Here's an article from the NY Times (look at the video about halfway down on the left). This has me in 2 minds. They searched out 10 bodybuilders with kidney issues then tried to link it to 'steroids'.
If you think about that statement it's very vague. It's like me saying I searched out 10 pharmaceutical drug users (drugs prescribed by their doctors) & then tried to prove 'pharmaceuticals' do this..not a single medicine or combination, but the whole field of prescription drugs!
It might be true that maybe a single steroid, or combination does do this, but bodybuilders take all sorts of stuff, not just steroids & there are many, many types of steroids. Also they eat a whole ton of protein, a whole ton of calories in general ¬ always healthy food when trying to bulk they often pile in junk...to single out steroids would need a whole raft of studies & proofs, not just one study of 10 guys who happened to take steroids & happened to have this kidney disease. What about the people who don't take steroids but get this disease, what about the other thousands that do take steroids, but don't get kidney issues.
You'd need to get a lot of studies to work out what's going on & the only way would be to know what people are taking & what it's doing. I'm not saying steroids don't have negative effects, looking at the benefits in size & strength these people get you know that if there was no downside then humans would already produce hormones in that quantity. But we really don't know that much. There does appear to be some cardiovascular damage, but that could be down to being so damn big, the heart & lungs struggle to feed the beast as much as steroids directly, it could increase the effects of any cancers possibly? Maybe even shorten life somewhat, might be possible (you 'wear out' quicker?). But to use this study as 'proof' that steroids cause kidney damage is a bit 'cherry picked data' for me to find credible. Maybe it does increase your odds of getting kidney disease, but with only 10 case found with the 1000's of bodybuilders, powerlifters, strongmen & athletes out there using steroids it's not exactly going to make many using athletes think twice about it I'd have thought?
Shame they can't run some studies in countries where it is legal & get some real results sorted out as it would be nice to have facts to give to our steroid using comrades in the gym.