Well, I am not an expert in blood test results. But the reason of your problem could be the salt you consume. Use only Sea Salt in your food, you can get it in every health food store.
I used to have quite a lot of problems with my kidneys (I am just 25 y.o.). I was born with kindneys displacement which caused blockage of urine resulting in inflammations. I was once diagnosed with two micro size kidney stones which caused a lot of discomfort, but they were so small that I passed them without even knowing that.
Half a year ago I started to use only Sea Salt in my cooking as well as I cut on all ready made foods with preservatives . I did not have any problems with my kidneys since than.