I m 74 years old and have been in good health all my life. I had a physical last week, including a blood test. y white blood count was 4.2 which led my doctor to refer me to a blood specialist (appointment in 3 weeks). Two days after the blood test, I felt extremely tired, lost my appetite and had minor nausea. That lasted for three days, at which time all went back to normal. I feel fine, have normal energy, and am not tired. Might my low WBC be related to whatever bothered me for those three days and not be something serious? I m very worried about the low WBC being something extremely serious, as it will be too late for me to change health insurance plans after my appointment.