Interesting! Asparagus does have a lot of good things in it, it's a super-food, but it also has a compound (I forget which one exactly) that only the kidneys can excrete. So they DO make more work for the kidneys. :( so best to drink more water and perhaps include parsley or another mild diuretic with the meal if you plan on eating asparagus.
Have you done a kidney cleanse yet? To spare your kidneys work and give them a break, sweat a lot. detox baths weekly at the very least. Saunas several times a week if you can. The more you sweat, the more you release uric acid and other things the kidneys must take care of. So sweating spares the kidneys.
Also be sure to feed the kidneys. Kidneys are very delicate, cod liver oil and the fat from raw whole milk is very helpful to them.