exactly the same time. Or even ever.
If doctors spent more time listening to the real concerns of parents, no matter how "illogical" those concerns are, they might have better relationships and be better able to meet their needs.
Grinsell, et al (2012). Sport related kidney injury among high school athletes. Pediatrics, 130(1), e40-e45.
Psooy, K. (2009). Sports and the solitary kidney: What parents of a young child with a solitary kidney should know. Canadian Urological Association Journal, 3(1), 67-8.