Hi my child is 4 and half had full blood count done has low lymphocites 2.7 then 3.7 I'm worried any advice would help thankyou?

I'm not sure. An absolute lymphocyte count of 2, 700 - 3, 700 in a 4 year old isn't abnormal. I'm curious who drew the test and why you feel it's abnormal. This is a discussion to have with the provider who ordered the test. If this is the total WBC count then it is a little low; the significance depends a lot on why the test was ordered in the first place. Again, a discussion to have with whomever ordered it.