Raised leukocytes happens in any human body when it is dealing with germs and infections. I had a Full blood count readout earlier last month in which the Neutrophil/Lymphocyte (works alongside leukocytes in attacking infection) ratio was 5.4. Normal ratios are below 3. Like you I investigated and because I found out that this is an indication of probable infection, I contacted Addenbrooke's Hospital, Cambridge for advice. They explained that this is a new automatic part of blood analysis because of Covid 19 (which thankfully I don't have!) and that my readings would always be elevated since I am on immunosuppressants. I would guess that when your leukocyte reading hit the top of the scale, your immune system was under attack, even if you were totally symptomless. In my Type 1 days I found it frustrating, but interesting, to see how much my blood sugar fluctuated when bugs and viruses were in the community. I'm sure you would find the same with your urine testing strips. Hope this helps!