What Does This Blood Test Report Indicate?

My mom s blood test results have shown elevated absolute lymphocyte counts the last 3 times she has had blood work done. On 8/7/13 it was 8038. On 2/19/14 it was 6157. On 8/26/14 it was 7500. She had blood drawn today and was told by her doctor that if it is high this time he will have to check her bone marrow. She seems healthy and in good shape. What would he be looking for, and should we be concerned?