Is WBC Count Of 4.7 A Cause For Concern?

my wife is 62 and is in good health. She walks daily and is 5 7 and weighs 120 lbs. She went on the plant base diet to just eat healthier. She actually lost 14 lbs. and now maintaining at 120. Her recent blood test gave her a 4.7 white blood cell count. a year ago it was 5.8. Is this necessarily reason for alarm??