I had my blood tested weekly for the first two months I was on 6MP and when those were okay it was changed to every 6-8 weeks. During my second year of 6MP I developed acute jaundice. My last blood test was fine (it had prob been done 3-5wks previously) and when I called my Dr with my complaints she sent me directly to the lab for a bloodtest and she called me that afternoon (after they faxed her) and had me stop all meds because of the results.
I feel it is important for 6MP to be monitored with bloodtests to be sure the liver is functioning properly.
I had no lasting damage to my liver because we caught it in time.
During my bloodtests, the wbc was always a bit elevated and attributed to the prednisone. I wonder now if it was the diseased portion of my colon that was constantly fighting a battle that was raising the wbc. Since having that diseased portion removed, 6MP now makes me horribly nauseous.