6 Year Old - Blood Test Results

My son recently had a blood test which showed, among other things, a BUN/Creatinine ratio of 41.3 (range is 6-22). This is almost exactly consistent with past results. The Dr. always says he's a bit dehydrated, but we are very mindful of drinking liquid, especially water, throughout the day. He was especially mindful of it before this past test, so I was surprised he was still in that range. Incidentally, he does not eat a lot of salty food, and almost no processed food, so that wouldn't be a factor. A few months ago at his well visit I mentioned that his urine has been foamy, but the Dr. did a urine test and it was fine. I've read, however, that the quick ones aren't always accurate. He also had a slight low calculated globulin rate of 1.9 (range is 2.1-3.5), and a slightly high A/G ratio of 2.7 (range 1.0-2.5). The reason for these blood tests is his constant tiredness (though he recently was diagnosed with mono - the tiredness has gone on for longer than that). He also has quite a bit of random mild to moderate stomach pain.

Incidentally, he has never been one to go to the bathroom often, even with all he drinks. We always chalked it up to a large bladder. His urine is light to clear, and never dark (as you would expect with dehydration).

I’m also concerned about his WBC count. Looking at all his results taken from 8 blood tests from 2010, they were in almost all low, ranging from 4.4-4.6. Last June it was 4.9; in January of this year it was 4.1, and this month is 3.8. What could this all mean? Should an autoimmune disorder be considered? His IGA Serum on this last test was 22.

He is following up with a couple of specialists due to some other readings, but I wondered if he should see a kidney specialist based on these readings. Anyone familiar with this?